|Baumhardt, Roland - Louis|
Submitted to: International Soil Tillage Research Organization Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/2/2000
Publication Date: N/A
Interpretive Summary: Dryland winter wheat and grain sorghum are grown on the semiarid North American Great Plains using the wheat-sorghum-fallow cropping rotation. In this rotation, no-till or sweep-till reduces evaporation and increases yields, but no-till becomes compacted and increases runoff more than sweep-till. We tested paratill, a residue saving chisel type plow, effects son soil density and rain infiltration. About 8 months after paratill (before planting wheat), we measured infiltration of rain applied at 2 in/hr with a rain simulator into no-till or sweep-till contour-farmed level-terraced watersheds. Infiltration amount was 1.5 inches for sweep-till compared with 0.75 inches for no-till. Paratill caused no significant increase in infiltration amount, i.e., infiltration with paratill was 1.05 inches compared to 1.1 inches without. Cone penetrometer resistance and soil bulk density was also measured with depth. Paratill treatments loosened the soil and reduced penetrometer resistance compared to no-till management, but sweep operations reconsolidated paratilled soil. We conclude that paratill did not increase rain infiltration into the Pullman clay loam soil with either sweep-till or no-till residue management, because the formation of soil surface crusts rapidly regulated infiltration.
Technical Abstract: Dryland winter what (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] are grown on the semiarid North American Great Plains using the wheat-sorghum-fallow (WSF) crop sequence. No-tillage (NT) or stubble mulch tillage (SM) reduces evaporation when used with WSF and increases yields. However, soil consolidation with NT increases runoff compared to SM. We measured steady infiltration of rain about 8 months after paratill (PT) (before planting wheat), using a rotating disk rainfall simulator on either NT or SM managed Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustoll). Subplots in six contour-farmed level-terraced watershed previously cropped using a dryland WSF rotation and NT or SM management were paratilled to a 0.35-m depth at 0.75-m intervals following sorghum harvest. Infiltration amount was 32.4 plus or minus 3.9 mm for SM compared with 21.9 plus or minus 2.5 mm for NT. No significant increase in infiltration amount was due to PT, i.e., infiltration with PT was 26.7 plus or minus 5.7 compared to 27.5 plus or minus 7.4 mm without PT. Paratill reduced cone penetration resistance with depth compared to NT, but the SM sweep operations consolidated paratilled soil. We conclude that PT did not increase infiltration into SM or NT managed clay loam because rain infiltration was regulated by the formation of a surface crust.