| Abstract: | Influence of NPK on performance of the stem-nodulating legumes Sesbania rostrata and Aeschynomene afraspera in lowland rice The stem-nodulating tropical legumes S. rostrata and A. afraspera are promising green manure species for the low-input rice farming systems of lowland areas. Nutrient imbalances and soils low in available nutrients can considerably affect the use of biofertilizers. Use of mineral N, P, and K fertilizers in the growth of S. rostrata and A. afraspera as biofertilizers for lowland rice in the Philippines was evaluated. Applied P and K both stimulated growth, nodulation, and N2 fixation. N accumulation in PK fertilized S. rostrata was about 40% higher than in nonfertilized green manure. Mineral N application (urea) depressed nodulation and N2 fixation (ARA) in roots and resulted in an increased ARA in stem nodules. The legumes produced more N gains in the presence of small amounts of N. Use of S. rostrata and A. afraspera green manure increased in all cases significantly rice grain yield. Thus integration of mineral N, P, and K fertilizers in a green manurebased rice farming system can considerably improve biofertilizer production and increase rice grain yield. |
