EFFECT OF ORGANIC AND CHEMICAL FERTILIZER ON GROWTH AND YIELD OF PHYSIC NUT (Jatropha curcas L. ) IN SLIGHTLY SALINE SOIL

The study was carried out at the Suphanburi Agricultural Research and Development Center, U-thong district, Suphanburi province during 2009-2011. The soils are classified as Kamphaeng Saen soil series. The objectives were to study appropriate management on slightly saline soil to increase the physic nut yield and to study the effect of soil amendments on changes to the soil's chemical properties. The experimental design was a randomized complete block design with 3 replications. The 10 treatments were: 1) control; 2) chemical fertilizer; 3) compost, 2 kg plant(-1) year(-1); 4) compost, 4 kg plant(-1) year(-1); 5) farmyard manure, 2 kg plant(-1) year(-1); 6) farmyard manure, 4 kg plant(-1) year(-1); 7) compost, 2 kg plant(-1) year(-1) + bio-extract; 8) compost, 4 kg plant(-1) year(-1) + bio-extract; 9) farmyard manure, 2 kg plant(-1) year(-1) + bio-extract; and 10) farmyard manure, 4 kg plant(-1) year(-1) + No-extract. For treatments 2-10, chemical fertilizer (15-15-15) at a rate of 156.25 kg ha(-1) was applied. The results showed that utilization of organic fertilizer plus chemical fertilizer resulted in increased growth of physic nut but this was not significantly different from the control treatment. Application of organic fertilizer had no effect on growth and yield of physic nut, however the use of organic fertilizer plus chemical fertilizer tended to give yields higher only than for chemical fertilizer and the control of 1906.25, 1421.69, and 1040.63 kg ha(-1), respectively, but these were not significantly different. After the experiment, the soil electrical conductivity (EC0) changed slightly. No effect of the organic fertilizer and chemical fertilizer was found, however, variation in the EC0 was found. Soil organic matter tended to decrease while the available phosphorus tended to increase. Generally, the available potassium tended to increase except in the control treatment and the treatment with only chemical fertilizer.