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Adding Organic Manure to Your Crops

By Neal Kinsey

Manures are an excellent source of nitrogen. I work with farmers, who use a lot of manures in some areas, and I have other areas under consultation where there is no livestock for thousands and thousands of acres, and nothing organic is applied. A real saving factor in my area has been a broiler production facility that generates more than 30,000 tons of manure a year. Most of it is moved out to farmers.

Most of the farmers in southeast Missouri didn’t consider the value of manures when I settled in the area. It was generally not available to those who had gone out of the livestock business. In time some of us sat down and worked out some figures. One farmer tried it on 400 acres and another one tried it on a few less acres. Now the man who contracts for disposal of the manure has no trouble at all finding someone who wants it. In fact, my clients want it all if the quality is good.

Several items merit front burner consideration when applying manures. Number one, even the same type of manure can vary greatly in terms of fertilizer value, and the nutrient content will vary from fall to spring, depending on contents of the feed. Manures can be nutrient rich. Once you know what the total nitrogen content is, divide by two to compute the nitrogen potential for the next crop.

organic manure added to a field
A sprayer adds liquid manure to a field.

There are tremendous differences between poultry, cow and hog manures, and there is even a difference between layer and broiler manure. Layers are fed extra calcium to strengthen the eggshells. Broilers generally do not get this ration.

One client had 26,000 layers and farmed 160 acres. He had his soils analyzed because his fields weren’t producing good crops any longer. He had put so much layer manure on his farm and pushed the calcium level so high, it started tying up all his trace minerals. He was destroying his farm with the manure. It took about five years to get that problem solved because he didn’t choose to buy sulfur for remedial application.

Manures will drive calcium out of the soil except where cal­cium is highly supplemented, such as for egg production. The problem is that magnesium will take the calcium’s place. The farm mentioned above didn’t have excessive magnesium. In fact, it had basically the kind of magnesium levels needed. By the time we got finished with the switch, both were a little on the high side, but not extreme. When the calcium got high, it tied up his iron and certain other trace elements. This was what kept hurting his crops.

Every soil is different. You have to analyze what is going to happen to the several nutrients. When you analyze soils, you have to remember that just because a certain program works on one farm, that doesn’t mean it is going to work on the farm down the road. Every time the numbers change, a new set of circumstances come into view, with a new set of possibilities and potential problems.

If you use manure and it reduces calcium, but magnesium goes too high, in the end if the proper nutrient balance is to be achieved, you will likely have to use some sulfur to get magne­sium down to a reasonable point. So growers might as well start with sulfur in the first place, but be careful if calcium levels are low and magnesium levels are high. This inventory of facts should prompt us to remember that manure will take out some calcium. Manures will supply extra nitrogen, phosphate and potash to be certain, and is always a better source than physical measurements suggest. Nevertheless, an analysis gets you into the ballpark.

Source: Hands-On Agronomy