Impact of tillage on runoff in long term no-till wheat systems

Abstract

Adoption of no-till cropping systems continues to increase worldwide due to enhanced soil and water conservation, reduced inputs and maintained crop production. Soil compaction, particularly in grazed systems, can become a concern within no-till cropping systems and occasional tillage may be a method to relieve these concerns. However, there is no data within the US Southern Great Plains examining the impact of tilling long-term no-till wheat cropping systems and the potential subsequent impacts on runoff characteristics. The objective of this study was to evaluate the impact of tilling long term no-till wheat systems on runoff water quantity and quality. The study was conducted within a field that had been in no-till wheat with occasional grazing for seven years. Seven tillage treatments were evaluated, including: no-till, conventional till, and soil aeration using roller angles of 0°, 2.5°, 5°, 7.5°, and 10°. Rainfall simulation studies providing a 7cmh−1 storm event were conducted approximately three months after tillage. Results showed that conversion from no-till to conventional tillage increased runoff volume by 38%. Total sediment losses were at least 2.8 times greater from conventional till plots than no-till and aerated treatments. Nutrient concentrations were similar among tillage treatments. However, total P and ammonium-N loads in runoff water were significantly higher from conventional till plots compared with other tillage treatments. Aeration did not provide a consistent trend and generally provided no significant improvement in runoff characteristics compared with no-till. Initial results indicate no advantage of tilling long term no-till wheat systems in regard to runoff quality and quantity three months after tilling.