Intercropping of indeterminate forage legumes to contribute nitrogen in low-input upland rice based cropping systems

• Published in: Philipine Journal of Crop Science (Philippines) Vol. 14; no. 1
• Main Authors: Samson, B.T, Magbanua, R.D, Aggarwal, P.K, Garrity, D.P. (International Rice Research Inst., Los Banos, Laguna (Philippines). Multiple Cropping Dept.)
• Format: Journal Article
• Language: English
• Published: 01.05.1989
• Subjects: ABONOS VERDES; ARROZ DE SECANO; AZOTE; CULTIVO INTERCALADO; CULTURE INTERCALAIRE; ENGRAIS VERT; LABLAB PURPUREUS; MACROPTILIUM ATROPURPUREUM; NITROGENO; ORYZA SATIVA; RIZ PLUVIAL; SISTEMAS DE CULTIVO; SYSTEME DE CULTURE
• ISSN: 0115-463X

Upland rice is generally produced on soils with low inherent fertility with no inorganic nutrients applied. The utility of incorporating indeterminate forage legumes as sources of green manure to increase the N available to upland rice was examined. The indeterminate forage legumes lablab (Lablab purpureus) and siratro (Macroptilium atropurpureus) were intercropped or relay cropped with upland rice. The excess vegetative growth of the forage legumes was clipped back and the tops deposited as green leaf mulch between the adjoining rice rows to transfer N to the rice crop. Subsequent to the harvest of the rice crop, the forage legumes were allowed to continue to grow throughout the dry season. The dry season biomass accumulation of the legumes was incorporated into the soil just prior to seeding the following rice crop. The forage legumes contributed 120-210 kg N per hectare to the rice crop. Rice grain yields were increased by as much as 1.0 to 2.0 t/ha and total dry matter by over 6.0 t/ha. Lablab proved to be effective as an in situ green manure nitrogen source for upland rice. Its most productive spacing was 120 cm with five rows of upland rice in between the forage rows.