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Residual Fertilizer, Crop Sequence, and Water Availability Impact Rotational Nitrogen Balances
Author(s) -
Maaz Tai,
Pan William
Publication year - 2017
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2016.08.0457
Subject(s) - canola , agronomy , fertilizer , crop rotation , sativum , environmental science , brassica , crop residue , crop , nitrogen , chemistry , biology , ecology , agriculture , organic chemistry
Inter‐seasonal N carryover increased subsequent crop N recovery. Increases in yield and N uptake after pea were partly attributed to higher N supply. The benefit of pea preceding winter wheat increased with increasing available water. Constructed rotation N balances incorporated inter‐seasonal changes in soil N supply. Rotational N use was modeled across a range of water‐limited environments.Accounting for multiple N sources provides an opportunity to improve rotational nitrogen use efficiency (rNUE) relative to single seasons. The project objectives were to assess the residual effects of fertilizer on subsequent crop yields and N recovery, attribute differences in winter wheat ( Triticum aestivum L.) yield due to changes in N supply following pea (Pisum sativum L.), examine changes in N balances and grain yields across varying water availability, and develop and apply a multi‐year regression model that assesses changes in rotational N balances in water‐limited cropping systems. Fifty to 160 kg N ha −1 were unaccounted for following spring canola ( Brassica napus L.) harvest, and excessive fertilization led to increases in post‐harvest residual N and crop residue N. Subsequent crops accumulated 10 to 15 kg more grain N ha −1 , when following fertilized canola, while rotational apparent fertilizer N recovery ranged from 3 to 15%, primarily in the second year. The residual effect of fertilization was only attributed to residual soil N since net N mineralization was not statistically affected. Economic optimal yields of winter wheat were almost 900 kg ha −1 greater following pea than wheat due to elevated soil N supply and other rotational effects, increasing with water availability. A method of analyzing rotational N use is presented that integrates the effects of year‐to‐year changes in N supply across a range of yields, from which N balances may be constructed based on the emerging relationships among yield potential and soil and plant N processes.