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http://www.ehow.com/how_2128658_use-foliar-fertilizers.html
How to Use Foliar Fertilizers
By Dr. Christopher J. Kline
eHow Community Member
Foliar Feeding is a technique for feeding plants by applying liquid fertiliser directly to their leaves. The most touted benefit of foliar fertilizers is their capacity to promote maximum nutrient absorption. This is based on the belief that foliar fertilizers cause an increase in sugar levels in plants which then stimulate soil activity and plant nutrient uptake.
Difficulty: Moderately Easy
Instructions

Step 1

Know The Benefits of Foliar Feeding
In addition to promoting maximum nutrient uptake, foliar fertilizers may have other benefits including the prevention of plant diseases and fungal attack. The reason is that, foliar fertilizers cover the leaves and stems, the plant parts that are susceptible to pests and parasites. Perhaps the biggest side benefit of foliar feeding is that it can increase the plants uptake of nutrients from the soil.

Feeding through the leaves works more quickly than adding fertilizer to soil which then has to be taken up through a plant's root system. Foliar feeding is not a substitute for root feeding, but used in conjunction with root feeding, foliar feeding can increase its effectiveness. By applying a foliar fertilizer directly to the leaf, it increases the activity in the leaf, at the same time increasing chlorophyll and thus photosynthesis. Because of this increased activity, it increases the need for water by the leaf. In turn this increases water uptake by the plants vascular system, which in turn increases the uptake of nutrients from the soil.

Foliar feeding is also finding favor unong many organic gardeners. Organic gardening involves cultivating naturally healthy soil. This is a gradual process which can make it difficult to provide some trace nutrients in sufficient quantity. By foliar feeding, trace nutrients can be suplemented directly, without disrupting soil development.

Step 2

The Basics For Applying Foliar Fertilizers:
• It is always advisable to dilute foliar fertilizer first before application. Too much concentration of foliar fertilizers may cause foliage burning. Make sure the solution is not too concentrated by spraying a few healthy leaves to see if there is any damage. If the leaves curl or look unhealthy in any way two days after spraying, dilute the mix by 50% and try again.
• Make sure that the PH level of your foliar fertilizer spray is at a neutral range. If the spray is a concentrate that is mixed with water, use pH adjusted water or distilled water for making the solution.
• Foliar fertilizer sprays achieve best effect by using a fine mist, allowing the liquid to drift over the plants.
• Nutrient absorption of foliar fertilizers is enhanced when the air is humid and moist with a temperature of 80 degrees or below (Fahrenheit). This is due to the fact that the plants' main nutrient canals, the stomata, are open in low temperatures. The best time to spray is in the morning so the spray has time to dry.
• After foliar feeding the first day, spray the plants with pH adjusted water daily for a few days. This provides the plant an opportunity to absorb any fertilizer residue.
• For better nutrient absorption, make sure that your foliar fertilizer sprays reach the undersides of leaves, where the stomata are located.
• Sea-based nutrient mixes, especially seaweed and alge concentrates are great for foliar feeding, because they have all the trace elements plants need in suspension and it may be harder to balance these elements within the soil.
• Another good, relatively new product is vermi liquid from worm farms. It is full of different nutrients which are wonderful for foliar feeding.
• To minimize runoff and help these sprays stick to the leaves, add a quarter of a teaspoon of liquid detergent to each gallon of spray.
• For indoor plants, apply once a month. For flowers and vegetables outside, apply every two weeks, preferably in the mornings.
• For best results, plants are often sprayed during their critical growth stages such as transplanting time, blooming time and just after fruit sets. By applying during flower set, foliar feeding may cause a dramatic increase in fruit production.

Step 3

Choose the Right Products
Modern foliar fertilizers are concentrated solutions using very high grade elements, in which the nitrogen, phosphorus and potassium are combined to the desired ratio in a controlled environment. The fertilizing elements in these high tech sprays are true solutions, soluble, and thus very available to plants. To most of these commercial foliar solutions, trace elements in the form of chelates are added, along with seaweed and /or humic acid, or other additives depending on preference, to give a balanced fertilizer, supplying not only NPK, but all the trace elements as well as growth hormones and vitamins etc.

Advantages of Using a Foliar Fertilizer

http://ezinearticles.com/?Advantages-of-Using-a-Foliar-Fertilizer&id=1230662

Advantages of Using a Foliar Fertilizer
By Michael Straumietis

Foliar fertilizer is a type of fertilizer designed to be delivered directly to the leaves of your plants in the form of a fine mist. For years, many farmers and gardeners believed that intentionally making your leaves moist like this was damaging to them. This bit of folk wisdom was debunked in the 1950s by two scientists who studied foliar feeding at Michigan State University. Today, foliar feeding is used on large farms on a massive scale. But why should you, the smaller hydroponics grower, invest in a quality foliar fertilizer? Here are some major reasons why:
Bigger Yields - The success of your plants essentially revolves around how many nutrients it can successfully receive and process. While the root zone is the primary way your plants will receive nutrients, it is possible that they still are not processing them at the speed that would most benefit your plants. Using a quality foliar fertilizer can give your plants that extra boost that they need to truly grow to their potential. For you this means you can enjoy healthier plants and bigger yields with surprisingly little effort.

Healthier Plants - Any experienced gardener knows that a pest, bacterial, or viral attack can happen at any moment. The only way to shield yourself form such an attack is to make certain that your plants are as healthy as they can possibly be. A quality foliar fertilizer accomplishes this by providing extra nutrients that your plant may need to boost its immunity. So if some harmful bacteria get introduced to your system, there will be less of a chance of infection. If your plants are infected, the damage will probably be less than if your plants were not as healthy to begin with.

Immediate Results - The stomata of a leaf have the ability to soak up the nutrients remarkably quickly. Studies even show that leaves can soak up these nutrients faster than roots can. Gardeners do not have to wait weeks or even months to see if their foliar fertilizer is working. It is common to notice healthier, perkier plants in just a matter of days. For most, this feature of foliar feeding can prove to be a tremendous time saver. There is nothing worse than trying a new technique only to discover months later that it has done nothing to improve your plants or, worse yet, has harmed them. Foliar feeding allows you to make adjustments to how you improve your plants quickly because you see the results very quickly.

Inexpensive - One of most significant benefits of using a foliar fertilizer is that it is cheap when compared to many other means of boosting your plants growth. Using a CO2 generator, for example, is a tremendously effective way of getting your plants to grow quickly. But smaller growers may not be able to afford such a device, or else may not be able to accurately measure the CO2 concentrations of their grow room. If CO2 levels get too high, it can even kill your plants. But foliar feeding just needs a quality fertilizer, pH balanced water and a spray bottle that can spray in a fine mist.

Effects of Foliar Fertilizers and Growth Regulators on Alfalfa Yield and Quality

http://www.plantmanagementnetwork.org/pub/cm/research/alfalfa

Effects of Foliar Fertilizers and Growth Regulators on Alfalfa Yield and Quality

Marvin H. Hall, Robert C. Stout, and W. Scott Smiles, Department of Crop and Soil Sciences, Pennsylvania State University, University Park, PA 16802
Corresponding author: Marvin H. Hall. mhh2@psu.edu
Hall, M. H., Stout, R. C., and Smiles, W. S. 2002. Effects of foliar fertilizers and growth regulators on alfalfa yield and quality. Online. Crop Management doi:10.1094/CM-2002-0429-01-RS.

Abstract

Alfalfa (Medicago sativa L.) requires relatively high quantities of nutrients to achieve optimum yields. Commercially available foliar applied fertilizers and growth regulators reportedly provide adequate nutrient levels and increase alfalfa stem number, yield, and quality. The objective of this research was to determine the effectiveness and profitability of several commercially available foliar fertilizers and growth regulators to stimulate shoot development and increase forage yield and quality on high fertility soils in Pennsylvania. Eight treatments including controls of no soil additives and lime were compared to foliar applied treatments including water, liquid fertilizer, and four commercial products at four location-year environments. None of the foliar applied products increased stem density, yield, or quality of alfalfa in environments where initial or adjusted soil pH 6.5. Consequently the additional cost of foliar applied products was not recovered in yield or quality increases of alfalfa compared to maintaining adequate soil pH and fertility through traditional lime and fertilizer amendments.

Introduction

High-yielding alfalfa (Fig. 1) is a high consumer of plant nutrients in that each ton removes approximately 60 and 20 lb per acre of K2O and P2O5, respectively (1). Traditionally, these nutrients have been provided to the plants through applications of manure or dry fertilizer to the soil. Recently however, companies have been marketing liquid fertilizers and growth regulators that are foliar applied to alfalfa. These foliar applied fertilizers augment or replace traditional fertilizer applications.

Application of the plant growth regulator cytokinin can stimulate plant growth (2,6,10,12,14). Tompkins and Hall (12) reported that cytokinin application to alfalfa stubble increased the number of shoots and DM yield per plant in both greenhouse and field studies. In low density alfalfa stands, commercial use of this growth regulator may stimulate shoot development and temporarily maintain herbage yields. However, commercial use of cytokinins to enhance crop yields has been limited. Kinetin, a form of cytokinin, is labeled by the U.S. Environmental Protection Agency for use on small grains, vegetables, and oil seed crops (9). Commercial cytokinin application to alfalfa plants has not been reported; however, application to another legume, pea (Pisum sativum L.), caused dormant lateral buds to rapidly elongate into fully developed shoots (8).

Foliar application of macro- and micronutrients to alfalfa, either alone or in combination with a plant growth regulator, is currently available to farmers as a method for improving yield and forage quality. However, there is limited unbiased information available regarding the effectiveness or profitability of these products. Consequently, this research was undertaken to determine the efficacy and profitability of commercially available foliar fertilizers and growth regulator products on alfalfa.

Experiments and Results

In October of 1999, uniform stands of established alfalfa at two locations (Farm 1 and Farm 2) were divided into four replicates of eight 6-x-15-ft plots in a randomized complete block design. Similar plots were designated at another location (Farm 3) in October of 2000. The three locations were within 3 miles of each other near Rock Springs, PA (40°48’N, 77°52’W, elevation 1220 ft) and were on a Hagerstown silt loam (fine-loamy, mixed, mesic Typic Hapludalfs) soil. Soil pH and fertility at Farm 2 and 3 were in the “optimum” to “high” range according to soil tests (Table 1). Soil pH was low at Farm 1 so lime was added to bring pH up to 6.5 in seven of the eight plots. The alfalfa stand was older at Farm 1 and had only about 30% plant density relative to the other sites (Table 1).

Table 1. Alfalfa stand age, plant density, and soil nutrient levels prior to initiation of the studies at three locations in Pennsylvania.

	Farm 1	Farm 2	Farm 3
Stand age (years)	5	3	2
Density (plants per ft2)	5	14	17
pH	5.9	6.5	6.8
	--- lb per acre ---
P2O5*	251	130	122
K2O†	309	309	262
	--- meq per 100g ---
Acidity	2.0	2.0	0.0
K	0.33	0.33	0.28
Mg	0.5	1.1	1.4
Ca	4.5	6.8	6.3
CEC	7.4	10.2	8.0
	--- % Saturation ---
K	4.4	3.2	3.5
Mg	7.2	10.8	18.0
Ca	60.8	66.1	78.1

* Determined using the Mehlich 3 method (13).

In 2000, foliar treatments were applied in accordance with company recommendations to the plots at Farm 1 and 2 (Table 2). In 2001, thin stands at Farm 1 resulted in the alfalfa field being rotated to corn; however, the treatments were applied at Farm 2 again and also at Farm 3. Precipitation and average daily temperatures during the 2000 and 2001 growing seasons were within 4.5 inches and 0.5°F, respectively, of the previous 20-year average. Dimethoate insecticide (0,0-dimethyl S-[N-(methylcarbamoyl)methyl] phosphorodithioate) was applied as needed to control potato leafhopper (Empoasca fabae Harris) throughout the studies. Alfalfa was harvested four times each year at a 3-inch stubble height from all treatments when the average maturity was late vegetative to first flower based on the mean stage count method described by Kalu and Fick (5). At harvest, a 3-x-15-ft strip was removed from the center of each plot with a flail-type mower. Approximately 2 lb of the harvested material was dried in a forced air oven for dry matter determination.

Table 2. Lime and foliar treatments applied to alfalfa at three locations over a 2-year period.

Trt	Lime*	Foliar applied materials†	Cost‡ ($/acre/yr)
1	None	None	0
2	Yes	None	0
3	Yes	Water at 20 gal/acre	25
4	Yes	5 lb per acre 18-18-18	65
5	Yes		100
		Applied at green-up in spring: 7.5 lb/acre ‘Nutrient Express 18-18-18’ 1 qt/acre ‘Tech-Flo-Cal Bor’
		Applied seven days after each cutting: 4.0 lb/acre Nutrient Express 18-18-18 3.0 lb/acre 20-5-5-17S 1 qt/acre Tech-Flo-Cal Bor
		Applied in the fall: 7.5 lb/acre Nutrient Express 4-41-27 1.0 pt/acre Cytokinin product
6	Yes		60
6	Yes	Applied within two days after each cutting: 1.0 gal/acre ‘Foli-zyme’ 4.0 oz/acre ‘Stimulate’	60
7	Yes	Conklin Company, Inc. (Shakopee, MN)	234
7	Yes	Applied at green-up in spring and seven days after each cutting: 4.0 gal/acre ‘Feast’ 3-18-18 2.0 qt/acre ‘Sidekick’ 0-0-25-17S 1.0 pt/acre calcium 1.0 pt/acre boron 1.0 pt/acre zinc 8.0 oz/acre ‘Foliar x-cyto’	234
8	Yes	Growers Nutritional Solutions (Milan, OH)	87
8	Yes	Applied at green-up in spring and two days after each cutting: 2.0 gal/acre ‘Growers’ fertilizer solution 0.2 gal/acre vinegar	87

* Lime was applied only at Farm 1 in the fall prior to initiating the foliar treatments to raise pH up to 6.5. Consequently, this treatment was not tested at the other locations.
† Foliar treatments were applied in a water solution at 20 gal per acre except for Conklin Company’s product which was applied in a water solution at 5 gal per acre in compliance with product application instructions.
‡ Includes cost for foliar applied material and a charge of $5 per acre per application but does not include cost for lime.

Before the third harvest each year, two randomly-selected 1-x-1-ft areas within each plot were hand-harvested three inches above the soil surface. Alfalfa herbage from the two areas within a plot was combined. Leaves and stems were separated and stem number determined. Leaves and stems were dried in a forced-air oven at 140°F for 48 h, weighed and then combined before being ground to pass a 0.04 inch screen prior to analysis. Only the third harvest each year was hand-sampled for morphological and quality determinations because previous studies had shown that differences in these parameters were greatest in summer growth (4).

Forage quality was predicted using near-infrared reflectance spectroscopy (NIRS). In 2000, 42 samples were selected from the complete set of 64 samples using the SELECT computer program described by Shenk and Westerhaus (11) and analyzed for crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF). Crude protein was determined as Kjeldahl N x 6.25, and ADF and NDF concentrations were measured using the procedures of Goering and Van Soest (3). These 42 samples were used to create a calibration equation to predict constituents of all samples collected in 2000. The coefficients of determination (r2) exceeded 0.968 for all NIRS prediction equations. In 2001, quality constituents were predicted using the equation developed in 2000.

Data were subjected to exploratory analysis to determine if the assumptions of analysis of variance held. Homogeneity of variance was tested using Hartley’s F-max test (7). As a result of this test, data from each location-year environment were analyzed separately. All statistical analyses used SAS Institute (SAS Inst., Cary, NC) software. Tukey’s multiple comparison procedure was used for mean separations. Differences reported in this paper are all at the P £ 0.05 level of significance.

Differences in yield between treatments occurred in only one of the four location-year environments. At Farm 1, the no-lime treatment yielded less than all the other treatments (Table 3). When lime was added, yields were not different regardless of foliar fertilizer or growth regulator treatments. This difference in yield at only one location-year environment can be attributed to the low pH at that location. When pH was at acceptable levels (Farm 2 and 3) or adjusted to an acceptable level (Farm 1), other treatments had no effect on yield. Yields at Farm 2 and 3 averaged 6.4 and 8.3 tons per acre, respectively.

Table 3. Season-total dry matter yield and third-harvest plant morphology at Farm 1 in 2000.

Treatments	Yield (ton/acre)	Stems (per ft2)	Leaf:Stem Ratio
None	4.8	43	1.5
Lime	5.3	39	1.5
Lime and water	5.4	41	1.6
Lime and 18-18-18	5.3	43	1.4
Lime and Miller Chemical & Fertilizer Corp. products	5.6	45	1.5
Lime and Stoller Chemical of FL products	5.7	44	1.4
Lime and Conklin Company Inc. products	5.4	43	1.4
Lime and Growers Nutritional Solutions products	5.4	44	1.6
LSD (0.05)	0.4	NS	NS

Number of stems per unit area and leaf:stem ratio were not affected by treatment at any location-year environment. The average number of stems per unit area at Farm 1 was 42 stems per ft2 and the other locations averaged of 68 stems per ft2. These differences can be attributed to fewer plants per ft2 at Farm 1. It was assumed that the greatest impact of foliar applied products would be the increase in stem numbers in thin alfalfa stands like that at Farm 1, but in fact none of the products had any effect on stem numbers.

There were no treatment differences at any location-year environment for the forage quality parameters measured. Crude protein, ADF and NDF were 22.2, 32.6 and 42.9% of dry matter, respectively, when averaged across all treatments, locations, and years.

The foliar-applied products used in this research did not increase alfalfa yield or quality, or alter plant morphology when soil pH and fertility were at recommended levels. Consequently, the additional cost of these products ($60 to $234 per acre per year) cannot be justified over maintaining adequate soil pH and fertility through traditional liming and fertilization practices.

Foliar Feeding: Fact or Fiction?

http://www.global-garden.com.au/burnley/apr98dte.htm

Foliar Feeding - Fact or Fiction?
by Dr.Peter May

Providing plants with nutrients remains a great mystery to many horticulturists. The many options available (inorganic or organic?, soluble or slow release?, different nutrient combinations or ratios?, soil or foliage applied?) make decision making difficult. In this article I thought I would look at one of the components of this problem, that being the question "Can a plant absorb nutrients through its leaves and is this a viable option for gardeners to use?" Like the answers to many other horticultural queries, the answer to this one is a qualified yes. Plants can absorb nutrients through their foliage but not in great quantity and sometimes not very quickly. Despite those limitations, foliar feeding is sometimes worthwhile to consider.

The usual uses of foliar fertilizer is in trace element nutrition where the plant does not require large quantities of the nutrient in question. Since many trace element problems occur as a result of unfavourable soil conditions (for example high soil pH), foliar applications can sometimes be more effective than applying the fertilizer to the soil. Examples of nutrients which can be applied in this case are zinc, manganese, copper and molybdenum. As an example, an application of molybdenum to cauliflower to overcome whiptail disorder would be 0.25 g ammonium or sodium molybdate per litre of water, applied as a spray early in the growth of the crop. This spray will be held on the foliage more effectively if a wetting agent is included in the spray (because of the waxy nature of the leaves). Given that many trace elements can become toxic if excess is applied, the use of any trace element fertilizer should be based on an accurate diagnosis of a problem rather than an application, "just in case".

Nitrogen is also readily absorbed by leaves and foliar fertilizing can be used to supply nitrogen. Urea is the best source of nitrogen for foliar use and many commercial products use urea as their nitrogen source. Check the fertilizer product label if you are not sure. If you are using pure urea as a foliar fertilizer, make sure it has the impurity biuret at no more than 0.4%. Again, this will be stated on the label. A foliar spray mixture for general use is 10 g urea and 30 g potassium nitrate per litre of water. For sensitive plants, use this at half strength. A wetting agent will be useful if the leaves are waxy. To supply all of a plant’s nitrogen needs through the leaves will require several applications because of the amount that a plant takes up, but foliar feeding can be a way of getting rapid absorption taking place. Should any of the spray fall onto the soil then it will behave as any other fertilizer and ultimately be absorbed by the roots.

One issue which one also has to consider here is that some elements are only absorbed into leaf tissue very slowly. In these cases, foliar fertilizing is unlikely to be of any real use. Two important examples of this are the elements iron and phosphorus. This is something of a pity as both of these elements can become unavailable in soil through unfavourable soil conditions.

Foliar-fertilizer therapy – A Concept in Integrates Pest Management

Foliar-fertilizer therapy — a concept in integrated pest management

a) Department of Plant Pathology, ARO, Newe Ya'ar Research Center, P.O. Box 1021, Ramat Yishay 30095, Israel
b) Golan Research Institute, University of Haifa, P.O. Box 97, Qasrine 12900, Israel

Use of fertilizers has been implicated in degradation of the environmental quality of lakes, rivers and aquifers. There is also widespread public concern about the use of pesticides, including fungicides, on farms and their potential effect on our environment and food. However, it is certain that the use of fungicides as part of intensive agriculture has stabilized our food supply and permitted millions of people to live longer lives. Data from our laboratory and others have indicated that foliar sprays of phosphate and potassium salts can induce systemic protection against foliar pathogens in various crops such as cucumber, maize, rose, grapevine, apple, mango and nectarine. Expression of disease tolerance is dependent on a number of factors including use of fertilizers and pesticides. Therefore, the possible dual role of NPK fertilizers in activation of the mechanism(s) which induce plant protection against pathogens was studied. Data from the application of this concept to various host-pathogen interactions are presented in the present review. A single phosphate spray of 0.1 M solution induced a systemic protection against powdery mildew in cucumber caused by Sphaerotheca fuliginea and against common rust in maize caused by Puccinia sorghi, and northern leaf blight (NLB) caused by Exserohilum turcicum. This systemic protection against powdery mildew in cucumber, common rust or NLB in maize was obtained on upper leaves after NPK fertilizer application on the lower leaves. In both the latter host-pathogens interactions, growth increase was also observed in maize plants as a result of one foliar spray of phosphates. In addition, it was evident throughout all the experiments that a single application of phosphates was effective in suppressing the lesions of powdery mildew on the diseased foliage of cucumber, greenhousegrown roses, field grown mango, nectarine and grapevine. This phenomenon was investigated in combination with fungicides.

Hydroponic Foliar Fertilization

Foliar Fertilization in Citrus: Important Considerations for Belize

http://www.belizecitrus.org/cga/popups/articleswindow.php?id=16&print=print

Foliar Fertilization in Citrus: Important Considerations for Belize
By Francisco Gutiérrez

CitriNews: October 2002 Vol. 5, Iss. 2; Citrus Research and Education Institute

Concept

Foliar fertilization in citrus is not a general nutrition management practice in Belize. However, experience has shown that combining granular and foliar programs can improve tree vigor and yields. It has long been recognized that micronutrient deficiencies in citrus are more readily corrected by foliar sprays than by soil applications, except in the case of iron deficiency. The effects of applications of nitrogen, phosphorus and potassium fertilizers to the canopy have been investigated very little but there seems to be good potential for providing these nutrients through the canopy. Some researchers and grove managers argue that all the necessary fertilizer requirements can be applied through the leaves. However, the long term effects of a totally foliar programme are not known.

Potential for improving yields in a more efficient and cost-effective manner

Leaves have the ability to absorb and transfer nutrients to the areas in the tree where these are required. Foliar applications provide a fast supply of nutrients to the tree, especially during times of greatest nutrient need, such as flowering and during leaf and root flushes. Foliar applications are 5 to 30 times more efficient than granular applications for various reasons. The leaves are not prone to the same conditions as the root system. Roots may undergo periods of dormancy causing limited uptake activity such as during extreme cold and hot soil conditions. The roots may be subject to pest and diseases (nematodes and pathogenic fungi), as well as extreme soil conditions such as high aluminum and calcium content caused by extremes in pH, and saline conditions which reduce their efficiency in nutrient uptake (Figure 1). In these cases foliar applications can provide the tree with the nutritional requirements. Because of the higher efficiency, foliar applications can reduce the amounts of nutrients applied to the agroecosystem. Recently, there have been great concerns over the amounts of nutrients particularly the nitrates that may leach down and contaminate ground water levels. Foliar applications have reduced the amounts of nutrients that eventually get to the water sources. Apart from these advantages, foliar applications can reduce costs because these can be combined with other foliar spray programs, such as greasy spot and post bloom fruit drop control applications.

There are some limitations to consider when applying foliar nutrient sprays. There is a limit as to how much the tree canopy can absorb. This implies that one application is not enough to provide all the nutrient needs for the tree. Pushing the limits may cause spray burns and loss of the foliage. This may be aggravated in that not all forms of nutrients can be readily taken up by the leaves. Phosphorus fertilization may pose a problem in that leaves can take up the nutrient as phosphoric acid and this may be phytotoxic in high amounts. The phosphite form is safer but may be cost prohibitive. In the case of nitrogen, this element can be applied as ammonium nitrate or urea. However, the source of urea has to be very low in biuret content (less than 2%) or else this compound can cause severe leaf chlorosis.

Research conducted in California, USA indicates that a minimum of three applications of nitrogen may be necessary to provide the nutritional needs for an orange tree. A tree may only be able to tolerate up to 0.35 lbs of elemental nitrogen per application under ideal canopy conditions, that is, a thick canopy of healthy leaves. Under humid tropical conditions, greasy spot infestations (Mycosphaerella citri) can cause severe defoliation and drastically reduce leaf area and photosynthetic capacity and consequently, nutrient uptake. Other diseases such as sooty mold (Capnodium sp) may pose a similar problem. Other problems that may reduce efficiency are the possibility of rain after application, which may wash off most of the nutrients from the canopy.

Foliar fertilization also depends heavily on specialized application equipment. Airblast sprayers are probably the most appropriate equipment for application. However, these need to be fitted with proper nozzles and be properly calibrated to deliver the right amounts of fertilizer solutions to the trees, without forgetting to apply under ideal environmental conditions. All of these limitations may combine to make foliar applications less efficient and therefore very expensive. Growers who want to consider this option should check that all inefficiencies are corrected before carrying out a foliar fertilization programme.

Liming of groves in acid soils is an important factor to consider if foliar programs are to be carried out on a citrus grove. Growers may believe that it may not be necessary to correct pH if they are basing fertilizer programs on foliar sprays. The logic may be based in the knowledge that there is no effect on the nutrients applied on the foliage, such as occurs with the tying up of phosphorus in acid soils and the excessive leaching of nitrogen and potassium that occurs due to a low cation exchange capacity of acid soils. In Belize, the main problem associated with acid soils is the high aluminum content. Aluminum is toxic to the root system and should be neutralized whatever the method of fertilization used. Weed control should also be carried out because weeds compete for the little reserves of nutrients from the soil, as well as water.

Can foliar fertilizer sprays substitute granular applications?

Relatively little work has been done on foliar fertilization with nitrogen, phosphorus and potassium and many questions still remain on a few aspects of foliar fertilization. Some of the leading works have established that applications of low-biuret urea and phosphorous acid have managed to increase flowering, fruit set and fruit production. Foliar applications of potassium nitrate or mono-potassium phosphate have been found to increase the size of the fruit. However, most studies have been carried out with trees that had good nutrient levels to begin with, so that the foliar applications were complementary to normal fertilization practices. The effects of foliar applications of NPK on starved trees are not known and the long term effects of a totally foliar programme are much less known. In theory any plant can be sustained with foliar feeding but in reality it would probably not make any practical and economic sense for citrus.

Biologically speaking, trees are designed to feed primarily from the roots. In nature, trees depend totally on their root systems for water and nutrients. In the case of citrus, even trees that receive little nutrition tend to depend on the reserves of the soil for survival. Research indicates that organic soils can contain as much as 2000 lbs of nitrogen per acre in the organic matrix. Of course not all of this reserve is available to the plant at one time. Nitrogen and other nutrients are slowly released during the decomposition of the organic mater. This source of nutrients is probably what keeps unfertilized trees productive for a few years before outright decline of the grove.

Citrus trees also tend to accumulate reserves of nitrogen in the tree skeleton, which are then made available to young leaves, flowers, and fruits as may be needed. A study conducted in Israel concluded that more than 80% of the nitrogen in new growth is derived from the tree skeleton. This concept is very important for fertilization practices. It means that when a grower fertilizes a tree, the sinks are replenished first and consequently these nutrients are relocated to the areas where needed most. It also explains why sometimes the effects of a granular fertilization are not usually seen immediately. It also indicates that fertilizer timing may not be all that important as is actually believed. It means that trees need to be kept fertilized periodically and not be allowed to be depleted of all its reserves.

In this respect, foliar fertilization can play an important role in supplying nutrients in times when the tree reserves are low and fast action is required. It must be stressed however, that foliar fertilization should be done in a complementary manner and not as a substitution for granular fertilization.

Foliar fertilizer practices in Belize

Although not very common, foliar fertilization programs have shown good results on citrus in Belize. Foliar fertilizations are combined with granular applications for better results. An efficient program that seems to work very well is applying one cycle of granular fertilizers and substituting the second application with a foliar spray of nitrogen and micronutrients. Experience has shown that there is a great improvement in the canopy condition in that there is denser and greener foliage and consequently improved yields. The success of a good foliar application is greatly tied to the soil conditions in the grove. Foliar programs seem to enhance tree vigor and productivity significantly on groves that are on relatively fertile, organic, and well drained soils. On marginal soils, such as acid pineridge soils, the effects of foliar applications are so short lived and frequent applications are required to sustain even a low level of production. The sandy, acid and infertile soils have a limited nutrient base and the tree will depend almost totally on granular or foliar applications to survive and be productive. Under these conditions, granular fertilizers are not very efficient because of the extreme acid conditions. Foliar fertilization may solve the problem but then it becomes a matter of economics. Too many applications may not be cost effective. On fertile organic soils, the nutrient base is much better. Experiences in the industry show that there are certain soils that can sustain relatively good yields for a few years with little or no fertilization. This difference is due to the good nutrient base in the soil. Foliar fertilization has always been considered the best method for correcting secondary and micronutrient deficiencies. Table 1 shows the amount and sources of micronutrient and secondary nautrients that can be foliar applied.

Foliar Feeding

http://www.grounds-mag.com/mag/grounds_maintenance_foliar_feeding/

Foliar Feeding

By Wesley Totten and Bert McCarty, Clemson University

Fertilization exists to supply essential nutrients to plants to achieve desired color, growth and pest resistance. As the demands of the turf are increased from lower mowing heights and increased traffic levels, additional fertility is needed to promote growth and recovery, especially in sand-based soils. Nitrogen (N) is the key element in turfgrass fertility programs. Nitrogen strongly influences the color, growth and density in turfgrass; therefore, turf managers place an emphasis on this particular nutrient. However, as the trend towards low-input turfgrass maintenance programs increase, practices such as foliar fertilization, or foliar feeding, have become more popular. But how effective is this application technique in regard to nutrient uptake by turf foliage?

FOLIAR FEEDING

Foliar feeding is the entry of small amounts of liquid fertilizer through the surface of plant shoots. This allows for rapid nutrient utilization by the plant, and also provides the applicator the ability to blend the fertilizer with other products, such as pesticides and micronutrients. Current formulations of liquid fertilizers are believed to penetrate mostly the transcuticular pores on foliage, which are open virtually all the time compared to stomata. Nutrients also enter stomata, but these often are closed due to environmental stresses and darkness. Also, the majority of the stomata are located underneath leaves, away from fertilizer spray patterns. Drawbacks to foliar feeding include the inability to apply large amounts of N, phosphorous (P) and potassium (K) without potentially burning the foliage. Therefore, frequent applications at a low volume are required to maintain consistent color and plant growth.

FOLIAR ABSORPTION

Many products claim to be true foliar fertilizers that can solve most fertility problems. However, the majority of these products lack published research to substantiate these statements. A primary concern is whether you are applying a true foliar-absorbed fertilizer. Research on banana plants determined whether foliar applications of urea were absorbed through foliage or washed off and absorbed through roots. Up to 65 percent of the foliar-applied urea was absorbed within 25 minutes, with the majority being absorbed by the lower (or younger) surface of the foliage — where the greatest number of stomata exist. Similar findings were reported in coffee, cacao and McIntosh apple. The lower leaf surfaces and younger leaves rapidly absorbed urea from foliar applications as compared to older leaves and upper leaf surfaces. Complete absorption of the urea occurred in coffee and cacao in less than 24 hours and in banana by 30 hours. The absorption of urea by the lower surface of younger McIntosh apple leaves was as high as 85 percent in a two-hour absorption period, compared to the lower leaf surface of older leaves.

Many foliar applied products also contain “hidden” ingredients, such as iron, not specified on the label. So while you may be satisfied with the results, you may not realize which ingredient, specifically, is providing this response. One way to identify it is to know exactly which elements can be absorbed and moved through the plant. Mobile elements such as N, magnesium and sulfur are transported through phloem tissue in leaves. Meanwhile, immobile elements such as calcium and boron will not move through the phloem, thus, would not be as effective if applied as a foliar fertilizer.

Previous research has reported approximately 55 percent of 15N-urea applied was absorbed by tall fescue and Penncross creeping bentgrass. Similar results occurred among eight cool-season turfgrasses with absorption of N ranging by cultivar from 31 to 61 percent over 72 hours. Lower values have been observed in Kentucky bluegrass and perennial ryegrass as the absorption of applied 15N-urea ranged from 43 and 35 percent, respectively, over 48 hours. In 2002, N adsorption rates were compared among six warm-season turfgrasses. Long-term N recovery analysis showed that St. Augustinegrass exhibited the most efficient recovery of 84 percent of applied N allocated to new leaf tissue, while centipedegrass was the least efficient at 63 percent allocated. Also, 15N uptake analysis proved Tifway bermudagrass exhibited more efficient 15N adsorption than Meyer zoysiagrass, with the majority of the N being located in the shoots (38 to 63 percent).

Previous research in McIntosh apple focused on parameters hindering foliar urea uptake. These included existing N levels in the foliage, pH of the spray, temperature and the influence of wetting agents. High existing nitrogen levels in the foliage and low temperatures (~21°C compared to 32°C) promoted best absorption. Also, incorporating a wetting agent into the spray (Tween 80 and Tween 20) approximately doubled the percent of urea absorbed, compared to a pure water solution.

Most research indicates that with urea, for instance, liquid and dry (granular) formulations produce little differences in turf growth and quality. However, previous research with urea noted foliar feeding accounted for 95 percent of plant use compared to approximately 10 percent use from soil applications. In an attempt to address efficacy questions, studies compared fluid and foliar nutrition programs to conventional programs (conventional programs designed by select golf course superintendents in the state of Nebraska) on Providence creeping bentgrass. Fluid and foliar programs were comparable to the conventional programs in terms of color and density while incorporating 25 to 80 percent less N. Furthermore, it was suggested foliar fertilizers should not replace conventional fertilizer programs (liquids and water-soluble controlled-release granular fertilizers). However, “true” foliar fertilizers can increase the growth and vigor in turf under high maintenance, especially under stresses such as increased heat. Also, with the increased attention placed on N and phosphorous leaching, liquid fertilization could be very beneficial. The low input required by foliar applications could pose a smaller risk to the environment in terms of leaching.

CURRENT RESEARCH

If you couple a foliar-absorbed product with a sound, granular soil-based fertility program, the potential to produce high-quality turfgrass with minimal rates is feasible. To build upon previous research and to determine advantages and disadvantages between dry and liquid fertilizers applied to turf, research is being conducted at Clemson University to address: (1) what is a true foliar fertilizer; (2) what is their effectiveness; and (3) long-term effects on plant vigor and recuperative potential of foliar vs. granular fertilization programs. Researchers are evaluating various annual N rates with various ratios of liquid vs. granular products on creeping bentgrass, with emphasis on the long-term response to this. In addition, laboratory studies will identify how much liquid fertilizer is actually being foliar absorbed. Such research could supply turf managers with knowledge needed to determine the effectiveness of these foliar products and their cost effectiveness.

Wesley Totten is a graduate research assistant and Bert McCarty, Ph.D., is professor of turfgrass science, both in the Department of Horticulture at Clemson University (Clemson, S.C.).

Effects of Boron Foliar Applications on Vegetative and Reproductive Growth of Sunflower

http://aob.oxfordjournals.org/cgi/content/abstract/92/4/565

Effects of Boron Foliar Applications on Vegetative and Reproductive Growth of Sunflower

A. ASAD, F. P. C. BLAMEY1 and D. G. EDWARDS
-School of Land and Food Sciences, University of Queensland, Brisbane, Queensland 4072, Australia

Foliar application may be used to supply boron (B) to a crop when B demands are higher than can be supplied via the soil. While B foliar sprays have been used to correct B deficiency in sunflower (Helianthus annuus L.) in the field, no studies have determined the amount of B taken up by sunflower plant parts via foliar application. A study was conducted in which sunflower plants were grown at constant B concentration in nutrient solution with adequate B (46 µM) or with limited B supply (0·24, 0·40 and 1·72 µM) using Amberlite IRA-743 resin to control B supply. At the late vegetative stage of growth (25 and 35 d after transplanting), two foliar sprays were applied of soluble sodium tetraborate (20·8 % B) each at 0, 28, 65, 120 and 1200 mM (each spray equivalent to 0, 0·03, 0·07, 0·13 and 1·3 kg B ha–1 in 100 L water ha–1).

The highest rate of B foliar fertilization resulted in leaf burn but had no other evident detrimental effect on plant growth. Under B-deficient conditions, B foliar application increased the vegetative and reproductive dry mass of plants. Foliar application of 28–1200 mM B increased the total dry mass of the most B-deficient plants by more than three-fold and that of plants grown initially with 1·72 µM B in solution by 37–49 %. In this latter treatment, the dry mass of the capitulum was similar to that achieved under control conditions, but in no instance was total plant dry mass similar to that of the control. All B foliar spray rates increased the B concentration in various parts of the plant tops, including those that developed after the sprays were applied, but the B concentration in the roots was not increased by B foliar application. The B concentration in the capitulum of the plants sprayed at the highest rate was between 37 and 93 % of that in the control plants. This study showed that B foliar application was of benefit to B-deficient sunflower plants, increasing the B status of plant tops, including that of the capitulum which developed after the B sprays were applied.

Foliar Fertilization for Turfgrasses

Foliar Fertilization of Soybeans. II. Effect of Biuret and Application Time of Day

Foliar Potassium Fertilizer Sources Affect Weed Control in Soybean with Glyphosate

http://www.plantmanagementnetwork.org/pub/cm/research/2007/potassium/

Foliar Potassium Fertilizer Sources Affect Weed Control in Soybean with Glyphosate

Kelly A. Nelson, Research Assistant Professor, Division of Plant Sciences, University of Missouri, Novelty 63460; and Peter P. Motavalli, Associate Professor, Department of Soil, Environmental and Atmospheric Sciences, University of Missouri, Columbia 65211

Abstract

Field research in 2003 and 2004 evaluated soybean injury, weed control, yield response, and cost-effectiveness of foliar-applied, commercially-available K fertilizers with glyphosate. Fertilizer sources were applied at the highest soluble rate for dry formulations or were used as the carrier with glyphosate. All K-fertilizer sources had less than 10% injury 7 and 14 days after treatment (DAT) except 0-0-30-0 (%N-%P2O5-%K2O-%S). Tank mixtures of 0-0-62-0, 14-0-46-0, 0-0-50-17, and 3-18-18-0 with glyphosate controlled common ragweed, common lambsquarters, common waterhemp, and giant foxtail greater than 85% and had grain yields similar to glyphosate plus diammonium sulfate (DAS). Gross margins when glyphosate was tank-mixed with 0-0-62-0, 14-0-46-0, and 0-0-50-17 ranged from $290 to 300/acre which were similar to glyphosate plus DAS. This research demonstrated that several K fertilizer sources may be combined with glyphosate for cost-effective foliar fertilizer applications while minimizing crop injury and maintaining weed control.

Introduction

The incidence of K deficiency in the Midwestern US has increased in recent years due to reduced K availability in areas with compaction and periodic drought, reduced fertilizer applications for soybean [Glycine max (L.) Merr.] because of low commodity prices, increased corn (Zea mays L.) grain yields in corn-soybean rotations (4), and increased acreage of continuous soybean production in states such as Missouri (12). Soil test K data for Missouri indicated that over 50% of the soil samples tested in the low to medium range for K (5), suggesting that large agricultural areas may be responsive to K fertilization.

Several studies have evaluated response of soybean to foliar fertilizer mixtures applied during early and late stages of soybean development (6,9,17). Soybean response to a foliar application of K2SO4 increased grain yield over 10 bu/acre when compared with non-treated or MgSO4 controls on a low to medium soil test K (16). A large carrier volume was required for optimum foliar K sulfate application rate due to the low solubility of K sulfate which would limit the use of this particular fertilizer source as part of an integrated crop management system.

Over 80% of the soybeans grown in the United States are glyphosate- resistant (7). A single-postemergence application of glyphosate (N-(phosphonomethyl)glycine) has been used as a non-injurious, cost-effective weed management treatment for glyphosate-resistant soybean production in the northcentral US (21). Salts in the spray solution have increased, decreased, or had no effect on control of weeds with glyphosate (13,14,15). Diammonium sulfate (DAS) has been used with glyphosate to reduce hard water antagonism of weed control with glyphosate (14,15). In addition, recent formulations of glyphosate as a K-salt have been commercially-available (10,19). Nalewaja and Matysiak (14) reported that K was one of the least antagonistic cations of glyphosate, but that anions were important for overcoming spray solution salt antagonism of glyphosate. Potassium nitrate, K chloride, and K sulfate were predicted to be the least antagonistic cation-anion complexes in the spray solution with glyphosate (14). Compatible, commercially-available fertilizer tank mixtures with glyphosate could help offset application costs associated with separate foliar fertilizer applications and provide essential nutrients to the crop.

Some research has evaluated crop response to commercial fertilizer tank-mixture treatments with glyphosate; however, limited research has evaluated weed control with these production systems (1,11). Most of this research has focused on N fertilizer and not K fertilizer sources. Similarly, little information is available regarding the compatibility of foliar K sources with glyphosate and the effects of these K fertilizer mixtures with glyphosate on crop injury and weed control. In addition, recent formulations of glyphosate as a K-salt have been commercially-available (10,19). We hypothesized that the addition of K fertilizer to the spray mixture of formulated K-glyphosate would not reduce weed control effectiveness compared to application of the glyphosate alone or with DAS. The objectives of this research were to: (i) determine soybean yield response and salt injury from different foliar-applied K fertilizer sources; (ii) assess the impact of foliar K fertilizer sources on weed control when tank-mixed with a glyphosate-based herbicide; and (iii) evaluate the cost-effectiveness of applying K fertilization with glyphosate-based herbicides for no-till glyphosate-resistant soybean production.

Evaluating Fertilizer Tank Mixtures with Glyphosate

Field experiments were conducted in 2003 and 2004 at the University of Missouri Greenley Research Center near Novelty, MO (40°01’N, 92°11’W) on a Putnam silt loam (fine, smectitic, mesic Vertic Albaqualfs) soil. The soil had a high initial soil test K (370 lb/acre in 2003 and 270 lb/acre in 2004) using a 1 M NH4OAc extracting solution at pH 7. All plots were 10 by 35 ft with four replications. All treatments were applied with a CO2-propelled hand-boom calibrated to deliver 15 gal/acre at 18 lb/inch2, traveling 2.8 mi/h, and equipped with 8002 flat-fan nozzles (Spray Systems CO., Wheaton, IL) spaced 15 inches apart and 16 inches above the canopy. Commercially-available K fertilizer sources included K carbonate (NA-CHURS/ALPINE Solutions, Marion, OH) (0-0-30-0 as %N-%P2O5-%K2O-%S), K chloride (PCS, Potash Corp. of Saskatchewan, Northbrook, IL) (0-0-62-0), K nitrate (SQM North American Corp., Atlanta, GA) (14-0-46-0), K phosphate + urea (NA-CHURS/ALPINE Solutions, Marion, OH) (3-18-18-0), K sulfate (Great Salt Lake Minerals Corp., Overland Park, KS) (0-0-50-17), K thiosulfate (Tessenderlo Kerley Inc., Phoenix, AZ) (0-0-25-17), and K thiosulfate + urea-triazone (Tessenderlo Kerley Inc., Phoenix, AZ) (5-0-20-13). A DAS treatment was included since it is commonly used as an additive with glyphosate at 0.75 lb ae/acre to reduce the antagonistic effects of hard water on weed control (15). Grain was harvested with a small-plot combine and grain yields were reported with grain moisture content adjusted to 13%.

All data were subjected to analysis of variance using PROC ANOVA (Version 9.1, SAS Institute Inc., Cary, NC). Percent data for injury and weed control were transformed to the arcsine prior to the analysis. The transformation did not affect the conclusions so the original data are presented. All data were combined over years and main effects were presented when there was an absence of interactions. Weed control data were presented separately each year due to slight differences in the primary weed species and population density present each year. Means were separated using Fisher’s Protected LSD at P ≤ 0.05.

Glyphosate-resistant soybean, ‘Asgrow 3701’ (Monsanto, St Louis, MO) were no-till planted on 19 May 2003 and 20 May 2004 in 15-inch rows at 180,000 seeds/acre. A factorial arrangement of treatments was used in a randomized complete block design. Fertilizer source was one factor and was either applied alone to weed-free plots or tank-mixed with glyphosate (Roundup WeatherMAX, Monsanto, St. Louis, MO) and applied to weedy plots.

Since K fertilizer sources vary in solubility and possible compatibility with glyphosate, a compatibility test was conducted prior to applying the treatments to the field experiment to determine the solubility of the K source and pH (Oakton Instruments, Vernon Hills, IL) of the spray solution. Solution pH measurements were replicated twice and combined over years. The liquid fertilizers were utilized as the carrier and dry formulations were added until the solution was almost saturated. Based on this preliminary test, the highest soluble rate of each commercially-available foliar K fertilizer was applied with glyphosate with K rates from 1.6 to 46 lb/acre. A slight precipitate formed when 3-18-18-0 or 0-0-25-17 was tank-mixed with glyphosate, but this precipitate did not affect application of these products. Spray boom height was adjusted to maintain 30% overlap when 0-0-30-0 was applied alone or tank-mixed with glyphosate.

At the time of spray application, air temperature was 88°F with 59% relative humidity on 24 June 2003 and 81°F with 45% relative humidity on 23 June 2004. Common lambsquarters (Chenopodium album L.) (number of plants per area at time of application = 10/m2), common ragweed (Ambrosia artemisiifolia L.) (1/ft2), and common waterhemp (Amaranthus tamariscinus Nutt.) (6/ft2) were the primary weeds in 2003, and giant foxtail (Setaria faberi Herrm.) (2/ft2) and common waterhemp (4/ft2) were the primary weeds in 2004. Soybean was 6 to 8 inches tall at the V4 to V5 stage of development (3), giant foxtail was 6 to 10 inches tall with 3 to 4 leaves, common ragweed was 4 to 8 inches tall with 8 to 14 leaves, common waterhemp was 3 to 10 inches tall with 4 to 14 leaves, and common lambsquarters was 4 to 6 inches tall with 12 to 18 leaves at the time of application.

Soybean injury was determined 7 and 14 days after treatment (DAT) on a scale of 0 (no effect) to 100 (complete crop death). Soybean plants and weeds were harvested from a randomly placed 10 by 30-inch quadrat 28 DAT and weighed to determine soybean recovery and weed control. Soybean fresh weight was determined immediately after harvest. Weeds were dried and percent dry weight reduction was calculated as 100[1-(total weed dry weight/non-treated weed dry weight)]. Visual weed control was evaluated 56 DAT on a scale of 0 (no effect) to 100 (complete plant death) to evaluate regrowth of weed species.

A gross margin was calculated as the [(grain yield * market price) – (cost of foliar fertilizer + fertilizer application cost in absence of herbicide)] to determine the economic benefit of using foliar K sources mixed with and without glyphosate for soybean production. The market price for soybean was estimated at $5.40/bu and fertilizer application cost was $5.00/acre (18). Fertilizer cost was estimated for 3-18-18-0 at $43.00/gal, 0-0-30-0 at $39.40/gal, 0-0-25-17 at $39.40/gal, 5-0-20-13 at $60.90/gal, 0-0-50-17 at $1.23/lb K, 0-0-62-0 at $1.28/lb K, 14-0-46-0 at $3.30/lb K.

Soybean Injury

Commercially-available K fertilizers vary in relative solubility which resulted in application rates that ranged from 1.6 to 46 lb of K per acre for the 15-gal/acre carrier volume utilized in this research (Table 1). Spray solution pH was 7.4 to 12.5 prior to the addition of glyphosate. Formulated glyphosate lowered solution pH with all K sources except 3-18-18-0 and 0-0-30-0. Spray solution pH of glyphosate plus DAS, 0-0-50-17, 14-0-46-0, or 0-0-62-0 was similar to glyphosate plus water; however, solution pH ranged from 6.9 to 12.3 when glyphosate was tank-mixed with 3-18-18-0, 5-0-20-13, 0-0-25-17, or 0-0-30-0. Solution pH of the fertilizer and glyphosate mixtures may be confounded by the cation-anion complex in the spray solution (14).

Table 1. Spray solution pH of K fertilizer sources alone and with
glyphosate at 0.75 lb ae/acre prior to application.

Fertilizer additivex (%N-P2O5-K2O-S)	K rate (lb/acre)	Solution pH
Fertilizer additivex (%N-P2O5-K2O-S)	K rate (lb/acre)	Alone	Glyphosate tank mixture
None	0	7.4	5.1
DAS	0	7.2	4.8
0-0-50-17	1.6	7.9	4.7
14-0-46-0	4.6	7.8	4.7
0-0-62-0	15.6	9.0	4.7
3-18-18-0	26.8	8.1	8.0
5-0-20-13	29.0	11.1	9.0
0-0-25-17	38.6	7.7	6.9
0-0-30-0	46.0	12.5	12.3
LSD (P ≤ 0.05)		0.7

x Abbreviations: DAS, diammonium sulfate; 0-0-30-0, K carbonate;
0-0-62-0, K chloride; 14-0-46-0, K nitrate; 0-0-50-17, K sulfate;
3-18-18-0, K phosphate + urea; 0-0-25-17, K thiosulfate;
5-0-20-13, K thiosulfate + urea-triazone.

Soybean injury was primarily necrosis of leaves exposed to the foliar applications of fertilizer additives alone or tank-mixed with glyphosate (visual observation). All treatments, averaged over the weed-free and glyphosate tank mixture treatments, injured soybean less than 10% 7 DAT except 0-0-30-0 and 5-0-20-13 (Table 2). Glyphosate tank-mixed with 0-0-30-0 or 5-0-20-30 injured soybean greater than the fertilizer source applied alone 14 DAT. The adjuvants present in the glyphosate formulation possibly increased uptake of the foliar K fertilizers which increased soybean injury. Soybean fresh weight was reduced by 0-0-30-0 when compared to the non-treated control 28 DAT.

Table 2. Soybean injury main effect 7 DAT, injury interaction between K additives applied alone in a weed-free environment and tank-mixed with glyphosate at 0.75 lb ae/acre 14 DAT, and fresh weight main effect 28 DAT.

Fertilizer additiveb (%N-P2O5-K2O-S)	Injury 7 DAT	Injury 14 DAT (%)		Fresh weight 28 DAT (lb/ft2)
Fertilizer additiveb (%N-P2O5-K2O-S)	Injury 7 DAT	Weed-free	Glyphosate tank mixture	Fresh weight 28 DAT (lb/ft2)
None	0	0	1	0.34
DAS	0	0	1	0.35
0-0-50-17	0	1	0	0.35
14-0-46-0	0	1	1	0.34
0-0-62-0	3	2	3	0.34
3-18-18-0	6	3	5	0.36
5-0-20-13	10	3	8	0.28
0-0-25-17	7	5	6	0.31
0-0-30-0	15	6	16	0.26
LSD (P ≤ 0.05)	4	3		0.07

x Abbreviations: DAS, diammonium sulfate; DAT, days after treatment;
0-0-30-0, K carbonate; 0-0-62-0, K chloride; 14-0-46-0, K nitrate;
0-0-50-17, K sulfate; 3-18-18-0, K phosphate + urea;
0-0-25-17, K thiosulfate; 5-0-20-13, K thiosulfate + urea-triazone.

Weed Control

Glyphosate plus 3-18-18-0, 14-0-46-0, 0-0-62-0, or DAS reduced weed dry weights similar to the weed-free control 28 DAT (Table 3). Control of common ragweed, common lambsquarters, common waterhemp, and giant foxtail was greater than 85% with glyphosate plus 3-18-18-0, 0-0-50-17, 0-0-62-0, 14-0-46-0, or DAS 56 DAT (Table 4). None of these treatments except 3-18-18-0 affected spray solution pH when compared to glyphosate alone or with DAS (Table 1). Glyphosate solubility was probably reduced at the high pH levels which reduced herbicide absorption into the plant (13,20) and resulted in poor weed control when 5-0-20-13, 0-0-25-17, or 0-0-30-0 were combined with glyphosate.

Table 3. Weed dry weight reduction with glyphosate at 0.75 lb ae/acre
tank-mixed with K fertilizer sources 28 days after treatment (DAT) in
2003 and 2004.

Fertilizer additivex (%N-P2O5-K2O-S)	K rate (lb/acre)	Dry weight reductiony (%)
Weed-free	0	100
None	0	99
DAS	0	99
0-0-50-17	1.6	92
14-0-46-0	4.6	96
0-0-62-0	15.6	94
3-18-18-0	26.8	97
5-0-20-13	29.0	75
0-0-25-17	38.6	67
0-0-30-0	46.0	83
LSD (P ≤ 0.05)		8

x Abbreviations: DAS, diammonium sulfate; 0-0-30-0, K carbonate;
0-0-62-0, K chloride; 14-0-46-0, K nitrate; 0-0-50-17, K sulfate;
3-18-18-0, K phosphate + urea; 5-0-20-13, 0-0-25-17, K thiosulfate;
K thiosulfate + urea-triazone.
y Total dry weight reduction was calculated as: 100[1-(total weed dry weight/non-treated weed dry weight)]. Weeds included common
lambsquarters in 2003, common ragweed in 2003, common water-
hemp in 2003 and 2004, and giant foxtail in 2004. The non-treated
weed dry weight was 0.21 lb/ft2.

Table 4. Control of common lambsquarters in 2003, common ragweed in 2003, common waterhemp in 2003 and 2004, and giant foxtail in 2004 56 DAT with glyphosate at 0.75 lb ae/acre plus K fertilizer sources on a high soil test K.

Fertilizer additivex (%N-P2O5-K2O-S)	Control (%)
	Common ragweed	Common lambs- quarters	Common waterhemp		Giant foxtail
	Common ragweed	Common lambs- quarters	2003	2004	Giant foxtail
Weed-free	100	100	100	100	100
None	100	99	99	94	97
DAS	100	100	100	100	100
0-0-50-17	96	97	99	98	99
14-0-46-0	95	89	91	98	100
0-0-62-0	95	86	95	93	98
3-18-18-0	99	95	98	98	100
5-0-20-13	50	19	45	70	70
0-0-25-17	26	6	31	64	65
0-0-30-0	29	26	34	68	91
LSD (p<0.05)	17	22	15	13	16

Yield and Gross Margins

The average soybean grain yield in 2003 and 2004 for plots which had weeds and were not treated with glyphosate was 33.7 bu/acre (data not shown). The addition of DAS to glyphosate increased soybean grain yields 3.8 bu/acre compared to when glyphosate was added alone (Fig. 1A). Significant reductions in grain yield occurred when 0-0-25-17 and 0-0-30-0 were mixed with glyphosate due to a combination of crop injury and reduced weed control. The weed-free application of 0-0-30-0 increased soybean grain yield 3 bu/acre and was the most injurious K source when compared with the non-treated, weed-free control. This response may be similar to treatments that cause crop injury yet increase grain yield due to a reduction in the incidence of disease (2,8). This has been observed when herbicides such as lactofen were applied to soybean (2). Tank mixtures of 0-0-50-17, 0-0-62-0, and 14-0-46-0 with glyphosate or applied alone had grain yields and gross margins (Fig. 1B) similar to glyphosate plus DAS. Gross margin return was significantly reduced when 0-0-30-0, 0-0-25-17 and 5-0-20-13 were tank-mixed with glyphosate which may be due to a combination of crop injury, reduced weed control, and/or cost due to the high application rates of these fertilizer additives in this research.

Chart

Fig. 1. The effect of fertilizer additive on soybean grain yield (A) and gross margin (B) in a weed-free environment and tank mixtures with glyphosate at 0.75 lb ae/acre with a high soil test K. Fertilizer additives included: DAS, diammonium sulfate; 0-0-25-17, K thiosulfate; 0-0-30-0, K carbonate; 0-0-50-17, K sulfate; 0-0-62-0, K chloride; 3-18-18-0, K phosphate + urea; 5-0-20-13, K thiosulfate + urea-triazone; 14-0-46-0, K nitrate. The non-treated control grain yield was 33.7 bu/acre. Gross margins were calculated as [(grain yield * market price) – (cost of foliar fertilizer + fertilizer application cost in absence of herbicide)].

Conclusion

Tank mixing K fertilizer sources with glyphosate may be a flexible management option for foliar K application to reduce K-deficiency in soybean. Mixtures of K fertilizer with glyphosate could help offset application costs associated with separate foliar K fertilizer applications and allow for in-season response to K deficiency when management or climatic conditions warrant application. However, proper selection of K fertilizer source is important because some K fertilizers may reduce weed control or cause crop injury that may lower grain yield.
The amount of K available to the plant may depend on the source solubility and compatibility with glyphosate. This research has determined that 14-0-46-0, 0-0-50-17, 3-18-18-0, and 0-0-62-0 controlled weeds similar to glyphosate plus DAS, and soybean grain yields were similar to the weed-free control in a soil without K deficiency. The greatest amount of K available to the plant would be with 0-0-62-0 or 3-18-18-0 tank-mixed with glyphosate while maintaining crop safety and weed control. Potassium uptake through the leaf may be affected by the presence of an adjuvant in the spray solution that may influence phytotoxicity. Soil test K at the research site used in this study was relatively high, but the primary objective was to evaluate the impact of K source on weed control with glyphosate.

Additional research may need to compare foliar K uptake with soil uptake to determine the impact of K source on glyphosate solubility and the resulting effects of the K source on herbicide absorption, and assess the economically optimal rates of K sources for weed control while providing a supplemental K source. This research demonstrated that several K fertilizer sources may be combined with glyphosate for cost-effective foliar fertilizer applications while minimizing crop injury and maintaining weed control.

Foliar Feed Plants

http://www.growersmineral.com/crops/indepth-articles/foliar-feed-plans

Foliar Feed Plans

In an issue of the Minnesota Farm Guide an article entitled "Foliar Fertilizer Feeding Leaves Plants Feeling Full" discussed the idea of using foliar feeding as an accepted agricultural practice.

By Jim Halbeisen, Director of Research

In an issue of the Minnesota Farm Guide an article entitled "Foliar Fertilizer Feeding Leaves Plants Feeling Full" discussed the idea of using foliar feeding as an accepted agricultural practice. The author referred to a custom agricultural applicator who was having success with different foliar products from a company that listed ways they thought foliar feeding would fit in with various farming operations. The article was very informative even though the company's foliar spray experience is quite limited.

Because this paper circulates in Minnesota, the University of Minnesota felt they needed to respond. The article, shown in figure one, appeared in a similar publication within a few weeks. It is apparent the U. of M. doesn't believe foliar feeding of nutrients to plants gives economic benefits.

The U. of M. article caught the eye of our District Manager/customer Ben Bechtel who farms in northwestern Wisconsin. He felt this article was hurting his Growers Mineral Solutions (GMS) business. Ben also knew that foliar spraying GMS had been quite successful on his own farm, so he rebutted U. of M's. George Rehm with his own letter, figure two.

Since nutrient foliar spraying acceptance is growing very quickly, by now farmers potentially interested could be confused by these recent opposing ideas. So how do they address these differing opinions?

When a farmer evaluates seed corn or measures the influence of an aphid spray, he has to run test plots to see what pays. When GMS came into existence in 1955 Dr. V. A. Tiedjens and J. P. Henry asked farmers to first check the profitability of GMS on test plots. This is still the case today. Growers Chemical Corporation says test plots will show farmers which responses give the best economic returns. We at Growers Chemical Corporation feel the science behind the foliar spraying of nutrients is very good, that foliar feeding has tremendous economic possibilities for all farming operations and it bears farmers' investigations.

Historically, water soluble salts of various elements, some of which came from manure and water mixtures, were first used in foliar feeding. The first published reports on foliar feeding nutrients appeared as early as 1844, and numerous others have substantiated its viability since. A great boost to the study of foliar absorption of mineral nutrients came with the availability of radioactive tracers in 1938. For the first time, accurate measurements of uptake and transport of elements were conducted, and a means of distinguishing between nutrients absorbed by the foliage and the roots was available.

Early doubters suggested that the above ground portions of plants could not absorb fertility elements. However, research sponsored by the United States Atomic Energy Commission using radioactive isotopes conducted at Michigan State University and reported in scientific publications in the early to mid 1950's, demonstrated conclusively that fertility elements applied as foliar sprays to plant leaves could be absorbed and utilized by plants.

Dr. H. B. Tukey, who was then head of the Department of Horticulture at Michigan State University, stated to the Joint Committee on Atomic Energy, for the 83rd Congress of the United States that when "we apply fertilizer nutrient materials to the above ground growing portion of the plant we have seen that materials are absorbed by the plant and move rather freely in the plant. The amounts may at first seem relatively small, but to offset this handicap, the efficiency is high. In fact, this is the most efficient method of applying fertilizer to plants that we have yet discovered. If we apply these materials to the leaves in soluble forms, as much as 95 percent of what is applied may be used by the plant. If we apply a similar amount to the soil, we find about 10 percent of it to be used." This is important!

In the 1930's Dr. V. A. Tiedjens participated in research showing that when dry fertilizer was dissolved in water and applied to the soil, it significantly improved its absorption into the plant.

Later he worked on the idea of using less quantities of fertility elements applied directly to plants, and, in the process, discovered he needed to substitute higher grade raw materials for those normally found in dry fertilizers.

In 1935 Dr. Tiedjens invented soilless culture equipment, and, in the 1940's, he was employed by The Standard Oil Company of New Jersey to establish hydroponic vegetable gardens on the islands of Aruba and Curacao in the Dutch West Indies. Drawing on this experience, he found which elements were not only necessary for healthy plant growth, but, also, what balance or ratios between them was best.

Dr. Tiedjens experimented to determine how these elements could be supplied in an economical, safe and easy to use format in the real world of farming. He demonstrated that small amounts of balanced fertility, in the proper form, correctly sprayed on the plant, showed results that were economically competitive with plants grown with larger amounts of dry fertility conventually spread on the soil. Thus he became one of the first practical advocates of foliar fertilization of the above ground portions of plants, which, incidentally, can by-pass or eliminate the soil's tendency to tie-up ground applied fertility.

Several positive articles concerning foliar spraying of plant nutrients appeared in the 2003 agricultural press (see Fluid Journal and American Fruit Grower at GrowersMineral.com, press release section). In addition, research at Purdue University suggests certain inserted genes influence uptake and tissue concentrations of certain micro nutrients in GMO soybeans. This research is causing some agricultural chemical people to remark, "If this influence can cause micro nutrient deficiencies, and if these deficiencies can impact growth and development, they may be responsible for a portion of the 'yield drag' associated with glyphosate resistant soybeans." We agree with those who express the idea that timely foliar spraying of micro nutrients could help replenish these deficiencies.

As a result of the farming style North American agriculture has pursued in recent years, foliar nutrition has today firmly established itself as a useful technique in the Mineral management of crops. Meanwhile, Growers Chemical Corporation's many years of experience has given it the expertise needed in the series of complex and interdependent events that take place during the foliar application of nutrients.

These events, and conversations with many GMS farmers over our sales area seem to indicate a very high level of interest in the foliar feeding of nutrients. Those farmers seriously looking into foliar feeding crops should definitely consider working with a company with over 50 years experience with the art of foliar nutrition.

Figure 1
News Article

Figure 2

This is a rebuttal on the article on "Foliar Spray" in the Country Today written by an Extension Agent/Professor from Minnesota.

All I have to do is recall 1988. Everyone can remember the severe drought.

That year was my second year of using foliar spray. We had corn waist high that had been rolling and curling for about 10 days. There was no rain in the forecast and the crops were getting worse every day. I called the Director of Research at Growers in Ohio and asked him about foliar spraying the corn crop. He told me they had been spraying one gallon of food pure 10-20-10 foliar solutions every 7-10 days on their crops and getting good results.

The next evening - 19th of July - we sprayed 25 acres of corn that was growing on sandy soil at Radisson, WI. I used two gallons of their 10-20-10 food pure solution. On the 22nd day of July we had 5 1/2 inches of rain. (Just 3 days after spraying). Later it looked like spring all over again. Everything was green and healthy. We harvested that crop the last week in November. We measured one acre and weighed over the scale, 137 bushel per acre at 20% moisture. The corn had very good feed quality.

I picked my neighbor's corn; he used the conventional dry program. It made 45 bushels at 30% moisture and poor feed quality. In 1998 another drought happened in our area. We went 38 days without rain. It was July 6 - August 14th. I sprayed 2 gallons of Growers on the 10th of July and again on the 1st of August. My corn that year cribbed at 135 bushel/acre of very high quality feed. 10.25% protein for ground ear corn No mold or aflatoxins.

After talking to my neighbors who used the conventional dry program, I found that had yields of 38 and 68, up to than 90 bushels per acre less. They also had aflatoxins and mold in their corn. So, Mr. Extension Agent, you might tell some people that foliar spray doesn't work but there are a lot of farmers that know it does work very well. It also produces high quality feed.

Mr. Extension Agent, there is a right time to spray; it must be at a certain stage of plant growth, time of day, and it must be a food pure solution before your plant will accept it. I feel there are a lot of factors you seem to have overlooked. If you would like to further discuss foliar program versus conventional programs you can contact me.

Cotton Response to Foliar Nutrient Application in UNR Cotton

http://msucares.com/nmrec/reports/2001/cotton/production/nutrient_unr.pdf

COTTON RESPONSE TO FOLIAR NUTRIENT APPLICATION IN UNR COTTON

N. W. Buehring, R. R. Dobbs, and M.P. Harrison.
Northeast Branch Experiment Station; North Mississippi Research and Extension Center; Mississippi State University; Verona, MS 38879

ABSTRACT: An ultra narrow row cotton study was conducted evaluating the influence of foliar slow release N (CoRoN, 25-0-0, N-P-K), N + K [CoRoN, 10-0-10, (N-P-K) plus 0.5% B] liquid solutions, and conventional foliar N applications of potassium nitrate (KNO3) and feed grade urea (46%N) applied either at pinhead square or sequential applications starting at pinhead square or first bloom. The environmental growing season for 2001 was highly variable with dry conditions from mid July through August 6, followed by excessive rainfall in late August and early September. Foliar fertilizer treatments had no visual effect on cotton growth and maturity. The CoRoN (10-0-10, plus 0.5% B) at 1 gpa applied at first bloom and repeated 14 days after first bloom had 560 lb/ac more seedcotton than the water check. Solubor and the water check had similar but lower yield than all other treatments of foliar nutrients applied. Foliar nutrients with nitrogen and potassium in combination generally showed higher yield than nitrogen or solubor applied alone.

CITATION: Buehring, N.W., R.R. Dobbs, and M.P. Harrison. 2002. Cotton response to foliar nutrient application in UNR cotton. Annual Report of the North Mississippi Research & Extension Center, Miss. Agric. & For. Expt. Sta. Info. Bull. 386. pp. 164-165.

MATERIALS AND METHODS: A study was conducted during the 2001 growing season evaluating foliar applications of slow release nitrogen [CoRoN (25-0-0)], slow release nitrogen + potassium + boron [CoRoN (10-0-10) plus 0.5% B] as liquid solutions, and conventional sources of foliar N sources as potassium nitrate and feed grade urea applied either at pinhead square or sequential applications starting at pinhead square (Table 1). The study was conducted as a randomized complete block design with 4 replications on a Leeper silty clay loam soil.

Fall fertilizer (P and K) application was based on soil test recommendations. Soil test indicated high P and low K level. Potash (K2O) at 200 lb/ac was applied broadcast to the soil surface 10/30/00. Nitrogen as ammonia nitrate was applied surface broadcast at 80 lb N/ac on 6/19/01. All foliar nutrient treatments were applied at 4 mph with TXVS-4 nozzles with a 5 gpa carrier volume and 34 psi boom pressure. The pinhead square applications were made 7/03/01. The first bloom and 9 days after first bloom applications were made 7/25/01 and 8/08/01, respectively. The 9 days after first bloom application had to be delayed due to unfavorable weather conditions until 14 days after bloom.

Land preparation consisted of disking 12/11/01; subsoiling 12/11/01; and disking 12/12/01 The study was doalled on 4/02/01 and repeated prior to planting on 5/23/01. Gramoxone (paraquat) + surfactant at 0.38 lb ai/ac + 0.4 pt/ac was applied as a burndown 4/21/01 for henbit control. Roundup Ultra (glyphosate) at 1.2 lb ai/ac was applied 5/08/01. Paymaster 1218BG/RR cultivar was planted in 9.5 rows at 100,000 seed/ac on 5/23/01. Temik 15G (aldicarb) at 0.52 lb ai/ac was applied in-furrow at planting. Roundup at 1.0 lb ai/ac was applied postemergence on 6/12/01 and repeated 6/26/01. Staple (pyrithiobac) at 1.5 oz ai/ac was applied postemergence broadcast on 7/10/01.

The major cotton insect pests in the 2001 growing season were tarnish plant bug (Lygus lineolaris), budworm (Heliothis virescens), and bollworm; (Helicoverpa zea). The following cotton insecticides were applied when insects were at threshold levels or higher. All insecticide applications were made with TXVS-4 nozzle, 5 gpa carrier volume, 45 psi, and 4 mph rate of travel. Bidrin (dicrotophos) at 0.25 lb ai/ac was applied 7/06/01 and repeated 7/19/01. Ammo (cypermethrin) at 0.1 lb ai/ac was applied 8/07/01. Karate-Z (lambda-cyhalothrin) at 0.03 lb ai/ac was applied at 0.5 lb ai/ac on 7/09/01. Pix (mepiquat chloride) at 0.03 lb ai/ac was applied 7/27/01 and repeated at 0.044 lb ai/ac on 8/30/01. Cotton was defoliated 9/21/01 with Finish (ethephon + cyclanilide) + Free Fall (thidiazuron) at 1.0 + 0.125 + 0.083 lb ai/ac. The center 11 rows of cotton were harvested with a stripper 10/23/01 . Plot seedcotton weights were recorded. Grab samples from each plot of seedcotton were collected and ginned with small sample gin to determine percent lint turnout and lint yield. All data were analyzed with statistical analysis and treatment means were separated with Fisher Protected LSD at the 5% probability level.

RESULTS AND DISCUSSION: Rainfall during the growing season was highly variable with normal rainfall in May, followed by no rainfall from July 13 to August 6, and excessive rainfall in late August and early September. However, cotton yield was about normal. During the growing season, no observable differences in treatments were noted. Seedcotton yield indicated a mean yield of 3914 lb/ac (Table 1). Solubor and the water check had lower yield than all other foliar nutrient treatments. Foliar N as feed grade urea (46% N) showed lower yield than treatments which contained nitrogen and potassium. One application of CoRoN (10-0-10) at first bloom produced similar yield to an application at first bloom followed by a repeat application 14 days after bloom or KNO3 applied at first bloom and repeated 14 days after first bloom. CoRoN (25-0-0) at 0.5 gpa applied at pin head square produced similar yield to treatments which contain nitrogen and potassium, [CoRoN (10-0-10) and KNO3 (13.5-0-45)].

MilesDr. H. B. Tukey - renowned plant researcher and Head of Michigan State University's Department of Horticulture at Michigan State College

Charlie O’Dell - Virginia Tech - Extension Emeritus

Wesley Totten and Bert McCarty - Clemson University

Dr Rich Cooper - NC State University

University of Tennessee - Prof. T.S. Osborne, Agronomist

Drs. Witter and Turkey - Michigan University - Reviewed in Readers Digest

Agricultural Chemicals Magazine - July 1962

Barney Gordon, Agronomist - North Central Experiment Field - KSU