Bk. Pradhan et Ss. Mondal, INTEGRATED NUTRIENT MANAGEMENT FOR SUSTAINING PRODUCTIVITY AND FERTILITY BUILDING OF SOIL UNDER RICE (ORYZA-SATIVA) - BASED CROPPING SYSTEM, Indian Journal of Agricultural Sciences, 67(7), 1997, pp. 307-310
A field experiment was conducted during, pre-rainy season, rainy seaso
n, winter season and summer season of 1989-91 to evaluate the producti
vity, fertility build-up of soil and the economics involved in differe
nt rice (Oryza saliva L.) - based cropping systems. The productivity o
f rice was maximum (4.98 and 5.69 tonnes/ha) when both rainy- and summ
er-season rice in sequence were green-manured in situ with prickly ses
ban or dhaincha [Sesbania cannabina (Retz.) Pers.; syn S. aculeata (Wi
lld.) Poir.], grasspea or khesari (Lathyrus sativus L.) respectively a
long with 100% of the recommended dose of N, P and K (60, 14.2 and 25
kg/ha and 80, 22 and 41.5 kg/ha respectively in rainy- and summer-seas
on rice). However, comparable yield (4.84 and 5.42 tonnes/ha) was obta
ined when both rainy and summer-season rice in sequence were green-man
ured in situ along with 75% of the recommended dose of fertilizers (N4
5P10.6K18.7 and N-60 P16.5K31 in rainy and summer season respectively)
. Green-manuring twice in a year before transplanting of both rainy- a
nd summer-season rice improved the soil-nutrient status (260 kg N/ha,
16.1 kg P/ha and 21 kg K/ha). Green-manuring with sesban and khesari w
as found equivalent to 19.4 and 31.1 kg fertilizer N/ha during rainy-
and summer-season rice respectively. Maximum net production value (2.1
1) was recorded in the sequence where both the rice crops were green-m
anured with legume along with 75% recommended dose of N, P and K. Fert
ilizer-use efficiency was improved (40.05)when any legume crop was inc
luded in a cropping sequence involving 2 rice crops, and the improveme
nt was maximum (41.42) when legume crop was buried into soil before tr
ansplanting both rainy- and summer-season rice. Hence the recommended
dose of N, P and K may safely be reduced by 25% if green-manure is pro
vided to both the rice crops in sequence.