Rice Responses To A Short-Duration Green Manure .2. N Recovery And Utilization
No hay miniatura disponible
Fecha
Autores
Título de la revista
ISSN de la revista
Título del volumen
Editor
Wiley
Resumen
Descripción
Recent research demonstrated that fast‐growing tropical legumes [mungbean, Vigna radiata(L.) Wilczek and cowpea, V. unguiculata(L.) Walp.], when used as a green manure for lowland rice (Oryza sativaL.), can increase grain yield by 2 Mg ha−1, and that supplemental inorganic applications increase yield further. To guide research on the combined use of inorganic and green manure N, apparent N recovery (kg N uptake kg−1N applied) and N utilization (kg grain kg 1N uptake) were determined in three experiments. The experiments were conducted on a fine mixed isohyperthermic Aeric Tropaqualf in the Philippines during the 1983 and 1984 wet seasons. In two experiments, factorial combinations of inorganic N (0 and 80 kg N ha 1) and green manure growth duration (20, 30, and 40 days in the first year; 25,35, and 45 days in the second year), were tested. Apparent N recoveries from inorganic fertilizer and green manure were 49% in 1983 and 41% in 1984. At N levels < 51 kg N ha−1, inorganic N utilization was inferior to green manure N utilization in 1983 but similar in 1984. In the third experiment, mungbean was planted at 300 000 and 600 000 plants ha−1and grown for 20, 30, and 40 days before incorporation. Inorganic N (80 kg N ha−1) was applied to plots that were fallow during the green manure growth period. Apparent N recovery from both sources was 33%. Utilization of N from 80 kg inorganic N ha−1was slightly more efficient than from an equivalent quantity of green manure N. Although differences were noted, the experiments suggest that apparent recovery and utilization of N from short‐duration green manures are similar to those from inorganic N fertilizers. Research is required to determine how efficiency from the combined use of both N sources can be maximized.