Nitrogen Dynamics in Soil as Influenced by Long-term Manuring and Fertilization under Rice Grown on Vertisol of Chhattisgarh Jadhao S.D.*, Bajpai R.K., Tiwari Alok1, Bachkaiya Vinay1, Singh Muneshwar2, Kharche V.K., Mali D.V., Sonune B.A. Department of Soil Science and Agricultural Chemistry, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, 444104, Maharashtra 1Department of Soil Science and Agricultural Chemistry, IGKV, Raipur, Chhattisgarh 2Indian Institute of Soil Science, Bhopal, Madhya Pradesh *Corresponding author Email: sdjadhao@rediffmail.com
Online published on 27 August, 2019. Abstract Effect of nutrient management practices on nitrogen (N) dynamics in rice grown on a Vertisol was studied after 16 years in an ongoing long-term experiment initiated during 1999–2000. The experiment comprised of different levels of NPK fertilizers alone and in combination with farmyard manure (FYM), blue green algae (BGA) and green manuring (GM) was laid out in split-plot design with four replications. Application of 100% NPK + FYM (5 t ha−1) significantly increased the organic N fractions viz., hydrolysable NH4+-N (165 mg kg−1), amino acid-N (271 mg kg−1), amino sugar-N (36.8 mg kg−1) and hydrolysable unknown-N (127 mg kg−1). The mineral N (nitrate-N + ammonium-N) content (57.3 mg kg−1) was significantly increased with the application of 100% NPK + FYM. A decrease in N fractions was observed with advancement of crop growth stage and increase in the depth of soil from 0–15 to 15–30 cm. The contribution of inorganic and organic N fractions to total N was noted to the extent of 7 and 73%, respectively under 100% NPK + FYM, whereas comparatively lower contribution of these fractions was recorded in control treatment. The contribution of hydrolysable unknown N (HUN) to total hydrolysable N ranged between 21 to 31%, the highest contribution was noted in control (31%) and least contribution was recorded in 100% NPK + FYM. The grain yield (6.45 t ha−1) of rice was increased significantly with the combined application of manures and fertilizers. The total uptake of N by rice was increased significantly with the conjoint use of fertilizers and organic manure. The N recovery efficiency was decreased with increasing fertilizer levels. The rice grain yield was significantly correlated with various N fractions; the highest correlation coefficients among organic N fractions observed with total hydrolysable N at maximum tillering and harvest were r = 0.698** and r = 0.610** in surface and r = 0.635** and r = 0.593** in sub-surface layer of soil, respectively. The mineralizable N was significantly correlated with all fractions of N, except with HUN and non-hydrolysable N. The multiple regression analysis indicated that hydrolysable NH4+-N and HUN are dominant N fractions in contributing rice grain yield and N uptake. Top Keywords Amino acid-N, amino sugar-N, hydrolysable NH4+-N, inorganic-N, rice. Top |