The influence of long - term fertilization on the lucerne forage quality

Forage quality of alfalfa (Medicago sativa L.) is essential in relation to animal feeding. The increase of available nutrients in the soil by fertilization is one of the ways to influence it. The aim of this thesis was to evaluate the impact of long-term fertilization on the quality and the stand structure of alfalfa. The long - term experiment with fertilization was established in 1955 at the Research Institute of Crop Production in Prague - Ruzyně. The experiment with alfalfa stand was established in the spring of 2013, as undersowing alfalfa in spring barley. Six different variants of fertilization were evaluated: an organic or mineral unfertilized variant (control variant); the mineral fertilized variants with low and high doses of N - P - K; a variant fertilized only with manure and the variants fertilized with manure and a combination of low and high doses of N - P - K. The forage samples were taken from the first cut in 2015, in four replications, and the number of plants/m2 (R / m2), the number of stems/m2 (L/m2) and the maximum stem length (MSL) was determined. The mass percentage of leaves was determined in the ten longest stems. The crude protein content (CP), the content of neutral detergent fiber (NDF) and neutral detergent fiber digestibility (NDFD) were determined in the samples. The mineral fertilization significantly influenced the stand structure, while the increasing doses of mineral fertilizers decreased the number of plants/m2. The number of stems/m2 was not clearly influenced even by one type of fertilization. The maximum length of stems increased with the mineral fertilization. Although the yield on the monitored plots was not affected by the fertilization, there is shown an increasing trend with increasing doses of the mineral fertilizers, as it is positively correlated with the length of stems. The mass fraction of leaves was reduced by mineral fertilization. The organic fertilization increased the CP content in the leaves, while fertilization with mineral nitrogen showed a tendency to decrease the CP content in the forage. The content of NDF and NDFD of forage is increasing with the organic fertilizers. High doses of mineral fertilizers have a negative effect on NDFD in alfalfa stems, while in the leaves N - P - K fertilization has a positive effect on NDFD. The combinations of organic and mineral fertilizers, culminating with the higher dose of N - P - K has a positive effect on NDFD. The effect of the long - term fertilization on forage quality can manifest differently in the leaves and stems of legumes. Therefore, it is advisable to monitor the quality of these parts separately. The mineral fertilizers significantly affects the stand structure and increases yield, which has rather a negative effect on the quality. The organic fertilization does not substantially increase yields, but it improves forage quality, especially the digestibility