Tillage Effects on Grain Sorghum and Wheat Yields in the Texas Rolling Plains

Soils of the Texas Rolling Plains have poor structure, low soil organic matter contents, and low water holding capacity. Alternative farming practices must be explored to conserve and improve this natural resource. An 11‐yr (1979‐1989) field experiment was conducted at the Texas A&M University Research Station at Munday to determine the effects of tillage (reduced vs. conventional) and residue management (with vs. without residue) on grain yields of continuous grain sorghum [ Sorghum bicolor (L.) Moench] and continuous wheat ( Triticum aestivum L.) under dryland and irrigated conditions. A grain sorghum—wheat rotation (double‐crop) under reduced tillage was included in the irrigated study. Yields of reduced‐tillage grain sorghum in dryland and irrigated studies were as high or higher than yields of conventional‐tillage grain sorghum. Removal of surface residues in irrigated grain sorghum caused a significant decrease in yields. In contrast, reduced‐tillage systems and surface residues caused reductions in yields for dryland and irrigated wheat, which may be the result of decreased plant populations caused by poor seed‐to‐soil contact when planting through surface residues and N deficiency caused by immobilization. The average yield of irrigated wheat or grain sorghum using reduced‐tillage double‐cropping (2 and 3 Mg ha −1 , respectively) was lower relative to wheat (3.5 Mg ha −1 ) and grain sorghum (4.6 Mg ha −1 ) grown continuously under conventional tillage.