Soil biochemical and microbial response to wheat and corn stubble residue management in Louisiana

Abstract

AbstractThe effects of crop residue on soil conditions depend on the quality and management of the residue. Management practices that do not use physical disturbance (prescribed fire and no‐till) were investigated for their potential impacts on soil chemical and biological properties. Surface soil samples (0–5 cm) were collected across no‐till and prescribed fire treatments of wheat (Triticum spp.) in 2014 and 2015 and in 2014 in corn (Zea mays L.) stubble residue at 0 h (before management) and at 1 h, 6 h, 24 h, 7 d, 1 mo, and 6 mo after management. There was a lack of difference between prescribed fire and no‐till management responses in soil chemical and biological properties. However, similar responses in prescribed fire and no‐till management over sampling time of NO3––N, NH4+–N, enzyme activity, and absolute abundance of ester‐linked fatty acid methyl ester biomarkers suggest that abiotic factors and systems management (i.e., fertilizer applications, crop rotation) had a greater influence in these humid subtropical production systems. Additions of soybean [Glycine max (L.) Merr.] residue and N fertilizers in a wheat (Triticum aestivum L.)–soybean rotation increased NH4+–N concentrations by 153%, N‐acetyl‐β‐d‐glucosaminidase activity by 247%, and relative abundance of Gram‐negative bacteria and saprophytic fungi regardless of residue management. Nitrogen fertilizer applications in corn systems also increased NH4+–N concentrations (322%) along with relative abundance of actinomycetes and saprophytic fungi. These results suggest that no‐till and prescribed fire management are viable residue management options that maintained soil organic matter and inorganic N concentrations; however, further investigation is needed to evaluate the long‐term (>2 yr) impacts on soil health.