Bol Roland, Eriksen Jorgen, Smith Pete, Garnett Mark H, Coleman Kevin, Christensen Bent T
Department of Soil, Environmental and Ecological Sciences, IGER North Wyke Research Station, Okehampton EX20 2SB, UK.
Rapid Commun Mass Spectrom. 2005;19(22):3216-26. doi: 10.1002/rcm.2156.
The Askov field experiment (Denmark), established in 1894, provides a unique opportunity to examine long-term effects of animal manure and mineral fertilizer on soil organic matter quality and turnover. This sandy loam soil is classified as Alfisol (Typic Hapludalf). Soil C, N, S, 13C, 15N, 34S and 14C contents were measured in a selection of archived soil samples (1923, 1938, 1945, 1953, 1964, 1976, 1985, 1996 and 2000) from unfertilized (O), animal manure (1 AM) and mineral fertilizer (1 NPK) treatments. These treatments are imbedded in a four-course crop rotation of winter cereals, root crops, spring cereals and a clover/grass mixture. The contents of C, N, S, 13C, 15N and 34S in selected crop samples (1953-1996) and in contemporary samples of animal feed and manure were also determined. Temporal soil nutrient and isotope trends between fertilizer treatments were significantly different, except for S content in 1 AM and 1 NPK. The total soil C and S was higher in 1 AM and 1 NPK than in the O treatment. The total soil N content (1 AM>1 NPK>O) and the delta15N content (1 AM>1 NPK and O) were also different. Analyses of plant, animal feed and manures confirmed that differences in soil 15N values were related to delta15N values of added source inputs. Soil and crop delta13C values were similar, but manures had slightly lower values. The variation of soil delta34S (and total S) from 1923 to 1996 was larger in the O than 1 AM and 1 NPK plots reflecting changes in atmospheric S inputs. The total contents of soil C, N and S were significantly correlated, but their isotopic signatures were not, suggesting that the C, N, S turnovers in soil are subject to different controls. The 14C content was generally higher in the 1 AM than 1 NPK and O, with bomb-14C incorporation modelling indicating that mean residence time (MRT) was ca. 170 years in the 1 AM, but closer to 250-290 years in the 1 NPK and O treatments. The measured trends in soil C and 14C during 1923-1996 were successfully modelled using the RothC model. The OM accumulation in the Askov soils was generally dominated by microbial decomposition products rather than by recalcitrant components of the various inputs.
阿斯克夫田间试验（丹麦）于1894年设立，为研究动物粪便和矿物肥料对土壤有机质质量及周转的长期影响提供了独特契机。这种砂壤土被归类为淋溶土（典型弱发育湿润老成土）。在一系列存档土壤样本（1923年、1938年、1945年、1953年、1964年、1976年、1985年、1996年和2000年）中测量了土壤碳、氮、硫、13C、15N、34S和14C含量，这些样本来自未施肥（O）、动物粪便（1AM）和矿物肥料（1NPK）处理地块。这些处理被纳入冬小麦、块根作物、春小麦和三叶草/草混合物的四轮作物轮作体系。还测定了选定作物样本（1953 - 1996年）以及当代动物饲料和粪便样本中的碳、氮、硫、13C、15N和34S含量。除1AM和1NPK处理中的硫含量外，肥料处理之间的土壤养分和同位素时间趋势存在显著差异。1AM和1NPK处理中的土壤总碳和总硫含量高于O处理。土壤总氮含量（1AM>1NPK>O）和δ15N含量（1AM>1NPK和O）也存在差异。对植物、动物饲料和粪便的分析证实，土壤15N值的差异与添加源输入的δ15N值有关。土壤和作物的δ13C值相似，但粪便的δ13C值略低。1923年至1996年期间，O处理地块土壤δ34S（以及总硫）的变化幅度大于1AM和1NPK处理地块，这反映了大气硫输入的变化。土壤碳、氮和硫的总含量显著相关，但其同位素特征不相关，这表明土壤中碳、氮、硫的周转受不同控制。1AM处理中14C含量通常高于1NPK和O处理，通过核弹14C掺入模型模拟表明，1AM处理的平均停留时间（MRT）约为170年，而1NPK和O处理更接近250 - 290年。利用RothC模型成功模拟了1923 - 1996年期间土壤碳和14C的实测趋势。阿斯克夫土壤中的有机物质积累通常以微生物分解产物为主，而非各种输入的难降解成分。
