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Sources of nitrogen for winter wheat in organic cropping systems

Petersen, Søren O.; Schjønning, P.; Olesen, Jørgen E.; Christensen, S. and Christensen, B.T. (2013) Sources of nitrogen for winter wheat in organic cropping systems. Soil Science Society of America Journal, 77 (2), pp. 696-697.

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Document available online at: https://acsess.onlinelibrary.wiley.com/doi/abs/10.2136/sssaj2012.0147


Summary

In organic cropping systems, legumes, cover crops, residue incorporation, and manure application are used to maintain soil fertility, but the contributions of these management practices to soil nitrogen (N) supply remain obscure. We examined potential sources of N for winter wheat (Triticum aestivum L.) in four experimental cropping systems established in 1997 on three soil types. Three of the four systems were under organic management. Topsoil N, depth of the A horizon, and cumulated inputs of N since 1997 were determined at plot level. Labile soil N pools (mineral N, potentially mineralizable N [PMN], microbial biomass N [MBN]) were monitored during two growth periods; at one site, biomass C/N ratios were also determined. Soil for labile N analysis was shielded from N inputs during spring application to isolate cumulated system effects. PMN and MBN were correlated across all sites and rotations (r2=0.72). The MBN corresponded to 46-85, 85-145 and 74-172 kg N ha-1 at the three sites and differed significantly between cropping systems, but MBN could not explain differences in wheat grain N yields. Instead, a multiple linear regression model explained 76 and 82% of the variation in grain N yields in organic cropping systems in 2007 and 2008, showing significant effects of, respectively, topsoil N, depth of A horizon, cumulated inputs of N, and N applied to winter wheat in manure. Thus, soil properties, and past and current management all contributed to winter wheat N supply.


EPrint Type:Journal paper
Subjects: Crop husbandry > Crop combinations and interactions
Soil > Soil quality > Soil biology
Soil > Nutrient turnover
Farming Systems > Farm nutrient management
Research affiliation: Denmark > DARCOF III (2005-2010) > CROPSYS - The effect of cropping systems on production and the environment
Denmark > CROPSYS
ISSN:0361-5995
DOI:10.2136/sssaj2012.0147
Deposited By: Petersen, Dr. Søren O.
ID Code:22015
Deposited On:10 Jan 2013 15:18
Last Modified:06 Jun 2022 15:58
Document Language:English
Status:Published
Refereed:Peer-reviewed and accepted

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