Home » Gary Zimmer on 50 Years of Biological, Organic Farming

Gary Zimmer on 50 Years of Biological, Organic Farming

Roller in cover crop field
A roller lays down covers crops at the author’s farm in Wisconsin.

By Gary F. Zimmer

A little bit about myself before we dig into my 50 years of experience in biological farming: I was born and raised on a dairy farm in northeastern Wisconsin. I worked on the farm for two years after high school, but I wanted to be a veterinarian so I left the farm and went to college. After further evaluation of what a career of life as a veterinarian would be like, I switched my major to dairy nutrition and furthered my education with a master’s degree from the University of Hawaii. I was getting a lot of book learning but not much practical training. I always said I was over educated and under trained when I came out of graduate school. 


When I was in graduate school, I was involved in a project finding a fiber source for the Hawaiian dairy industry that was grown in Hawaii. In the late 1960s, that meant pineapple. Pineapple byproducts consist mainly of leaves, which are high in fiber. Shortly after starting to feed pineapple leaves to the dairy herd, cows began to abort, and some people drinking the milk got sick. The problem turned out to be the insecticide used to grow the pineapples. Milk had to be dumped for six months because the insecticide accumulated in the cow’s fat and it took a long time to clear their system. It was a real eye opener for me. People were eating these pineapples that had made the cows sick.  I started questioning agriculture. Maybe “better living through chemistry” wasn’t the answer.

Along with questioning agricultural practices I had always trusted, in graduate school I began questioning other things as well. Maybe the military doesn’t always take us where we belong.  Maybe all politicians aren’t honest. Maybe the college professors don’t have all the answers. Maybe if I get sick a doctor can’t bail me out. I didn’t want to live my life given all of the answers. When it came to questioning agriculture, the question I began to ask was, “how do I get soils healthy and mineralized?”

My start on my path toward biological farming came from my first job: teaching a farm operations and management class at Winona Technical College in Winona, Minnesota. It was a two year, post-high school course with half the year spent in class and the other half on a farm. It was a real learning experience. My training was in dairy nutrition, and in addition to teaching nutrition I also had to teach soils, agronomy and farm finance. I needed help. I brought in a lot of outside speakers and I also regurgitated a lot of stuff from books. Teaching was a much larger learning experience for me than sitting in class trying to learn from a professor.

One of the outside speakers I brought in to teach about soils was a Brookside Labs consultant. He talked about soil balance, the need for calcium, choosing better fertilizer sources, earthworms, and using a Miller offset disc and a Graham chisel plow for better soil physical structure management. I had never heard of such things.  After the speaker left, the students evaluated what they had heard.  They asked me what I thought of the Brookside speaker’s recommendations, and I said that for me it made perfect sense. 

From the Brookside speaker I learned that soils can be managed similar to how we manage a good dairy cow. Dairy nutrition is a program encompassing all we do for the cow: mineral balance; using a variety and balance of feed stuffs; providing a balance of types of feed for maximizing the biological function of the rumen; and adding the extras like kelp, natural sea salts, probiotics, yeast, chelated trace elements, and natural mined minerals; and feeding highly mineralized home grown forages. Farming soils biologically is similar.

Teaching at Winona Technical College was a learning experience for me.  I have always liked school, and I continue to be a student of farming.  I get about 15 agricultural magazines a month for my reading, and then there’s the internet, meetings, getting out on farms, and going to major farm shows like Acres U.S.A. Eco-Ag and the MOSES conference, to mention my favorites.  There are a lot of great books written a long time ago about farming that most people don’t read any more but that are filled with great knowledge.  Two series’ that have been very influential on me are the LH Bailey series from Cornell and the Albrecht papers and books.  I have read them all.  I also enjoy Newman Turner’s books and have learned a lot from Louis Bromfield’s book, Malabar Farm.  Louis Bromfield held field days at his farm in Ohio in the 1940s and 1950s, and one field day brought in over 8,000 people!  The theme of that field day event was building six inches of topsoil in five years.  Bromfield did this by leaving straw on the fields as a mulch, growing clover and applying manures. He took soil tests and applied not only the phosphorus and potassium that was needed but calcium, sulfur, and traces and all from natural sources.  He had a rotovator for shallow incorporation of residues, and used a chisel plow because root growth was needed as top soil was being built.

I left teaching because these were young students and dad controlled the farm — so trying all the new ideas wasn’t happening. A few students did manage to do on-farm trials. One student tested a product on his hay field called Planters II, which was made from gypsum that had been mined in Colorado with a few extra ingredients added. The feed test from that field changed. The question now was not what to add to your home grown feeds to balance the ration, but how do you grow the ideal feed for a dairy cow? Soluble calcium, sulfur and boron were essential. What started the phrase I often use, “calcium is the trucker of all minerals and boron is the steering wheel,” was observations I made from these initial trials with my students. The farmers were getting higher quality forage with more mineral content and higher digestibility by applying calcium and boron to the soil.

After I left teaching I went to work for Brookside Laboratory. They followed the Albrecht principles of balancing soil minerals, and I had some incredible teachers and farming experience all across the country.  The farmers I was working with taught me a lot, partially through their questions and partially their constraints, be those money, desire, old habits or skepticism. They were skeptical in part because the local educators and fertilizer companies didn’t say good things about Brookside. But I was never good at sales. I don’t like talking someone into buying a product or system by twisting their arm. My method was educating the farmer, and I still certainly had a lot to learn myself. I also lacked confidence as I hadn’t used many of these practices and products on farms. I needed a farm where I could test out for myself what I was recommending, so I packed up the family and moved to southwestern Wisconsin.  We bought a small farm there where I could test and learn about these products and farming methods I was recommending. I also left Brookside and found a job closer to home. 

Shortly after moving to Wisconsin I met a couple of young ambitious people wanting to start a natural farm inputs business. Their project was headed by Ralph Engelken from Greeley, Iowa. He had written a book called The Art of Natural Farming and Gardening and focused on making and selling compost. I was brought in to do the soil testing and consulting with the farmers. Compost alone is not a complete fertility program; minerals need to be added to meet the crop’s fertility needs, and from this Midwestern BioAg was started. This was in the early 1980s and interest rates were sky high. Farmers were going broke every day. Did you ever try going to the bank to borrow money to start a business when 25% of the businesses like yours were going bankrupt? They laughed us out the door!

What made us different from the other ag businesses was that we had different products, different sources of NPK than the industry standard, as well as calcium and trace elements. Instead of recommending anhydrous ammonia, DAP and potassium chloride, we recommended and sold ammonium sulfate, MAP and natural rock phosphate. These products weren’t available anywhere else in the Midwest at the time. We started working with dairy farms because of my background in dairy nutrition, and because the dairy farm gets paid twice for growing high yielding, mineralized crops: once for growing it and once more for feeding it.

Our business goal was to have 10 consultants, each working with 40 dairy farmers. I told the farmers if they let me work with their forage fields and their dry cows, I could change their farm. With the high interest rates and low farm prices, times were tough. Farmers didn’t have money. They needed to get better at what they were doing or lose their farms. Sustainable agriculture got started during this time, and many farmers switched to the principles of organic farming, including tighter rotations, better manure use, and a higher quality of natural fertilizers. 

To get this new company off the ground, I wrote newsletters, went to farm shows, spoke at field days and put on farm meetings during the winter. This was an education company making its living by helping farmers to become biological and selling unique products for the soil and for the cow. I taught farmers about how to choose the right source of calcium to fit their farm, how to minimize tillage, and how to feed more quality forages to the cows and less purchased feeds and supplements. Some farmers started doing intensive rotational grazing. When farmers had no money for fertilizer other than the manure they had on their farms, soil mineral levels would start to go down because they were using up soil reserves of some of the nutrients. By applying a balanced blend of minerals to fit their soil’s deficiencies, crops improved, cows got healthier and my fertilizer business was growing. 

Five years after starting, we’d reached our goal of working with 400 farms. Now what?  Charles Walters, the founder of Acres U.S.A., wanted me to write a book. I had been speaking at his conferences and he said I had a lot of good ideas but talked so fast many people missed a lot of it. So, write a book, he said. 

In addition, after being on many farms, I found that getting farmers to trial new products and practices was hard. I wanted my own research farm. So at one of our annual meetings I announced my future plans to write a book and own a research farm. I didn’t want to lock myself into a box like I had before with my goal of 400 farms, so I said I wanted to change agriculture in the world. To do that, I needed to reach more people and that meant writing a book and owning a farm. 

The farm purchase was relatively easy, and one year later we owned a research farm. Writing a book was a lot harder. It took me 10 years to finish it. Charles Walters kept asking where the book was, and I told him I kept changing my mind every year as I continued to learn more.  He said, “If you keep doing that you will never finish it!” and told me to send me what I had so far. I eventually did, and The Biological Farmer came out in 2000. The release of the book got me invited to speak around the world, and what an education that was! Within two months of the book’s release I was on a tour in Australia, then I was off to South Africa, Europe, New Zealand and China, not to mention all over the U.S. and Canada. Seeing the same biological farming principles applied to different climates, soils and crops — and adopted by different types of farmers — was eye opening. It was like a big jig saw puzzle was starting to come together for me. I could see where some of the pieces fit, but not all.

No matter where in the world I was, the principles of biological farming were the same. Biological farming is all about soil health, promoting root growth and supplying needed minerals. You have to create that ideal home for the biology — they like their food on top and to be mostly left alone. They need to be fed well — not by soluble, high salt fertilizers, but low salt, slower release nutrients tied to carbon to feed the microbial life.

In the beginning, the research farm was trial after trial, as we implemented and tested products and practices. In one plot I grew corn on corn for ten years in a row to see what would happen to soil quality over time, with one part of the field getting manure, a second part getting a biological starter, a third getting soluble nitrogen, and the fourth plot just corn on corn with a starter and nothing else. The whole field had an interseeded mix of rye grass and clover yearly. No herbicides or insecticides were used. I was trying to prove that with manure and a cover crop you could grow corn on corn and keep it healthy and high yielding. In the end what worked best was mineral balance and cover crops.

Another area of the farm was put into a multi-year calcium study comparing three different sources of calcium: high-cal lime, gypsum, and Bio-Cal, which is a fertilizer I designed. These are silt loam, neutral pH, high magnesium soils. I grew corn and beans on the plots. The high calcium lime never did respond, and it wasn’t the right fit for those soils and that cropping system. The gypsum, applied at 1000 lbs/acre, took a while to get a response. The Bio-Cal was instantly off to a great start. I applied 1000 lbs/acre each year and at first saw a big response, but after a while that was overkill and I had to stop because my calcium levels were getting too high.  But it was a great way to compare products and proved to me where these calcium inputs worked best.

In another project, I grew alfalfa on alfalfa, and started by taking a soil test and doing the math, applying whatever nutrients the soil test said were missing. I did that for several years in a row, and proved that while a soil test is a great guide, following it to the letter isn’t going to get you where you need to be.  There’s a lot more to soils than just the numbers on the soil report, and while you need balanced minerals you also need to take care of the biology and do “tillage with a purpose” to control air and water and manage the decay of residues.

We hosted field days on that farm for 25 years so I could share what I’d learned. As time went on, we ran out of places to test things. The whole farm was changing from all of the trials I was doing. We used balanced fertilizers everywhere, dropped the chemicals, and converted the farm to organic production.  We later bought the farm across the road as my son was getting older and wanted to farm. My son and I bought a dairy herd and added more land, and in the end the field days weren’t about plots and testing things, but to show what had been achieved on the farm after 25 years of biological farming.

Developing new fertilizers was at the core of what I wanted to accomplish. At first it was just using other sources than what was commonly sold: MAP instead of DAP, potassium sulfate or KMag instead of potassium chloride. I created blends adding rock phosphate, ammonium sulfate, and sulfate trace minerals. As time went on, I saw a need for creating a homogenized trace mineral blend. So instead of adding one pound of zinc per acre and trying to get it mixed well into a blend, I tried mixing it with other minerals like humates and natural rock minerals and then pelletizing the mix. I wanted each pellet to have the exact same analysis so I could get better distribution across the field. With homogenized blends, we could spread that pound of zinc throughout a 50 pound homogenized blend with other traces added. At the same time I was working to deliver a high-quality fertilizer that was time released.  I was not so concerned about pounds and solubility, but about nutrient delivery. I came up with a fertilizer formula that all of my fertilizers had to have:

  1. A balance of soluble nutrients to timed release.
  2. A balance of all of the nutrients a crop needs, coming primarily from natural, mined sources.
  3. Low pH.  Instead of having the soil on the acidic side in order to release nutrients, why not have the fertilizer low pH so around each pellet there is a microclimate where the pH is lower and nutrient availability is higher all season long?
  4. A low-salt index so the fertilizer is soil life friendly.
  5. A carbon source in the fertilizer blend.

My “five things” requirement for fertilizers led to the development of new fertilizer blends that were carbon-based. I started including humates or composted manures in the pellets. I also had several different calcium sources for different conditions. The question was always: how fast can I change my soils, grow good crops, and stay within a budget? How much, how often, what blend, and what are the expected results? You can take a soil test and see excesses and deficiencies, but that addresses your soil correction — improving the soil condition overall. You also have to have high-quality crop fertilizers that include nutrients specific for that crop in those soil conditions, adding nutrients above and beyond what the soil in its present condition can provide. It’s not a small task.

In order to gauge how the fertilizer is performing you need to test the plants. Tissue tests and sap tests give clues as to what nutrients the crop is able to access.  The downside to these tests is that they give you a picture of how the plant is doing that day, so they need to be taken regularly to get a sense of what’s happening across the growing season. But testing the plants is one of the best ways to see if your fertility program is really performing.

I believe in using dry, blended fertilizers as it is still the most cost effective way of growing healthy, high yielding crops if the soil is managed properly. If you have decent soils, they are rich with balanced minerals, great soil structure and biological life. If your soils are in great shape, do you need to add a crop fertilizer and add biologicals? Not many farmers ever achieve that level of soil health, so crop fertilizers provide what your crop needs each year.

While I am a big advocate for dry fertilizers, liquids also have their place. Applying liquids as a starter or a foliar and adding nitrogen and some minerals seems to be a profitable practice for many farmers given their soil conditions. Seeing that I want carbon in my fertilizers to feed biology, for a time adding humates seemed to be the best choice. Then along came the use of molasses. A sugar source works great with many liquids, but what about adding plant stimulants to the mix as well? Things like kelp, fish meal, or biologicals containing specific organisms that fill a need in the soil. I’m sure many have their place, but you need to know when, how much, and what problems you are trying to solve.  Are you just covering up a problem in your soils that could be addressed by using cover crops, balanced minerals and better soil building practices?

In my career I have come a long way in my understanding of minerals. I now have a much better understanding of mineral use, products that are available, and how and when to apply them to grow bumper crops. I know it can seem confusing, but once you start making positive changes you will be pleased with the results. Of course minerals aren’t the whole story, there are still the physical and biological aspects of soil health.

Soil health has become a much more popular topic of conversation in the farming world. There is a lot more information out there, and a lot of success stories being shared. Regenerative ag, soil health, cover crops, compost, no-till, minimum tillage and strip till are all becoming main stream. For tillage, compaction is still a major problem, maybe even a bigger problem now given our big equipment and wild weather patterns. I’m a real believer in shallow incorporation of residues and subsoiling to build good soil structure. We can’t have a crust on the surface or let the soils get water logged, and we need to grow “roots.”  Fill the soil with both living and decaying roots. For this to happen the soil needs to be well aerated. That’s why I like strip tillage. Not only can you concentrate added nutrients in the root zone, but if they are the right ones you’re planting in a zone that allows roots to really grow. 

The story of soil organisms hasn’t changed — they like a roof over their head, they need to be fed and mostly left alone, and they need to breathe. Keeping the ground covered, having a diversity of plants, creating an ideal home for soil life to flourish is now also better understood and value is being put in the need to do so. I like the minerals I add to my fields to be in the carbon/biological cycle, meaning my plants and then soil life takes up minerals and then releases them in a plant-available form across the growing season. Once the plants take up minerals or they’re tied to carbon in compost or humates, the minerals can’t leach or get away. They are there to be released slowly as the plants need them.

In this country we have created problems that need solutions, but we also have opportunities to fix them. The large farms with lots of livestock and lots of manure are not close to enough land to haul it and effectively spread it all.  I see the future as making energy from the manure on those farms and then taking the concentrated biology and nutrients left over from that process, adding a balanced mineral blend, and using them to make carbon-based biological fertilizers. Now the manure is in a form that can be trucked so it can be moved to where it’s needed. 

And here we are in 2021. We are ready to regenerate the soils. Soil health, human health, cover crops, and biologicals are all topics of conversation and I never thought this would happen in my lifetime. We have no choice but to make changes as our climate is changing. Farmers must adapt. The need for putting more carbon in the soil certainly comes as an opportunity for farmers that are ready. 

We are hosting a field day event at our farm in July, and will be sharing what we are doing now and what we’re planning to do as we look to the future on the farm. I am always experimenting with new things: new types of crops, agroecology, perennial crops, or just the best use of the land for the current climate and soil conditions. I have invited the Savanna Institute to our summer field day to talk about some of the perennial crops I’m putting in, including blueberries and elderberries. They’ll share their plans for infrastructure, market research and training in southern Wisconsin to help farmers successfully incorporate perennial crops as part of a whole farm system.

There have been a lot of changes over the past few years. I still farm with my family, and have also started a consulting business with my daughter, Leilani, who speaks on biological farming and co-authored my last two books with me. Zimmer Ag is just beginning, and our kick-off will be the classes we are doing at the farm this July with the Acres U.S.A. team. We’ve also made a lot of changes on the farm over the past few years and I’m looking forward to sharing what we’ve been up to. We have changed from growing row crops, silage and forages to growing 100% forages for the cattle and one-year corn followed by one-year soil building for the crop acres. If you want to change the soils on your farm, you can take baby steps or you can jump in. We have slowly gotten to where we are today, but you certainly don’t need to go as slowly as we did. We are willing to share our farm, our knowledge and our experiences and look at a new model for land use in our area. Come visit our farm this July and learn and enjoy the beautiful scenery around Spring Green, Wisconsin. I hope you can attend.

Gary F. Zimmer is the author The Biological Farmer.