Dealing With Herbicide Drift

By John Peragine

Nature can be unforgiving to farmers. Honest people trying in earnest to make a living growing crops regularly face storms, drought, hail and many other types of natural disasters. Today, unfortunately, these people’s neighbors sometimes add to the problem by introducing one more difficulty: herbicide drift.

All farmers face pressure from weeds. These pesky plants can consume resources — sunlight, water and nutrients — necessary for optimum plant growth. There are three primary ways to deal with the dilemma: pull, cut or use some other physical mechanism to kill the weeds; ignore them and take a loss of production; or use a substance to kill them.

Hand weeding is not typically cost-effective beyond a small acreage farm, forcing larger farms to either accept a decrease in yield or use a chemical to kill the plants. Some herbicides have little negative impact on the environment or the plants they are sprayed on. Unfortunately, though, most large-scale crops are sprayed with volatile chemicals.

Grape Vine damage caused by herbicide drift
Damage to grape vines caused by 2,4-D drift. Photos by Michael L. White, ISU Extension & Outreach Viticulture Specialist

Agricultural technology over the past century has allowed farmers to deal with weeds in a very direct and definitive manner with the use of chemical herbicides. A common herbicide is the phenoxy type (2,4-D and dicamba). This is sprayed over crops like corn around the periphery of fields and is quite effective in killing broad-leaf weeds; it is equally effective in killing similar plants such as grape vines, and dicamba is currently the topic of much discussion through-out the Midwest and beyond where it has been linked to non-target crop plant damage.

The Environmental Protection Agency defines drift as “The physical movement of pesticide droplets or particles through the air at the time of pesticide application or soon thereafter from the target site to any non- or off-target site. Spray drift shall not include movement of pesticides to non-or off-target sites caused by erosion, migration, volatility, or windblown soil particles that occurs after application or application of fumigants unless specifically addressed on the product label with respect to drift control requirements.”

There are two types of pesticide/ herbicide drift: particle and vapor. Particle drift occurs when small droplets of pesticides or herbicides travel via the wind from the field they were being applied to onto other crops.

Vapor drift occurs when temperatures in the upper 80s and 90s cause already-applied pesticides/herbicides to volatize into a vapor. These vapors then drift over great distances and destroy crops that are not immune to its destructive compounds.

The good news is that many states have laws to protect farmers from the damages caused by herbicide drift. In Iowa, laws were enacted around grape-producing regions in the western part of the state to stop the use of highly volatile herbicides in the late 1970s. The damage was done, though, and it took almost 30 years for the grape industry to bounce back. Spray drift causes a reduction in yield, poor fruit quality and even grapevine death. Problems can continue years after the drift exposure, reducing the life of a vineyard.

The degree to which crops are damaged from drift depends on the level of the susceptibility of the crop, its growth stage, environmental conditions, herbicide formulation, droplet size and the spray height above the target.

Emotions Run High

Because livelihoods are on the line, frustration and anger over herbicide drift often arises, and conflicts can ensue. Neighbors, farmers and companies will often apologize and promise they will not allow drift to occur again, but this is not always honored. Included on page 34 is a sample letter template that can be used to attempt to start a more positive conversation about drift.

If your neighbor does not respond in a positive way, you could seek assistance from your state department of agriculture.

Sample Letter

ABC Farm 123
Any Street
Anywhere, USA

XYZ Neighbor 124 Any Street Anywhere, USA

Re: Herbicide drift concerns
Dear Neighbor, I hope this finds you well and that you are having a good growing season.
I am writing to remind you that we have grape vines on two sides of the Old Grain Mill field in Hamlet township. We have registered on Driftwatch, which has a good map that shows where the vines are in case you have any questions. Here’s a link if you would like to see the online map:
I’ve also included a map that shows the location of the vineyards. Grape vines are especially sensitive to glyphosate, dicamba and 2,4-D.
We have appreciated the care you have taken over the years to avoid any problems. Unfortunately, we have had friends in the grape community who’ve had severe damage, so it seemed like a good idea to bring this up again.
Thanks for your attention to this. We’ve also spoken with your landlord about our concerns. If you have any questions, don’t hesitate to call.
Yours truly,
Friendly Farmer

Organic Solutions

There are a number of organic herbicides on the market, but they should be given the same attention as their synthetic counterparts. Organic herbicides do not offer a residual effect, which means they break down quickly after their application. This is good in that it reduces toxicity, but it also means that they have to be used more often.

Organic herbicides are not selective and can kill basil as easily as a weed, so application should be done carefully. They should be applied directly onto weeds on warm, sunny, non-windy days. They often contain fatty acids, vinegar or acetic acid, or essential oils like citrus, eugenol or clove.

Corn gluten meal can be used on larger farms, as it is a natural pre-emergence weed control for broad-leaf and grass weeds.


Sometimes the damage due to drift is so severe that compensation is necessary to replace lost crops. Michael White, Iowa State University Extension & Outreach Viticulture Specialist, says that over 95 percent of drift damage cases are settled out of court.

White suggests waiting before accepting payments from an insurance company. Some damage does not become evident until after the winter. Even though insurance companies do not like to carry claims over into another year, it is best to try to delay and not settle too soon. Once damage is suspected, White recommends taking pictures of healthy plants and damaged plants every week or two to demonstrate the progression of the damage.


Editor’s Note: This article appeared in the March 2019 issue of Acres U.S.A. magazine.

Deciding What Amount of Nutrients to Apply

By William McKibben

There is a table (Figure 4 below) below that I find help­ful in deciding how and what level of nutrients to apply to adjust soil nutrients. This table shows the means (mass flow, diffusion or intercep­tive root growth) by which nutrients are taken up through the roots. This table also shows, with the exception of copper and iron, that most nutrients are picked up out of the liquid solution by either mass flow or diffusion. The mass flow nutrients that are anions (negatively charged ion) are nitrogen (N), sulfur (S), boron (B) and molybdenum (Mo). The cations (positively charged ions) calcium (Ca) and magnesium (Mg) are more free to move in solution and travel longer distances whereas other nutrients such as phosphorus (P), potassium (K) and manganese (Mn) move very little in solution. The later nutrients typically move from areas of high concentration to low concentration, but can bond quite readily in clays and with other nutrients which reduces their mobility.

nutrient flow through roots
Figure 4.

The other very critical factor to consider is how do most of the nutri­ents move within the plant once the roots have taken them up. Nutrients like calcium, boron and manganese travel primarily in the xylem or the water transport system of the plant. This is primarily in one direction and very dependent upon the evapotranspiration (ET) happening in the plant. Calcium, boron and manganese are necessary nutrients for root development—especially calcium as it needs to be in contact with the growing root. Nutrients such as potassium and phosphorus on the other hand can travel freely in the phloem. If these nutrients are only surface applied due to no-till practices, then they will become stratified and subject to uptake only as long as the roots are active in the surface.

Looking again at Figure 4, this table can also help with interpretation of plant tissue analysis. For example, plants that are short or deficient in copper may indicate a lack of this nutrient in the soil or a root development problem. This may be a physical structure, compaction, or another nutrient problem (such as calcium level affecting root growth). I have seen an almost fourfold increase in copper deficiencies found in soybeans over corn crops. This might be just the difference between the soybean taproots and the fibrous root system of corn plants. Personally I think a lot of the problem is related to compaction issues since many of our beans are no-till planted into corn stalks. Plants tend to grow at the rate provided by the least available nutrient. Compaction issues will almost always result in many other nutrient deficiencies (especially potassium and phosphorus). There will be more on identifying nutrient deficiencies using tissue analysis later in this book.

Source: The Art of Balancing Soil Nutrients

A Guide to Reading Soil Test Results

By Charles Walters

What is a Soil Test?

A reliable soil test includes three parts:

  • Proper sampling, with field and cropping history, and yield goals.
  • Chemical tests for nutrients available for crop growth.
  • Reliable recommendations for nutrients and amendments needed to attain desired yield goals.
Klaas Martens: Soil, Testing & Fertility from the 2009 Eco-Ag Conference & Trade Show. Listen in as the popular agronomist and successful organic farmer teaches his methods for managing soil testing, data and inputs.

Reading a Soil Test

The following is how laboratory results are reported at Texas Plant & Soil Lab — other labs utilize similar terms.

Texture — Ranges from 1 (sand) to 3 (loam) to 6 (heavy clay)

Cation Exchange Capacity (CEC) — Texture determines the CEC. Textures of 1 = 3-8 CEC. Textures of 6 = 30-50 CEC.

Organic Matter (O.M.) — Humus increases CEC. About 3.5 CEC increase for each percent increase in humus. O.M. improves tilth (soil physical condition), water and nutrient holding capacity. The more the better. Ideal O.M. levels for corresponding texture levels (1-6 respectively) = 2.8, 3.1, 3.6, 4.1, 4.5, 4.8.

Natural Extracting (CO2) — Plants produce natural carbonic acid in the root zone which can be used to obtain nutrient values that are more realistic and calibrates to the plant uptake.

NO3 (N) — This highly soluble nitrate ion moves easily up and down with water and is a constantly changing value. Plant uptake is rapid. Excess can be toxic.

P2O5 (P) — Extracted with CO2, the amount is reported in pounds per acre for the top foot of soil. The amount reported is available to a crop in a normal growing season. Responses can be expected below 40 pounds per acre and high phosphorus requiring crops may respond to additional phosphate of up to a 200 pounds per acre tested.

Potassium (K) — Extractable using CO2. This is the amount available to the crop in a growing season. Readings range from of 80 ppm to 120 ppm for crops with high potash needs. Soil availabilities vary with texture, soil moisture conditions, interference from sodium levels and ratios of Na, Ca and Mg.

pH — The acidity measurement is variable. Most crops prefer a pH between 6.5 and 7.3. Neutral is 7.0, above is alkaline and below is acid. The desirable pH level is a nebulous, dynamic determination that is highly variable.

Electrical Conductivity (EC) Salts — This is a measure of total water-soluble salts expressed as mmhos/cm. EC x 640 = total dissolved solids in ppm.

Salt Cations — Water-soluble cations determined by the atomic absorption spectrophotometer. Calcium is important and should exceed 100 ppm.

CO2 extractable (carbonic acid equivalent) is the same as the plant root process. Sodium is the main extractable harmful element and should be below 180 ppm. The amount of extractable calcium reserve in the soil is also reported and must be known to properly manage excess salts.

Na (CO2)/Ca (H2O) and Na (CO2)/Mg (H2O) — These ratios help evaluate salt problems and are indicators of the soil’s physical con­dition for water, air and root penetration. The Na:Ca ratio should be less than 6 for good internal drainage. The Na:Mg ratio should be below 20 for regular crops and below 10 for sugar-producing crops such as melons, citrus, sugarcane, etc.

Source: Ask the Plant

Examples of How to Adjust to Your Soil Test Results

By Neal Kinsey

Reading your soil test and knowing what to do are two different things. Here are some examples of how to apply results to your fields based on what your soil test is indicating. It will give you confidence that you are on the right track to increasing your overall soil health.

Except in the case of wheat and other small grains, if the soil test indicates that you need ten pounds of copper sulfate but that amount represents a cost that is too high, you could consider putting on two pounds for the next five years instead of ten pounds all at once. You can build copper levels this way because that nutrient is so stable in the soil. Almost every soil analyzed is deficient in copper. The few exceptions are where there is natu­rally occurring copper in the soil or where manure has been used, or along rivers where soil has been moved in by constant flooding, and where alluvial deposits keep the soil built up. The other place where we don’t have copper deficiencies is where large amounts of pesticides containing copper have been used in the past, and where turkey litter is commonly used.

When crops on soils with adequate fertility that test low in copper fail to respond to copper applications, a molybdenum test should be considered. Both need to be present in adequate amounts, since either one can influence the amount a crop can take up of the other one.

A farmer from Iowa I had worked with for eight years called me one day. He said he had a problem with some of his corn going down. He wanted me to look at the soil test. He had 80 acres split into four 20s, and one had a 1.5 copper, his lowest level. I told him that his copper was 1.5 ppm and he was going to have the weakest stalks there. It was true. He said, “Well, since that is true, what about the next field?” We went through all the data until he hit 2 ppm. In each case he lost corn from lodging, but the lower the copper level below 2 ppm, the worse the corn was lodged.

Copper gives resilience to a plant. The other key to flavor after sulfur is copper. Copper doesn’t move in the soil. If you see a copper deficiency at all, it is like sulfur. It shows the deficiency in the young­est growth first. Adequate nitrogen means you get better copper uptake. Too much nitrogen means you actually decrease the avail­ability of copper to the plant. Wheat is a crop that responds well to copper. If the other needed nutrients are adequate, but you are below 2 ppm copper and you put enough copper on your wheat to get above 2 ppm, it will produce an extra five bushels (300 pounds/acre) of wheat.

I was asked to make a consulting trip to Germany in 1985. The client who asked me there had arranged for speaking engagements to several groups of farmers. He told me to tell them just what I had done on his farms. In Germany, they use the taller varieties of wheat, but they also use growth regulators to keep plants short. When the subject turned to copper, I mentioned that if the soil had below 2 ppm and copper was put on, it would increase yields by five bushels per acre. I also told them that every soil I had checked in Germany was below that level. One man raised his hand, stood up and spoke for two or three minutes. The interpreter leaned over and said, “This is the man who is in charge of fertility for the university in this area. He is telling the farmers why they don’t need to really worry about the copper that you said should be put on.” When he had finished, a doctor of fertility research rose and reported a ten-year study (unknown to me) just completed which had shown exactly the same results I had mentioned on wheat production.

Copper sulfate, 22.5 or 23 percent, is water-soluble and can be applied to soil or as a foliar. A word of caution here. When cop­per is mixed in solution with other elements it may show as compatible in the mix, but use it up. Do not let it set in your spray tank, pumps or hoses overnight. It can harden to the point that the entire spraying apparatus has to be scrapped. I won’t bother with other copper sources if I can get copper sulfate because I know it works, and I know how much can be applied safely. A ten-pound application of copper sulfate—after 12 months time—will raise the copper level by 0.6 ppm on the spe­cific test we use. A copper level is the easiest to build and main­tain, and zinc is next in the pecking order. Both have staying power in the soil.

Zinc aids in the absorption of moisture. Along with potassium, think of zinc in critical moisture situations. It also helps transform carbohydrates. It regulates plant sugar use. Zinc plays a role in enzyme system functioning, as well as with the growth regulators normally present in the plant and protein synthesis.

Consider zinc needs, especially in sensitive crops such as corn and grain sorghum, also soybeans and dry beans. As far as zinc levels are concerned, the minimum is 6 ppm. Below that, enough should be applied the first year to get up above the 6 ppm figure. There has never been a soil—in my experience at least—that required more than 30 pounds of zinc sulfate to completely take care of the worst zinc deficiency, provided limestone didn’t have to be applied at the same time. If lime is applied, the lime won’t drive out the zinc, but it will affect zinc availability. If you need zinc and lime and put on the lime but don’t put on the zinc, expect your zinc level to get worse. Zinc probably gives a response more often than any other micronutrient when it is applied for crop production. I see many soils that need zinc. All can be taken care of, generally with excellent response. Only a few crops do not respond well to zinc when only slightly deficient, one of them being wheat. Again, for zinc, 6 ppm is the minimum. Excellent means at least 10 ppm, and an excess is 35+ ppm.

A classic sign of zinc deficiency in corn is the whitish stripe in the leaf color, which looks much like a magnesium deficiency. In the field, often I can’t tell whether it is a zinc deficiency or a magnesium deficiency. The difference between zinc and magne­sium deficiencies should be that zinc will be white and magne­sium will be white on top with a purplish color on the bottom.

High phosphorous, high calcium or high potassium levels can induce zinc deficiencies as does the overuse of nitrogen. Also, as the pH goes up from 6, when a soil has good zinc levels, availability begins to decrease. It can go as high as pH 7 before it decreases good zinc availability to the point that it becomes a problem. Heavy cuts, such as when the field has been graded or the topsoil has been taken away, or when eroded soil allows sub­soils to appear, strong zinc deficiencies become evident.

Zinc is not easy to leach away. It is held well on clay and humus. Once zinc levels are improved, it is relatively easy to keep them up. When zinc sulfate is applied on the tests we have, an exact relationship between the amount of zinc applied and the increase shown on the soil test can be expected. Using 36% zinc sulfate at an application of 10 pounds per acre will exhibit a 3.6-pound increase of zinc on the test. The correlation is classic. Putting on ten pounds of 36% zinc sulfate means putting on 3.6 pounds of zinc per acre. A soil test — when the zinc is finished breaking down — should show an increase of 3.6 pounds of zinc. That translates into 1.8 ppm, meaning every 10 pounds of zinc sulfate applied will raise the zinc level by 1.8 ppm. There is one other thing to be remembered about pure zinc sulfate. Put on ten pounds of zinc sulfate today, then come back next year and pull a soil test on the same day. That zinc is only going to be halfway to its final level. You are only going to see a 0.9 ppm increase in the soil. When you put on sufficient zinc it will not reach the desired level for two years, but will supply enough zinc for the crops grown for both years.

Some firms say they have a 36% zinc product, it being a 36% oxysulfate. It is cheaper at the counter, but it does not always build zinc levels. There are some zinc oxide products that have been pulverized and then prilled, which have also proved effec­tive for increasing the levels in the soil. Apply ten pounds, the same as with 36% zinc sulfate, and see if next year the deficiency is still there. Pure zinc sulfate is the sure choice.

With the exception of boron, on most soils the technology exists in order to build the levels of trace elements to a point that it is not an annual expense, but basically an initial expenditure. Then afterwards, it is a matter of testing and fertilizing as need­ed over the years to keep the levels up. Many farmers, ranchers and growers initially resist the addition of trace elements to increase fertility levels, objecting to the added expense. But when you consider the years spent taking from the soil without adding the traces back, replenishing should be expected. And supplying those micronutrients have helped increase corn yields by 20-30 bushels, and wheat from 5-25 bushels per acre. Micronutrients, when applied in the right form, to build up the levels in the soil will help quality and crop yields accordingly.

Some farmers who have livestock have always felt they shouldn’t have to be concerned with trace elements because their manure or compost would take care of it. I work with many farmers who use manures and compost, and this is rarely the case. Think about it. When a soil is deficient in copper and adequate copper is not being supplemented, how can enough be in the manure? Manure is generally low in sulfur, boron and copper—the nutrients most often lacking in our soils used for growing the crops. Keep in mind, when manure is applied, you can influence the soil nutrient level to only the extent of what is there in the first place. Nevertheless, manure is certainly helpful and in certain soils even sufficient to keep the trace elements that are present in a soil most available for plant use, while at the same time helping to recycle those that are picked up in the feed. And therefore, as the use of manures in an area declines, the need for trace elements will increase.

Most soils we analyze just do not have an adequate supply of trace elements to assure that the crop will do its best. So keep in mind that just because there are enough of the major elements for the crop, does not assure that trace element levels will also be adequate.

Under the present economic circumstances, every farmer needs to have the confidence that he is on a solid footing, and doing all he can to supply his crops the fertility needed from start to finish. The misconceptions and misunderstandings about soil fertility make this even harder to accomplish. The more farmers or those involved in a soil fertility program understand the reasons behind micronutrient recommenda­tions, the more confidence there will be in those recommenda­tions and the decisions made on how to use them. The lack of any nutrient, whether needed in major, secondary or trace amounts, hurts the soil and all that must live from it.

Source: Hands-On Agronomy

Understanding Solubility & Paste Testing

By William McKibben

Paste Testing

Low exchange capacity soils especially have a lot of issues when it comes to holding enough nutrients and maintaining colloidal balance. Sand with low organic matter is basically a soilless media. Since many of the nutri­ents required for crop production are not on the colloid, I find that the paste test is absolutely the best test for this situation. I also use the paste test along with the standard test on the higher exchange capacity soils. Since most of the nutrients taken up by plants are picked up by mass flow or diffusion at the air/water interface near the plant roots, the paste test better correlates to tissue analysis than the standard test.

The paste test is done primarily by taking a large sample, approxi­mately 200-400 grams of a composite soil mixture and saturating it with distilled water (or even better is to use clients’ irrigation water) until it becomes a pancake batter consistency.

Making Paste Analysis Recommendations

Making recommendations from a paste analysis incorporates both the SLAN approach and the BCSR approach. First, it is critical to meet the minimum strategic nutrient levels for growth and reproduc­tion (Figure 16). Secondly, the nutrients in solution should be kept in balance to minimize interference issues. Even if all the strategic levels have been met, if a nutrient such as potassium is two or three times higher than the desired level, other cations such as calcium and magne­sium should be elevated in order to maintain a balance. The type of crop and the level on the standard test would help make that determination. For crops such as corn or alfalfa that require a lot of potassium if the standard test does not show good levels of potassium, I would probably let the level stand and not elevate the calcium and magnesium. When raising levels to just balance out one nutrient, care must be taken not to create a salt issue. If the nutrient in excess is sodium and irrigation is available, flushing the soil may be the best solution. Most of the sodium issues that I see are created by irrigation practices. Irrigating with poor quality water or using poorly designed irrigation systems may result in the accumulation of sodium and/or bicarbonates.

Discussion of Paste Guidelines

The guidelines for the paste test shown on Figure 16 are just that —guidelines. I cannot emphasize enough that everyone needs to adjust these numbers based on their own crop tissue analysis and the subsequent crop response. There is one unknown factor that we face when using paste numbers and this is what I call the “flow rate into solution.

Paste level guidelines
Figure 1.0

Solubility Testing

Just what is a soil paste or solubility test and when should you consider running the analysis? Solubility analysis is an attempt to see what is in the soil solution, or that which can readily go into solution off the colloid.

The diagram below is a conceptual picture of a root hair in the soil solution in proximity to a clay particle or soil colloid.

The diagram 1.0 is a conceptual picture of a root hair in the soil solution in proximity to a clay particle or soil colloid. The standard soil analysis measures the dots (nutrients) floating in solution as well as the dots (nutrients) held on the surface of the clay mineral, but not those trapped between the clay layers. In a standard soil test, the minerals attached to the surface of the clay particle are removed for analysis by using an extracting solution. A solubility analysis primarily looks at only the blue dots (nutrients) floating in solution.

Soil test diagram

It makes perfect sense to look at a test that measures nutrients only in solution when you study the research work done by Barber and Olsen in 1968 and Dennis in 1971. That research showed the bulk of the soil nutrients taken up by plants was through mass flow and diffusion from the soil solution. Very little nutrition enters the plants by the roots directly intercepting nutrients from the colloid or soil particles. So when should you use a solubility analysis? Those soils with exchange capacities less than 10 should be the first targeted for solubility analysis. This includes all sandy soils even calcareous sands, which tend to get exaggerated TECs on the standard soil test. It is nearly impossible to balance and hold that balance on low exchange capacity soils.

It makes perfect sense to look at a test that measures nutrients only in solution when you study the research work done by Barber and Olsen in 1968 and Dennis in 1971. That research showed the bulk of the soil nutrients taken up by plants was through mass flow and diffusion from the soil solution. Very little nutrition enters the plants by the roots directly intercepting nutrients from the colloid or soil particles. So when should you use a solubility analysis? Those soils with exchange capacities less than 10 should be the first targeted for solubility analysis. This includes all sandy soils even calcareous sands, which tend to get exaggerated TECs on the standard soil test. It is nearly impossible to balance and hold that balance on low exchange capacity soils.

Since the holding capacity of low exchange soils is so small, plants grown on these soils primarily get their nutrition from applied nutrients with variable degrees of solubility. Solubility analysis will take you to a whole new level of understanding the relationship of soil and plant nutrition. When combined with the standard soil test and plant analysis you will get a much clearer picture of what soil nutrition means.

Source: The Art of Balancing Soil Nutrients

How to Read a Soil Test

By Charles Walters

The first step on the road to achieving healthy soils able to sustain productive plants is the soil or plant analysis test. For optimum results, the initial test relies heavily on proper sampling.

Quality samples submitted to the laboratory and excellent testing methods can produce the most accurate results possible but without an interpretation of the nutrient recommen­dations that speaks to the grower — all may be for naught.

Graphs and charts filled with color-coded lists of numbers speak volumes to those that know how to read them. But the uninitiated may glean just a fraction of the total message.

A soil or plant analysis test from a quality laboratory contains much more than just the raw data. Using an integration of field and cropping history with the test results, interpretations and recommen­dations are formulated to tell the grower the meaning behind the num­bers. It is these soil and plant test interpretations and recommendations that matter most and have the greatest benefit for many people.

Agronomist Esper K. Chandler, author of Ask the Plant and founder of TPS Lab, was asked to look at several plant and soil analysis tests from different crops and give his expert interpretation of the results. The results are below. For each example, Chandler’s com­ments offer new insight and enlightenment about what the results said to him. The soil and plant test samples presented in this chapter are actual real-life examples included here with Chandler’s dictated interpretation and recommendations — presented so others can gain a deeper insight into the important messages held within. For each example, the most important messages have been highlighted and explained by Chandler.

Above: A Guide from TPS Lab on Compost STA Test Reports. 

Source: Ask the Plant;

Using Lime to “Restock” the Soil

By William A. Albrecht

When limestone is put on the soil, it accepts acidity from the clay, just as other minerals do in the rock weathering processes. As a carbonate, it changes the active acid, or hydrogen, into water, of which compound the hydrogen is not such a highly active acid element. Therefore, the lime­stone corrects or neutralizes the soil acidity.

It has, however, been shown that this neutralizing effect from the liming operation is not so much the particular benefit derived by the crop, because compounds of calcium that do not neutralize the acidity, like calcium chloride, calcium sulfate or gypsum, and even ordinary cement for example, can improve the legume crop as well as calcium carbonate. Liming the soil puts calcium (or both calcium and magnesium if dolomitic limestone is used) on the clay, and thereby makes up this shortage on the list of nourishment of the crop.

It feeds the plant this one nutrient that the better forage legumes need so badly for their good growth and which is so readily removed from soils under higher rainfalls. It is the calcium put in, more than the acidity put out, that comes as the beneficial effect from liming the soil.

A farmer liming his fields after harvest.
A farmer liming his fields after harvest.

Source: Albrecht on Calcium

Key Elements for Maximum Yield

By Charles Walters and Esper K. Chandler

If you’re looking for a basic checklist to ensure you are maximizing your corn yields, here are some ideas. Build your own checklist using these tips:

During Early Start

Use good vigorous seed. Aid plants with a small amount of high-P pop-up fertilizer in the furrow with a balance of all nutrients and plant growth stimulators (hormones) such as 1-2 oz. of PGR-IV or equivalent (such as enzymes, microbes, energy and humic acid 1-2 pts./ac.).

At Early Growth

Physiologically, the number of rows of grain are fixed during the embryo stage before the plant has 7 leaves (12 inches tall). Prior to this at the three to four leaf stage, analyze for nutrients in the whole plants. Applying corrective foliar application of nutrients, hormones, enzymes, humic acid and other plant growth aids can help plants overcome weather and other field stresses to optimize genetic yield potentials.

Creating a routine every year focused on yields is a best practice for all farmers.

At Boot Stage

Analyze the nutrients in the youngest mature leaf. Just prior to pollination apply plant growth stimulators (hormones) plus needed foliar nutrients (especially zinc and other growth enhancers), which can stimulate roots and the entire plant functions to boost yields.

After Pollination

Analyze the nutrients in the ear leaf. When silks first turn brown and the grain is filling, supplemental nutrients, especially readily available N (and other aids) in foliar or irrigation application, may greatly increase yields by filling all the grains on the ear.

Any one of these or a combination of all has been shown to increase profits!

Source: Ask the Plant


Boosting Yields By Balancing Nutrients

By Marcy Nameth & Charles Walters

Ensuring that corn absorbs the right balance of nitrogen, phosphorus and potassium is crucial to increasing global yields, a Purdue and Kansas State University study finds.

A review of data from more than 150 studies from the United States and other regions showed that high yields were linked to production systems in which corn plants took up key nutrients at specific ratios — nitrogen and phosphorus at a ratio of 5-to-1 and nitrogen and potassium at a ratio of 1-to-1. These nutrient uptake ratios were associated with high yields regardless of the region where the corn was grown.

“The agricultural community has put a lot of emphasis on nitrogen as a means of increasing yields, but this study highlights the greater importance of nutrient balance,” said Tony Vyn, Purdue professor of agronomy. “We will not be able to continually boost global corn yields and achieve food security without providing adequate and balanced nutrients.” The paper was published online in the Agronomy Journal.

While U.S. corn producers have long relied on nitrogen fertilizers to improve yields, they should not overlook other nutrients such as potassium and phosphorus, Vyn said.

Rows of organically managed corn on the left compared to rows of conventionally managed corn on the right
The corn grown on the organically managed soil (left) in the long-term Rodale Farming Systems Trial has greater drought tolerance than the conventionally grown corn (right) due to better water-holding capacity.

“Growers need to be as concerned about the amount of potassium available to their plants as they are about nitrogen,” he said. “Corn’s demand for nitrogen and potassium is similar. We need to focus on the nitrogen-potassium balance because that’s where we have the greatest deficiency in terms of application, especially in the eastern Corn Belt.”

Soil expert and author William McKibben, The Art of Balancing Soil Nutrients, from the 2009 Eco-Ag Conference & Trade Show. (1 hour, 8 minutes). Listen in as McKibben talks about the steps you can take after you receive your soil test results to help balance your soil.

Inputs vs. Efficiency

Agricultural historians still debate whether wheat or corn rate top historical billing. The land now known as Iraq is recognized as the birthplace of grain production. Ironically, Texas Plant & Soil Lab par­ticipated with the USDA and the 1st Cavalry Division in a wheat crop restoration project in Iraq that failed due to bureaucratic inefficiency. Wheat, in fact, was an international crop before there were nations, and the diligent work of plant breeding proceeded long before there were universities to teach the art. The art of feeding the soil to feed plants was well established in Homer’s time, but refinements of that art are still continuing to this day.

Corn is the one crop that exhibits production potential beyond the dreams of possibility. Twinning, even three ears per stalk, is evi­dently possible, even practical, albeit elusive.

High-density corn population can deliver more stover than ears per acre, but “How much of our resources should we be willing to spend to achieve the maximum grain and/or silage performance?” That question about production goals suggests more than one approach to other production programs. How many nutrients and how much water are we tying up in stalks before the factors of production run into that leaf, and the photons of energy process takes place? Energy must be stored in the grain — and more than one ear of grain on that stalk produces maximum economic yield (MEY). The whole picture always remains in question. The main source of energy is sunlight.

It hits that surface of the leaf and ignites all those miracles that go on within that leaf. “If we look at the physiology of that plant,” Agronomist Esper K. Chandler notes, “and plant growth hormones, activators . . . there are so many compounds, it dazzles the imagination. We have looked at three or four major hormones, but there are several dozen others we have not even looked at yet.”

This is not to say that independent investigators are not looking, but often hormone/enzyme-type products are being overlooked. Activators have arrived on-scene. Natural products can stimulate the overall func­tions of that plant physiology, but it all goes back to the sun’s photons of light reaching that leaf. In turn, the leaf has to have the proper moisture and flow of nutrients so that the photosynthate factory can function.

Chandler, co-author of Ask the Plant, admits that it puzzles him. “When I look at the Krebs cycle, compounds, sugars, starches, enzymes, as well as hormones — my head swims.” A head that swims often calls up memories of events occurring before the arrival of the present impasse. In Chandler’s case, it was a reminder that the farmer’s job is to work with Nature, not against her. The sheer complexity of Nature’s system knocks into a cocked hat the idea that our brand of research science has disposed of all the variables. We are nonetheless impelled to influence the demands and foibles of nature. And so the esoteric formulas of natural/organics beckon, even though the pursuit of economic yield stays on course, mov­ing straight ahead.

The prep sheets that Chandler and his associates put out are not filled with doctrinaire imperatives divorced from bottom-line reality. Chandler cautions, “We can’t keep buying inputs for the fields without reference to what the stuff is doing to the bottom line. You see corn being grown in the Higher Plains where water is a finite resource. The Ogallala Aquifer is going down. In 10-15 years we’ll be searching for water. At the same time we have the sunlight units up there as well as growing conditions that enable those 300 and 400 bushels. Even so, there is a wasting away of resources with overpopulation of stalks, and overuse of water. In specific areas it may be good arithmetic — but poor economics.”

Unlike the government, Chandler never underwrites failures. His forté is called good practices. There are cross-currents. In the case of the High Plains and corn, the saving factor has become drip-irrigation, a system that becomes an inherent partner with the balanced nutrition that Chandler stresses, monitored by leaf and petiole analysis that pro­ceeds almost as routinely as a dairyman taking a somatic cell count.

“Science-led and spoon-fed” might well serve as a Chandler slogan, along with “ask the plant.” “Spoon-fed” and “ask the plant” are more than wishful thinking. It takes discipline and a desire to bring the prob­lem into compliance with his own objectives, which, more often than not, break traditional practices.

Chandler remembers the basics and he tags them with the term “efficiency.” Mass inputs do not constitute efficiency. Fence-row to fence-row farming does not square with maximum economic yields. Chandler never works out a crop equation without a full appreciation of the fixed costs and the variable expenses. Usually this means increasing yields with available inputs, in effect testing earlier yields, not with “get bigger,” but with “get smarter.” The real function is to bring the farm back to a natural state, one in which the natural nitrogen cycle works to the maximum possible, and one that serves up a natural carbon cycle as a working mechanism.

Source: Ask the Plant; The November 2014 issue of Acres U.S.A.

Reading Tissue Analysis to Determine Health

By William L. McKibben

Tissue analysis is a great way to verify soil additive claims. I am sure everyone has heard many claims about using this or that product will release nutrients locked up in the soil. What better way to find out than to use a tissue analysis and plant weights to really see if this is true.

This guide to understanding tissue analysis (from an agronomist’s point of view) is probably a very different approach than that from which a plant physiologist might take.

The place to always start is with the established tissue guidelines. Keep in mind though that many of these guidelines were set up over 40 years ago. Therefore we may need to constantly tweak the numbers to achieve maximum quality and production. I believe that one of the most impor­tant steps in tissue analysis is being able to relate the data back to plant weight. Plants adjust their growth based on the least available nutrient and therefore will slow down growth and size to match their nutrient feed uptake. It is for this reason that when good and bad tissue samples are analyzed, they come back from the lab looking very close to the same.

corn plant weights chart
From the Art of Balancing Soil Nutrients.

When it comes to plants, bigger is generally better, with healthier and larger plants tending to provide bigger yields. Therefore when sampling tissues, it is imperative to collect the same number of leaves or plants and weigh them. Even though you may not be comparing tissue within a field, you will be comparing them to your healthy, high-yielding crop standard. Figure 87 shows a weight range of corn plants collected at the pre-6 leaf collar stage for whole plants and at the 7-leaf collar stage.

You can see there is wide range of weights within the various maturi­ties of the corn plants collected at the pre-6 leaf collar stages. This range varies as much as 300 percent. This data was collected over one season and tissue analysis was preformed on each composite sample of 12 plants or leaves. The weight range narrows considerably when sam­pling only the leaves and this sampling probably would not be necessary unless you are making a comparison between good and bad plants.

desired nutrient levels for corn chart
Courtesy of Balancing Soil Nutrients.

The range of the nutrients varies about 200% for the whole plants, but narrows somewhat when just looking at the leaves. When examin­ing the data for individual samples the heaviest plants usually do not have the highest nutrient values. The lighter samples have some of the highest nutrient numbers. Therefore comparing all these samples on an equal basis without adjusting for the weight for the whole plant samples is like comparing a 300-pound mini-horse to a 2,000-pound drafthorse. The horse blood analysis would be very comparable, but the level of work that could be done by each horse would be vastly different.

This adjustment by weight is really only practical for crops planted on an individual basis like corn. Wheat could be done, but it would be very time consuming. For turfgrass, tissue numbers could be adjusted by clipping weight. It would not be very practical to collect whole fields, but collecting sample areas and calculating that to the whole field, green or tee could be done without too much problem.

Why sample this early in the crop maturity anyway? Grass crops such as corn and wheat determine some of their yield very early. Corn, for instance, is determining the number of ear kernel rows around the 6-leaf collar stage. It would also be good to sample corn at the tassling stage—another critical time in which ear length is being determined.

Soybean yields are determined during the back third of the season so I tend to hold off tissue sampling until that time unless something is restricting the growth during the earlier vegetative stage. Tissue sam­pling is best done prior to the critical times in the crop lifecycle.

With a standard soil test the amount of exchangeable nutrients in the soil is known. A paste test tells what is in solution and now we know that the tissue test tells us how well the nutrients are being picked up out of the solution. Using a combination of testing tools such as the standard and paste soil test along with tissue analysis will go a long way toward understanding crop production issues.

Ultimately all crop production issues can come back to nutritional problems. Unfortunately these crop production problems, whether quality or quantity issues, are not always related to the level of nutrients in a soil. Diseases or root pruning caused by insects can easily restrict nutrient uptake too. Also remember that compaction is still the top reason for limiting nutrient uptake.

corn nutrient range chart
Courtesy of Art of Balancing Soil Nutrients.

Figure 88 shows a seed treatment test that I was working on in 2007. Although there were large differences in weights and nutrient levels at 6-leaf collar stage, the yields were essentially the same at harvest with the exception of the outside 6 rows. The outside 6 rows received limited compaction. I have in the past tested the soil in the outside 15 feet and found it to have poorer fertility than the center of the field. The compaction, along with fertility shortages in the center of the field, neutralized the gains set up by the seed treatment. Many of the disease issues in crops are nutritionally related. I am certainly not qualified to discuss this topic in much depth, but the book Mineral Nutrition and Plant Disease written by a number of authors and edited by Datnoff, Elmer and Huber is certainly a book that should be in everyone’s personal library.

Personally I have seen that fungicide applications on soybeans have not yielded much response, especially where a foliar application of manganese was applied to improve plant nutrition.

Source: The Art of Balancing Soil Nutrients by William McKibbin