Water loss characteristics of Korat soil under selected surface management practices
1986
Pongmanee Tongbai
The results indicated that in the low rainfall period of the NE rainy season, during May-Jun, before the peanut planting season, bare soil was the best practice for soil water conservation. Sunhemp was the most outstanding crop with highest water use efficiency, dry matter production and water conservation ability and seemed to be the best green manure crop. During the peanut planting season, all other cultural practices reduced evaporation loss from bare soil more than the conventional practice of planting peanut on a flat bed with 20 x 30 cm spacing. A 90 cm1840broadbed with 5 cm thick straw mulch was the best conservation practice. Evapotranspiration values for the season were 380-440 mm for 5 peanut treatments, 391 mm and 436 mm for siratro and lablab, with the lowest 376 mm for sunhemp. Rate of water decrease from saturation to drained upper limit (DUL) showed exponential relation of D = e to the 4.98 - 0.9t power. DUL of this profile was 310 mm, 8 mm higher than FC. The lower limit of water extraction were 222, 209 and 195 mm for fallow plot, peanut and cover crop and every plot was higher than PWP. Extractable water were 88, 116 and 101 mm for fallow plot, cover crop and peanut, all lower than
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