Conventional tillage (CT) increases the exposure of soil to erosion and is associated with lower soil moisture and organic matter than conservation tillage. Conservation tillage may benefit farmers in semi-arid regions of south Texas due to limited rainfall and lower input costs of no-till (NT) systems. The objective of this long-term study was to evaluate the effects of NT in a dryland cotton-sorghum cropping rotation system on soil moisture, bulk density, penetration resistance, C : N, N, P, K, and crop yields. This randomized block design experiment was established on a Victoria soil in Corpus Christi, TX, and has four replicates of cotton (Gossypium hirsutum 'DPL 1044') and sorghum (Sorghum bicolor 'DKS 53-67') rotated under NT or CT. Soil samples were taken with a 30-cm push probe with depth increments of 0 to15 cm and 15 to 30 cm. Soil moisture, pH, ECw, NO3-N, P, K, Ca, Mg, S, Na, total N, SOC, and penetration resistance were measured before planting and after crop harvest beginning in 2014 after four years of tillage treatment. Cotton yield was not different between treatments, except for the drought year of 2013 when 88% greater cotton yield occurred with NT than CT. Sorghum did not produce grain in 2013 regardless of treatment, and yields were only effected by treatment in 2012 when yield was 33% greater in NT than CT. Sorghum had 69% residue coverage, which was 12% greater than the cotton residue coverage. The average crop residue coverage for both crops was 58% greater with NT than CT. Soil moisture and bulk density was not impacted by treatment; however, bulk density was 6% greater at 15-30 cm than 0-15 cm for CT. Soil pH, ECw, NO3-N, P, K, Ca, Mg, S, Na was not effected by NT; however, NT had greater total soil N content than CT in the 0 to 15 cm depth and lower in the 15 to 30 cm depth and SOC was greater in the 0 to 15 cm depth in 2014 with NT than CT, but lower in the 15 to 30 cm depth. No-till had a lower surface penetrometer resistance than CT in year five. No-till is an economically viable alternative to CT in this region because of risk mitigation in drought years.
