Rebuilding Soil Fertility
The first in a series of articles aimed at helping growers improve both crop and livestock nutrition by improving productivity in the soil
What kind of soil fertility should the average farmer or grower expect to have? Most farmers have land that has been in production for many years. A sizeable portion of that land will have received at best N-P-K and lime over those years. But many who make their living in agriculture tell us that in spite of new seed varieties and good management practices, their yields have either stagnated, or begun to drop. When it comes to production and / or quality, this is the case in spite of using as much or even more fertilizer than before. A large number of clients tell us at the start of using our program that they just want to achieve what they used to achieve in terms of the crops they are growing.
Follow the program to get results. We have clients who sample every different type of soil in every field every year and strive to do all that the soil test indicates needs to be done. And for "high dollar" crops this may be followed by several leaf tests per year. Clients have been amazed at the increased productivity of their "good soils" after 3 years of following the recommendations for improving those soils. For yields to reach this point we find there is more to bringing them up in fertility than just adding nitrogen, phosphate and potassium. The higher the yields have been, the more this proves to be the case; soils do not have an endless supply of the required range of nutrients in a form that is available for plant use, other than what is supplied with typical N-P-K fertilization.
Assessing the cost. Most growers will not be so blessed as to have soils that can be built up or restored to excellent fertility levels on the same fertilizer budget they have been using year to year. The exceptions would be those who have maintained an excellent liming program and / or have been successfully using higher amounts of phosphate and potassium. If you are working with large acreage, just expect that in the beginning it may cost you more than a "sensible" budget will allow. That is - until you verify on some of your own land that these expenditures will truly pay for themselves.
Where to start. If a soil fertility building program appeals to you, but you wish to limit your budget, consider sampling perhaps 10% of the acreage to learn what is shown to be needed. Do not just sample the worst 10%;that will generally be the most expensive soil to correct. Send some good soils, some average areas, and some problem soils for testing. This will give an idea of what it will take in all of these various situations, and provide an opportunity to see what nutrients are there in your better soils as compared to the poor ones.
Next, determine to set aside enough of your fertilizer budget for at least a field or two, so as to follow through on the program each year for the next three years. Make the acreage large enough to buy materials in economic quantities and small enough so as not to cause economic hardship for your overall operation. It doesn't have to be the entire acreage you tested, but it should be substantial enough to validate whether the benefits of fully implementing the program will justify the fertilizer costs.
The Soil Test. The Albrecht Model of Soil Analysis & Recommendations is a soil management program designed for the grower. The soil analysis measures the nutrients available to the plant from the soil by performing specific nutrient tests in the same way every time. Such measurements, related back to the soil chemistry, effectively reflect the soil's ability to provide the elements (in the form the plant requires) for both top production and top quality. The test results in most instances will show a correlation between yield and the balance between soil nutrient levels.
Yield variation will map to soil nutrient balance. As a test, some clients have provided a map correctly drawn according to GPS zones or yield monitoring, without any hint of yields, and asked us to tell them from the soil samples where the good and bad yields will be! And it is true: the areas of "good yield" will usually be the areas shown by the soil test to be closest in terms of nutrient balance, and areas of "poor yield" are more likely to be shown as most lacking in essential nutrients which affect that crop. The Albrecht model of testing is that accurate - if the soil sampling is done as prescribed, and the correct way to interpret the levels is understood.
The accuracy of the test is further verified in the fact that for every pound of plant-available fertilizer material that has been applied, the test will correctly show this to be the case, as long as the soil pH is not excessively high. The test for micro-nutrients reflects the addition of those elements, pound for pound in the soil. This is true as long as they are properly applied and adequate time is allowed for the materials to show up as available on the soil test. Even with a very high pH, you can generally build the levels, it just requires more time and material to do so. From our experience, many growers with excellent yields are still losing out in terms of quality and even better production, because trace elements are so limiting in their soil.
Understand the Numbers! Every soil testing company will have its own set of measurements, generally very different to those as shown when using the Albrecht Model of testing. For example, we express the levels of trace elements such as zinc, copper, and manganese differently when compared to other soil test reporting methods. As a rule, our measurements will be expressed as much higher numbers. This may cause alarm to some consultants and fertilizer dealers if they are not trained to know what these levels actually represent! And these persons may say (incorrectly) that levels are already too high, when in actual fact, the level reflected is still quite deficient.
The important thing though is how well the numbers can be used to interpret what that particular sampled area performs like at the present time, what the potential is when the proper levels are achieved, and what is required in terms of materials to achieve those levels. Is the soil test accurate enough, and the person who uses it to provide advice at least experienced enough to determine the good production areas from the bad, and explain how the levels on the soil test will be affected by the materials and the recommended amount he suggests? Test your soil tester, that includes us too if you wish!
More on Albrecht Model Concepts. There are several concepts in reference to the Albrecht Model of soil testing which can be verified by the test itself, in addition to the observance of field conditions. Some of those concepts will be briefly mentioned here, and we hope to expand upon them in subsequent articles.
First is the concept of soil balance. Some people say there is no such thing as balancing the soil. But in terms of soil testing, measuring which nutrients are present, and what happens when others are added, will verify that increasing the availability of one element in the soil will reduce the availability of one or more of the others. In other words, when adding a nutrient to the soil to be maintained there until the plant can use it, that particular nutrient can only be held for use when some other element has been displaced to make room for it.
The Albrecht Model is based on this concept. And in fact, what happens in terms of that balance is an extremely beneficial principle to understand concerning how it relates to soil productivity. (Hands On Agronomy is a good book to begin that study.) The soil-balancing program is built upon the understanding that every time we add an element that is deficient, it will have the greatest effect upon reducing any other element that is excessive in that soil. In other words, if we have too little of one nutrient in the soil, we will have too much of something else. Supplying what is lacking is the primary approach to controlling any excess in the soil. This is the meaning of soil balance using the Albrecht Model.
Just keep in mind that it is always best to first correct deficiencies in order to help control any excesses. This may not completely solve the problem, but it is always the best and most efficient beginning. Extreme excesses may require continued use of another element at maximum amounts in order to help completely eliminate the excess and the related problems it causes. An excess is always a problem for growers, because too much of one element in the soil means there is not enough of something else. In that regard, balancing soil nutrients, one against all others measured, is extremely important to fertility, quantities produced, and the quality of what is produced.
Feed the soil to feed the plant is another vital concept of the Albrecht Model of soil building. Too many fertilizer programs are built upon trying to feed the plant and would, if possible, by-pass the soil altogether. But essentially, the soil is the plants stomach. When properly nourished, the soil provides for the biological processes required to completely decompose residues and effectively convert needed nutrients from them for use by the crop to be grown there. That is why we advocate feeding the entirety of the soil by broadcasting materials that can re-build soil nutrients levels. Use a leaf analysis to feed the plant and a soil analysis to feed the soil.
Creating the proper environment is the true goal of the Albrecht Model for soil biology. This is dependent upon the correct soil chemistry (supplying each nutrient in the proper amounts), which determines the physical structure of the soil. When the chemistry is right, only then can the physics be right. And when the chemistry (the right amount of each nutrient) is correct, and the physics (25% air, 25% water, 45% minerals, 5% humus) is correct, then we have the proper environment in which the biology can thrive.
Visit our Contact Us page and let us know if this is the type of soil building program you feel could be helpful. And while you're at it, we hope you will click on the "Questionnaire Section" shown on the contact page, and let us know which of the training programs that we conduct would be of interest to you.
At Kinsey Agricultural Services, Inc. we specialize in improving problem soils, as well as those generally considered to be about normal.
- Neal Kinsey