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Composition and Organic Carbon Distribution of Organomineral Complex in Black Soil under Different Land Uses and Management Systems

Hou, Xueying, Han, Xiaozeng, Li, Haibo, Xing, Baoshan
Communications in soil science and plant analysis 2010 v.41 no.9-11 pp. 1129-1143
soil organic carbon, land use, soil fertility, organomineral complexes, soil management, chemical composition, particle size, silt fraction, sand fraction, nitrogen fertilizers, phosphorus fertilizers, organic fertilizers, animal manures, clay fraction, soil aggregates, grasslands, carbon sequestration, tillage, land restoration, China
Organomineral complexes form the basis of soil fertility and have significant effects on the soil environment. In this research, we aimed to study the composition and organic carbon (C) distribution of organomineral complexes in a black soil under different land uses and management by means of ultrasonic dispersion and particle assortment. The results showed that the fine sand-size complex (20-200 μm) was dominant under different land uses and management. Silt-size (2-20 μm) and fine sand-size content increased with nitrogen and phosphorus application (NP) and NPM (NP together with organic manure) treatment, whereas clay-size (0-2 μm) content decreased. The content of <20-μm complex in GL (grassland) was less than in BL (bareland), and >20-μm complex showed the opposite trend. The silt-size content increased with the increase of SOC (soil organic C). A negative relationship was observed between the clay-size complex content and SOC content. Land-use change resulted in different dynamics in C sequestration in soil. The content of <20-μm complex in GL was more than in NP and NPM; GL has potential to sequester more C than tilled soil because of the stability of SOC stored in the <20-μm fraction. Long-term application of organic manure and vegetation restoration increased the OC (organic carbon) content of all sizes of complexes; the OC contents of clay-size complex were in the order GL > NPM > NP > BL > NF (no fertilizer applied) and increased the proportion of OC in >20-μm complexes, indicating that OC content in sand-size fractions increased with total SOC content.