Assessment of Sustainable Production on Paddy Field Treated with Green Manure Crops Using Sustainability Index

Abstract

Assessment of sustainable production on a cropland can help to determine the most proper management practices. In this study, we evaluated the sustainable production on paddy field treated with green manure crops using sustainability index which based on nutrient index, microbiological index, and crop index related to nutrient-supplying capacity. Especially choosing appropriate indicators from a minimum data set (MDS) were used the principal components analysis (SI-2) as well as expert opinion (SI-1) usually used in sustainability index. Six treatments including the two tillage treatments and two green manure crops were investigated as follows; (i) moldrotary + rotary tillage without green manure crop (Con), with (ii) hairy vetch (Con-HV), and (iii) hairy vetch + green barely (Con-HV+GB), (iv) rotary tillage without green manure crop (Rot), with (ii) hairy vetch (Rot-HV), and (iii) hairy vetch + green barly (Rot-HV+GB). Con-HV and Rot-HV in SI-1 were maintained sustainability while Rot-HV and Rot-HV+GB in SI-2. Especially, treatments (Con and Rot) without green manure crops were more unsustainable than with green manure crops because of the low value of microbiological and crop index than with green manure crops. Meanwhile, sustainability indices and grain yield had the high correlation values (R²=0.756 and 0.928 in SI-1 and SI-2, respectively). These results meant that application of green manure crops such as hairy vetch could improve both yield and soil quality in paddy.