Comparison of Two Different Pasture Species Compositions for Recovery of Deep Soil Nitrogen during Winter

Surplus nitrate (NO3-) beneath animal urine patches is highly vulnerable to leaching, particularly during winter when soil drainage is often highest. Most common pastures in New Zealand (i.e. Lolium perenne) have relatively shallow root systems and produce low dry matter (DM) yields during winter months. Recent investigations suggest that alternative pasture species may be able to recover more soil nitrogen (N) during winter and consequently reduce NO3- leaching losses (Moir et al., 2013; Malcolm et al., 2014; 2015). However, further work is required to better understand the importance of root system architecture and plant growth of these alternative species during this cool period. The objective was to determine the ability of L. multiflorum (Italian ryegrass) and F. arundinacea (tall fescue)-based pastures to recover mineral-N from different soil depths under simulated winter conditions and determine the relative importance of plant growth/metabolic activity and root system architecture