Improved weed control methods during non-crop periods have increased precipitation storage efficiency such that more soil water is available for crop growth. Also, new crop varieties are more efficient in converting water into grain, thus the need for fallow may be less than historically perceived. This study is evaluating crop rotations to increase cropping intensity and subsequently, reduce the amount of fallow. A crop rotation study with 16 rotations was initiated in 1990 on a Weld silt loam at the Central Great Plains Research Station. With all rotations, we are minimizing tillage.
Tillage is required to incorporate herbicides for sunflower.
Standard agronomic practices for seeding rates, planting dates, varieties, and weed control are being followed. Precipitation was favorable for crop growth in 1999. For example, in 1999, with favorable precipitation, wheat yield was not affected by rotation. Low wheat residues in continuous cropping may have reduced corn yields. It appears that corn is synergistic to proso, as proso yields are highest when corn is the preceding crop.