Abstract

            Tillage frequency and type can affect soil biochemical transformations, physical properties, rainfall utilization, nutrient availabilities and ultimately crop yields.  This study was conducted on a semi-humid/subtropical soil (hyperthermic Udic Pellustert) under non-irrigated conditions to measure effects of long-term tillage variables on selected soil chemical, physical and microbiological properties.  Cotton (Gossypium hirsutum) lint yields were measured over the multi-year experiment.  Tillage variables performed over the 18-year study included no-till (NT), minimum till (MT),  MT + in-row deep chisel (MT-Ch) and conventional tillage (CT).  Results of soil studies showed significant lowering of surface soil pH by NT while CT and MT systems produced only small changes on this alkaline-calcareous soil.  Extractable soil P and SOC were increased in the surface layers by zero tillage.  Extractable soil K was highest in NT soil. Soil microbial biomass was also positively influenced by the NT and MT systems.  Soil compaction was highest for NT cotton followed by the CT and MT systems.  Multi year summary of yields for the Victoria clay indicate largest yield benefits from the NT system will occur during the droughty years.  However, even in years with adequate to excessive soil moisture both NT and MT systems produced equal or more lint than the CT or deep chisel systems.  Lint yields increased substantially with time for all tillage systems with the greatest improvement in the NT yields. Results of this experiment indicate both NT and MT systems have a positive influence on soil quality and are viable alternatives for cotton production in Texas.