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Ameliorating dense clay subsoils to increase the yield of rain-fed crops


Sale, P and Tavakkoli, E and Armstrong, R and Wilhelm, N and Tang, C and Desbiolles, J and Malcolm, B and O'Leary, G and Dean, G and Davenport, D and Henty, S and Hart, M, Ameliorating dense clay subsoils to increase the yield of rain-fed crops, Advances in Agronomy, 165 pp. 249-300. ISSN 0065-2113 (2021) [Refereed Article]

Copyright Statement

Copyright 2021 Elsevier Inc

DOI: doi:10.1016/bs.agron.2020.08.003


The yield of rain-fed crops needs to increase to meet the requirements of a growing human population. One way to achieve this is to store more rain in the root zone of soils and increase its use by crops. This will be difficult where poorly structured, dense clay subsoils occur. These subsoils limit crop yields by reducing root growth, and the uptake of soil water and nutrients. Reduced root growth results from physical factors, such as low porosity restricting the movement of air and water, high soil strength and temporal water logging which impedes the roots. Chemical factors such as alkalinity, salinity, and sodicity may further restrict root growth in neutral pH and alkaline clay subsoils.

This review will focus on the challenging task of improving structure in these dense clay subsoils and to overcome physicochemical constraints in the subsoil, in order to increase crop yields. Early attempts to ameliorate these subsoils using tillage practices, and amendments in some cases, were rarely successful. A more recent and successful approach has been to deep-band nutrient-rich organic amendments in the subsoil, and to follow with a field crop. This increased root growth in the subsoil, and was often associated with improved subsoil structure. It was able to produce substantial and prolonged increases in crop production. A key benefit was an increase in plant available water in the subsoil and the utilization of this water by the crop. The impact of the practice depends on the amount and distribution of rainfall, and this results in increased financial risk for the farm business. Specialized machinery will need to be developed to handle the amendments, while the form, rate of incorporation, and placement depth of amendments will need to be optimized to reduce high upfront costs of the practice.

Item Details

Item Type:Refereed Article
Keywords:crop yields, rain-fed crops, clay subsoils, soil structure
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Crop and pasture production
Research Field:Crop and pasture improvement (incl. selection and breeding)
Objective Division:Plant Production and Plant Primary Products
Objective Group:Other plant production and plant primary products
Objective Field:Other plant production and plant primary products not elsewhere classified
UTAS Author:Dean, G (Mr Geoffrey Dean)
ID Code:152693
Year Published:2021
Deposited By:Research Performance and Analysis
Deposited On:2022-08-23
Last Modified:2022-09-08

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