Weed Control and Fertility Comparisons in Solid Seeded and 30" Row Soybeans

PROJECT BACKGROUND
I farm 1,400 acres of which 400 acres are presently in CRP. I have been farming since 1978. I fatten some cattle and hogs every year. I began ridge-tillage in 1982 and no-tilling in 1993 and also use the rotary hoe for weed control and to reduce herbicide use.

Randy Citrowske, a 16 year employee, operated most of the equipment and was available at the field days to answer questions. Michaelson Farm Partnership owns the land that was rented for the plot. Land Stewardship Project and Western Minnesota Sustainable Farming Association were a source for evaluating what barriers to examine.

PROJECT DESCRIPTION AND RESULTS
In this project I worked on my weed control and fertility barriers from an economic perspective in both solid seeded and 30” row soybeans.

I discovered that the weed control was a major barrier. The soybeans were planted May 20th through the 22nd. Due to rain, I was unable to get back into the field with a rotary hoe until June 9th, at which time I got unsatisfactory results and called SARE. I was given permission to drop the “on-farm inputs” portion of my weed control and on June 10th I sprayed 3 ½ oz. Pursuit and 1/8 oz. Pinnacle on all of the plots.

The economics for spreading compost was not present on a one year basis. On April 30th and May 17th I spread 3 ¼ tons per acre of compost worth approximately $60.00 per acre. It provided me with 32 ½ #N, 240#P, 26#K, 10#S, 286#Ca, 26#Fe, and ½ #Zn. The off-farm input was 21#N, 61#K, and 24#S, for $22.60 per acre. It cost me $37.40 extra for the compost and the extra return was only $15.60 (2.6 bu/acre x $6.00) so the carry over nutrients from the compost needs to be worth $21.80 to break even.

The 30” rows yielded more than the solid seeded soybeans by over 3 bu. per acre on both the compost plots and the purchased fertilizer plots. In this project I would have had better yields and increased the chances of using the rotary hoe for weed control by using all 30” rows, but I had hoped that I could increase my yields by solid seeding (which is common in this area), reduce weed germination, eliminate cultivating, and make up the difference with rotary hoeing and hand weeding.

I ended up harvesting eight plots each of 30” rows with purchased fertilizer averaging 31.3 bu/acre, 30” rows with compost averaging 33.9 bu/acre, solid seeded with purchased fertilizer averaging 28.2 bu/acre, and solid seeded with compost averaging 30.74 bu/acre.

I am not ready to give up on solid seeding since it was only my first year and I am already set-up to go another year. I am also still composting since I personally believe the carry over nutrients are worth at least the $21.80 that was not returned to me the first year. I will continue to watch for opportunities to use less herbicide or none at all. This is possible because I use primarily post applied herbicide which gives me an opportunity to use a rotary hoe when applicable and make weed pressure evaluations.