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Optimisation of N release

influence of plant material chemical composition on C and N mineralisation

Gunnarsson, Sophie (2003). Optimisation of N release. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae. Agraria, 1401-6249 ; 381
ISBN 91-576-6422-6
[Doctoral thesis]

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Abstract

Nitrogen mineralisation from green manure needs to be managed to meet crop N demand and minimise N losses. One way of achieving this can be to use differences in chemical composition between plant materials as a means to steer the processes either towards immobilisation or mineralisation during specific periods. The overall objective of this thesis was to improve the understanding of N mineralisation processes during decomposition of temperate-zone grasses and legumes, especially in relation to concentrations of specific carbohydrates and N compounds. Possible ways of using differences in composition as a means to steer the N mineralisation pattern were also investigated. Mineralisation of C and N during decomposition of pure plant components and materials were studied under controlled conditions. The most abundant plant components could be subdivided into three groups based on when they had their main influence on C and N mineralisation. This subdivision can be used when choosing plant material to achieve a desired effect on the pattern of N mineralisation. To enhance immobilisation of N during the initial days of decomposition plant materials rich in free sugars and fructans may be used. To prolong the initial immobilisation phase for a period of up to two weeks plant materials rich in starch, pectin, or with a hemicellulose characterised by a high arabinose-to-xylose ratio may be used. To reduce N mineralisation during later stages of decomposition plant materials dominated by slowly decomposable structural carbohydrates, such as xylan and cellulose, may be used. Under Swedish field conditions these periods will be approximately two to three times longer than this depending on the time of incorporation due to lower temperature and suboptimal moisture conditions. In order to obtain the necessary information about concentrations of pectin, arabinose and xylose detailed plant analysis, rather than the common proximate neutral/acid-detergent analysis, is required. More knowledge is also required concerning the significance of the effect of chemical composition on N mineralisation in a field situation. New tailor-made plant materials with a greater range of chemical properties, compared to the present plant materials, may be needed to achieve the intended effects in a field situation.

Authors/Creators:Gunnarsson, Sophie
Title:Optimisation of N release
Subtitle:influence of plant material chemical composition on C and N mineralisation
Year of publishing :April 2003
Volume:381
Number of Pages:54
Papers/manuscripts:
NumberReferences
ALLI. Gunnarsson, S. & Marstorp, H. 2002. Carbohydrate composition of plant materials determines N mineralisation. Nutrient cycling in agroecosystems 62, 175-183. II. Gunnarsson, S. Marstorp, H. & Witter, E. Influence of non-cellulose structural carbohydrate composition on plant material decomposition in soil. (Submitted) III. Gunnarsson, S. Influence of plant carbohydrate composition on net N immobilisation and mineralisation. (Manuscript). IV. Sindhøj, E. Andrén, O. Kätterer, T. & Gunnarsson, S. Projections of 30-year soil carbon balances for a semi-natural grassland under elevated CO2 based on measured root decomposability. (Submitted).
Place of Publication:Uppsala
ISBN for printed version:91-576-6422-6
ISSN:1401-6249
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:P Natural resources > P35 Soil fertility
P Natural resources > P33 Soil chemistry and physics
Subjects:Not in use, please see Agris categories
Agrovoc terms:green manures, chemical composition, degradation, mineralization, carbon cycle, nitrogen cycle, pectins, hemicellulose, arabinose, xylose
Keywords:green manure, chemical composition, decomposition, C mineralisation, N mineralisation, free sugars, fructans, pectic substances, hemicellulose, arabinose, xylose, cellulose, protein
URN:NBN:urn:nbn:se:slu:epsilon-47
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-47
ID Code:212
Department:(NL, NJ) > Dept. of Soil Sciences
Deposited By: Sophie Gunnarsson
Deposited On:03 Apr 2003 00:00
Metadata Last Modified:02 Dec 2014 10:02

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