The nutritive value and yield of alfalfa in relation to phosphorus, potassium and magnesium fertilization on sulphur post‐mining lands

Abstract

The yield and nutritive value of alfalfa (Medicago sativa L.) cultivated together with grasses under conditions of various levels of P, K and Mg treatment were determined. The study was carried out on reclaimed, calcium carbonate‐rich soils of sulphur bore‐hole mine lands. The levels of basic nutrients, total sulphur and selected micro‐ and macro‐elements in the first cut of alfalfa were determined. The mean yields of green mass, dry matter (DMY), crude protein (CPY) and true protein (TPY) were significantly (P<0.001) positively correlated with P concentration in alfalfa. Any appreciable effect of K and Mg on yield was not found. The crude protein level in alfalfa was significantly correlated with Cu content (P < 0.01 ). The content NDF was positively correlated with P concentration and negatively with gross energy level in alfalfa (P<0.001). Then the P concentration was negatively correlated with Na, Mg and Cu assumulation and negatively with Zn content. Despite a high level of mineral treatment with PKMg deficiencies of these nutrients in alfalfa were found. An excessive accumulation of total sulphur was not detected despite a very high sulphate concentration in soil substrate. The treatment with phosphorous caused a significant decrease in the Ca: P ratio in alfalfa.