Depth dynamics of soil N contents and natural abundances of 15N after 43 years of long-term fertilization and liming in sub-tropical Alfisol |
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| Authors: | Avijit Ghosh Brahma Swaroop Dwivedi Dipak Ranjan Biswas Mahesh Chandra Meena Abhijit Sarkar |
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| Institution: | Division of Soil Science and Agricultural Chemistry, ICAR-Indian Agricultural Research Institute, New Delhi, India |
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| Abstract: | The aim of this study was to understand impacts of long-term (43 years) fertilization on soil aggregation, N accumulation rates and δ15N in surface and deep layers in an Alfisol. Soil samples from seven treatments were analysed for N stocks, aggregate-associated N in 0–30 cm and the changes in δ15N in 0–90 cm depths. The treatments were: unfertilized control (control); recommended N dose (N); recommended N and phosphorus doses (NP); recommended N, P and potassium doses (NPK); 150% of recommended N, P and K doses (150% NPK); NPK + 10 Mg FYM ha?1 (NPK + FYM) and NPK + 0.4 Mg lime ha?1 (NPK + L). Results revealed that plots under NPK + FYM had ~39% higher total N concentrations than NPK + L in 0–30 cm soil layers. In NPK + L, macro-aggregates had 35 and 11% and microaggregates had 20 and 9% lower δ15N values than NPK + FYM in 0–15 and 15–30 cm soil layers, respectively. However, plots receiving NPK + FYM had ~39% greater deep soil (30–90 cm) N accumulation than NPK + L. These results would help understanding N supplying capacity by long-term fertilization and assist devising N management strategies in sub-tropical acidic Alfisols. |
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| Keywords: | Wheat based cropping farmyard manure C/N ratio deep soil N accumulation δ15N |
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