Strip Cropping Systems to Reduce Energy Inputs and Optimize Profitability
1) Determine the production and economic impact of wheat introduced into a conventional
corn-soybean alternate strip rotation in a ridge tillage system.
2) Determine the potential of this 3-crop rotation to minimize insect, nematode, and weed
pressures and thus reduce pesticide use.
3) Determine the effect of interseeding legumes with wheat on the potential fertilizer N savings,
N availability to corn, and economics in a ridge tillage system.
4) Measure the border row vs. inside row effects of each crop on yield, pest incidence, N
utilization, land utilization, and production economics.
5) Evaluate the ability of potential soil tests to predict available soil N for corn following
soybeans and following wheat with and without interseeded legumes.
An experiment was started in 1991 to establish a crop rotation system where four single crop
production components (ridge tillage; 3-crop wheat-corn-soybean; narrow (15' wide), alternate
strips; and legume interseeding) could be studied as an integrated farming system. The rotations
(continuous corn, corn-soybean, wheat-corn-soybean where the wheat was interseeded with
either Nitro alfalfa, vetch, or nothing) were setup in 1991 on a Webster clay loam on the Lynn
Sorenson farm in Freeborn County, Minnesota. In 1992, nitrogen rates of 0, 40, 80, and 120 lb/A
were applied to corn following soybean, wheat, wheat + alfalfa, and wheat + vetch to determine
the N credit due to fixation by the legumes. Band application of reduced rates of herbicide were
applied to both corn and soybeans. Mechanical weed control and ridge building were
accomplished through cultivation. Yields and grain moisture of wheat, corn and soybean were
taken in 1992 to evaluate the border vs. inside row effects of the strips, the interseeded legumes,
and the response to N as affected by the cropping systems. Data on vetch and alfalfa yields, weed
seedbank counts, root ratings and lodging to evaluate corn rootworm (CRW), tunnel counts to
assess European corn borer (ECB) damage, and soybean cyst nematode (SCN) egg counts were
Yield data obtained in this second year, based on the assumption that the center 2 rows of a
6-row strip or the center 7 rows of the 21-row wheat strip represent a "whole-field" yield, showed
(1) 4 percent higher corn yields and 14 percent lower soybean yields compared to a "whole-field"
average when grown in alternate strips, and (2) 7 percent higher corn yields, 5 percent lower
wheat yields, and 8 percent lower soybean yields when grown in the 3-crop strip rotation
compared to a "whole-field". Excessive spring regrowth of Nitro alfalfa and hairy vetch resulted
in significant competition to the corn, resulting in stunted early growth, delayed maturity, and 20
percent lower corn yield compared to following wheat without a legume. Pest evaluation showed
very little evidence of CRW or ECB activity. Soybean cyst nematode populations were
considerably lower in the 3-crop system (no soybeans in 1991 or 1992) compared to those
systems that included soybean in either 1991 or 1992. Weed counts indicated substantially more
small grass and broadleaf weeds in corn following wheat in the 3-crop system compared to corn
following soybean in the 2-crop rotation.
Potential Contributions and Practical Applications:
After only two years, it is difficult to project too far; however it appears this type of cropping
system could offer the following benefits: soil erosion control, reduction of insect activity,
creation of wildlife habitat, and improvement of water quality.