Development of legumes after reseeding in permanent grassland, as affected by nitrogen fertilizer applications

Abstract

Legumes in grassland can increase locally grown protein in fodder while reducing the nitrogen (N)‐fertilizer requirements. Although the benefits of forage legumes are known, there was a decline in their use in the past due to inexpensive N‐fertilizer, soya products from abroad, and variable legume persistence. In recent years, mounting environmental concern has sparked new interest in legumes. To quantify the effect of legume reseeding and N‐application on permanent grassland on crude protein (CP) and dry matter yield (DM), a multifactorial trial was set up. Factors considered were clover species (red clover, white clover), N‐application rate (0–170 kg N ha−1), N‐ fertilizer type (mineral‐N, organic‐N), and cutting management (3, 5‐cut). Legume percentages were scored, and DM‐ and CP‐yield was measured for three years. Crude‐protein gains after legume reseeding were considerable and between 2.5–3.4 after red clover and 0.4–1.7 t CP ha−1 3 years−1 after white clover‐reseeding even when compared to the control‐high‐N treatment. Legume percentages were negatively correlated to N‐rates down to rates as low as 42 or 85 kg N ha−1 for a three‐ or five-cut management, respectively. Nitrogen‐applications increased the yield (DM, CP) of control plots, whereas for legume‐reseeded plots yield remained unchanged or was reduced. Differences due to N‐fertilizer type were small or non‐existent. Reseeding of clover was shown to be a viable method to increase crude protein in permanent grassland for about three years (red clover) and possibly beyond (white clover).