Studies on effect of long term integrated nutrient management on carbon pools and soil quality in soybean-safflower safflower sequence
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Date
2019-06-11
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Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani
Abstract
Soil organic carbon (SOC) is basic building block for all life on the earth. Moreover, it is very important for maintaining soil quality, productivity and sustainability. The present investigation entitled “Studies on Effect of Long Term Integrated Nutrient Management on Carbon Pools and Soil Quality in Soybean-Safflower Sequence” under All India Coordinated Research Project on Long-Term Fertilizer Experiment was carried out during the year 2015-16 and 2016-17. Long term fertilizer experiment was commenced from 2006-07 at Departmental Farm, Department of Soil Science and Agricultural Chemistry, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani (MS) to study the effect of manures and fertilizers on soil carbon pools, yield and soil properties under soybean-safflower cropping sequance on Vertisol (Typic Haplusterts). The experiment was laid out in Randomized block design (RBD) with twelve treatments replicated four times. The treatments comprises T1-50% NPK, T2- 100% NPK, T3-150% NPK, T4-100% NPK + Hand weeding, T5-100% NPK + ZnSO4@ 25 kg ha-1, T6-100% NP, T7-100% N, T8-100%NPK + FYM @ 5 Mg ha-1, T9-100% NPK- Sulphur, T10-FYM@ 5 Mg ha-1, T11-Control and T12- fallow. The soil samples were collected from each treatment at 0-15 and 15-30 cm depth during both the years and analyzed for physical, chemical and biological parameters of soil and soil quality. The experimental soil was moderately alkaline in reaction, medium in bulk density, good porosity, high water holding capacity, low in hydraulic conductivity, medium in organic carbon and calcium carbonate, high cation exchange capacity, medium in available nitrogen and phosphorus and high in available potassium, sulphur, sufficient in zinc, available iron, manganese and copper.
Integrated use of organic manures and chemical fertilizers improved soil carbon pools viz. organic carbon, total carbon, inorganic carbon, water soluble carbon, carbohydrate carbon, light fraction carbon, particulate organic carbon, labile and non labile carbon pools and maintain soil health and fertility. Among the different fertilizer treatments, application of 100 % NPK + FYM @5 Mg ha-1 followed by 150 % NPK showed highest seed and straw yield of soybean and safflower. Physical indicators like porosity, maximum water holding capacity and hydraulic conductivity were significantly improved with the application of 100% NPK + FYM @5 Mg ha-1 and there was slight decrease in bulk density with combined application of organic manure and inorganic fertilizer. However, pH and EC were found to be significantly improved with the application of 100 % NPK + FYM @ 5 Mg ha-1 and CaCO3 was statistically non-significant, but it was maximum in treatment (T11) absolute control. Further, incorporation of FYM along with chemical fertilizers increased available nitrogen, phosphorus, potassium, sulphur, DTPA extractable iron, manganese, copper and zinc in soil as compared to control and imbalanced fertilizers application. Whereas, more amount of zinc was observed with 100% NPK + ZnSO4 @ 25 kg ha-1. Moreover, significant the highest microbial population and enzymatic activities like dehydrogenase, acid and alkaline phosphatase activities were observed in upper layer with the combined application of 100% NPK + FYM @ 5 Mg ha-1 and helped in improving soil quality. While, nutrient concentration and uptake of N, P2O5, K2O, S, Zn, Fe, Mn and Cu in seed and straw of soybean and safflower were found to be significantly highest with application of 100% NPK + FYM @5 Mg ha-1. Further, A positive correlation was observed between soil carbon pools viz. organic carbon, inorganic carbon , total carbon water soluble carbon, carbohydrate carbon, particulate organic carbon, light fraction organic carbon labile carbon, non labile carbon and soil physical, chemical and biological properties. While bulk density, pH, electrical conductivity were negatively correlated with carbon pools and soil properties. Improvement in Carbon Management Index (CMI) was recorded under integrated use of organic manure and inorganic fertilizer over their sole application of organic manures and inorganic fertilizers alone. The sustainable yield index (SYI) was found to be consistently increased with the application of 100% NPK + FYM @ 5 Mg ha-1.
Based on the results obtained from the long-term fertilizer experiments it can be concluded that the application of 100% NPK + FYM@ 5 Mg ha-1 was beneficial with respect to build up of soil carbon pools, soil fertility, nutrient uptake, higher productivity, sustainability, soil quality and ensuring soil health in soybean-safflower cropping sequence grown on Vertisol.
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