Variation of stabilised, microbial and biologically active carbon and nitrogen in soil under contrasting land use and agricultural management practices

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• 作者：Dilly ; Oliver ; Blume ; Hans-Peter ; Sehy ; Ulrike ; Jimenez ; Miguel ; Munch ; Jean Charles
• 关键词：Agricultural management ; Carbon ; C/N ratio ; Land use ; Mineralisation ; Nitrogen
• 刊名：Chemosphere
• 出版年：2003
• 出版时间：July, 2003
• 年：2003
• 卷：52
• 期：3
• 页码：557-569
• 全文大小：368 K

文摘

Land use and agricultural practices modify both the amounts and properties of C and N in soil organic matter. In order to evaluate land use and management-dependent modifications of stable and labile C and N soil pools, (i) organic C and total N content, (ii) microbial (C_mic) and N (N_mic) content and (iii) C and N mineralisation rates, termed biologically active C and N, were estimated in arable, grassland and forest soils from northern and southern Germany. The C/N-ratios were calculated for the three levels (i)–(iii) and linked to the eco-physiological quotients of biotic-fixed C and N (C_mic/C_org, N_mic/N_t) and biomass-specific C and N mineralisation rate (qCO₂, qN_min). Correlations could mainly be determined between organic C, total N, C_mic, N_mic and C mineralisation for the broader data set of the land use systems. Generally, the mineralisation activity rate at 22 °C was highly variable and ranged between 0.11 and 17.67 μg CO₂–C g⁻¹ soil h⁻¹ and −0.12 and 3.81 μg (δNH₄⁺+δNO₃⁻)–N g⁻¹ soil h⁻¹. Negative N data may be derived from both N immobilisation and N volatilisation during the experiments. The ratio between C and N mineralisation rate differed significantly between the soils ranging from 5 to 37, and was not correlated to the soil C/N ratio and C_mic/N_mic ratio. The C/N ratio in the ‘biologically active’ pool was significantly smaller in soils under conventional farming than those under organic farming systems. In a beech forest, it increased from the L, Of to the Ah horizon. The biologically active C and N pools refer to the current microbial eco-physiology and are related to the need for being C and N use efficient as indicated by metabolic qCO₂ and qN_min quotients.