Apsoil

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ARTICLE IN PRESS
Applied Soil Ecology xxx (2010) xxx–xxx

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Applied Soil Ecology
journal homepage: www.elsevier.com/locate/apsoil

Soil organic carbon, nutrients and relevant enzyme activities in particle-size fractions under conservational versus traditional agricultural management
Shuping Qin a,b ,Chunsheng Hu a,∗ , Xinhua He c , Wenxu Dong a , Junfang Cui a,b , Ying Wang a,b
a Key Laboratory of Agricultural Water Resources, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, The Chinese Academy of Sciences, 286 Huaizhong Road, Shijiazhuang, Hebei 050021, China b Graduate University of the Chinese Academy of Sciences, Beijing 100049, China c NorthernResearch Station, USDA Forest Service, Houghton, MI 49931, USA

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Micro-scale investigation is helpful for better understanding of the relationships between organic matter, microorganisms and nutrients in soil, and for better interpretation of modifications induced by soil management. The soil particle-size fractions (2000–200, 200–63, 63–2, and 2–0.1 m),contents of soil organic carbon (SOC), total N (STN), available P (SAP), dissolved organic C (DOC), light fraction organic C (LOC), microbial biomass N (MBN), basal respiration (SBR), and relevant enzyme activities of C, N and P transformations, such as -glucosidase ( -G), N-acetyl- -glucosaminidase (N-G), protease, urease and alkaline phosphomonoesterase (APH) were analyzed to study the effects of8-year-period conservational (no-till with residue retention) (CAM) versus traditional agricultural management (moldboard plowing without residue retention) (TAM) to a Haplic Cambisol soil in the North China Plain (NCP). Our results showed that CAM significantly enlarged the stocks of SOC, DOC, LOC, STN and SAP in the 0–10 cm layer, increased the contents of SOC, STN and SAP in the sand fractions,and promoted all of the enzyme activities in the bulk soil and all of the four particle-size fractions. Our results suggested that CAM increased the nutrient contents in the sand fractions by both enlarging the content of particulate organic matter and enhancing the activities of enzymes involved in nutrient cycling in these fractions. On the contrary, the contents of SOC and nutrients in the siltand clay fractions were relatively resistant to the conversion from CAM to TAM, indicating the limitation of CAM for stable SOC sequestration. © 2010 Elsevier B.V. All rights reserved.

Article history: Received 3 November 2009 Received in revised form 14 March 2010 Accepted 16 March 2010 Keywords: Conservational agriculture Particle-size fractions Soil enzyme activities Soil nitrogen andphosphorus Soil organic carbon

1. Introduction Traditional agricultural management (moldboard plowing without residue retention) (TAM) is dominant in the North China Plain (NCP), an intensive agriculture area with 320,000 km2 and over 200 million population. This agricultural strategy has resulted in serious environmental problems, such as groundwater contamination (Hu et al., 2006) and soil organiccarbon (SOC) loss in the NCP (Wang et al., 2007). Conservational agricultural management (notill with residue retention) (CAM) has recently been expanded in the NCP to increase crop yields whilst reducing soil erosion and environmental degradation (Wang et al., 2007), compared with TAM. Tillage and residue management play an important role in SOC turnover, aggregate formation and microbialabundance in soil (Lagomarsino et al., 2009). No-till and crop residue retention tend to decrease the turnover rate of macro-aggregate (Six et al., 2000),

∗ Corresponding author. Tel.: +86 311 85814360, fax: +86 311 88150953. E-mail address: meimei841114@163.com (C. Hu). 0929-1393/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.apsoil.2010.03.007

resulting in SOC...