การใช้เชื้อไรโซเบียมร่วมกับปุ๋ยเคมีและปุ๋ยอินทรีย์เพื่อเพิ่มผลผลิตและโปรตีนในถั่วเหลือง | Rhizobium application accompanied with chemical and organic fertilizers to improve seed yield and protein in soybean

Experiments were conducted to find out the way to improve soybean yield and protein content via nitrate tolerant rhizobium inoculant compared to intolerant inoculant in liquid media (Both inoculants are mixed strains.) accompanied with chemical and organic fertilizers. A randomized complete block design with three replications of 10 treatments was applied. The treatments were 1) no rhizo.+no fert. 2) liquid form of rhizo. only 3) liquid form of rhizo +chemical fert. 12-24-12 (25 kg/Rai) 4) liquid form of rhizo + 12-24-12 (25 kg/Rai) +compost (3,000 kg/Rai) 5) liquid form of rhizo +compost 6) nitrate tolerant rhizo only 7) nitrate tolerant rhizo +12-24-12 (25 kg/Rai) 8) nitrate tolerant rhizo +12-24-12 (25 kg/Rai)+compost 9) nitrate tolerant rhizo +compost 10) no rhizo+12-24-12 (25 kg/Rai). The study was carried out in four seasons in the dry season and the late rainy seasons, at Chiangmai Field Crops Research Centre in 2008 and 2009. Data were collected for the rate of N2 fixation (determined by acetylene reduction assay-ARA), number of root nodules, nodule dry weight, stem dry weight, seed yield, seed protein content and germination. Inoculants and forms of inoculants were not statistically different for rate of nitrogen fixation. The average ARA values for the application without fertilizer treatments were 9.90 µmol C2H4/plant/hr and 10.00 µ mol C2H4/plant/hr for nitrate tolerant and liquid rhizobium, respectively. Chemical fertilizer lowered the rate of N2 fixation, 1.87 µmol C2H4/plant/hr for nitrate tolerant rhizobium and 2.54 µmol C2H4/plant/hr for liquid rhizobium. Number of root nodules, nodule dry weight, weight of dry stems and seed yield were not significantly different between inoculants, with or without chemical fertilizer and compost or with both fertilizer treatments. Therefore seed treated with rhizobium before planting could replace and also provide higher net income over variable costs. Moreover, rhizobium only and rhizobium with chemical fertilizer were not significantly different in seed protein content (41.7-42.1%).