New nitrogen fertilisation experiments challenge the old yield responses of forage grasses in Finland

摘要

Nitrogen (N) is the most important nutrient in yield formation of grass. Finnish N fertilisation recommendations and restrictions are based on field experiments mainly conducted from 1960 - 1970 with cultivars and management practices common for thattime. The objective of this study was to update the yield response function of N to be better suited for modern grassland farming. Field experiments were conducted at two study sites in 2015 - 2017 with two modern cultivars of Phleumpratense L. and one cultivar of Festuca pratensis Huds. Development of DM yield, nutritive value and N balance were studied with eight N fertilisation levels (0, 150, 200, 250, 300, 350, 400 and 450 kg N ha~(-1) year~(-1)). The cultivars were harvested three times per seasonat the optimal stage for silage. The results indicate that the DM yield response is significantly stronger and N is used more efficiently for DM production than in the old experiments without compromising the nutritive value, especially during the firsttwo years. The average maximum DM yield was as much as 1.5 times higher than in the old research results. The results have significant implications for the production economy and perceptions of the environmental consequences of grassland production.