NUTRIENT DYNAMICS IN DIFFERENT DENSITY PLANTATIONS OF SEMAL (Bombax ceiba L.) WITH SESAMUM-LENTIL CROPPING SYSTEM
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Date
2021
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Dr.RPCAU, Pusa
Abstract
The present investigation was carried out at agro forestry research area of Dr. Rajendra Prasad Central Agricultural University, Pusa (Samastipur) in calciorthent of the north-west alluvial plain of north Bihar. Yield performance of sesamum-lentil cropping system during Kharif and Rabi season of 2020-21, changes in physicochemical properties of soil, litterfall, nutrient return, litter decomposition, and nutrient release pattern were studied under different densities of 6-year-old Bombax ceiba plantations. The experiment was in randomized block design comprising five treatments (5 × 2 m, 5 × 3 m, 5 × 4 m, 5 × 5 m, and treeless control) replicated 4 times. The soil texture of the research area is sandy loam with a pH of 8.5, low level of organic carbon (0.36%), available N (169 kg ha-1), P2O5 (24.2 kg ha-1) and K2O (132.3 kg ha-1) with the higher percentage of free calcium carbonate (36%). The carbon storage and carbon sequestration potential of the plantations have been also estimated. In Kharif season sesamum (Sesamum orientale var. Krishna) and in Rabi season lentil (Lens culinaris var. HUL 57) were grown as intercrops applied with the recommended doses of fertilizers. The crop yield, tree growth, biomass yield, and carbon sequestration potential were tested by one-way analysis, whereas soil physicochemical properties and soil carbon stock was tested by two-way analysis of variance, where agroforestry systems were considered as the first factor and soil depth as the second factor. The yield parameters were measured after the harvest of each crop and soil properties were measured before sowing and after harvesting of each crop. The yield of intercrops decreased under the agroforestry systems. Yield decrement was 14.0 to 46.2% and 9.81 to 34.5% in grain and straw of sesamum, whereas 17.8 to 37.7% and 13.5 to 23.7% in grain and straw of lentil, respectively. The nutrient content in grain and straw of sesamum and lentil was found higher in the agroforestry system and uptake was found higher in sole cropping. The relative light intensity was recorded higher in the Kharif season and among the treatments, sole crops received maximum light intensity. There was a noticeable improvement in soil properties (pH, EC, and BD), nutrient status (N, P2O5, and K2O), soil organic carbon (SOC), SOC stock, and active carbon. Availability of plant nutrients was higher in the upper (0 - 15 cm) soil layer than the lower soil layer (15 - 30 cm). The yield of the crops, nutrient uptake by grain and straw, and average light intensity were found lower in higher density (5 × 2 and 5 × 3 m), whereas nutrient content in grain and straw, soil properties improvement found maximum in higher density. There was a 24.79 to 41.81% increase in SOC stock after harvest of lentil crop up to 0-30 cm soil depth. In the winter and rainy seasons, there were 54.38 to 59.81% and 41.44 to 49.73% litterfall occurred, respectively. The nutrients returned by litterfall was in the sequence of Ca > N > K > Mg > P and the higher litterfall and nutrient return occurred in lower spacings. For the total decomposition of leaf litter, it took 11 and 12 months in higher and lower density, respectively and it took 71 to 86 days for half decay of litter. The widest spacings (5 × 4 and 5 × 5 m) had height and diameter at breast height on average 19 % and 26 % higher. The volume of the tree was significantly superior under the plantations in higher spacings. The total biomass (26.5 Mg ha-1) was maximum in the higher density (5 × 2 m) plantations, followed by 5 × 4 m (25.8 Mg ha-1). Total carbon storage varied from 10.0 to 12.6 Mg ha-1 in 5 × 3 and 5 × 2 m spacing respectively. The maximum carbon sequestration rate was 1.53 Mg C ha-1 year-1 in both 5 × 2 and 5 × 4 m spacing.