Mycorrhizal Inoculation to Increase Yield of Soybean Direct-Seeded Following Rice of Different Growing Techniques in Vertisol Soil, Lombok, Indonesia

This study aimed to examine the impact of cultivation techniques and organic fertilization of rice, and arbuscular mycorrhizal fungi (AMF) inoculation of zero-tillage soybean on yield of soybean direct-seeded following rice in two year sequences of rice-soybean cropping (2010 and 2011) in vertisol soil taken from Central Lombok, Indonesia. The pot experiments were conducted in a glasshouse, with two treatment factors for rice crops, i.e. rice cultivation techniques (T1= Conventional, T2= SRI (System of Rice Intensification) without AMF, and T3= SRI with AMF inoculation in nursery), and organic fertilization (O1= without organic (NPK only), O2= organic manure + NPK at full recommended doses in the first or half the doses in the second year, and O3= organic manure + NPK at half the recommended doses in the first or without NPK in the second year), and AMF inoculation of soybean plants (M0= without, and M1= with AMF inoculation). The results indicated that AMF inoculation of zero-tillage soybean direct-seeded following rice crops in vertisol soil more significantly increased grain yields of soybean grown following conventional rice (with an average increase of up to 35.6%), compared with following SRI-rice (only 10.6 - 18.8% increase), indicating a need for AMF inoculation of soybean plants grown in vertisol soil following conventional rice. Different cultivation techniques and organic fertilization of rice plants also significantly affected yield of the soybean direct-seeded immediately after harvest of the preceding rice, which indicates positive impacts of organic fertilization of rice on grain yield of soybean following rice.