Organic carbon fractions and aggregate stability in aquatic soil under different fertilization

Abstract

Abstract: As an essential indicator of soil quality,soil organic carbon (SOC) and its fractions play an important role in many soil chemical,physical,and biological properties.A field experiment was conducted to determine the effects of different nutrient regimes on aquatic soil organic carbon fractions and aggregate stability in Northern China Plain.Seven nutrient regimes were installed:(i) control,(ii) NP,(iii) NK,(iv)PK,(v)NPK,(vi) NPK+S (wheat straw),(vii) NPK+M (farmyard manure).The results showed that soil total organic carbon (TOC) and total nitrogen (TN) were markedly higher in combined application of organic and chemical fertilizers than in chemical fertilization.By fractionalizing SOC,it was observed that in comparing with treatment NPK,treatment NPK+M had significantly higher soil easily-oxidizable C (EOC),particulate organic C (POC),light fraction organic C (LFOC) and water-soluble organic C (WSOC),being increased by 23.8%,39.9%,42.5% and 32.1%,respectively.The proportions of LOC,POC,LFOC and WSOC to TOC in chemically fertilized soil,especially in treatment PK,were observably lower than those in organically fertilized soil.Incorporation of organic sources into aquatic soil showed the highest microbial biomass C (MBC) and mineralizable organic C (MNC),followed by treatments NPK,NP and NK,and treatments PK and CK had the lowest MBC and MNC.A combined application of organic and inorganic fertilizers increased the content of > 250 μm water stable aggregate (WSA) significantly (P<0.05),but decreased the clay dispersion rate (CDR).Correlation analysis showed that WSA was significantly (P<0.01 or P<0.05) and positively related to the determined organic fractions,and positively related to LFOC,POC and MBC,with the correlation coefficient r=0.87^**,0.92^** and 0.84^**,respectively.There were significantly negative correlations of clay dispersed rate (CDR) to TOC,POC and LFOC,with r=-0.70^*,-0.78^* and -0.73^*,respectively.

Key words: Forage rye, Tillering dynamics, Accumulated temperature, Planting density, Equal design method

CLC Number:

S158.3

YANG Changming, OUYANG Zhu, DONG Yuhong . Organic carbon fractions and aggregate stability in aquatic soil under different fertilization[J]. cje, 2005, (8): 887-892.

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