Plant density in red clover (Trifolium pratense L.) pastures as an early predictor of forage production

Abstract

Red clover (Trifolium pratense L.) is an alternative of great potential productivity for dairy systems, particularly in heavily compacted soils. Plant density (PD) during pasture establishment can be related to forage production and used as an early indicator of pasture quality. However, biomass predictive models for red clover are not readily available. To predict red clover biomass a few weeks after sowing would help farmers to adopt suitable management practices. The aim of this paper has therefore been to model the relationship between red clover biomass and PD at different time points during pasture establishment to identify the best monitoring moment for estimating future herbage productivity. A multi-environment trial, including several seeding rates simulating different levels of establishment within each of the nine environments, was conducted in Uruguay. Seedlings were counted 3, 7 and 12 weeks after sowing (WS). Biomass of first-cut (C1) harvest was linearly related to PD at 7 WS, whereas a second-order polynomial on PD at 7 WS was a significant predictor of accumulated biomass one (Y1) and two (Y2) years after sowing. PD at 3 WS was a strong predictor of biomass only in high-yielding environments. In such environments, more than 64 plants m−2 at 3 WS suggest a high probability of achieving annual yields above 10,000 kg DM ha-1. Therefore, early PD determination (3 or 7 WS) is a good indicator of annual productivity in pure red clover pastures.