Effects of Ca:Mg ratio and pH on soil chemical, physical and microbiological properties and grass N yield in drained peat soil
Joachim Deru, Nyncke J. Hoekstra, Maaike van Agtmaal, Jaap Bloem, R.G.M. de Goede, L. Brussaard, N.J.M. van Eekeren
Abstract
ABSTRACT In three dairy grasslands on peat, minerals were added to manipulate the soil Ca:Mg ratio with or without effect on pH. The responses of soil properties and grass N yield were measured. CaCO 3 application led to higher soil Ca:Mg ratio and pH KCl compared to the untreated control, decreased N total and C total , and increased P availability. Grass N yield increased in the first year by only 6% of the reduction in soil N total , but not in the second year. A higher pH increased SOM decomposition, especially in soils with high P availability. MgCO 3 reduced the Ca:Mg ratio, had little influence on soil parameters and no effect on grass N yield. In contrast, CaSO 4 and MgSO 4 did not influence pH KCl but reduced grass N yield in most cases. Results suggest stabilisation of organic matter by Ca binding in treatments with added Ca. We conclude that grass N yield was not linked with changes in Ca:Mg ratio but with soil pH. The pH effects on SOM decomposition depended on P availability and Ca binding. Hence, to avoid potentially large soil losses of C and N, the current agricultural advice on pH management in peat grasslands should be better adapted to local edaphic characteristics.