ARS | Publication request: Long-Term Conservation Tillage and Residue Additions at the Palouse Conservation Field Station, Pullman, WA

Submitted to: Conservation and Production Field Day Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: May 15, 2010
Publication Date: N/A

Technical Abstract: One hundred years of agricultural production on the Palouse has depleted half of the native soil organic matter (SOM). Can this trend be reversed through management practices? Organic matter feeds soil microbes; provides nutrients to crops; holds water and contributes to aggregation. How much residue is needed to increase SOM? The objective of this study was to determine the effect of no-till and one-pass tillage (chisel) and various levels of residue on soil quality over time. Soil quality parameters were assessed to further define management practices that are soil building rather than degrading. Soil organic matter slowly increased in long-term no-till and chisel. The percentage of SOM in no-till research plots on a side slope at the Palouse Conservation Field Station increased from 1.9 percent to 3.6 percent in the top 7.5 inches over the course of 20 years. Soil organic matter increased to 3.2 percent when the soil was tilled with a one pass-chisel. Long-term no-till also increased the proportion of aggregates in the larger sized soil fractions. No-till stored a greater proportion of the soil carbon in the larger size aggregates, thus protecting more of the carbon from loss due to erosion when compared to nearby conventionally tilled sites. Long-term no-till results in changes to microbial communities and increases in the fungi:bacteria ratio. Data from these long-term experiments will allow us to better assess the productivity and quality of soils in the dryland cropping region of the Inland Pacific Northwest. This information will allow the identification of soil quality parameters that can be used in the development of best management practices for conserving soil quality and enhancing crop production.