Conservation agriculture practices for upland rice based cropping system
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Date
2021
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Department of Agronomy, College of Agriculture, Vellanikkara
Abstract
Conservation agriculture (CA) is an approach to manage agro-ecosystems for improved and sustained productivity, increased profits and food security while preserving and enhancing the resource base, which emphasize minimum soil disturbance, permanent soil cover and diversified crop rotation. In India and Kerala, there is dearth of information on resource-conserving techniques, for productivity, profitability and soil health. Hence the present study entitled “Conservation agriculture practices for upland rice based cropping system” was carried out at Agronomy Farm, College of Agriculture, Vellanikkara from May 2019 to March 2021 to develop a conservation agricultural practices for upland rice-okra-green manure cropping system. Rice–okra-green manure cropping system with conservation practices were compared with rice–okra-green manure cropping system without conservation practices. The experiment was laid out in RBD with 10 treatments replicated thrice and was repeated for two years keeping the same layout. The treatments consisted of Direct seeding rice (DSR) in flat bed (FB) + brown manuring (BM)- okra+ green manuring (GM)-cowpea, DSR in FB+ BM- okra + crop residue mulch (CRM)- cowpea, DSR in FB+ GM- okra + GM-cowpea, DSR in FB+ GM- okra + CRMcowpea, DSR in raised bed(RB) + BM- okra + GM-cowpea, DSR in RB+ BM-okra+ CRM-cowpea, DSR in RB+ GM- okra + GM-cowpea, DSR in RB+ GM- okra+ CRMcowpea, DSR in FB – okra-fallow, DSR in RB- okra-fallow. Conservation treatments had significant influence on growth, yield parameters and yield of rice. Growth and yield attributes were highest in direct seeding rice in flat bed + green manuring which had an yield increment of 49 % compared to control ie., direct seeding rice in flat bed without any conservation agriculture practice. Raising rice crop in raised bed without cowpea intercropping also resulted in 23 % higher rice yield compared to rice grown alone in flat bed. Conservation treatments had significant influence on weed suppression. Growing of cowpea as an intercrop in rice and its incorporation at 25 DAS either by cutting it and spreading as mulch (green manuring) or decomposing it using 2-4-D application (brown manuring) either in flat bed and raised bed resulted in 58-73% reduction of weeds in upland situation. Physiological parameters like leaf area index, crop growth rate, relative growth rate and net assimilation rate were found higher in direct seeding rice in flat bed+green manuring. Significantly higher values of nutrient uptake, resource use efficiencies such as water use efficiency, partial factor productivity of NPK, net returns and B:C ratio in direct seeding rice in flat bed + green manuring proved the superiority of this conservation practice in rice over conventional DSR-okra-cowpea. Okra crop was raised in sequence with rice in the same field keeping the layout undisturbed. Field was made weed free before sowing with minimum soil disturbance using brush cutter after harvest of rice. Conservation agriculture practices applied to both rice and okra had significant influence in the growth and yield performance of okra. From the results it was observed that growth and yield parameters were higher when okra was raised on flat bed with the application of previous crops residue as mulch. DSR in FB+GM–okra+ CRM recorded the highest okra yield of 16.47 t/ha with 71-83 % reduction in weeds compared to control ie DSR in flat bed - okra. Physiological parameters like leaf area index, crop growth rate, relative growth rate and net assimilation rate were found higher in conservation treatments compared to non-conservation treatments. The highest NPK uptake, resource use efficiencies such as water use efficiency, partial factor productivity of NPK and high B:C ratio were recorded in DSR in FB +GM –okra + CRM. Cowpea was raised after okra by keeping the same layout in all conservation treatments and the field was kept as fallow in non-conservation agriculture treatments. The highest biomass yield of 1920.22 kg/ha was recorded in DSR in FB +GM –okra + CRM -cowpea at 45 DAS. While assessing the whole cropping system, conservation treatments recorded 72.60 % land use efficiency and 300 % multiple cropping index but whereas non conservation treatments recorded 60.27 % land use efficiency and 200 % multiple cropping index. Among the different conservation agriculture practices applied to rice –okra-green manure cropping system, DSR in FB +GM –okra + CRM –cowpea recorded the highest cropping system resource use efficiency, net profit and and a B:C ratio. Soil physical, chemical and biological properties were improved due to the effect of conservation treatments over non conservation treatments. Water holding capacity was increased by 31.96 %, porosity by 16.66 % and the soil moisture by 39.83 % in DSR in FB +GM–okra + CRM–cowpea over the non conservation method.The highest soil carbon stock and sequestration at 0-15 and 15-30 cm soil depth were recorded in DSR in FB +GM –okra + CRM–cowpea. At 45 cm only a meagre storage was recorded in DSR in FB +BM –okra + CRM –cowpea. The treatments without conservation agriculture practices ie DSR in FB–okra-fallow showed a negative value for sequestration. It indicates the loss of carbon in conventional method. A slow increase in sequestration after each crops clearly indicated that conservation agriculture practices for a long run will sequester the carbon to entire soil profile. The result of the present two years study indicated that in a rice-okra-green manure cropping system in upland, direct seeding rice in flat bed with green manuring followed by okra with crop residue mulch of previous crop followed by cowpea as green manure can be recommended as a cost effective and sustainable conservation agriculture practice as it resulted in higher system yield, better weed control, sustained the soil health and higher B:C ratio.
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PhD
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Citation
175208