Impact of No-till in Cotton-Sorghum Crop Rotations in a Semi-Arid Environment.

Conventional tillage (CT) exposes soil to erosion and is usually associated with lower soil moisture and organic matter than conservation tillage. Conservation tillage is not widely adopted in the semi-arid regions of south Texas. The objective of this long-term study was to evaluate the effects of no-till (NT) in a dryland cotton-sorghum cropping rotation system on soil moisture, bulk density, compaction (soil penetration resistance), C:N, N, P, K, and crop yields. This randomized block design field experiment was established on a fine smectitic hyperthermic Sodic Haplusters soil near 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 moisture and chemical properties were taken with a 20 cm push probe with depth increments of 0-10 cm and 11-20 cm. Soil moisture, C:N, N, P, K, and compaction were measured before planting and after crop harvest in 2014 after four years of tillage treatment. Soil moisture was not impacted by treatment or depth (14.86 ± 0.42%). After four years of NT, bulk density increased by 30% compared to CT. Soil penetration resistance was greater with NT versus CT and cotton versus sorghum, but sorghum or cotton yields from 2010 to 2014 were not different between treatments. The C and N content, increased 36,405 kg/ha-1 and 3,583 kg/ha-1, respectively, with NT. Treatment had no influence on soil N, P, and K concentrations, but there was greater NO3-N in the lower 15 cm and greater P and K in the upper 15 cm. Currently yearly environmental variability has had a greater influence on soil moisture and crop yields than the treatments. Subsequent years of research are necessary to determine the feasibility of NT integration in this region.