Effect of nitrogen management on crop productivity and soil health under rice-wheat cropping system in calcareous soil of Bihar
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Date
2023
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Dr.RPCAU, Pusa
Abstract
A field experiment was conducted during kharif and rabi season of 2018-19 and 2019-20 at Research Farm of Dr. Rajendra Prasad Central Agricultural University, Pusa to study the effect of nitrogen management on crop productivity and soil health under rice-wheat cropping system in calcareous soil of Bihar. The soil of the experimental plot was sandy loam in texture, calcareous in nature having pH 8.36, electrical conductivity (0.39 dS/m), bulk density (1.41 g/cc) with low in organic carbon (0.38%), available nitrogen (205.81 kg/ha) and potassium (112.47 kg/ha) and medium in available phosphorous (20.78 kg/ha).
The experiment was laid out in factorial randomized block design with three replications. The treatments used in the experimental field included two factors, organic and chemical sources of nitrogen. A total of eight organic nitrogen sources were used viz., M1 - Control, M2 - Mycostraw @ 50% RDN, M3 - Mycostraw @ 75% RDN, M4 - Mycostraw @ 50% RDN + 25% RDN through vermicompost, M5 - Mycostraw @ 50% RDN + 25% RDN through vermicompost + green manure, M6 - Mycostraw @ 50% RDN + green manure, M7 - Mycostraw @ 75% RDN + green manure and M8 - Mycostraw @ 75% RDN + microbial consortium (Azospirillum + PSB) while three chemical nitrogen sources were used as N1 - 50% RDN, N2 - 75% RDN and N3 - 100% RDN. Dhaincha was used for green manure. 75% RDF was used in the wheat crop.
Application of mycostraw @ 50% RDN + 25% RDN through vermicompost + green manure treatment recorded significantly higher plant height, number of tillers/m2, leaf area index (5.37) and SPAD value (39.60) of rice which was statistically at par with treatment mycostraw @ 75% RDN + green manure and mycostraw @ 50% RDN + green manure. Among chemical fertilizer treatments, 100% RDN recorded significantly higher plant height, number of tillers/m2, leaf area index (4.87) and SPAD value (39.89) at all growth stages of rice. Dry matter accumulation, length of panicle (24.34 cm), number of grains/panicle (101.05), grain yield (54.35 q/ha) and straw yield (68.75 q/ha) in rice were recorded significantly higher value in treatment receiving mycostraw @ 50% RDN + green manure over rest of the treatments but was statistically at par with mycostraw @ 75% RDN + green manure and mycostraw @ 50% RDN + 25% RDN through vermicompost + green manure. Among chemical fertilizer, 100% RDN showed significantly higher length of panicle (24.00 cm), number of grains/panicle (99.58), grain yield (47.04 q/ha) and straw yield (59.67 q/ha) of rice over 50% RDN but was statistically at par with 75% RDN.
Significantly higher plant height, number of tillers/m2, dry matter production at different growth stages and number of spikes/m2 (320.57), length of spike (10.92 cm), number of spikelets/spike (24.88), grain yield (36.06 q/ha) and straw yield (43.53 q/ha) were recorded in treatment with mycostraw @ 75% RDN + green manure in wheat but was statistically at par with treatment mycostraw @ 50% RDN + green manure, mycostraw @ 50% RDN + 25% RDN through vermicompost + green manure, mycostraw @ 50% RDN + 25% RDN through vermicompost and mycostraw @ 75% RDN + microbial consortium with Azospirillum and PSB. Chemical fertilizer treatments did not produce any significant effect on all these growth, yield attributes and yield at different growth stages of wheat.
Maximum rice equivalent yield (103.23 q/ha) and gross returns (₹ 1,86,347/ha) were recorded in treatment with mycostraw @ 50% RDN + green manure which was significantly surpassed all other treatments. But it was statistically equivalent with mycostraw @ 50% RDN + 25% RDN through vermicompost + green manure and mycostraw @ 75% RDN + green manure. Under chemical fertilizer treatments, maximum rice equivalent yield (92.93 q/ha) and gross returns (₹ 1,63,024/ha) were found in 75% RDN treatment and was statistically at par with 50% RDN. Net return was significantly maximum in mycostraw @ 50% RDN + green manure (₹ 1,13,424/ha) over rest of the treatments. Among chemical fertilizer, 75% RDN recorded significantly higher net returns (₹ 94,978/ha) over other treatments.
Among the various organic manure treatments, mycostraw @ 50% RDN + green manure recorded significantly higher N, P & K uptake by rice as compared to other treatment but was statistically equivalent with mycostraw @ 75% RDN + green manure, mycostraw @ 50% RDN + 25% RDN through vermicompost + green manure. In case of wheat, mycostraw @ 75% RDN + green manure recorded significantly higher N, P & K uptake by wheat and was statistically at par with mycostraw @ 50% RDN + 25% RDN through vermicompost + green manure and mycostraw @ 50% RDN + green manure. Under chemical fertilizer treatments, N, P & K uptake by rice was significantly higher in the treatment receiving 100% RDN but was statistically at par with 75% RDN. In case of wheat, N, P & K uptake was not significantly influenced.
Soil pH, electrical conductivity and micronutrients could not reach the level of significance due to both the factors (organic manure and chemical fertilizer). Mycostraw @ 75% RDN + green manure plots recorded significantly higher value of water holding capacity (31.39%), water stable aggregates (50.94%) but recorded lower bulk density (1.365 g/cc) as compared to other organic treatments but was statistically at par with treatment mycostraw @ 50% RDN + green manure and mycostraw @ 50% RDN + 25% RDN through vermicompost + green manure. Water holding capacity, water stable aggregates and bulk density were not significantly influenced by chemical fertilizer treatment. Available N, P2O5 and K2O in post-harvest soil were significantly higher in mycostraw @ 75% RDN + green manure as compared to other organic manure treatments while in chemical treatments, it did not show any significant effect on available N, P2O5 and K2O. The soil of mycostraw @ 75% RDN + green manure plots recorded significantly higher value of soil microbial biomass carbon (289.55 mg/kg soil), bacterial population (5.06 x107 CFU/g soil), fungal population (4.16 x 104 CFU/g soil) and actinomycetes population (2.57 x 107 CFU/g soil) as compared to other organic treatments but was statistically at par with treatment mycostraw @ 50% RDN + green manure and mycostraw @ 50% RDN + 25% RDN through vermicompost + green manure. Microbial population and soil microbial biomass carbon were not significantly affected with application of chemical fertilizers.