Cover Crop Treatment Impacts on Selected Soil Health Indicators in Two Tennessee Long-term No-till Corn-Soybean Rotations

Soil hydraulic conductivity (K_sat) and soil microbial biomass carbon (SMB-C) estimates in Tennessee no-till corn (Zea mays L.) and soybean (Glycine max L.) rotation systems may be changed with cover crops. This study assessed differences in K_sat rates and SMB-C values under common cover crop treatments of two no-till corn and soybean rotation systems in west and middle Tennessee. Wheat (Triticum aestivum L.), cereal rye (Secale cereale L.), wheat/crimson clover (Trifolium incarnatum L.), cereal rye/crimson clover, a five species mix (containing cereal rye, crimson clover, whole oats (Avena sativa L.), daikon radish (Raphanus sativus L.), and hairy vetch (Vicia villosa L.)), a three species mix (containing wheat, crimson clover, and Austrian winter peas (Pisum sativum L.)), and another three species mix (containing cereal rye, crimson clover, and Austrian winter peas) were planted as winter cover crops and compared with a control (no cover crop) at two University of Tennessee Research & Education Centers: the University of Tennessee's Research and Education Center at Milan (UTRECM) and the Middle Tennessee Research & Education Center at Spring Hill (MTREC). The UTRECM site was dominated by two soil series: Providence silt loam (Fine-silty, mixed, active, thermic Oxyaquic Fragiudalf) and Center silt loam (Fine-silty, mixed, active, thermic Aquic Hapludalf). The MTREC site also had two soil series: Maury silt loam (fine, mixed, active, mesic Typic Paleudalf) and Huntington silt loam (fine-silty, mixed, active, mesic Fluventic Hapludoll). K_sat rates were measured using a SATURO Dual-Head Infiltrometer from METER Group Inc. (Pullman, Washington). SMB-C values were estimated using the microBIOMETER® test from Prolific Earth Sciences (Montgomery, New York). The K_sat and SMB-C data from both locations provided no statistically significant treatment results and had large spatial variability. It is hypothesized that the lack of significant differences for infiltration or SMB-C between cover crop treatments is due to the current agricultural management on both landscapes which provides a good habitat for earthworms and other soil macro-arthropods and thus the development of extensive preferential flow pathways resulting in soil moisture regimes that also provide suitable conditions for soil microbial biomass.

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