Minerals for Healthy Soil & High-Quality, Top Yields

By Gary F. Zimmer

It’s a new century, and there is more knowledge about farming and the role of minerals, and there are more farmers paying attention to it. When it comes to farming, we know what the “base” is: putting all the pieces together including minerals, biology and soil structure — and using crop fertilizers that provide above and  beyond what the soil can dish out in terms of nutrients and biology.

Cover crop improves soil health and quality

A fall mixed cover the author grew after rye was harvested. He used the cover crop to capture nutrients in a biological form and to cycle nutrients to get more minerals into the following cash crop.

Even though there’s a lot of discussion about soil health, no-till and soil structure in farming right now, not enough attention is paid to minerals.

It seems like so much of agriculture is spending its time and money chasing magic biologicals, foliars or plant protection and not focusing on doing everything you can to feed your crop a balance of minerals and prevent the problems in the first place.

So what is your limiting factor or constraint that interferes with plant production and plant health? You need to understand that your farming practices have a lot of influence on plant health, and plants that are healthy protect themselves — just as you have an immune system that functions well if you are healthy. Reduce stress; eat a balanced diet with a balance of nutrients; eat a variety of foods that are clean without foreign compounds to fight and a good biological balance. If you get all that right do you need to take supplements?

It’s not farming the same way it was in grandpa’s day because there was a lot he didn’t know. He didn’t understand nutrients, soil health or soil fertility, and didn’t have the tools we have. He was stuck with a “plow.” If I asked you to do everything you could to get your soils healthy and mineralized, what would you do?

Soil Testing

We know there are over 20 minerals needed to grow plants. We know there is a certain level of minerals needed in the soil (a sufficiency level), and that there is a balance or a ratio between them. We also know soil with “perfect” soil testing results does not always grow perfect crops.

Soil testing is not looking for perfection in numbers, it is a tool to identify limiting factors: nutrients that are deficient or in excess. It hopefully doesn’t matter which soil testing lab you use; they all use extraction methods that give clues as to mineral levels and what type of soil it is based on CEC, pH and organic matter. It’s simple to add the nutrients that are short and not to add more of what you already have enough of.

Trust the lab, and then in three to five years, after you have made the necessary corrections, retest with the same lab, pulling your soil samples the same way and at the same time of year. Monitor your plan.

The next question is what type of material to use for correction and how much to use? I always like to start balancing soils by correcting calcium and phosphorus. When correcting your soil for calcium and phosphorus, start by finding the right source and right amounts to fit your soils.

The amount depends on your budget and the crops to be grown. Livestock manures and natural mined materials like rock phosphate, lime, gypsum and K-mag are some of my top choices.

If the pH is low, lime it. Choose the correct type of lime, either high calcium or dolomite, depending on your soils, and don’t overdo it. I never like to go over 2 tons per acre of lime at a time. If the pH is fine and calcium is low and magnesium high, use gypsum.

Calcium works best when boron is added with it. The other minerals like potassium sulfur and traces can be added with your crop fertilizer rather than in a soil corrective, but can’t be ignored.

Crop Fertilizers

While fixing the soils you also need to get a good crop in order to pay the bills. You use crop fertilizers to feed this year’s crop. Crop fertilizer is a balance of nutrients chosen to fit your situation. I don’t want to make this complex — if you want pick the right crop fertilizer yourself, I suggest you read the latest edition of my book The Biological Farmer, Second Edition. There are a lot of examples and guidelines in the book on how to choose fertilizers for different crops and soil types.

Crop fertilizers can be dry or liquid. My first choice is dry as you can get more nutrients for your money. You can also easily add carbon, make homogenized balanced blends and control your pH.

I like my fertilizers to be low in pH because around each pellet in the soil the zone remains acid, keeping nutrient availability longer. I also don’t want all my nutrients to be soluble when added; I prefer some for now and some in a time-released form.

Healthy biologically active soil

The soils on a farm the author has been managing for 10 years using lots of biology through crop rotations and mixed cover crops, and feeding the soil a balance of nutrients including calcium, sulfur and trace minerals. The soil has excellent structure, improved organic matter since the author took over managing it, and you can see the aggregation and earthworm channels — all signs of a healthy, biologically active soil.

For organic farmers, I like to use biology to grow nitrogen and release nutrients already in the soil, and on top of that add natural mined sources that also contain other minerals like sulfur, silica and many rare needed micro trace elements like selenium.

For trace element fertilizers I use sulfate trace minerals mixed with humates that are a low pH natural mined mineral. For an organic farmer, trace elements are restricted so you need to have a test to prove you need them. But why would anyone buy them if they don’t need them?

Test both your soils and crops to see if you have enough minerals and if they’re getting into the plants. I like adding carbon sources to fertilizers, like mixing minerals with humates or putting the minerals in compost, or adding molasses to liquids. It is not only food for the soil biology but also buffers the minerals and gives them something to hold on to so they don’t tie up or leach.

For the organic major elements, mixing compost with humates, K-Mag, potassium sulfate, rock phosphate and gypsum works well. For organic farmers nitrogen needs to be grown or supplemented with manures.

For the biological farmers we have been building our base fertilizer from nutrients collected from dairy manure out of anaerobic digesters. This manure matrix has lots of biological bodies and properties along with many humic substances. To make blends that fit the farms we can mix in MAP for phosphorus, ammonium sulfate, K-Mag, potassium sulfate and traces — all added to the matrix to give us our carbon base. Our calcium crop fertilizer includes adding humates, sulfur and hydrated lime. The calcium sources should be spread on the land separately from the granulated dry fertilizers due to volume needed and price.

Liquid crop fertilizers can be used and work best as in-row or foliar on high testing, highly mineralized soils. I like higher quality nutrients in the liquids and mix them with carbon sources like molasses or humates.

If I have given you enough information, you will know why you’re applying certain minerals and will have confidence you’ll figure out how.

Supporting Soil Biology with Minerals

After you’ve worked out what minerals you need for both your soil corrective and your crop fertilizer, the next step is to address soil biology and soil health. I think it’s logical — create an ideal home and feed the biology a variety of foods.

Plants determine the soil life, so the more plant variety you have, the more diversity in soil life, and the more success you’ll have growing healthy crops. Digestibility of those crops feeding different types of soil biology is also a big part of it. Mature, rank, “brown” plants are hard to eat and slow to digest. They may build organic matter in soils, but do not provide enough soluble nutrients for the crop to grow.

Young, succulent, highly digestible plants feed more bacteria in the soil, which eat the easy stuff and provide not only a lot of nitrogen but also other nutrients that feed your crop. So choose the plants you want to feed your soil life and the maturity of those plants to achieve the results you’re after.

Soil life wants its food on top and to be left alone. But if the food just lays on top of the soil, how does the biology eat it? It’s like putting the livestock feed on the other side of the fence!

I believe shallow incorporation of plants makes the most sense. Soil life needs air to survive — the fence post rots off near the surface. To support healthy soil life we need to feed them a diversity of plants, apply manure, compost and undigested plant material (like your cover crop) and make sure they have air and water with no crust on the soil. The soil life also needs a balance of minerals. Take every opportunity to have growing plants on the soil. Living roots keep feeding the soil biology, even in winter.

You need healthy soil life in order to maximize the cycling and plant uptake of the minerals you applied, and good soil structure is necessary to protect your soil life.

With a lot of residues mixed in near the surface you protect the soil, avoid crusting and allow rain to soak in.

Because you can’t let the soils be waterlogged if at all possible, I run deep rippers through my fields when compaction starts to be an issue so the water has an easy path to soak in. The only time I would do aggressive tilling like plowing or chiseling is if I’m making a major correction of nutrients or applying a lot of manure.

It’s middle zone where there are many roots and earthworm channels. That “middle zone” (from about 3 inches to 8 inches down in the soil) is what I want to leave alone to protect the breathing tubes for soil life and channels for new roots to follow.

Get your biology and your soil structure right in order to get your minerals cycling. Lay out a plan, observe and measure. Get help from a consultant if needed. Remember, it’s easier to choose your soil testing lab than it is to choose your consultant. That can be a difficult process. You have to get smart enough to ask the right questions. You have to find someone who really understands your farm and your goals. It has to be logical.

When it comes to fixing your farm, the first area of compaction you may need to address is between your ears. Keep an open mind. Look at the big picture. Once the base is laid down then it can be easy to judge if additives are a benefit. Evaluate those additives on the base that was there when they were tested.

If my soils are really working, I don’t seem to get results from all the biologicals, foliars and extras. It’s much easier and more fun and profitable when the system is working right.

In The Field

The map and soil test presented in this article are from a farm I bought three years ago. It had been rented for over 20 years, growing mostly conventional corn in the last decade or so.

I farm organically, and it takes 36 months from the last prohibited substance before an organic crop can be sold for newly transitioned land. Normally I would use those two growing seasons to “fix” the soil by adding compost, manures, minerals, growing cover crops, ripping to reduce compaction, shallow incorporating cover crops and residues and building organic matter and soil health. After those two growing seasons, you would not be able to recognize the soils I started out with.

On this particular farm, the soils are really out of balance with extremely low calcium and pH levels. Because of this and my desire to test new things, I am building the soil more slowly. I grew two years’ of cereal rye and harvested the seed since I can use it as cover crop seed for the rest of my farm. I did some mineralization with soil correctives, deep ripped the fields, and have made some progress now after two growing seasons but this farm still has a long way to go. If I would have soil tested it before I bought it, I would have had second thoughts.

The farm has about 45 tillable acres, and I am setting it up for row crops, vegetables and some livestock. My goal is to have the farm productive and profitable so a family can make a living on it. If you look at the farm map on page 26, you’ll see that fields 1, 6 and 8 are level enough, and it’s possible to irrigate those fields and grow vegetables.

If you take a closer look at this soil report, the first question you need to answer is: What type of soils are these? Based on the CEC of 8 to 16 they are sandy to silt loams, and the organic matter is mainly in the 2% range. Most fields have a low pH. With a pH this low, some of the mineral levels shown on the soil report are falsely high. Once the pH comes down, those reported mineral levels will come down as well. High iron can be a problem, but this will change as I remineralize these soils.

Note Field 6. It has a pH of 4.7 with a 16 CEC and 4.4% organic matter. It looks to me like a perfect place to grow blueberries, as these need high iron and manganese, which show up at this low pH.

Lime is needed across the farm, but also phosphorus. I like to start correcting with calcium and phosphorus, and these soils need some of both. While the soils are still acid before I lime it, it’s a perfect opportunity to apply rock phosphate, which is calcium phosphate.

I decided to put on 1,000 pounds per acre rock phosphate — there’s no magic in that number, but logistically it made sense because I have 45 acres, and one truckload holds 25 tons which works out to just about 1,000 pounds per acre. I also put on compost at 2 to 4 tons per acre and poultry manure at 2 tons per acre each year for the two years I’ve been farming it so far. The poultry manure is from laying hens and is a good source of phosphorus and calcium. I also deep ripped the soil last year because it was hard and tight. I grew cereal rye both years, as I needed cover crop seed and straw.

balance soil nutrients for quality crops

The cereal rye crop the author grew during transition to organic production on the farm.

Last summer after the rye harvest I put on 2,000 pounds per acre of high calcium lime and planted a cover crop blend that included oats, radish, alfalfa, clovers and a forage grass mix. Some of that blend will be used as hay this year as I start my crop rotations and some will be shallow incorporated this spring to plant organic corn. The soil is a long way from being fixed, but it’s on the right path.

I will continue to apply a manure/compost mix each year and a crop fertilizer containing rock phosphate, HumaCal, K-Mag, potassium sulfate and a homogenized trace mineral blend. This will go on at 400-500 pounds per acre. This is a lot of fertilizer and costly, but I have lots of fixing to do. As you can see from the soil test, it needs lime, calcium, phosphorus, potassium and traces.

When I plant row crops, I have liquid in the planter and will apply 5 gallons per acre of a fish fertilizer along with 5 gallons of a molasses crop fertilizer blend.

Everyone asks, “What does your fertilizer cost”? On this farm I will have a large investment in the soils, but over time it would cost me a lot more if I didn’t fix it. Once it’s fixed, I will still use a crop fertilizer but at much lower levels, depending on crops grown and the minerals those crops are removing.I will always plant cover crops and apply manure and/or compost, and I will also practice tillage with a purpose so I can maintain and continually improve soil health. My investment in my soils will pay off before long in fewer problems, higher yields and higher profits.

In two or three more years I will retest the soils to check progress. This will give the soil correctives time to impact mineral balance and then I can fine-tune the fertilizer applications from field to field. For now, all of the fields need help.

My rotation will be hay on the steeper fields, with corn in rotation on the leveler ones, and a corn/beans/small grains and cover crops rotation on the rest of the fields, eventually adding in vegetables once the soils are in better shape.

Fixing soils and growing good crops is not that difficult. Fix the base of minerals, biology and soil structure; give it time to adjust to the changes you’ve made; test the soils again in five years to see how you’re doing and adjust your fertilizer program to match the soils and crops. It’s a method that really works, and I expect to grow high-yielding, healthy crops on this farm.

This article appeared in the December 2017 issue of Acres U.S.A.

Gary Zimmer is founder and Chief Visionary Officer of Midwestern BioAg. Zimmer is an internationally known author, speaker and consultant. He owns Otter Creek Organic Farm, a family-operated, award-winning farm near Lone Rock, Wisconsin, and has been on the board of Taliesin Preservation Inc. since 2011. Zimmer is the author of three books, The Biological Farmer, Second Edition, The Biological Farmer and Advancing Biological Farming (available from Acres U.S.A.), and numerous articles on soils and livestock nutrition.

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