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Management of N mineralization from crop residues of high N content using amendment materials of varying quality
Author(s) -
Rahn C.R.,
Bending G.D.,
Turner M.K.,
Lillywhite R.D.
Publication year - 2003
Publication title -
soil use and management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.709
H-Index - 81
eISSN - 1475-2743
pISSN - 0266-0032
DOI - 10.1111/j.1475-2743.2003.tb00304.x
Subject(s) - amendment , loam , sugar beet , chemistry , mineralization (soil science) , crop residue , cellulose , lignin , agronomy , reducing sugar , soil water , leaching (pedology) , zoology , sugar , nitrogen , horticulture , food science , biology , ecology , organic chemistry , political science , law , agriculture
. A potential technique for reducing overwinter leaching from high N containing crop residues is to immobilize the N released during decomposition by co‐incorporating materials of a wider C : N ratio. This article describes the use of laboratory incubation experiments to investigate the effects of a wide range of such amendment materials on the mineralization of N from sugar beet and brassica leaf residues in a sandy loam and a silt loam. These materials were of varying quality, with C : N ratio ranging from 15 : 1 to 520 : 1, and cellulose content from 0 to 34%. Amendments were added at a fixed rate of 3.5 mg C g −1 of dry soil, equivalent to around 10 t ha −1 C (to 20 cm depth). The soils were then incubated at 15°C, and net mineral N derived from the leaves was measured at regular intervals over 168 days. Net mineralization of residue N was greatest with molasses (C : N ratio of 18 : 1), whereas paper waste (C : N ratio of 520 : 1) reduced N mineralized by up to 90% compared with a soil‐only control. As the concentration of cellulose and lignin in the amendment materials increased, so the amounts of N mineralized decreased, with 62 and 54% of variance in N mineralized explained by cellulose and lignin content, respectively. Reduced levels of mineral N were associated with higher levels of biomass‐N. The levels of N 2 O‐N lost from sugar beet residues on day 14 were significantly reduced from 66 to 5 g ha −1 where compactor (cardboard) waste had been mixed into sandy loam, but this effect was not observed in the silt loam. These techniques could lead to greater efficiency of N use in rotations through reduction in N losses, and provide alternative routes for disposal of wastes when the EC Landfill Directive is implemented.