Carbohydrate composition of plant materials determines N mineralisation

• Published in: Nutrient cycling in agroecosystems Vol. 62; no. 2; pp. 175 - 183
• Main Authors: Gunnarsson, Sophie, Marstorp, Håkan
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.02.2002
• Subjects: Carbohydrate composition; Carbohydrates; Cellulose; Composition; Fructans; Hemicellulose; Leaves; Lignocellulose; Mineralization; Nitrogen; Phleum pratense; Polysaccharides; Proteins; Saccharides; Substrates; Sugar
• ISSN: 1385-1314; 1573-0867
• DOI: 10.1023/A:1015512106336

To improve the synchrony between N mineralisation and crop N demand itis important to identify properties of the plant materials that can be used topredict the N mineralisation. We hypothesised that the timing of decompositionof plant carbohydrates relative to that of plant proteins could be used todetermine the course of net N mineralisation. We started by studying thedecomposition of several plant carbohydrates, both as single substrates and incombination, to find out how they affected the net N mineralisation fromproteins. As the next step, we combined nitrogen-rich Medicagosativa leaves with Phleum pratense thatcontained large amounts of sugars and fructans. We also combined M.sativa leaves with Trifolium pratense thatcontained large amounts of pectic substances and hemicellulose. Finally, wecombined M. sativa leaves with Loliumperenne that contained large amounts of lignocellulose but lowamounts of sugars and fructans. With the addition of P.pratense, the course of N release changed to an initial Nimmobilisation followed by a net N mineralisation. Addition of L.perenne only slightly affected the N mineralisation rate ofM. sativa leaves initially, but reduced amounts of Nmineralised thereafter. The effect of T. pratense wasintermediate between that of P. pratense and L.perenne. Our results show that by combining plant materials withdifferent carbohydrate and protein compositions it is possible to affect the Nmineralisation. However, to utilise subtle differences between plant materials,detailed analysis of non-cellulose polysaccharides may be necessary.