Effect of liming on phosphorus in two soils of different organic matter content: II Changes in the availability of phosphorus to turnip rape (Brassica campestris) 

Authors

• Helinä Hartikainen Department of Agricultural Chemistry, University of Helsinki, 00710 Helsinki 71

DOI: https://doi.org/10.23986/afsci.72135

Abstract

The effect of calcitic limestone treatments on the availability of P to turnip rape was studied with two acid mineral soils of pH 4.8 (CaCl2) in a pot experiment during two growing seasons. The soil reactions of a connected incubation test served to interpret the results obtained in the pot experiment. The experimental soils represented soil types of dissimilar responses to liming in regard to P availability. In the muddy fine sand (3 % of org. C), initially poor in easily soluble P, liming enhanced plant growth as well as P uptake in the second year. However, in spite of intensified P removal, the final content of water- soluble P in the limed soils was not lower than in the unlimed ones. This was assumed to demonstrate an augmented availability of P. Also in the fine sand soil (6.4 % of org. C), rich in water-soluble P, liming slightly improved growth of the second harvest in the pots not treated with P, but it did not affect P removal. In the pots amended with P, on the contrary, liming had no effect on the dry matter yields, but it tended to depress P withdrawal. Nevertheless, all the limed soils contained finally less water-soluble P than the unlimed ones, which suggests a diminished availability. The results of the pot experiment demonstrate that a relatively low soil pH does not necessarily limit growth of turnip rape, provided no nutrient deficiency or metal toxicity occurs.