Soil Quality Parameters Under Conservation Management in the Mississippi Delta.

Development of optimal conservation management systems is needed for cotton (Gossypium hirsutum L.) production in the Mississippi Delta region. In a study near Stoneville, MS, soil quality parameters were evaluated during the period from 2001 to 2006 in two conservation tillage systems [no-tillage (NT) or reduced tillage (RT)] and three cover crops [rye (Secale cereale), balansa clover (Trifolium michelianum ssp. balansae), or none].  Soils were sampled in late spring each year prior to planting cotton.  Independent of tillage or soil depth, both cover crops accumulated more soil C than no cover, and nitrogen was greater in clover compared to rye or no cover crop. Likewise, soils from clover plots had greater aggregate stability compared to rye or no cover crops plots, however, neither cover crop nor tillage affected bulk density. Water dispersible clay content significantly increased with soil depth (Pr >0.01), and NT clover > NT rye or NT no cover (Pr>0.05) independent of depth.  The major factor influencing infiltration was intra-row position, but infiltration rates were six-fold greater under RT compared to NT (Pr >0.01), with a lesser effect of cover crop (Pr >0.06, clover > rye or no cover).  There was no effect of tillage or cover crop on reniform nematodes or earthworms as both organisms were present in low numbers in plots with higher clay content.  Collectively, both cover crop and reduced tillage contributed positively to soil quality.  However, depending on soil type, a minimum tillage system may provide better infiltration and less compaction critical to sustain higher cotton yields.