Submitted to: International Soil Tillage Research Organization Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/16/1997
Publication Date: N/A
Technical Abstract: Stubble mulch tillage (SMT) and no-tillage (NT) are suitable for crops in the Great Plains, but long-term NT use may lower yields, soil quality, and production sustainability. We determined bulk density (BD), penetration resistance (PR), and water content (WC) in 1994 in plots of a study started on Pullman (Torrertic Paleustoll) soil at Bushland, TX, in 1982. The study yinvolved SMT and NT in rotation and continuous cropping systems for drylan winter wheat and grain sorghum. Data were analyzed to compare tillage methods, cropping systems, rotation phases, land conditions (level or nonlevel), and crops effects. Soil BD and PR always increased with depth and WC often increased, and the tillage X depth interaction always was significant. Soil BD and PR were lower in the tillage layer in SMT than in NT plots, but no definite trends occurred for BD below 10 cm. The PR often was greater with NT than with SMT below 10 cm, even though the WC was greater with NT. Soil BD, PR, and WC differed also for some comparisons besides those involving tillage. Based on regression analyses, PR was related to BD and WC of the profile and most depth increments with SMT. With NT, PR was related to BD and WC for the profile, but only to WC for individual depths. These results indicate a soil strength factor largely independent of BD and affected by WC influences PR with NT. We conclude stable biopores in NT soil led to development of a rigid structure that reduced effects of BD differences among NT plots on PR. Although PR was greater with NT, it has not resulted in lower yields in plots used for the study. The overall results (crop yields and soil conditions) suggest long-term use of NT will not lower the quality and production sustainability of this and similar soils under dryland cropping conditions.