Reference bulk density and critical degree-of-compactness for no-till crop production in subtropical highly weathered soils.

Reichert, J. M., Suzuki, L. E. A. S., Reinert, D. J., Horn, Rainer and Hakansson, I. (2009) Reference bulk density and critical degree-of-compactness for no-till crop production in subtropical highly weathered soils. Soil & Tillage Research, 102 (2). pp. 242-254. DOI 10.1016/j.still.2008.07.002.

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The concept of degree of compactness (DC) referred to as field bulk density (BD) as a percentage of a reference bulk density (BDref), was developed to characterize compactness of soil frequently disturbed, but for undisturbed soil such as under no-tillage critical degree of compactness values have not been tested. The objective of this study was to compare methods to determine BDref and limits of DC and BD for plant growth under no-tillage in subtropical soils. Data from the literature and other databases were used to establish relationships between BD and clay or clay plus silt content, and between DC and macroporosity and yield of crops under no-tillage in subtropical Brazil. Data of BDref reached by the soil Proctor test on disturbed soil samples, by uniaxial compression with loads of 200 kPa on disturbed and undisturbed soil samples, and 400,800 and 1600 kPa on undisturbed soil samples, were used. Also, comparisons were made with critical bulk density based on the least limiting water range (BDc LLWR) and on observed root and/or yield restriction in the field (BDc Rest). Using vertical uniaxial compression with a load of 200 kPa on disturbed or undisturbed samples generates low BDref and high DC-values. The standard Proctor test generates higher BDref-values, which are similar to those in a uniaxial test with a load of 1600 kPa for soils with low clay content but lower for soils with high clay content. The BDc LLWR does not necessarily restrict root growth or crop yield under no-tillage, since field investigations led to higher BDc Rest-values. A uniaxial load greater than 800 kPa is promising to determine BDref for no-tillage soils. The BDref is highly correlated to the clay content and thus pedotransfer functions may be established to estimate the former based on the latter. Soil ecological properties are affected before compaction restricts plant growth and yield. The DC is an efficient parameter to identify soil compaction affecting crops. The effect of compaction on ecological properties must also be further considered. (C) 2008 Elsevier B.V. All rights reserved.

Document Type: Article
Keywords: soil compactiondirect drilling reference bulk density root and crop growth limiting water range african forestry soils physical-properties soybean yield arable soils systems susceptibility losses barley growth
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
Kiel University
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.still.2008.07.002
ISSN: 0167-1987
Projects: Future Ocean
Date Deposited: 11 Feb 2011 12:14
Last Modified: 29 Jul 2019 06:02

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