EFFECT OF IRRIGATION AND NUTRIENT MANAGEMENT IN INDIAN MUSTARD (Brassica juncea) – DIRECT SEEDED AUTUMN RICE (Oryza sativa) CROPPING SYSTEM IN ASSAM
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Date
2019-07
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AAU, Jorhat
Abstract
A field experiment entitled “Effect of irrigation and nutrient management in Indian mustard (Brassica juncea) – direct seeded autumn rice (Oryza sativa) cropping system in Assam” was carried out at the Instructional-cum-Research (ICR) Farm, Assam Agricultural University, Jorhat during two consecutive rabi (Oct- Feb) followed by summer (Feb-June) seasons of 2016 - 2017 and 2017-2018 to evaluate the optimum irrigation and nutrient management practices on growth an yield of the crops. The treatments consisted of four levels of irrigation viz., I0-Rain-fed, I1-IW:CPE=1.20, I2-IW:CPE=1.40 and I3-IW:CPE=1.60 and five levels of nutrient management practices viz., N1- Recommended dose of fertilizers (RDF), N2 – RDF + FYM @ 5t/ha, N3 -75% RDF (N) + 25% N through FYM, N4- 50% RDF (N) + 50% N through FYM and N5- 50% RDF (N) + 50% N through FYM + Bio-fertilizers (Consortium of Azotobacter and PSB), laid out in a split-plot design with irrigations in the main plots and nutrient management practices in the sub-plots and were replicated thrice. The soil of the experimental site was sandy loam in texture, acidic in reaction (pH 5.6), medium in organic carbon (0.65%), low in available N (226.63 kg/ha), available P2O5 (21.18 kg/ha) and available K2O (127.71 kg/ha). The bulk density, field capacity, permanent wilting point and water holding capacity of the soil were 1.38 g/cc, 26.60%, 10.25% and 41.28%, respectively. Results revealed that irrigations at IW:CPE=1.60 followed by IW:CPE=1.40 resulted in higher growth in terms of plant height, dry matter accumulation, crop growth rate and branches per plant as well as yield attributes like number and weight of siliquae per plant and number of seeds per siliqua. The effect of these was reflected in higher yield of seed, stover and oil yield under the same irrigation regimes. The maximum values of N, P and K uptake, weed biomass, microbial population, evapotranspiration and total water use were also observed under these treatments. The higher gross and net returns with higher B:C ratio were found under the irrigation regime IW:CPE=1.60. Pooled over two years also showed similar trend on seed yield of Indian mustard. In regards to nutrient management practices, application of 50% RDF (N) + 50% N through FYM + Bio-fertilizers followed by RDF + FYM @ 5t/ha brought about higher values in growth parameters, yield attributes, yield of seed and stover and oil yield and uptake of N, P and K by both seed and stover over rest of the treatments. Pooled data of two years on seed yield of mustard also showed similar trend. The evapotranspiration and total water use and water use efficiency of the crop were also higher under these treatments. However, comparatively higher gross and net returns and B:C ratio associated with the treatment 50% RDF (N) + 50% N through FYM + Bio-fertilizers. In case of direct seeded autumn rice, application of irrigations at IW:CPE=1.60 and IW:CPE=1.40 resulted in statistically similar values in most of the cases of growth parameters viz., plant height, number of tillers, dry matter accumulation and crop growth rate as well as yield attributing characters like number and weight of panicles/m2 and grains per panicle and were higher over lower irrigation regime and rainfed. These
led to produce higher yields of grain and straw and thereby resulted in higher uptake of
N, P and K by the crop under the said treatments. The favourable influence of the
irrigation regime IW:CPE=1.60 was observed on weed biomass, microbial population,
evapotranspiration and total water use by the crop in which it recorded higher values
over rest of the treatments. Though the cost of cultivation was considerably more with
IW:CPE=1.60, it produced higher gross and net returns with higher B:C ratio.
Application of 50% RDF (N) + 50% N through FYM + Bio-fertilizers followed
by RDF + FYM @ 5t/ha resulted in higher growth parameters, yield attributing
characters, grain and straw yields, uptake of N, P and K by the crop and
evapotranspiration, total water use and water use efficiency over rest of the treatments.
Pooled over two years data also showed at par effect on grain yield of rice due to these
treatments. The highest gross and net returns and B: C ratio were observed under 50%
RDF (N) + 50% N through FYM + Bio-fertilizers.
In regards to Indian mustard-direct seeded autumn rice cropping system, the
irrigation regime IW:CPE ratio 1.60 or IW:CPE ratio 1.40 along with the application of
50% RDF (N) + 50% N through FYM + Bio-fertilizers or RDF + FYM @ 5 t/ha found
to produce higher rice equivalent yield of the crops as well as gross and net returns and
B: C ratio over other practices.
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