Crop Rotation and Tillage Effects On Soil Properties.

Shifts in cropping systems from long-term rotations including forages to mostly annual crops has intensified tillage, but has also led to the development of conservation tillage practices such as no-till. There is a shortage of information about the interactive, long-term effects of rotation and tillage on soil productivity. The objective of this study was to assess the effect of rotation and tillage on soil physical and chemical properties. Continuous corn (Zea mays L.), corn-soybean (Glycine max [L.] Merr.), corn-soybean-wheat (Triticum aestivum L.), and continuous soybean sequences were split into conventional tillage and no-till subplots at two western Illinois sites and were sampled about15 years after establishment. Both bulk density and water aggregate stability were greater under no-till than under conventional tillage in the surface 20 cm of soil. Water aggregate stability was greatest for the corn-soybean-wheat rotation, and was greater for the other corn crop sequences than for continuous soybean. A similar pattern was detected for total nitrogen with greatest N content in soils under corn-soybean-wheat and lowest N content under continuous soybean; soil N was intermediate with the other corn sequences. In contrast, extractable P levels were greater in the sequences with soybeans grown more frequently, with greatest soil P in continuous soybean, followed by the corn-soybean rotation. These results indicate the addition of wheat to the corn-soybean rotation, and the use of no-till, might provide some benefits to soil productivity compared to continuous cropping or the corn-soybean rotation.