Nitrogen mineralization kinetics in rice and wheat residue amended soils under long-term saline and sodic water irrigation
Loading...
Date
2013
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Punjab Agricultural University
Abstract
Laboratory incubation experiments were conducted to study the influence of crop residue incorporation on soil properties and to assess the N-mineralization kinetics under long-term irrigation with saline (SaW) and sodic water (SW). Irrigation with SaW and SW significantly increased the pH, EC and ESP while application of gypsum and crop residues improved these properties. N-mineralization in different soils ranged from 233 to 392 mg N kg-1 in case of field addition and 84 to 285 mg N kg-1 in case of fresh addition of crop residues during incubation. Relative to canal water (CW) treatment, SW significantly decreased the mineral-N followed by SaW treatment. Application of gypsum and incorporation of crop residues in the field resulted in increase in mineral-N. Maximum cumulative N mineralization was observed in wheat straw (WS) amended treatment except in SW+G treatment. Fresh addition of crop residues resulted in net N immobilization and lower rate of N mineralization compared to unamended treatments. In SaW, SW and SW+G treatments, a dip in mineral-N was observed at 28 days in the amended treatments. Among the kinetic models,only first order model (FO) provided realistic solutions but with poor R2values (0.18 to 0.57). Nitrogen mineralization potential (N0) ranged between 171 and 383 mg N kg-1 and the rate constant (k) ranged from 0.020 to 0.411 day-1in different treatments.In case of fresh additions of residues, even FO model didnot provide solutions to any of the amended treatments. Compared to CW treatment, both SW and SaW irrigation significantly decreased the grain yield and N uptake by wheat. Incorporation of crop residues significantly improved the grain yield over the unamended treatment but increase in N uptake was not significant.
Description
Keywords
<significant., treatments