|Sudduth, Kenneth - Ken|
Submitted to: International Soil and Water Conservation Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/18/2019
Publication Date: N/A
Technical Abstract: Conventional cultivation of claypan soils leads to soil and water quality degradation and plot studies have highlighted trade-offs between erosion control and herbicide or nutrient runoff. There is a need for long-term field scale evaluation of practices that reduce sediment, nutrient, and herbicide losses by runoff. A 36-ha field located in Missouri was under a conventional corn-soybean system from 1993 to 2003 with fertilizer application and tillage prior to planting in the spring. A two management zones precision agriculture system was implemented from 2004 to 2014: wheat and soybean in 60% of the field, and corn and soybean in the remaining 40%. The system included no-till, cover crops, atrazine split-applications, and variable rates of nitrogen and fall-applied phosphorus. The objective of this study was to compare runoff water quality from the two management systems, based on flow and load duration curves, cumulative distribution functions, and conclusions from replicated plot studies. The precision agriculture system did not affect annual runoff but increased the frequency of low-flows. Sediment losses were reduced by 87%. Atrazine and phosphorus losses were lower than expected, despite the lack of incorporation into the soil. Nitrate-nitrogen losses decreased and resulted in an overall decrease of nitrogen losses despite a slight increase of ammonium-nitrogen losses. No-till, the presence of cover crops, the wheat filtering capacity, and different nutrient and herbicide application timing likely contributed to these findings. An aspirational management system is proposed to further improve on the performance and practicality of the precision agriculture system.