STUDIES ON SOIL HEALTH AS INFLUENCED BY DIFFERENT RICE FALLOW CROPPING SYSTEMS
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Date
2018
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Acharya N.G. Ranga Agricultural University
Abstract
Rice based cropping systems form an integral part of agriculture in Andhra Pradesh. Several intensive rice based cropping systems have been identified and are being practiced by the farmers. While intensive agriculture, involving exhaustive high yielding varieties of rice and other crops, has led to heavy withdrawal of nutrients from the soil, imbalanced and discriminate use of chemical fertilizers has resulted in deterioration of soil health. Suitable rice based cropping system has to be evaluated, to assess the stability in production. Experiments on cropping systems are ultimate solution to overcome the drawbacks of mono cropping system. Therefore, there is a need to develop a suitable cropping sequence which may be a viable option to improve the soil health. In addition to that, information on soil biological properties under different rice based cropping systems is meagre. As the cereal- cereal sequence is more exhaustive it is necessary to arrive at alternate fallow crops which may be used in rotation.
With this background, a field experiment was conducted for two consecutive years (2015-16 & 2016-17) on clayloam soils of Agricultural College Farm, Bapatla. The experiment was laid out in a two sample t-test for rice in kharif season with 2 treatments and replicated thrice. The treatments consists of M1 100% RDF, M2 (50% RDN+ 25% N through FYM + 25% N through neem cake + Azospirillum+PSB @ 2.5 kg ha-1(INM). During the immediate kharif, the experiment was laid out in a split plot design without disturbing the soil for succeeding rabi crops with the two treatments given to
kharif rice as main plot treatments and each of these divided into five sub-plots. The experiment was repeated in another field (same block) during kharif and rabi seasons. Popular cultivars of rice (BPT 5204), blackgram (PU 31), maize (Sandhya), Sorghum (NSH-54), Sunflower (Shreshta) and mustard (Konark) were used for this study.
It was observed that INM treatment had relatively improved the bulk density, water holding capacity and porosity but it was non-significant. Physico-chemical properties were also improved with inclusion of INM treatment compared to 100% RDF. With application of INM treatment, all the available nutrients of N, P, K, Ca, Mg, S and micronutrients increased their status in soil at initial stages and later it was decreased due to uptake by the growing plants. Regarding biological properties, the highest DHA activity, fungi, bacteria and actinomycetes populations were observed at panicle initiation stage when compared to other stages.
Data recorded on growth parameters viz., plant height, dry matter accumulation, yield attributes, yield and nutrient content of rice were significantly higher with the application of INM treatment. Application of organics along with 50% RDN produced the highest grain yield (5818 kg ha-1) which was superior over only inorganics i.e 4473 kg ha-1 during 2015 and 5896 kg ha-1 superior over 100% RDF i.e 4598 kg ha-1 during 2016 year. The increment of yield with INM treatment was 30.0% and 28.22% during 2015 and 2016 years, respectively.
Residual effect of INM treatment got the significantly higher values of plant height, dry matter accumulation, yield attributes, grain yield, stover yields of rabi crops of blackgram, maize, sorghum, sunflower and mustard crops, when compared to M1 treatment. The data regarding residual effect of INM treatment on soil properties after harvest of rabi crops also studied. The data revealed that irrespective of rabi crops, all the physical properties were non-significantly influenced by residual effect of INM. Even though, the increase of 1.6 to 9.75% was observed in improving physical properties. Available nitrogen, phosphorus, potassium were significantly increased in M2 with a per cent of 3.67 to 7.29% , 4.0 to 9%, 2.142 to 2.92% during 2016 and 2017 years, respectively. Micronutrient contents were also significantly increased with application of INM. Regarding biological properties, residual effect of INM had influenced the DHA activity by 11.8% and 13.43% during 2016 and 2017 years, respectively. Fungi (8.37 to 18.36%) bacteria (15.11 to 20.0%) and actinomycetese (5.9 to 16.45%) populations were increased by residual effect of INM.
Crop growth parameters, yield attributes, yield and nutrient content and uptake were significantly influenced by the residual effect of INM which was applied in the preceding kharif. Blackgram yield was increased by 6.33% and 7.52% in M2 when compared to M1 during first and second years, respectively. Maize crop kernel yield was increased by 13.68% and 25.93% with M2 treatment compared to M1 during first and second years, respectively. Sorghum crop grain yield was increased by 30% with treatment of M2 when compared to M1
treatment. Sunflower seed yield was increased by 40-50% apprx with inclusion of M2 than M1. Mustard seed yield was increased by 24 to 26% with inclusion of M2 compared to M1.
Soil physical and physico-chemical properties were non-significantly affected by rabi crops. Soil available nitrogen, phosphorus, potassium were significantly affected by rabi crops during 2015-16 and 2016-17 both the years. Among them, blackgram crop has increased soil available nitrogen by 32.5 kg ha-1 over initial value which was on par with mustard and sunflower sequence, which was superior over maize. The lowest available nitrogen was observed with maize. The highest mean available phosphorus was recorded in blackgram (72.8 kg ha-1) which was on par with sunflower (71.65 kg ha-1) and maize superior over sorghum sequence. Highest available potassium was recorded in blackgram (815 kg ha-1) followed by sorghum sequence, which was on par with other sequences and lowest was observed with sorghum sequence i.e the blackgram being legume, it has the capacity of fixing atmospheric nitrogen into soil and there by increased nitrogen, phosphorus and potassium contents and lowest values observed with sorghum (cereals) and maize due to their exhaustive nature. All the microbial populations of fungi, bacteria and actinomycetese were significantly increased by blackgram crop (being a legume and good root system) followed by sunflower, mustard (being dicot crops) and lowest was observed with sorghum and maize (being cereal crops and more exhaustive nature). So, in view of soil health, the rice-blackgram cropping system was the best cropping system.
The net monitory returns, B:C ratio, rice grain equivalent yield, production use efficiency, land use efficiency, protein equivalent yields were higher with rice-maize cropping system followed by blackgram, mustard, sorghum and sunflower cropping systems.
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D5666
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