By Neal Kinsey
High-quality, high-yielding crops are the goal for most farmers. But where do you begin? Some even insist that to have both is simply impossible to accomplish. For those who think that way, it will likely always be true. But for those who are looking for ways to improve and believe there is still room to do so, what should be considered first? And then where do you go from that point to make the most possible difference?
To get high-quality, high-yielding crops, begin with the soil where they will be growing by performing the closest examination of all the most important factors needed to meet every possible requirement. What provides the most advantage to the crop from that soil? Some will feel the answer here is a heavy fertilizer program for the crop. Sufficient fertilizer is extremely important, but to achieve high-quality, high-yielding crops, there is another requirement that is also essential to assure the greatest value from whatever fertilizer is applied.
For each soil to perform at its best requires a balance of water, air, minerals and organic matter. Specifically, if you want the soil to do its best it should contain a balance of 50 percent solids (ideally 45 percent minerals and 5 percent humus) and 50 percent pore space (composed of 50 percent water and 50 percent air). This is the correct physical composition of extremely productive, high-performance soils. To be consistently efficient it is a necessary requirement to develop the most effective biologically active environment to build the needed extensively developed root systems of high-quality, high-yielding crops.
But most soils are moderately to severely lacking when it comes to having the proper physical structure to provide the correct amount of water, air and minerals, let alone the needed humus. If soils are lacking this basic foundational set of requirements, until these problems are solved, the efficiency for top yields and quality will not be achieved from the crops being grown on that soil. And thus the next question should be, “If you don’t have the right physical structure in a soil, how do you solve that problem?”
Proper Soil Structure for High-Quality, High-Yielding Crops
You can only manage those things you can measure. Farmers, ranchers or other producers can manage physical structure, because in spite of what many so-called experts still insist cannot be done, the soil’s physical structure can be measured and needed corrections determined by use of a detailed soil analysis. This requires sufficient planning beforehand in that each significant difference in the field that is to be corrected should be sampled and analyzed separately. For most fields this will mean three to five areas or zones that will require a separate detailed analysis. As a rule, those who advocate the use of one soil test to develop a fertilizer plan to treat the whole field are selling their program of products to use, not the program needed for helping each farmer get the most from each different area of the field.
The physical structure of each soil is determined by the measured influence of the same four elements that most influence the pH of soils where high-quality, high-yielding crops are generally being grown. These four elements are calcium, magnesium, potassium and sodium. When soils have the proper combination of these four elements they will be most closely matched to the proper amount of water, air and minerals they should contain. For those soils that do not have the correct structure, the soil analysis can be used to determine what needed corrections should be required to achieve it and in what amounts.
Most of those involved in soil fertility and fertilization reject the methodology required to accomplish this program. They fail to grasp the need for a precise testing methodology and assume that all soil testing that reports the content of calcium, magnesium, potassium and sodium are essentially providing the same answer. Nothing could be further from the truth. All that is required to know better than that is to take samples of the same soil and send it to two different soil testing laboratories to see the difference.
And for those who doubt that would be enough, take a soil probe and prepare four sample bags. Mark them as numbers 1 through 4. Now choose a uniform area and take the first probe of soil and place it in sample bag #1. Take the next probe of soil down to the same depth from the immediate right or left of the first as close together as possible and place it in bag #2. For bag #3, drop down just below where sample 2 was pulled, still as close as possible without hitting the place where soil was removed for #1 or #2, and take a probe of soil for that sample bag. Then move over just below #1 and take the probe of soil to go into bag #4. If the uniform area is large enough, repeat this procedure at least four or five more times if possible. Now select two of these soils and send them to one of the labs and the other two to the other lab as if they are two different soils to be analyzed by both labs. Then compare the numbers when the test results come back.
As a rule, the numbers should be close to the same for the two samples each lab has analyzed, but quite different numbers should be expected when compared to the other soil lab’s test results. Without some training to gain a thorough understanding in order to grasp the need for using the same laboratory every time and using field work based on what the numbers actually show from that specific lab those who even want to understand will not grasp these concepts. And those who do not want it to work under any circumstances will keep using this common false assumption about all the lab tests being the same as a smokescreen to make their claims and try to discourage the true use of the program.
Keep in mind that in order to achieve high-quality, high-yielding crops, assuring the proper soil structure is the place to begin. And without using a detailed soil analysis to measure whether the soil has this physical structure and make any needed corrections, only soils that are already perfect could ever be up to the task. But for those who have the vision to proceed with a measureable plan when conditions are not ideal, the possibilities are extremely good and in many cases rather easily within reach.
Use the chemistry of the soil to correct the physical structure which in turn builds the house for the biology. Roots, earthworms, soil microbes and all other life in the soil are all strongly affected by the environment that is created when good soil porosity is present. That porosity, which helps determine the correct amount of minerals, water and air, is only present when the correct nutrients are present in specifically determined amounts. Because most soils do not have the proper structure, without this key, these same soils will never achieve their top potential in terms of yield and quality.
Fertility and Fertilization Support High-Quality, High-Yielding Crops
Once the proper structure of a soil has been addressed, then to be most effective supplying needed fertility levels with fertilizer and soil amendments is the next consideration. And again, for fertilization to be most effective in building high yields and quality, the importance of soil chemistry and its effects on physical structure must be correctly measured and properly considered. This is because the nutrient content of the soil determines how well all needed fertilizer that is applied can be taken up and utilized by the plants that are growing there. When the soil has too much of any element the excess will result in the crop not getting enough of something else it needs to support high-quality, high-yielding crops.
The most efficient uptake and utilization of nutrients begins with the calcium content of the soil. As Dr. William Albrecht would say, “Calcium is like the doorman that opens the way for all other nutrients to enter into the plant.” Without adequate calcium, it requires even larger amounts of all the other essential nutrients to produce the same yield.
And while considering the importance of calcium in the soil, beware of a trap that catches some growers striving for top quality and yields which prevents them from reaching such goals. This trap is trying to achieve a specific ratio for calcium to magnesium in the soil. With the system being advocated and utilized here for high-quality, high-yielding crops, such a program will not work. In fact, there is no one ideal ratio of calcium to magnesium for soils when they are being measured as available nutrients for the crop. That is because the calcium to magnesium ratio will vary from 7:1 on heavy clay soils, all the way to 3:1 on very light sandy soils.
As the clay decreases in a soil and as the silt and/or sand increases, the less magnesium by weight will be needed to provide what the plants need to grow best. It is the amount of negatively charged clay and humus particles in the soil that determines the amount of calcium and magnesium needed. The amount needed is expressed as the percent of the total nutrient-holding capacity of each individual soil. In the case of calcium the required level would be 60-70 percent, and for magnesium 10-20 percent of the soil’s total exchange capacity.
The soil test then needs to show how many pounds of that nutrient are needed to supply the proper amount for that soil to grow the best crops possible. Apply the proper pounds of material to correct any deficiencies and at the same time this begins to provide for achieving the correct percentage of each nutrient required to grow the best yield and quality on that land.
You may be able to grow a good crop without the addition of more fertilizer, but you cannot capture the land’s true potential without the proper amount of fertility. Calcium and magnesium provide for the long-range goals in terms of soil fertility needed to reach the best in regard to yield and quality. Without the proper amount of both of these needed nutrients the soil’s true potential will never be met.
Next consider that to produce the crop you need to grow this year, any nitrogen, phosphate, potassium or sulfur deficiency would generally take precedence over calcium and magnesium. This rule is especially true for crops other than legumes. Once these four nutrients are present in adequate amounts be sure you use a soil test that can measure this in order not to continue to apply them at the expense of other needed materials. For example, using an excessive amount of nitrogen will tie up copper. Copper provides stalk strength and resilience in the plant. In terms of nutritional value, copper is required for protein utilization in livestock. Too much nitrogen can contribute to stalk lodging and diminish protein value for the crop.
Phosphorous in excess is antagonistic to sulfur availability, ties up zinc and when excessive enough, also copper. Sulfur is needed for root development and plant protein. Zinc is needed for moisture absorption into the plant. So even though adequate to good P levels can positively influence root growth, too much can hinder proper root development because of its effect on S availability and, due to zinc tie-up, can be responsible for the failure to take up moisture even when it is present in the soil in adequate amounts.
Too much potassium can be a problem too. Once above 7.5 percent saturation it ties up boron. And in combination with sodium, together totaling 10 percent or higher, manganese uptake will be blocked. Boron is necessary for nitrogen utilization in the plant throughout the growing season. It also takes the starch out of the leaf to build fruit and grain size. Manganese is needed for seed germination, faster and taller growth, bloom and seed set and stalk strength. When the soil has too much potassium it will contribute to these problems.
Sulfur in excess is also a problem. When too much is present, it ties up nitrate nitrogen and inhibits phosphate availability. Too much sulfur can also reduce molybdenum availability. As long as it is utilized properly to feed the crops and reduce excesses of calcium, magnesium, potassium or sodium, sulfur is extremely beneficial, but once those needs are met, more than that will begin to cause problems. After assuring adequate N-P-K-S for the soil and crop and once the needed calcium and magnesium have been applied, then micronutrients that are deficient can become the nutrients that are limiting yield.
Trace Minerals for High-Quality, High-Yielding Crops
Boron, like sulfur and nitrogen, can be leached from the soil, especially in years where there is more than enough rain during the fruiting stage of the crop. Most soils are lacking the recommended minimum of 0.80 ppm and several good rains can make that even worse. When you do not get good grain fill with adequate P levels already in the soil, check the boron.
Iron can be a problem especially where calcium or phosphate is in excess in the soil. But before more is added it is best to check its availability in the subsoil. As long as the subsoil is higher in iron than manganese, if the roots can get down to it, there should be no problem.
Manganese tends to be deficient more often in cool, wet soils. All soils need at least 40 ppm for the type of testing we do. Woody plants do even better at 125 ppm+. Growing rice or use of ammonium sulfate tend to increase manganese availability in soils. But if there is a serious deficiency do not wait, for such methods are slow enough that they should only be considered once there is enough in order to assure that continues to be the case.
Copper should be at least 2 ppm on our tests. Above this level and in combination with adequate boron it is the key to control rust and fungal diseases. And because it helps in protein conversion in livestock, the first obvious sign is a slick shiny coat on the animals. Copper is also the third key to stalk strength behind potassium and manganese.
Zinc is perhaps the best-known and most often applied of the trace minerals. As long as there is enough potassium, zinc is the next key to proper water uptake by plants. Minimum for our testing is 6 ppm, but as the P level increases, so does the need for zinc. When zinc is applied, expect that only half of the potential increase will be in the first 12 months, then the other half in the next 12 months. And just as an extreme excess of phosphate ties up zinc, an extreme amount of zinc can also tie up P availability.
So in every instance when it comes to nutrient needs of the crop, it is possible to use so much that it will cause a problem with the availability of one or more other needed nutrients. Consider again, you cannot manage what you cannot measure. All of these can be properly measured and evaluated and once it has been done and the problems solved, only then can the greatest possibilities for yield and quality be determined.
Testing the soil and understanding how to interpret what those tests show in terms of actual nutrient needs are the beginning requirements for producing nutrient-dense foods and feeds.
By Neal Kinsey. This article was originally published in the October 2013 issue of Acres U.S.A. magazine.
Neal Kinsey has worked as a soil fertility specialist in his home state of Missouri since 1973, with clients in all 50 states and at least 70 other countries. He also conducts several training courses for interested farmers and growers each year as well as on-farm consultations for clients who want to make best use of the fertility program.