RESPONSE OF INTEGRATED NUTRIENT MANAGEMENT ON ACTIVE POOLS OF SOIL ORGANIC CARBON AND BIOLOGICAL ACTIVITIES UNDER RICE BASED CROPPING SYSTEM
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Date
2022
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DRPCAU, PUSA
Abstract
Being the backbone of India's food security, the Rice-wheat cropping system is the most profitable and prevailing cropping system in the Indo-Gangetic region, but recently it experienced significant decline in productivity because of depletion in soil organic matter due to low inputs of bio-resources and intensive crop rotation, depletion of soil fertility due to imbalanced use of chemicals and poor residue management leading to its burning. Residue management is a rising concern for better sustainability of Indian agriculture and environmental protection. Intensive cropping systems, lack of traditional use of agricultural crop residues, and lack of buyers of rice is pushing the farmers to opt for residue burning, which causes huge air pollution and global warming. To mitigate such problems IARI introduced a bio-decomposer method known as "Pusa Decomposer" to accelerate the decomposition of paddy straw in the field.
Thus, with such background the present study entitled “Response of integrated nutrient management on active pools of soil organic carbon and biological activities under rice based cropping system” was conducted in kharif 2021 and Rice was the test crop at research farm of RPCAU, Pusa, Bihar. The present experiment is third cropping cycle that is kharif 2021 and it was carried out in randomized block design with nine different treatments and each of the treatments
were replicated thrice in 3m x 4m plots. The treatments were T1 (100% RDF); T2 (50% N from Residue + 50% RDF); T3 (50% N from Residue + 50% RDF + Pusa Decomposer); T4 (50% N from Residue + 50% N from Green Manure); T5 (50% N from Residue + 50% N from Green Manure + Pusa Decomposer); T6 (Residue @ 2.5 tonnes ac-1 + Pusa Decomposer); T7 (Residue @ 2.5 tonnes ac-1) and T8 (Absolute Control).
Bulk density and water holding capacity showed non-significant difference among different treatments under study and similarly, soil pH and EC had no significant impact due to integration of different nutrient sources. However available nutrients in soil had significant effect. Application of fertilizer solely or its integration with CR and/or PD showed a significant increase in available N, P and K, but crop residue incorporation failed to increase available N and P significantly as compared to control treatment whereas, integrated application of GM and CR significantly increased N & P as compared to control. On the other hand available K was significantly increased under residue incorporation i.e., in T6 and T7 compared to absolute control.
Active carbon fractions like very labile and labile pools of carbon, Water-soluble organic carbon (WSC), microbial biomass carbon (MBC), acid hydrolysable carbohydrate (AHC) and soil respiration decreased with increase in the depth and all of them recorded higher value in the integrated treatments T3 and T5 and lowest value in absolute control (T8). It was observed that application of Pusa decomposer (PD) both in treatment T3 and T5 recorded increase in active carbon pools as compared to the corresponding treatments viz. T2 and T4 respectively only in surface soil (0-5cm).
Grain and straw yield and yield attributing characters like number of panicles per hill, number of filled grains per panicle recorded higher values in treatment T1. The treatment T2 and T3 were found to be statistically at par with T1 whereas, absolute control (T8) showed the lowest values which did not differ statistically with treatments T7 and T6 while, GM addition with CR in treatments T4 and T5 recorded significant increase in grain yield and yield attributes as compared to absolute control. The INM treatments did not significantly affect test weight and harvest index of rice. Plant height of rice during flowering stage and harvesting stage was maximum under treatment T1 (100% RDF) followed by T3 and T2. These treatments show significantly higher plant height as compared to organically treated plots and rest of the treatments
i.e., T4 to T8 were statistically at par. Days to 50% flowering recorded non-significant difference among different treatments.
The enzymatic activities indicated that the microbial activity in soil, recorded higher values on integration of 50% N from Residue with 50% RDF and Pusa Decomposer (T3) and in treatment T5 with 50% N from Residue + 50% N from Green Manure + Pusa Decomposer (T5) which were found to be significantly higher than T2 and T4 respectively.
The research findings indicate that the maximum benefits in terms soil quality or productivity was obtained under integration of 50% fertilizer, crop residue with pusa decomposer i.e. T3 which suggest the replacement of 50% fertilizer with crop residue incorporation and pusa decomposer not only increase yield but also improve soil health which is needed for the development of sustainable systems.