Semi-Arid Cropping Rotation System Under No-till Management.

Conventional tillage (CT) exposes soil to erosion and is associated with lesser 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 lesser 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 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 samples were taken with a 30-cm push probe with depth increments of 0-15 cm and 16-30 cm. Soil moisture, C:N, N, P, K, and penetration resistance were measured before planting and after crop harvest beginning in 2014 after four years of tillage treatment. Soil moisture was not impacted by treatment [RM1] [RM2] (13.03 ± 0.71%); however, bulk density increased by 30% compared to CT. Soil penetration resistance was greater with NT versus CT, and cotton versus sorghum. No-till increased (P < 0.0001) soil N content by 2,701 kg ha^-1; however soil C, P, and K were not affected by treatment.  Cotton yields were generally not different between treatments, except for increased yield with NT in drought (89% increase in 2013) and above average rainfall (14% increase in 2015). Sorghum yield was increased 28% by NT in drought (2012), but decreased 38% with NT when rainfall was above average (2015). Crop residue coverage was 58% greater with NT than CT and 12% greater for sorghum than cotton. No-till is an economically viable alternative to CT in this region because of risk mitigation in drought years.