INTEGRATED STRATEGIES FOR IMPROVED WATER QUALITY AND ECOSYSTEM INTEGRITY WITHIN AGRICULTURAL WATERSHEDS
Location: Water Quality and Ecology Research
Title: Conservation management in cotton production: long-term soil biological, chemical, and physical changes
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 31, 2013
Publication Date: N/A
Interpretive Summary: Conservation practices are an increasingly important component of sustainable management systems, and information about their influence on soil characteristics is needed. A six-year cotton field study was conducted in the Mississippi Delta, USA, to assess long-term changes in soil as influenced by conservation tillage (no-tillage and minimum tillage) and cover crop (rye and balansa clover versus no cover). Overall improvement in soil quality over time was observed for both conservation tillage practices and both cover crop practices. Both cover crops and no-tillage increased soil chemical properties such as total carbon, total nitrogen, and soil enzyme activity. Cover crop also resulted in soil structural improvements, including stability of soil aggregates. Moderate tillage slightly increased populations of reniform nematodes and earthworms, but neither was affected by cover crop. Implications for farmers are that, given parity in crop production, any of the combination of tillage and cover crop management practices should provide environmental benefits.
Conservation practices are an increasingly important component of sustainable management systems, and information about their influence on soil characteristics is needed. Various soil parameters were studied in a no-tillage (NT) or minimum tillage (MT) cotton (Gossypium hirsutum L.) production study near Stoneville, MS, in the Mississippi Delta Region, USA, that included cover crops [rye (Secale cereale) or balansa clover (Trifolium michelianum ssp. balansae)] versus no cover crop. Soils (0 to 2, 2 to 5, and to 15 cm) were sampled in late spring (2001-2006) before cotton planting. Independent of tillage, both cover crops accumulated more soil C than no cover, and N was greatest in clover plots. Soils (0 to 15 cm) from clover plots had greater aggregate stability compared to rye or no cover crop. The major factor influencing infiltration was intra-row position, but infiltration rates were six-fold greater under MT compared to NT (Pr >0.01), with a lesser effect of cover crop (Pr >0.06, clover > rye or no cover). Moderate tillage in MT slightly increased abundance of both reniform nematodes and earthworms, but neither was affected by cover crop. Fluorescein diacetate (FDA) hydrolytic activity was higher in clover (50%) and rye (20%) in surface soil, compared to no cover crop. Soil microbial community structure based on total fatty acid methyl ester analysis (2005-2006) indicated a significant cover crop effect, but not tillage. The mycorrhizal bioindicator (16:1w5c) was greater in soil with rye compared to clover or no cover crop, however, cotton mycorrhizal infection on cotton was 40% greater in fibrous roots from rye or clover plots compared to roots from no cover crop plots. Collectively, including a cover crop and reducing tillage as management factors contributed positively to parameters indicative of soil quality.