Integrated nitrogen management in maize-potato system in an acid Alfisol
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Date
07-01-19
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CSKHPKV, Palampur
Abstract
The present investigation was carried out at the experimental farm of Department of Soil Science, College of Agriculture, CSK HPKV, Palampur in randomized block design consisting of ten treatments combinations viz. control, 100 per cent mineral N, farmers’ practice, 100% mineral N +FYM (recommended), 25 and 50 per cent substitution of N through FYM, vermicompost and poultry manure, respectively. The experiment was conducted in maize-potato system for two years i.e. from kharif, 2015 to rabi, 2016-17. The soil of the experimental field was silty clay loam in texture, acidic in reaction (pH 5.31), medium in organic carbon (6.58 g kg-1) with 234, 21.4 and 185 kg ha-1 of available N, P and K, respectively. The micronutrient cations viz. Fe, Mn, Zn and Cu in the soil were 21.8, 19.1, 0.93 and 0.48 mg kg-1, respectively. Surface (0-0.15 m) soil samples taken at the harvest of each crop were analysed for water holding capacity, pH, organic carbon (OC), cation exchange capacity (CEC), available N, P, K and micronutrient cations viz. Fe, Mn, Zn and Cu. Microbiological properties i.e. microbial biomass carbon, microbial biomass nitrogen and soil respiration were also determined at harvest of potato, rabi 2015-16 and 2016-17. While different fractions of N were determined at the end of experimentation i.e. at the harvest of second crop of potato, rabi 2016-17. Plant samples of both the crops at the harvest of each crop, were analyzed for total N, P, K and micronutrient cations content and their respective uptake by both the crops were worked out. The present study revealed that integrated use of chemical fertilizer and different organic manures improved the soil physical, chemical as well as biological properties with highest value in the treatment where 100 % N was applied through chemical fertilizes +FYM at recommended rates. Highest yield of both the crops was recorded in same treatment and was significantly superior to the rest of the treatments followed by treatment where 50% N was substituted with poultry manure. Application of 50 per cent N through chemical fertilizers + 50 per cent N through poultry manure improved the nitrogen use efficiency as compared to the rest of the treatments i.e. 56.2 % at the end of experimentation. The contribution of different organic as well as inorganic forms of nitrogen viz., hydrolysable ammonical-N, amino acid-N, serine+threonine-N, hexosamine-N, unidentified-N, non hydrolysable-N, ammonical-N and nitrate-N, towards the total-N was 20, 23, 8, 7, 17, 15, 7 and 3 %, respectively. Different fractions of nitrogen were also found to be positively and significantly correlated with one another except non hydrolysable-N. Application of 50 per cent N through chemical fertilizers + 50 per cent N through poultry manure to both the crops recorded highest net returns as well as highest benefit cost ratio. It is concluded that the application of 100 per cent N through chemical fertilizers + FYM at recommended rates proved best treatment in terms of productivity, nutrients uptake and soil properties while 50 per cent N substitution through poultry manure proved to be the best treatment in terms of profitability and nitrogen use efficiency.