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Publication Date
1981
Description
Most soils in northeastern Victoria are acid, and problems commonly occur with lucerne (Medicago sativa) establishment and production. Aluminum and manganese have been recognized as major components of soil acidity. Liming to reduce exchangeable aluminum (Al) has been suggested as a rational approach to determining the lime requirements of lucerne growing in acid soils. This study was undertaken to clarify the relationship between soil acidity factors and lucerne growth and to provide a basis for liming recommendations in northeastern Victoria. The aim was: (1) to determine the effect of a range of rates of lime on establishment, production, and nutrient status oflucerne cv. Hunter River, and (2) to relate these parameters to changes of pH, Al, and available manganese (Mn) in the topsoil (0-15 cm) and subsoils. Three field experiments were established on the acid granitic soils of the Strathbogie ranges, where average rainfall is approximately 900 mm, with the major incidence in winter-spring. Each experiment was a replicated split-plot design with three main plots treated with ground agricultural limestone (80% CaCOa) drilled with the seed and six subplots with broadcast agricultural limestone applied and incorporated two months prior to sowing. Average annual lucerne dry matter over 3 years ranged from 1.1 to 6.5 metric tons (t)/ha on the unlimed plots and from 5.1 to 9.8 t/ha on the plots limed at the heaviest rate. In the topsoil, Al was virtually eliminated by the highest rate of lime application but was largely unaffected in the subsoils. At the site where Al in the subsoil was higher than 1.0 meq/100 g, lucerne production was considerably lower than at the other sites. Levels of Mn were reduced in the topsoil by lime; however, lucerne seedlings at all sites showed symptoms of severe manganese toxicity. The severity of the symptoms decreased with increasing rates of application of lime. Under any treatment, levels of manganese in mature lucerne varied throughout the year but were reduced by lime additions.
In this series of experiments, the determination of Al alone in the topsoil was not sufficient to determine the lime requirements of lucerne. In these soils, manganese toxicity occurred in seedling and mature lucerne when Al had been eliminated in the topsoil. Reductions in lucerne yield also occurred as a result of high levels of Al in the subsoil, and these levels were not affected by surface applications of lime. Lucerne yield was highly correlated with Al in the topsoil and subsoil and Mn in the topsoil. The pH of the topsoil and subsoil was rejected as a significant contributor to yield in the stepwise regression model used to analyze these data.
Citation
Mahoney, G P.; Jones, H R.; and Hunter, J M., "Effect of Lime on Lucerne in Relation to Soil Acidity Factors" (1981). IGC Proceedings (1981-2023). 8.
(URL: https://uknowledge.uky.edu/igc/1981/section3/8)
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Effect of Lime on Lucerne in Relation to Soil Acidity Factors
Most soils in northeastern Victoria are acid, and problems commonly occur with lucerne (Medicago sativa) establishment and production. Aluminum and manganese have been recognized as major components of soil acidity. Liming to reduce exchangeable aluminum (Al) has been suggested as a rational approach to determining the lime requirements of lucerne growing in acid soils. This study was undertaken to clarify the relationship between soil acidity factors and lucerne growth and to provide a basis for liming recommendations in northeastern Victoria. The aim was: (1) to determine the effect of a range of rates of lime on establishment, production, and nutrient status oflucerne cv. Hunter River, and (2) to relate these parameters to changes of pH, Al, and available manganese (Mn) in the topsoil (0-15 cm) and subsoils. Three field experiments were established on the acid granitic soils of the Strathbogie ranges, where average rainfall is approximately 900 mm, with the major incidence in winter-spring. Each experiment was a replicated split-plot design with three main plots treated with ground agricultural limestone (80% CaCOa) drilled with the seed and six subplots with broadcast agricultural limestone applied and incorporated two months prior to sowing. Average annual lucerne dry matter over 3 years ranged from 1.1 to 6.5 metric tons (t)/ha on the unlimed plots and from 5.1 to 9.8 t/ha on the plots limed at the heaviest rate. In the topsoil, Al was virtually eliminated by the highest rate of lime application but was largely unaffected in the subsoils. At the site where Al in the subsoil was higher than 1.0 meq/100 g, lucerne production was considerably lower than at the other sites. Levels of Mn were reduced in the topsoil by lime; however, lucerne seedlings at all sites showed symptoms of severe manganese toxicity. The severity of the symptoms decreased with increasing rates of application of lime. Under any treatment, levels of manganese in mature lucerne varied throughout the year but were reduced by lime additions.
In this series of experiments, the determination of Al alone in the topsoil was not sufficient to determine the lime requirements of lucerne. In these soils, manganese toxicity occurred in seedling and mature lucerne when Al had been eliminated in the topsoil. Reductions in lucerne yield also occurred as a result of high levels of Al in the subsoil, and these levels were not affected by surface applications of lime. Lucerne yield was highly correlated with Al in the topsoil and subsoil and Mn in the topsoil. The pH of the topsoil and subsoil was rejected as a significant contributor to yield in the stepwise regression model used to analyze these data.
