White clover content and grassland productivity in simulated grazing systems

Maintaining white clover (Trifolium repens) content in grasslands is a challenge for high output ecoefficient dairy farms on mineral soils that use biological N-fixation as a relevant source of N-input. Lower cutting height and cutting at an early growth stage have positive effects on the white clover content in grass-clover mixtures in mowing systems. Our objective was to quantify the effect of three grazing systems (rotational, continuous and lenient strip stocking) on clover content and dry matter production. Grazing was simulated with a Haldrup grass harvester and dried cattle manure pellets were applied to resemble the organic matter input from grazing cattle (50 kg N ha^‑1 yr^‑1). The experiment was established on sandy soil in 2011 in four replicates in sown grass-clover. Average clover content measured in June and October 2014 was lowest for lenient strip stocking and highest for continuous stocking. This resulted in 2014 in the highest grassland dry matter production for continuous stocking (15.0 Mg DM ha^‑1) and the lowest for lenient strip stocking (6.9 Mg dry matter (DM) ha^‑1). Rotational stocking occupied an intermediate position (11.9 Mg DM ha^‑1).