|Author:||Baumhardt, R. L. ; Jones, O. R. ; Schwartz, R. C.|
|Book Group Author:||NA|
Increasing precipitation storage as plant-available soil water increases dryland crop yields on the semiarid southern Great Plains. The dominant soil in this region is a Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustoll), which features dense subsoil layers that limit infiltration and root proliferation. Deep (~0.7 m) plowing may eliminate these layers, but the duration of treatment efficacy must be sufficient to recoup costs. Our objective was to quantify the long-term effects of deep ploughing on soil bulk density (BD), penetration resistance (PR), ponded infiltration, and crop yield. In fall 1971, paired 24- by 460-m level conservation bench terrace plots at the USDA-ARS Conservation and Production Research Laboratory, Bushland, Texas, USA were mouldboard ploughed to 0.7 m or untreated and, subsequently, maintained with conventional sweep tillage. Grain sorghum (Sorghum bicolor) was grown intermittently during the next 34 years for 15 paired yield comparisons. Compared with the control, deep ploughing significantly decreased BD and PR and increased water infiltration. Long-term mean grain yield of 2.86 tonnes ha-1 with deep ploughing was greater (P<0.05) than the 2.61 tonnes ha-1 yield in control plots. Approximately 89% of the 15-year 3.75 tonnes ha-1 cumulative yield increase with deep plowing occurred during 4 years with large early growing season rains. We attributed this yield increase with deep plowing to greater internal drainage that reduced crop injury during infrequent floods and not greater root growth through the dense subsoil. Thirty years after deep plowing, high water intake suggests that flow-limiting subsoil layers had not yet redeveloped. The sustained deep-plowing benefit extends the period to recoup the 1971 ploughing costs of US$160 ha-1.
|Pages:||677 - 682|
|Journal:||Soil Science Society of America Journal|
bulk density, clay loam soils, costs, crop yield, drainage,floods, infiltration, Mollisols, plant water relations, ploughing,resistance to penetration, soil types, water use efficiency, Texas, USA,Sorghum bicolor, Sorghum, Poaceae, Cyperales, monocotyledons,angiosperms, Spermatophyta, plants, eukaryotes, Southern Plains Statesof USA, West South Central States of USA, Southern States of USA, USA,North America, America, Developed Countries, OECD Countries, GreatPlains States of USA, Gulf States of USA, costings, plowing, UnitedStates of America, Field Crops (FF005) (New March 2000), Plant WaterRelations (FF062), Plant Production (FF100), Soil Physics (JJ300), SoilManagement (JJ900)