Thirty-four years of no-tillage and cover crops improve soil quality and increase cotton yield in Alfisols, Southeastern USA

Abstract

In subhumid Southeastern USA, rapid decomposition of initially low cotton residue limits the benefits of no-tillage system in regard to the soil quality. Long-term addition of cover crops may compensate the low cotton residue and further improve the soil physical quality under no-tillage system. We examined the long-term (34 yr) effect of two cover crop species, hairy vetch (Vicia villosa), and winter wheat (Triticum aestivum L.), and no cover crop, applied on conventional tillage and no-tillage on soil hydro-physical properties and cotton yield. Research was conducted on a Lexington silt loam in Jackson, TN, during 2015 and 2016. Soil physical properties including bulk density, cone penetration resistance, in-situ soil moisture content, wet aggregate stability, water infiltration and field-saturated hydraulic conductivity, soil water retention characteristics, and dry aggregate size distribution were measured. Bulk density assessed before the annual tillage did not differ significantly between no-tillage and conventional tillage systems. Cone penetration resistance showed a greater horizontal consistency of maximally resistant zones (>2 MPa) under tilled managements, indicating a possible presence of a plow pan immediately below the plowed soil layer. Differences in field soil moisture content among tillage and cover crops were more evident in drier periods of the growing seasons, resulting in 28.6% and 36.4% greater moisture content in vetch cover crop and no-tillage than no cover crop and conventional tillage, respectively. No-tillage and vetch cover crop also increased the wet aggregate stability by 13% at 0–15 cm. Results showed a significant tillage × cover crop interaction in soil hydraulic properties. Our result demonstrates that long-term incorporation of cover crops, particularly vetch with no-tillage, significantly improved the initial infiltration rate, cumulative infiltration, and field-saturated hydraulic conductivity and increased the mean weight diameter of aggregates by promoting the macroaggregation. Improvement in soil physical properties was associated with an increase in cotton lint yield under cover crop and no-tillage management.