Ecological succession on soil organic carbon pools and biological properties under different land use management system
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Date
2023
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Dr.RPCAU, Pusa
Abstract
To examine the Ecological succession of any management practices to test the applicability of different land use systems for improving CMI in restored ecologies, soils were sampled from 0–15, 15–30 and 30–45 cm deep layers of Napier, Litchi, Mango, Guava, Grassland -based silviculture systems. These were compared with samples from fallow land (F). Long-term experiments are regarded as important tools. Long-term fertiliser experiments could monitor the trends in crop yield resulting from changes in soil fertility. It is essential to monitor the long-term changes in soil nutrient status, and nutrient supplying capacity to ensure and improve crop productivity. These considerations have prompted to undertake the present investigation, which was carried out in an on-going field experiment started in Rabi 1988-89 under AICRP on STCR project at the Research Farm of Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur, Bihar, India. The experimental site experienced a sub-tropical climate with an average annual precipitation of 1345 mm, the summer was hot and humid, and too cold winter, and the experimental soil belonged to order entisols. The experiment was conducted in different land use management systems with random block design and split-plot design with four levels of fertilizers viz. no NPK (Fo), 50% of the recommended dose of NPK (F1), 100% of the recommended dose of NPK (F2) and 150% of the recommended dose of NPK (F3) were applied as treatments in main plots. The main plots were divided into sub-plots in which treatments viz. no manures (M0), compost @ 10 t ha-1 (M1), crop residue (M2), and compost + crop residue (M3) were superimposed over NPK levels, making a total of 16 treatment combinations with 3 replications. The study intended to assess the effect of the organic and inorganic treatments on soil health, and nutrient fractions in rice-wheat cropping system.
Weed flora was higher in guava, followed by Litchi and mango.
The increase was attributed to greater recycling of bio-litters. Litchi was found to have the highest C,N,P percentage and C/N ratio, lignin/ cellulose ratio as compered to guava and mango. Carbon fractions (active, passive, and slow pools) retained relatively 30-56 % greater in a secondary ecological succession of grassland as compared to cycling ecological succession.
Among nutrient management in the cycling ecosystem, NPK and organic matter addition restored a greater amount of carbon as compared to inorganic fertilizer application. However, all the C-pools are substantially lower in imbalanced fertilizer application.
A Higher amount of active C such as, SMBC, WSC, PMOC, and KmnO4-C at the surface layer was found in higher Napier, which could be due to the addition of leaf litters, fine roots, and residues over the fallow. SMBC was significantly higher in Napier, followed by grassland at all three depths, and SMBN and KmnO4-C were higher in Napier followed by guava land. However, SMBC of litchi, mango and guava was at par. Carbon pools like active, passive, and slow pool results were highest in the application of 150% NPK + compost and crop residue at par with 100% NPK + compost and crop residue over absolute control. The interaction between organics and inorganic fertilizers was the best interaction for SMBC, SMBN, WSC, AHC, POMC, HA-C, and FA-C at all three depths of soil. SMBC was found to be positively (R2 = 0.68) correlated with soil organic carbon content.
Secondary ecological succession is 3-fold higher in horticultural and pastoral land use management systems as compared to cycling ecological systems in terms of enzymatic activities and Ecological restoration.
Observations of soil biological properties soil enzymes (viz. dehydrogenase, FDA, β-glucosidase, urease, acid, and alkaline phosphatase, cellulase, Rubisco) were significantly influenced due to long term effect of various organics and inorganic fertilizers and their interactions. Combine application of 150% NPK + compost and crop residue resulted significantly higher activity in different enzymes in soil over absolute control and different land use system was found in higher Napier could be due addition of leaf litters, fine roots and residues over the fallow.
Observations of soil biological properties revealed a 1-fold increase in soil respiration at surface soil and a 1.4-fold increase in soil dehydrogenase activity over absolute control due to the interaction effect of 150% NPK+ compost + crop residue. Also, 150% NPK+ compost + crop residue was 2.7 times superior over absolute control for soil alkaline phosphatase activity at 0-15 cm.
The experimental findings of different land use management systems and the effect of long-term application of organics and inorganics on soil physical properties revealed a significant reduction in bulk density up to the application of 150% NPK as inorganics and a 15% decline was observed due to the conjoint application of compost and crop residue over control (no organics) and different LUMS were found non-significant. Water holding capacity increased significantly up to 150% NPK as inorganics and conjoint application of compost and crop residue recorded the highest percent increase (15.5 and 29.5% at both depths, respectively) over control (no organics). The MWD was significantly highest in guava as compared to grassland and at 0-15, 15-30, and 30-45 cm soil depths, respectively. Interaction effects of organics and inorganic fertilizers were non-significant for MWD at all the soil depths.
No significant changes were observed with soil pH and EC. Whereas, in Soils under Napier, guava had 32 and 20% higher SOC than fallow land in the 0–15 cm soil layer. Soil organic carbon increased up to 0.7-fold over absolute control with conjoint application of 150% NPK + compost + crop residue. Availability of N and P2O5 increased significantly up to 150% NPK, and organics were recorded highest with conjoint application of organics and inorganics. Due to the interaction effect between organics and inorganics, a 1.3 and 1.4-fold increase in the soil available N at o-15,15-30 cm and a 1- fold increase in available P2O5 was observed with 150% NPK + compost + crop residue over absolute control. Grasses tree–based DLUS, such as Litchi, Mango, Guava, fodder and Napier may be advocated as these practices improved soil physico-chemical properties and biological quality compared to fallow. We recommend the use of enzyme- based index (GMEA) to assess soil quality and its relative improvements in the organic farming approach due to its ability to measure variability arising from nutrient cycling processes. CMI is a valuable tool for explaining soil quality since it examines the ability of various management activities to determine the long-term efficacy of mineral nutrient availability, efficiency, and soil C pools. Organic amendments significantly improved the activities of C, N, P, and S cycling enzymes and SOC concentrations in surface and subsurface soils.
It is an ecological succession that for improvement of secondary and vertical ecological succession for improvement of pasture and horticultural development is more useful option and soil test crop response management in general further studies is required.