CROP INTENSIFICATION IN RICE-BASED CROPPING SYSTEM IN ASSAM
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Date
2017-07
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AAU, Jorhat
Abstract
A field experiment entitled “Crop intensification in rice-based cropping system in Assam” was conducted at the Shillongani farm of Regional Agricultural Research Station, Nagaon, Assam during kharif, rabi and summer seasons in the year 2014-15 and 2015-16 to study the effect of dates of rice transplanting under different methods of cultivation on productivity of Sali rice and their effect on rice-relay system in rabi and thereafter on fodder maize + green gram intercropping system during summer. The treatments of the experiment comprised three dates of rice transplanting viz. 20 June, 5 July and 20 July, and two methods of rice cultivation viz. conventional method and SRI method with four relay crops viz. lentil, pea, toria and niger. The experiment was laid out in a factorial randomized block design for the treatments in rice during kharif season and a split plot design for treatments of relay crops in rabi season assigning dates of planting and method of cultivation in the main plots and relay crops in sub plots with three replications. During summer, fodder maize and green gram in 1:1 row ratio was grown as intercrop in each plot. The soil of the experimental field was medium low land, moderately well drained, sandy loam in texture having organic ‘C’ content of 0.82%, acidic in reaction (pH 5.61), medium in available N (296 kg/ha) and K2O (195 kg/ha), and low in available P2O5 (21 kg/ha). Bulk density of 0-15 cm soil layer was 1.33 g/cc and that of 15-30 cm layer was 1.36 g/cc while the particle density of the layers was 2.06 and 2.08g/cc, in the respective layers. Total porosity was 35.44 % and 34.61% in the respective soil layers. All the crops were fed with recommended doses of fertilizers.
The results revealed that among the different dates of rice transplanting, 20th June transplanted crop recorded significantly higher plant height, number of tillers/m2, number of panicles/m2, number of filled grains /panicles and grain yield of rice as compared to the later dates of transplanting and it was followed by 5 July transplanted rice. Rice transplanted on 20th June recorded higher values in respect of growth, yield attributes, yield of relay as well as summer intercrops, REY of rice-relay, intercropping and whole system; production efficiency of the whole system; N, P and K uptake by rice, relay and intercrops as well as soil fungal and bacterial populations after harvest of rice, relay and intercrops. However, the soil available N, P2O5 and K2O content at the end of two year-crop cycle in 5th and 20th July transplanted rice were significantly higher than that of 20th June transplanted crop.
SRI method of rice cultivation recorded significantly higher values in respect of plant height, LAI, CGR, RGR, root: shoot ratio, panicles/m2, panicle length and weight, filled grains/panicle and 1000-seed weight, grain yield and harvest index of rice as compared to conventional method. In relay cropping, higher values of all the growth and yield attributes, seed yield, REY and harvest index of lentil and niger relay crops were found under SRI method of rice cultivation as compared to conventional method, while, in case of pea and toria relay crops, these were found to be slightly higher under conventional method of rice cultivation. In summer, SRI method of rice cultivation recorded higher values of all the growth and yield attributes, land equivalent ratio and relative crowding co-efficient of fodder maize and greengram in intercropping system. Further, under SRI method, higher uptake of N, P and K by rice, relay and intercrops and higher soil fungal and bacterial populations after harvest of rice, relay and summer intercrops as well as REY and production efficiency of the whole cropping system were observed as compared to conventional method. However, conventional method of rice cultivation recorded significantly higher values of soil available N, P2O5 and K2O content at the end of two year-crop cycle over that of SRI method.
Among the relay crops, pea and lentil relay recorded higher yield as compared to toria and niger. However, rice-lentil and rice-pea system were found most promising in respect of REY and economics of rice- relay system compared to rice-toria and rice-niger system.
In fodder maize and greengram intercropping system during summer, relay crops had significant effect on growth and yield attributes of fodder maize and greengram. Significantly higher values of plant height and green fodder yield of maize as well as competition index and competition ratio of intercropping system were recorded when summer intercrops were grown after rice-lentil and rice-pea relay crops as compared to rice-toria and rice-niger relay. However, significantly higher values in respect of number of pods/plant, seed yield and stover yield of greengram, higher land equivalent ratio and higher relative crowding co-efficient of intercropping system were found after rice-toria and rice-niger relay crops as compared to that of rice-lentil and rice-pea relay. Significantly higher values of REY and production efficiency of whole cropping sequence, and higher soil moisture content at 60 and 90 days after sowing of relay crops were found in rice-pea and rice-lentil system as compared to rice-toria and rice-niger. The soil fungal and bacterial populations after harvest of relay and summer intercrops were found more after lentil and pea relay crops as compared to toria and niger relay crops. However, lower values of residual available soil N, P2O5 and K2O content at the end of two year-crop cycle were found under the system involving pea and lentil relay crop as compared to toria and niger relay.
Rice transplanted on 20th June under SRI method relayed by lentil and followed by summer intercrops of fodder maize and greengram recorded the highest REY, production efficiency and benefit: cost ratio of whole system in both the years. Rice transplanted on 20th June under SRI method relayed by pea and followed by summer intercrops of fodder maize and greengram was more efficient in utilizing the soil available N, P2O5 and K2O resulting in the highest N, P and K uptake and thereby the lowest available soil N, P2O5 and K2O was recorded under this system.
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