Effect of soil moisture conservation method on yield of Jatropha | ผลของวิธีการอนุรักษ์ความชื้นดินต่อผลผลิตสบู่ดำ

Study on the effectmethod of soil moisture conservation method on yield of Jatropha, variety KUBP78-9 grown on Ultic Paleustalf, was carried out in order to compare the effect of no soil moisture conservation scheme (W1), plant residue mulch (W2), vetiver grass grown between Jatropha rows, slash and mulch (W3), and jack beanast cover crop (W4) on moisture changes within soil profile and yield of Jatropha. Drip irrigation at a rate of twolitres per plant was operated every two days during drought season (Dec 09-May 10). Results indicated that plant residue mulch tended to give the highest seed yield at 15% moisture content (200 kg rai-1) compared to the range of 130.9-145.3 kg rai-1 obtained from other treatments. Growing vetiver grass between rows of Jatropha then slash andmulch tended to give the greatest oil content of 37.3% in Jatropha seed. The highest total oil yield with the amount of 54.5 kg rai-1 was gained from the scheme using plant residue mulch, which was significantly higher than the ones without soil moisture conservation and jack bean as cover crop (37.6 and 29.9 kg rai-1, respectively). There was indifferent concentration of plant nutrients in Jatropha leaf at two months of age but the concentrations of major nutrients in treatments with vetiver grass and jack bean seemed to be lower than those with Jatropha grown solely. At fruiting stage (6-month old), plant residue mulch and vetiver grass intercropped equally brought on S contents of 0.50 g kg-1, which were significantly higher than did the other two treatments. Sulfer concentration in seed (0.42 g kg-1)obtained from the control and no soil moisture conservation, was significantly higher than those gained from the others.