The effect of fertilisation on the nutritive value of forage from the permanent Karst meadow. 2. concentrations of macro- and microelements

Abstract

A long term fertilizer experiment was designed in 1983 as a randomized block design in four repetitions. In 1994 forage samples were collected on unfertilised variant (0), variant fertilised with phosphorous and potassium (PK) and variant fertilised with phosphorous, potassium and nitrogen (NPK). Samples from the first, second and third cut were separated to grasses, legumes and forbs in which the concentrations of Ca, P, Mg, K, Na, Zn, Mn, Fe, in Cu were determined separately. Based on proportions of single botanical groups (grasses, legumes and forbs) the concentrations of elements in forage were calculated. Concentrations of the majority of elements in grasses, legumes and forbs of all three cuts were significantly affected by fertilisation. PK fertilisation reduced the concentrations of Mg and Mn and increased the concentration of P and K in forage. Compared to the unfertilised variant (0), NPK fertilisation reduced the concentration of Fe and increased the concentrations of P, K and Zn. Nitrogen fertilisation (NPK vs. PK) significantly increased the concentrations of P, Mg, Zn and Mn and reduced the concentration of Ca. With the exception of Cu, the concentration of all minerals analysed was significantly affected by consecutive cut. The concentrations of Ca, Mg and Mn were in second- and third-cut forage higher than in the first-cut forage. The highest concentrations of P and Zn were recorded in third-cut forage. Legumes and forbs contained two to three times more Ca, Mg, Zn and Cu than grasses. Therefore, the concentrations of these elements in forage were affected markedly by botanical composition of the sward. With respect to the requirements of dairy cows in lactation a large deficit of Na, Zn and Cu was observed while P was deficient only in forage from unfertilised variant.