A historical perspective on what’s possible when we question monocropping
On July 6, 1976, I was cultivating my soybeans and saw a stalk of corn growing directly in the row of soybeans. I accidentally pulled out the center of the stalk and attempted to kill the rest of it. On July 15, I was cultivating my Harasoy 63 soybeans and saw the same stalk of corn. It was 3 feet high (it grew four inches per day for nine days). This was incredible for northwest Ohio for that time of year. The next year I grew 28 acres of corn (Reid) intercropped with soybeans (Harasoy 63).
Fifty-three days after planting the soybeans, the soybeans started to decompose, which provided the corn with plenty of nitrogen. The corn grew about four feet in six days. It was seven feet tall on July 8 and grew to approximately 13 feet 6 inches tall. I believe that this was the tallest corn in northwest Ohio. The width between the rows of corn was 36 inches. I think the width between the rows of beans was about 7 inches. I planted beans 2.8 to 3 seeds per foot of row. On the test plot over three tenths of an acre, the soybeans grew to 36 inches tall. The other beans grew to 40 inches tall. (I think this was from 56 to 60 days after planting).
While the soybeans grew, they competed well with the weeds. I had two or three spots where the weeds overtook the beans and had to hoe them out. I decided to hand-pull weeds that were a half-inch or taller. It took eight days. The soybeans completely decomposed within two weeks, leaving a clean cornfield. The soil structure was completely changed, from a clay to a much bigger particle, almost to the point of the one picture in the old Encyclopedia of Organic Gardening. The ground opened up to at least six inches deep.
The local vo-ag class came out and did a yield analysis, and I ended up with 126 bushels per acre on the test plot. The corn in the test plot was grown on Dietrich’s Organic Farm in 1977 at Genoa, Ohio, with my mother, Veronica, as farm manager. I became a bed patient in 1978 and wasn’t able to keep developing this method (corn with soybeans — now called intercropping) even though it cost less than $50 per acre to do it, not counting land rent or labor. The local farmers were spending about $80 per acre and getting 77 bushels of corn per acre. I beat their yield by 49 bushels with less cost.
I got two tons (dry weight) of residue per acre from the soybeans. At 50 percent carbon, that is a ton of biologically active carbon per acre. Remember that biologically active carbon holds water. There was plenty of water in the fields where this was done, and the soil was easy to dig up. The field next to it was so dry and hard that I could stand on the top of a shovel, and it would not go down more than about 3/8 of an inch. I estimated my nitrogen on the test plot was 120 pounds per acre with a carbon-to-nitrogen ratio of 16.7 to 1.
On acreage, I estimated my nitrogen at 100 pounds per acre. That figures the C:N at 20 to 1. I also figured that in the 1970s, under best conditions, soybeans had the capacity of 240 pounds of nitrogen per acre in the Genoa area. In other areas of the United States it might be as high as 768 pounds of nitrogen (from soybeans) per acre.
I think that the Harasoy 63 soybeans worked because they started releasing excess nitrogen. The corn picked it up, grew really well, and wiped out the soybeans. We tried to use three other varieties of soybeans, but none of them worked with first-year corn crops. If you try planting corn with soybeans, be sure to plant the soybeans thick so they can compete well with the weeds. I would not recommend using another variety of soybeans for first year corn, but if you can still harvest corn without getting soybeans in the corn, you should try it. You would get up to 4.8 times your present yield of soybeans per acre in nitrogen the very first year. For a yield of 50 bushels soybeans, you would get 240 pounds of nitrogen per acre.
You should put nutrients on the soybeans so you can get the same yield of corn (or more) and the same quality or better. I think that the soybeans will tie up 10-15 pounds of available P2O5 per ton of residue. For the first year of corn, I would figure on 60 percent of present yield of soybeans, times 4.8, equals nitrogen content. Remember that if the nitrogen doesn’t get the corn the first year, it should get to the next crop.
Chris Dietrich is a long-time Acres U.S.A. reader and supporter.
