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Plant Nutrient Content of Corn Stalk Removal for Livestock Feed (07/06/17)

There are a couple reasons why corn growers might wonder about the economic value of baling corn stalks this year and shipping them to a buyer.

Plant Nutrient Content of Corn Stalk Removal for Livestock Feed

There are a couple reasons why corn growers might wonder about the economic value of baling corn stalks this year and shipping them to a buyer. First, more growers are considering no-till/strip till in eastern North Dakota, and dealing with high-yielding corn residue is a worry for many. Second, although the first alfalfa cutting in the west was surprisingly good for many ranchers, pastures are very dry and feed may be short in the fall.

The costs of shipping corn stalks are the baling and shipping of course, but corn growers must also consider the plant nutrient content (fertilizer equivalent) of the residue. Most studies on corn stalk value consider the total nitrogen (N), phosphorus (P), and potassium (K) content of the stalks cut at or near the soil level. A combine cuts the stalk at some height above the soil, sometimes near the soil, but more commonly a foot or even two feet above the soil. In my formative years, I worked on a MS degree at University of Illinois (‘76) and determined the fertilizer value of the ‘husklage’, which was the cobs and stalk/leaves that came out the back of a combine, collected by Quaker Oats at the time (residues to produce hydrocarbons- sound familiar?) for future storage and processing in a pilot project west of Champaign, IL. Assuming that the combines of today would run about the same height as a combine in 1975, the following are values I obtained for the stover portion of the husklage (husklage less the cobs). Most of these sites were harvested by the farmer when the grain moisture content was well below 20 percent.

franzen.1

In another of my MS studies, the change in corn stover N, P, and K (cut at soil surface) was documented from mid-September, when grain moisture content was 26 percent; to October, when grain moisture content was 16 percent; to November, when grain moisture content was below 14 percent and many leaves had become detached.

The pounds per acre of N, P2O5 and K2O at each harvest date are shown in the next table:

franzen.2

These data from my MS thesis are in accord with a more modern study by Mallarino and Oltmans (2011). Here is the link to this report http://crops.extension.iastate.edu/cropnews/2011/12/change-phosphorus-and-potassium-contents-cornstalks-over-time . Rainfall between black layer and harvest also helps to decrease plant K content over time, although it is unlikely to fall below 30 pounds K2O per acre before winter. When considering the cost of removing stalks, consideration of the N, P and K content of the stalks would be wise. Many soils in eastern North Dakota are no longer in the very high K soil test range. New K recommendations for corn in many soils in North Dakota will soon be based on a 200 ppm critical level instead of the 150 ppm level published today.

Dave Franzen

NDSU Extension Soil Specialist

701-799-2565

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