Effect of Dry-Season Soil Management of Water Conservation for the Succeeding Rice Crop in a Tropical Soil
1982
Hundal, S. S. | De Datta, S. K.
In tropical Asia, soil water conservation during the dry-season fallow is critical for early establishment of the first rice (Oryza sativa L.) crop and increases in sequential cropping intensity under rainfed conditions. Five dry-season fallow soil water conservation techniques using shallow rotovation (soil mulch), deep plowing followed by rotovation, herbicide-treated bare and straw mulched soil, and weedy control were evaluated on a clay soil. Soil water changes were monitored weekly to the 1.05-m soil depth. Soil temperature at the 10-cm depth, soil matric potential at the 15-cm depth, and fluctuations in groundwater table were measured regularly. Highest soil temperatures were obtained in the bare soil treatment. The straw mulch application maintained the lowest temperatures. By the end of the dry season, the soil had dried to the 1-m depth in the weedy control compared to 15 cm in soil mulch, 30 cm in straw mulch, and 45 cm in the bare soil treatment. Starting with initial soil water contents close to field capacity, a maximum water depletion of 248, 86, 55, 35, and 58 mm occurred in the weedy control, bare soil, straw mulch, plowed and rotovated, and rotovated treatments, respectively, at the end of the dry season. Groundwater table during this period varied from about the 1.5- to 1.75-m soil depth. Rainfall requirement was significantly reduced and early crop establishment was made possible when soil was kept weed-free during the dry-season fallow. Minor differences in water conservation occurred among soil mulch, straw mulch, and bare soil systems.
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