|Delate, Kathleen -|
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 14, 2012
Publication Date: October 24, 2012
Citation: Delate, K., Cambardella, C.A. 2012. Organic no-till production for grain crops in Iowa: Effects on crop productivity and soil quality. American Society of Agronomy Annual Meetings [abstracts], Oct. 21-24, 2012, Cincinnati, OH. CD-ROM. Technical Abstract: A multi-state, long-term organic experiment was established in 6 states in 2008 to examine effects of organic no-till production on crop productivity, yields, soil quality, and economic performance. Tillage treatments included conventional tillage (CT) and no-till (NT), with cover crop planted in the future NT plots as either hairy vetch (HV) or rye. Treatments were arranged in a randomized complete block design as a 2 x 2 factorial with treatment combinations replicated four times. Results from the Iowa site showed that corn and soybean plant populations were similar between treatments both years; and NT soybean yields (averaging 2.62 Mg/ha) were equivalent to CT organic soybeans (2.89 Mg/ha) in 2009, and in 2011, in a wetter, cooler year, NT soybeans averaged 2.08 Mg/ha compared to 1.88 Mg/ha in CT. NT organic corn averaged 1.82 Mg/ha compared to the tilled corn in 2009. Soil quality analysis in Fall 2009 indicated soil microbial biomass carbon (MBC) values were significantly greater in NT than in CT plots and at the end of the second season following oats (2010), residual soil nitrate-N, pH and electrical conductivity were greater under NT than CT and bulk density was significantly lower under NT. Although MBC was not significantly different in NT vs. CT in Fall 2010, NT MBC was numerically higher than CT MBC (NT–194 vs. CT–185 mg/g. Microbial biomass nitrogen (MBN) followed a similar trend with significantly greater MBN in organic NT over CT: NT–48 vs. CT–35 mg/g. Nitrogen mineralization potential and soil pH were significantly greater in organic NT soil compared to CT soil, and bulk density was significantly lower in NT soil in fall 2011. Results of this study demonstrate that the soil microbial community responds quickly to changes in soil management, in this case, reduced soil disturbance and increased surface residue cover under NT. Lower bulk density of NT surface soil results in greater porosity which can enhance microbial habitat through increased water-filled pore space. Our findings also show that within 3 years, organic NT management resulted in higher nitrogen mineralization potential, reflecting the soil’s ability to release N from labile organic N pools and improved fertility. We plan to continue this long-term experiment to verify long-term changes induced by the different soil management strategies.