“The Organic Soil Test, Soil Quality and Food Quality Relationship”

Presenter Joe Scrimger

Bio-Systems, Marlette, MI

Soil testing on Organic Farms has held some controversy just as it has on conventional farms in the past. Some Organic farms soil test and utilize information from the test while other farms take the test because they are required to certify.  In this seminar we want to accomplish an understanding of the soil test and how it can be a valuable tool on your farm. The soil test can help you build a soil system that will not only produce chemical free, but also nutritionally balanced crops that are more pest and disease resistant while being better feed for animals or food for people.

I come to this process after spending 25 years looking for answers in relation to degenerative diseases, specifically cancer and to some extent heart disease, and how it relates to the production practices used in our food systems. The goal of this presentation will not only be to learn about the soil test, but by the end of the seminar be able to relate to the process of how properly grown food will help reduce degenerative disease in our societies and to learn the value that this process holds for our farms and our communities.

“Why soil test?” To make sure we are all on the same page, we are looking for indicators that will help us map the way to economically build a healthy productive soil. I view the soil test process as not an exact science, but rather as a relative science that along with a proper recommendation sends you in an organized direction to build your soil in an economical manner that fits your farming operation.

In my personal history of running soil tests, there was a time in the late 70’s that I would have stated that conventional “Cation Exchange Capacity” (C.E.C.) test did not consistently relate to production results on the farms I had tested. Others currently use this reason for not testing. It wasn’t until I started to factor in the beneficial soil biology, which makes the minerals available to the plant, that conventional testing could be explained in actual production terms. A “Bio-Test” procedure was adapted to factor an indication of beneficial soil biology by checking nitrates and the water solubility of the minerals and comparing them to the C.E.C. test.

Another question that needs to be asked is “Is an organic recommendation different from a conventional recommendation?” When you look at the goal of the two systems there are basic differences right from the start. The conventional recommendation is based on volume production where the organic recommendation is based on quality production. A conventional recommendation is generally based on a fertilizer system where an organic recommendation is based on soil systems, which are clearly different approaches. Because the soil amendments used in organic systems tend to be organic matter or rock mineral, recommendations need to take into consideration not only that the balance is different, but also that the soil amendments release differently than conventional water soluble fertilizers.

With organic farming, especially in the transition phase, where you are building your soil system, it is important to have a soil nitrate test. This nitrate test should not only tell you whether there is left over nitrate in the soil from manure, compost or legumes used in the rotation, but also, over a series of tests, it should indicate if the soil organic matter is releasing nitrogen. A properly working soil at 3 percent organic matter (O.M.) should release close to 100 pounds of nitrogen over the course of the year, before the manure, compost or legumes are factored in.

It is my estimate, based on 25 years of testing North American soils, that 70% of the agricultural soils do not have proper proportion of beneficial soil organisms (BSO). This seems to be because of soil compaction and decreasing organic

matter levels. Most of agriculture does not have a properly functioning soil system; therefore, it doesn’t have the basis for a meaningful CEC test audit. This is indicated by the lack of most soil to produce nitrogen, along with a lack of calcium solubility indicated by the “Bio-Test”, which would indicate the lack of beneficial soil bacteria (BSB). Most soil phosphate is tied up in the soil because of a deficiency of beneficial soil fungal organisms. This is compounded by the process in which some compacted soils tend to act like low pH soils where the aluminum may be coming available, but not being considered as a reason for poor plant growth. Nutrient solubility is regulated by beneficial soil organisms and can be measured directly with a Soil Food Web test or indicated with a “Bio-Test” by comparing the soluble nutrient to the reserve nutrient at a peak soil activity period, such as in May or June with field crops.

With Organic Farming there is a focus on building organic matter and using practices that will decrease soil compaction such as green manure or compost use along with crop rotations and deep rooting legumes. Depending on the state of the soil at the start of the transition and the intensity of the soil building practices, the soil biology will start to improve in the first couple of years and can become active in 3-5 years. Proper balance may take 7-10 years to accomplish, after which it is very easy to maintain.

In the transition process, the soil test is an important gauge of what needs to be done to build the soil and also to tell you when you have accomplished the building that was set out to do. Many farmers like to follow recipes for building soil, but if they don’t change their recipe after the soil has accumulated adequate nitrogen release and potash levels they can begin to overfeed the soil and the plant. This can cause weed, pest, and disease pressure along with a decrease in feed value. The decrease in feed value is due to the excess nitrate and potassium that can end up in the plant tissue. A soil testing program that indicates soil minerals, along with biology, can help you approach a balance where you can become more efficient at decreasing your need for soil amendments, while consistently yielding very nutritious production. Soil balance does mean different things in different soil types or cropping systems. I find that it is most important to look at focusing on balancing when the soil is the farthest out of balance. As the soil approaches mineral and biological balance it will start to work more dynamically, in terms of living components. This works to keep it in balance.

In general, we are working to get a nitrate level in the 50-60 pound area for grass type crops like corn and wheat with a soil mineralization factor that will work to replenish the nitrate as the plant takes it up. This lets us feed 150 pounds of nitrogen to a crop without over feeding it at any one time. On legume crops 10-15 pounds of nitrate is adequate in the building phase. Nitrogen is a very important nutrient to have working in an organic soil system, but most likely we would have had to address the basics of pH and calcium levels to start to have some efficiency with nitrogen management and use.

Calcium carries the most value in an organic system because it tends to relate to most other nutrient releases. Sand soils won’t take as much high calcium lime as clay soils to raise their calcium levels on a CEC basis. A good target is 75% calcium base saturation with problem soils running higher in the transition. Applying calcium in the transition phase on problem soils does encourage soil bacteria if you are applying other organic matter sources such as manure, green manure or compost with the calcium.

Potash is the next nutrient that is looked at for balance. If potash is low and nitrogen is needed, manure, compost or blended organic fertilizers can be utilized. On the other hand, if the potash is high and nitrogen is needed, a nitrogen source without potash should be used such as feather, blood, or bone meal. If you have a high holding capacity with a clay or high organic matter soil, 2-3% potash may be enough. If the soil is a low holding capacity sand, 3-4% potash may be needed. This figure may be 250-450 pounds, depending on the soil type and the stage of transition. In general it doesn’t take as much potash to build or maintain adequate levels because potash is the easiest nutrient to get soluble in organic systems. Sulfate of potash (0-0-50-17.5) and sul-po-mag (0-0-22-18-22) both work very well where only potash and sulfur are needed. Greensand and granite meal will work to maintain levels but may be expensive and slow release in the building stage. Phosphate tends to be the hardest nutrient to balance organically, so we may focus on sulfur, magnesium and trace minerals before explaining phosphate.

Sulfur tends to be very important where you are working with extra nitrogen. This is usually the case while building a soil system “organically”. Additional sulfate sulfur from gypsum (calcium sulfate), sulfate of potash, or sul-po-mag all work well, pending what other nutrients are needed. The additional sulfur will help slow down the release of the nitrogen. By how it feeds the microbes that are processing the nitrogen, sulfur makes more complete protein in their bodies, which in turn will come back as slow release nitrogen. Ultimately, slow release nitrogen makes more sound protein in crops.

Magnesium is a nutrient that caries some controversy even in the “Sustainable Ag” community. In the past, conventional recommendation for lime usually said, “Just use dolomite lime”, even though it typically contains 20-25% magnesium and an equal amount of calcium. If soil test needs for calcium are 75% and magnesium 12-13% it is hard to balance the soil by adding dolomite lime. Magnesium may be needed on sand soils, but is rarely needed on clay soils. A small amount of dolomite lime (500-1000#), will take care of most soils’ magnesium, other sources such as Sul-Po-Mag or magnesium sulfate, can also be very good sources and are more soluble than dolomite lime.

Trace elements need to be looked at as part of the process that gives your soil more minerals to pass on to the plant. Sometimes the trace elements won’t make a yield difference, in the short term, but rather a quality difference that shows over time. This quality may be reflected in pest and disease resistance, more flavor in the crop or better vitality in the seed. The microbes in the soil also need trace elements to make complete protein in their bodies, which in turn compliment the protein production in the plant and is passed on to the animal. Where trace elements are low, a kelp and chelated trace elements solution can be used as a foliar and is an efficient short term approach for the plant, but the soil will need to be addressed. The sulfate form of trace minerals is organically approved if the need is documented by tests.

If your phosphate was low, below 100 pounds on a CEC or Bio-Test, it will need to be addressed early in the transition phase because most organic phosphate amendments are slow release and will take time to be weathered in and digested by the soil. Soil bacterial and fungal organisms may not be at adequate levels in the transition to digest the mineral forms of phosphate; consequently, a more soluble form such as bone meal or poultry compost may be needed.  Poultry compost and manure has been available in the past, but may not be as available in the future because of the GMO feed issue, unless it is coming from an organic or source identified farm. Poultry compost shouldn’t be over-used because of how it affects the nitrogen cycle. Colloidal phosphate, soft rock phosphate, and black rock phosphate are all typical mineral sources or phosphates that have been used traditional by Organic Farmers.

In the same way that nitrogen is a two part process of adding nitrogen sources to the soil and getting BSB to produce nitrogen, phosphate is a two part process of building the soil levels and getting the beneficial soil fungal organisms to digest it. If the soils have been depleted of organic matter or phosphate reserves this may take 5-10 years or longer. The

bacterial process for nitrogen production can be built relatively quickly and needs to be first and then managed while the soil fungal organisms are fed higher carbon compost and mature crop residues versus just green cover crops, which primarily feed the bacteria. Because phosphate tends to be slow release, especially in colder northern climates, it may take 300-400 pounds of reserve phosphate to come up with adequate soluble phosphate to support fast growth. This is why successful organic farmers of the past used to apply a ton per acre of rock phosphate that may last them 10 years or more. A common question is “Can soil test nutrient levels effect weed pressure?” I find that not all weeds can be explained by a soil test, but some of the common weeds that affect the farm in the transition phase can.

In order to understand the relationship of soil to weeds we need to build on what has been said already in relation to BSO and how they affect nutrient release, while looking at the history of weed control. Quackgrass, lambsquarters, and pigweeds are the most classic weeds to start you on the process of weeds as indicators in general. Quackgrass pressure will usually indicate a lack of soluble calcium and a lack of decay. Most of conventional agriculture has this problem and quackgrass was primarily why conventional agriculture came with attrazine and Roundup herbicides. Using these herbicides actually negatively affects decay, which is a living process partially plant in origin. Consequently, herbicide use reduces the soluble calcium farther, which creates more quackgress pressure. This is great if you are selling the herbicides but not so good if you are buying them. Because calcium is needed in most plants for basic proper cell structure, you can see that the process of using herbicides isn’t beneficial for many reasons. As many experienced organic farmers have found, surface tillage, which enhances decay, done properly will reduce overall quackgrass pressure.

Lambsquarters and pigweed, on the other hand, tend to be indicators of good soil. The problem comes when they become hard to control, which usually indicates excess nutrients in the way of nitrogen and/or potash. Because the plants and weeds live off of the soluble nutrients and potash is easy to make soluble, it is usually where the imbalance lies, especially in the transition when you are tying to build the soil. As you achieve better phosphate solubility, you actually don’t need as much nitrogen or potash because of the soil dynamics that you are accumulating. Timely cultivation, cover cropping and composting will all help control these broadleaf weeds in the transition to a balanced system.

If some of the farmers in the group are old enough to remember when a field could be plowed and planted and weeds were not always the first thing that grew, we may be getting back to a time when there was better soil structure. These soils had a smell to them that represented part of a soil test. This smell, which was a musty woodsy smell, could be sensed from the tractor seat and these soils raised better crops than they did weeds. This smell of the soil was one of the first soil tests and it is still one of the best tests today.

In general what we are doing is saying that “organic” can be more than just three years away from chemicals, if we use the tools that we currently have we can test minerals and biology in an affordable manner. If we utilize the knowledge that is available on how to remineralize our soils in the presence of the BSB, we will be achieving what the public needs – a system of food production that is environmentally sound and economically viable, that produces food, that can rebuild and sustain the wealth and health a nation. This can be done in a way that is actually more productive than the conventional agricultural model of the last 60 years and a soil test is just one of many tools we have available to us to accomplish this task.

Joe has farmed organically since 1975. Since 1980 he has owned and operated Bio-Systems, a soil testing and consulting business that serves the Great Lakes Area with biological technology and marketing services, along with Life Time Foods, a natural foods store. To contact Joe or Bio-Systems, please call 989-635-2864, fax 989-635-3888 or Email bio-systems@centurytel.net .