CONSERVATION IRRIGATION AND INTEGRATED NUTRIENT MANAGEMENT OF LATE SOWN TORIA IN RICE FALLOWS OF ASSAM
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Date
2019-07
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AAU, Jorhat
Abstract
A field experiment entitled “Conservation irrigation and integrated nutrient management of late sown toria in rice fallows” was conducted at the Instructional-cum-Research Farm of Assam Agricultural University, Jorhat during rabi season (December- March) of 2017-18. The toria variety used for the investigation was Jeuti (JT-90-1). The treatments consisted of five levels of conservation irrigation viz., I0-Rain-fed, I1- Mulching with rice straw @5t/ha, I2- One irrigation at 50% flowering, I3 - One irrigation at 50% flowering + mulching with rice straw @5t/ha and I4- Two Irrigations at 50% flowering and at pod development stages and three levels of integrated nutrient management practices viz., N1- Recommended dose of fertilizers (RDF), N2 - 50% N of RDF + 50% N as FYM and N3 - 75% N of RDF + 25% N as FYM + Bio-fertilizer (Consortium of Azotobacter and PSB), laid out in a split-plot design with conservation irrigation in the main plots and integrated 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 5.3), medium in organic carbon (0.48%), available N (271.24 kg/ha), available P2O5 (22.95 kg/ha) and available K2O (155.67 kg/ha). The bulk density, field capacity, permanent wilting point and water holding capacity of the soil were 1.48 g/cc, 24.46%, 11.23% and 36.38%, respectively. Results revealed that application of two irrigations at 50% flowering and at pod development stages resulted in higher growth in terms of plant height, dry weight and number of branches per plant as well as yield attributing characters like number of siliquae per plant and number of seeds per siliqua. The effects of these were reflected in resulting to higher yield of seed, stover and oil. However in all such cases, this treatment was found to be statistically at par with that of one irrigation at 50% flowering + mulching with rice straw@ 5 t/ha. The maximum values of N, P and K uptake, consumptive use and total water use were observed under two irrigations at 50% flowering and at pod development stages, followed by one irrigation at 50% flowering + mulching with rice straw@ 5 t/ha. Also, higher gross and net return and B: C ratio were found under the treatment of two irrigations at 50% flowering and at pod development stages which was closely followed by one irrigation at 50% flowering + mulching with rice straw@ 5 t/ha. Different integrated nutrient management practices brought about significant differences in growth parameters, yield attributing characters, seed, stover and oil yield, consumptive and total water use, water use efficiency and N, P and K uptake. The highest values in all such aspects as well total return and B: C ratio were recorded under application of 75% N of RDF + 25% N as FYM + Bio-fertilizer. The treatment combination of two irrigations at 50% flowering and pod development stages and 75% N of RDF + 25% N as FYM + Bio-fertilizer produced the highest seed, stover and oil yield which was closely followed by one irrigation at 50% flowering+ mulching with rice straw @5t/ha along with 75% N of RDF + 25% N as FYM + Bio-fertilizer.