The Framework of Biological Dairy Farming

By Gary Zimmer & Rebecca Brown

Biological farming is a dynamic system of farming that works with natural principles. Its purpose is to make a profit by growing healthy, mineralized foods that are nutrient-rich and of maximum quality for people. In order for this to occur, all stages of production including soil, forage, crop, animal, business and lifestyle management must be healthy and interdependent.

The biological cycle begins in the soil and is based on a healthy population of balanced microbiology—such as bacteria, fungi, protozoa and earthworms—which require soils with an adequate supply of properly balanced nutrients including, but not limited to, nitrogen, potassium, phosphorus, calcium, magnesium, sulfur, zinc, manganese, iron, boron and additional trace elements.

The biological farming approach that we use here at Otter Creek Organic Farms aims to improve and balance soil and forage/crop mineral levels by using a balanced fertilizer program, growing green manure crops, practicing proper tillage, employing tight crop rotations, utilizing a wide diversity of plant species, and measuring and monitoring all of these aspects.

Mineralized soil produces high quality forages, which yield healthy productive livestock; cows that have minimal or no health complications, breed back easily and efficiently produce ample, high quality milk with potentially fewer dollars invested in fertilizers, off-farm feed and supplements, and minimal vet bills.

You can see how biological farms often have a decreased cost of operation. As if that weren’t good enough, now consider that using a biological system often facilitates the transition to organic production and you’ve got a recipe for maximizing farm profits.


An essential starting point for implementing a biological or organic system is a beginning farm evaluation. Possible components of this evaluation include the right kind of soil test, feed and pasture tests, and visual soil and pasture assessment using a method that measures specific soil and pasture characteristics. Once this information is gathered, we have a baseline starting/reference point and can then put together a livestock, fertility and crop improvement plan based on those data.

Testing must be part of an ongoing monitoring system. After all, if you can’t measure or know whether you are making improvements, how can you have confidence that you are on the right road? Tests, however, can only give us clues about our feeds and soils. The more we monitor with both tests and observation, the more complete a picture of improvement we can get, although tests themselves are often incomplete. That said, we often take soil samples every three years because major changes that would show up on a soil test are usually gradual.

Just as soil tests don’t measure what’s in a soil (they only measure nutrients that are easily extracted and assumed to be usable by the crop), feed tests only measure parts and pieces of the feed but certainly not everything. They are only calculations—assumptions and estimates based on the “normal” range. Tests give us clues as to what is going on and offer a starting point, but we need to be detectives, gathering data from many sources in order to find out what is really going on. Testing is a management tool guiding our fertilizer and farming decisions. However, we find that the practice of intentional observation (which means slowing down and making time to observe) is often what separates out the best farmers.

If you raise crops in the “usual” way, such as using N-P-K soluble fertilizers and lime according to pH only (instead of taking into account levels of available calcium), have pure alfalfa stands and conventional corn, the estimates for test result ranges are more accurate because the tests and ranges are based on that conventional farming system. But with biological farming, the feed test results are going to be less predictable and those calculations and estimates may be far less accurate.

We have our soil tests performed at Midwest Labs and our tissue and feed tests at Dairyland Labs. To get the most accurate mineral results on forage tests, we use a wet chemistry test, rather than NIR (Near Infrared Reflectance). We obtain a series of complete tests throughout the growing season being sure to harvest at the proper time to insure maximum energy palatability and digestion.

Forage tissue testing (including trace minerals) is very important because it tells you what nutrients are actually getting into the plant. We are looking for limiting factors, ratios and health promoting indicators. All this diverse data plus whole-farm observation gives a much better picture of the soil-plant interactions in your forage production system.


Every nutrient has a function both in plants and animals and they all need to be provided, and in balanced proportions. The nutrients you put in a soil affect the nutrient uptake in the plant, which in turn affect digestibility, energy, flavor, mineral balance and protein quality of the plants.

There are two basic choices for providing nutrients to plants. One option is the use of soluble N-P-K chemical fertilizer. With this opinion, highly soluble chemical fertilizers essentially use soil merely as a medium through which the soluble nutrients travel to the plant. They may reduce the availability of the soil nutrients, reduce clover numbers, and cause soil health to decline over time.

For example, you can grow large quantities of nutrient-deficient feed with the use of soluble chemical nitrogen and potassium. Although it looks like you’ve grown a lot of feed, mineral uptake, balance and energy can certainly be short. You’ll need to feed more of this lower quality forage and add livestock supplements to maintain production levels.

Soluble nitrogen makes soils “lazy.” It encourages grass growth (rather than legumes) and interferes with calcium uptake in the plant. We believe it also has a negative effect on palatability, digestibility and animal health, and creates too many incomplete proteins, an opening for insect problems in the crop and health issues in livestock.

The second option is based on keeping soil microbes healthy so they can build humus and provide nutrients to the plant. The job of the successful biological and organic farmer is to get the soil mineralized and keep the soil habitat for the microbiology as close to optimum as possible so those microbes can build humus and govern the supply of nutrients to the plants. Soil health needs “air,” water, a healthy “home,” and the proper food. How do you do this? With proper tillage and soil mineral balance.

Additionally, when soil microbes build humus, which is the primary determinant of soil health, large amounts of carbon are sequestered from the atmosphere back into the soil.


There are four indicator minerals in plant tissue testing that tell a large part of the story about what’s happening on the land: calcium, boron, phosphorus and magnesium. These are indicator minerals because a complete biological system is required to get these four minerals up to the desired levels.

Grow or buy forages where these four minerals are high in the plant (for that plant species) and they will be the most palatable, digestible feeds you can deliver to livestock. Let’s look at each individually.

Calcium is the “trucker” of all minerals, meaning it largely governs plant availability of the other minerals. For this reason we consider it the most important soil nutrient. Among other attributes, calcium affects energy and digestible energy in plants, and is essential to microbe health. There is also a strong correlation between plant calcium levels, legume growth, soil health, reduced weed pressure and quality forage.

A vital baseline to biological farming is provision of enough soluble calcium to the plant. For calcium to be high, you will need adequate soil levels of actively exchangeable plant soluble calcium. (With high nitrogen, potassium ormagnesium levels, calcium levels may not be adequate in the plant. The goal is as close to a 1:1 ratio with potassium as possible and at around 2 percent calcium in feed tests.)

Just because the soil pH is within the ideal range (6.5-7), it does not mean you will automatically have high plant uptake of calcium, that additional calcium does not need to be applied, or that the soil doesn’t need lime. Providing a diverse supply of calcium sources is highly beneficial, even if pH is already at a “good” level.

There is no “one-size-fits-all” when it comes to different sources of calcium for different soil situations. However, one rule is that smaller amounts more often seem to work well on most soils. Calcium sources include calcium nitrate, gypsum, Bio-Cal®, OrganiCal® and HumaCal®, rock phosphate (if you also need phosphorous), burnt lime, and activated calcium (note that not all of these are organic). Choose the right source for the situation. Often, supplying a humate source with calcium yields good results. Organi- Cal® and HumaCal® have humates added. Fieldgrade lime is insoluble and performs well on low pH soil, when incorporated, because it needs the “acidity” of that soil to break down the calcium carbonate and make it available to the plants.

Spraying on a few ounces of a plant stimulant calcium may help by serving as a short-term fix but it won’t do in the long run. Remember, an alfalfa crop removes two hundred fifty pounds per acre of the available soil calcium.

Boron and calcium seem to work together. We like to call calcium “the trucker of all minerals” and boron “the steering wheel.” Boron is needed in relatively small volume, but it governs calcium uptake and sugar movements, both critical factors in producing more plant energy and plant pectins (the highly digestible carbohydrate that is closely associated with calcium). Boron is relatively easy to get in plants and to manage. It’s an anion (meaning that it is negatively charged), so it’s a highly soluble, leachable mineral, and thus readily available to the plant. For us in the Midwest, we normally add one pound per acre each year to fields, and sometimes more based on soil type. Some people in the East apply two pounds of actual boron annually.

Phosphorous at high levels in the plant is a great indicator of healthy, biologically active soils. Phosphorous exchangeability and organic matter are needed by the plant at high levels, but large amounts of phosphorous are often tied up in the soil, unavailable to the plant. Commercial phosphorous dumped on the ground does not simply get sucked up into the plant as nitrogen and potassium do. In fact, putting on soluble phosphorous has a negative effect on plants’ symbiotic interaction with mycorrhizae, the soil fungal group that aids in getting phosphorous into the plant.

We like to use natural rock phosphates, certain plant species, and biological activity to extract the phosphorous and convert it into a chelated, organic, plant-available form. Phosphorus and magnesium are synergistic; they are team-mates and should be at .35 percent or higher on feed tests. These are energy minerals, both of which are vital to production through photosynthesis and also to transportation. These two minerals are extremely difficult to get into the plant.

Magnesium is an indicator of many things, a major storyteller of soil balance and health. Magnesium levels can be high in the soil and yet be low in the plant. Magnesium carbonate (dolomitic lime) isn’t plant usable unless something breaks it down—this is carried out through soil biology acids, plants extraction or sulfurs. One more issue to keep in mind: there is an inverse relationship between potassium and magnesium. The higher the soluble soil potassium, the more potassium and the less magnesium the plant takes up. In order to get high plantmagnesium, you must not overdo potassium. Good biological activity along with a variety of plants to feed soil life is part of the success of getting magnesium into the plant.


Sulfur is needed to make proteins and build humus in the soil. Our Midwestern Bio-Ag consultants have suggested that we should really have “The Big Five,” not “The Big Four,” because sulfur should be added to the list of basic soil minerals. In order to get magnesium uptake in the plant, sulfur needs to be in good supply, so you can’t get ideal levels of “The Big Four” without good sulfur levels.

Each year a minimum of twenty-five pounds per acre of sulfate sulfur needs to be added to most soils. The goal for our feed test is a 1:1:1 ratio of phosphorus, magnesium and sulfur.


Cows are designed to eat a variety of forages (not grain), so utilizing high levels of diverse, nutrient-rich, high quality forages for an extended grazing season is the focal point of biological farm management. We want to assist cattle in production with high quality forages fed at the right level. We are not interested in pushing that cow into high production with lots of grain at the expense of the cow’s health and the health of the consumer.

Dairy nutritionists have parameters for what it takes to keep the cow producing well. What is missing from the forage has to be supplemented, quite often at a substantial cost, in order to meet the cow’s requirements. Because it takes time to get soils minerally balanced and healthy, extra supplementation to a cow’s ration is likely needed until the soil is balanced. Once quality forage production is achieved on the farm, more minerals and nutrients are provided through those plants and less supplementation is required. High quality, nutrient-dense forages offer more energy due to improved digestibility of the plant carbohydrates, resulting in more sugars, pectins, hemicellulose and other materials that are more digestible by the rumen bacteria.

Many farmers notice a difference with biologically fertilized crops, saying that they feed better even though they may or may not test differently. We also find that we can get better utilization of these minerals in the feed as they break down during the digestive process. Also, with the newer, improved Relative Forage Quality (RFQ) test, we do believe that we have moved a step closer to an accurate assessment of feed quality.

Keep in mind the fact that there are flaws associated with the current protein test techniques. For example, true protein is not measured in these tests, rather, nitrogen is, and then it is multiplied by 6.25 and the resulting number is assumed to indicate protein levels. In truth, proteins are made up of amino acids—carbon chain compounds with nitrogen attached, and some also carry sulfur and other minerals. If these minerals are lacking and nitrogen is in excess, the amino acids can’t be made and thus you have incomplete proteins. On the other hand, if extra nitrogen is available due to over-application or too much manure, then free nitrogen can get in the plant. The test can’t tell the difference; this free nitrogen is calculated as protein, but in fact it may not be.


There are two nutrient areas to consider: the first is soil correction to achieve soil balance, by supplying nutrients that are lacking, based on a complete soil test.

The second is crop fertilizers. These inputs are above and beyond soil correction inputs. These are specific blends for the crop you are growing and the soil type you have. A crop fertilizer doesn’t correct soil deficiencies and should be a balance of all nutrients, not just N-P-K.

The nutrient sources we are often managing on a grass-based dairy are manure, compost, and fertilizers (nutrients).

Fertilizers are rated on water solubility and price per unit. But what about the fertilizer’s effects on soil and soil life? How available is it to the plant? Are the nutrients stable, or will they leach away before the plants can use them?

You can do things to enhance nutrient uptake and fertilizer efficiency, such as adding carbon and balancing the soluble types with the slow release types. Balancing soluble to slow-release fertilizers provides timed release of nutrients.

Composting manure with lots of carbon stabilizes the nutrients, changing manure from a soluble to a slow release nutrient source.

With liquid manures, applying a light application of lime prior to manure application and a surface aeration is a good idea. Smaller, more frequent lime additions are more beneficial than larger doses. On low-phosphorus soils adding rock phosphate to liquid manure is a beneficial practice. We also like to add BioCal® when spreading liquid manure to help stabilize, optimize, and balance the use of nitrogen and potassium.

Foliar feeding with fish, molasses, kelp, magnesium sulfate, and/or micronized minerals is not a bad idea. This is an “extra” or short-term fix, not a replacement for a good soil mineral management program. Remember to include Epsom salts (magnesium sulfate) in your foliar program to help meet the annual needs for sulfur.

Nitrogen and highly soluble salt fertilizers can stimulate a “big pile” of low-nutrient feed, but we need to also consider energy and cow performance on these kinds of feeds. What impact do these materials have on soil life, root development and plant health?

You have to earn the right to reduce or eliminate nitrogen from your fertilizer program. As a biological farmer, you can “grow” nitrogen. If you set the conditions, then, in time, on most soils purchased nitrogen won’t be needed because the biology provides it. Healthy soil microbes are able to convert (fix) nitrogen from the air, which requires a microbe food source such as tilled-in green manure crops, cover crops or green carbon. Microbiology also provides nitrogen via legume nitrogen-fixing nodules and legume digestion when incorporated into the soil. Healthy, well-aerated soils with nutrient balance and diverse plant species naturally have a good nitrogen-to-carbon balance. Keep in mind that calcium favors legume production while nitrogen favors grasses.


We believe that careful, properly timed, shallow tillage is vital. Improper tillage can do severe damage to the soil structure and microbes. When major soil corrections with lime or minerals, or improvements in soil structure are needed, how do you do that by pouring things on the surface? Sometimes you need to till to apply soil correctives and till to re-establish pasture species. For our crop farming, we like to shallow till to incorporate nutrients and plants, and if needed, till the subsoil to loosen compacted soils and allow deeper root growth.

Zone tillage, shallow incorporation of plants and residues, and deep ripping work well on many farms. We do believe that subsoiling with a Yeoman plow or ripper (along with deep-rooting annuals and a good fertility program) has a place on a grazing farm and does a lot to relieve compaction, which often is a much bigger problem than realized.


You can’t let the soil put limits on the plants by limiting the type, quality, or amount of forage grown; and you can’t let the cow put limits on the plant, either through improper grazing management or soil compaction.





Potassium Magnesium Calcium Phosporous Sulfur
Level 218 234 1246 90 16
110-183 135-180 1316-1410 50 50

Soils on the Pennsylvania farm are high in potassium, magnesium and phosphorus, but slightly low in calcium and sulfur. We suggested treating the pasture with 1000 pounds per acre of low-magnesium dolomite applied once and then, if further testing shows a continued need, again in two years. For fertilizer, we recommended a Custom Blend for High-K Soil, which is low in potassium. It has an N-P-K rating of 0-0-0 but contains 12 percent calcium, 2 percentmagnesium and 7 percent sulphur, plus trace minerals and salt. The ingredients of the blend include fine, pelletized gypsum (calcium sulfate, sold as Cal-Sul), HumaCal, magnesium sulfate, potassium-magnesium-sulfate, composted and pelleted chicken manure, Redmond salt and a trace mineral blend, all permissible for this organic farm.

Soils on the farm in southern Maryland are low in calcium, phosphorus and especially sulfur and potassium but very high in magnesium. In addition, the soils are very sandy, which calls for more frequent but light applications of fertilizer. We recommended the application of gypsum (calcium sulfate) at 250-500 pounds per acre each year, along with a blend of fertilizer with an N-P-K rating of 8-9-9 to be lightly applied every three months. The blend contains HumaCal, ammonium sulfate, monoammonium phosphate, potassium-magnesium-sulfate and a trace mineral pack. We also recommended applying one ton per acre of chicken litter, twice a year, for one or two years in order to get more organic matter into the thin soil.



Zinc Manganese Iron Copper Boron
Level 4.0 4 97 1.5 0.4
Desired Level 5.0 20 20 5.0 2.0
Level 2.2 4 36 0.2 0.3
Desired Level 5.0 20 20 5.0 2.0

Soils on the Pennsylvania farm are low in manganese, copper and boron, have adequate zinc and are high in iron. We recommended a trace mineral mix called the Charger, composed of compost and sulfate forms of zinc, manganese and copper, along with borate.

Soils on the farm in southern Maryland are low in all trace minerals except iron. We recommended our conventional trace minerals pack, which is made up of sulfate forms of zinc, manganese and copper, along with borate and additional ingredients.

See also their Short Course in Cow Management.

This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly journal of the Weston A. Price Foundation, Winter 2010.

Gary Zimmer heads Midwestern Bio-Ag Products & Services, a manufacturing and consulting company that operates on over 5,000 farms, in 15 states with 80 consultants. He runs Otter Creek Organic Dairy Farm with his son and daughter in Wisconsin. He taught agriculture for many years, holds a graduate degree in dairy nutrition and lectures widely on the subject. He is the author of The Biological Farmer, and Advancing Biological Farming.

Rebecca Brown is a consultant in the Mid-Atlantic Region for Midwestern Bio-Ag. She grew up on a farm, studied agriculture in college, and has managed several grass-based livestock direct-marketing farms. While working on dairy farms for a year in New Zealand, she realized she enjoyed sharing information with farmers. She then spent nearly a year working and studying at Zimmer’s Otter Creek Farm before returning to the East to become a consultant. She can be reached at (774) 521-6100 or brownsuffolk (at) hotmail (dot) com.


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