YIELD AND NITROGEN RESPONSE OF LOWLAND RICE (ORYZA-SATIVA L) TO SESBANIA-ROSTRATA AND AESCHYNOMENE-AFRASPERA GREEN MANURE IN DIFFERENT MARGINALLY PRODUCTIVE SOILS IN THE PHILIPPINES
Kh. Diekmann et al., YIELD AND NITROGEN RESPONSE OF LOWLAND RICE (ORYZA-SATIVA L) TO SESBANIA-ROSTRATA AND AESCHYNOMENE-AFRASPERA GREEN MANURE IN DIFFERENT MARGINALLY PRODUCTIVE SOILS IN THE PHILIPPINES, Biology and fertility of soils, 21(1-2), 1996, pp. 103-108
Organic-N fertilizers in the form of flood-tolerant, leguminous, stem-
nodulating Sesbania rostrata and Aeschynomene afraspera may be useful
alternatives to resource-poor rice farmers if applied as green manure.
Therefore, the accumulation of N by these green manure species and th
eir effect on the performance and yield of wetland rice (IR 64) was ex
amined at four different sites in Luzon, Philippines. Soils deficient
in N, P, and K were selected and compared with the fertile Maahas day
of the International Rice Research Institute (IRRI) at Los Banos. The
green manure plants were, grown under flooded ed conditions for 49 day
s in the wet season of 1987, chopped, and then ploughed in before tran
splanting rice seedlings. In a second experiment, the effect of S. ros
trata green manure was studied under rainfed conditions. All green man
ure treatments were compared to an urea treatment (60 kg N ha(-1)) and
an untreated control. Both legumes developed well, even on the margin
ally productive soils. S. rostrata accumulated up to 190 kg N ha(-1) a
nd A. afraspera even accumulated 196 kg N ha(-1) in the shoots. In all
treatments, green manure increased grain yield significantly (P = 0.0
5) over the untreated control, by 1.3 - 1.7 Mg ha(-1). The yields were
comparable to those obtained with 60 kg N ha(-1) of urea fertilizer.
S. rostrata caused the highest grain yield, of 6.5 Mg ha(-1) on the Ma
ahas clay soil of IRRI. The apparent release of exchangeable NH4+-N in
the soils after green manuring and the rice grain yield response Show
ed that both green manure species may provide sufficient available N t
hroughout the development of IR 64 in the wet season. In the rainfed m
arginal soil site, green manure with S. rostrata produced even higher
rice grain yields than urea. Green manure therefore seems particularly
attractive for poor farmers on marginally productive soils, at least
as a temporary strategy to improve yield and yield sustainability.