Jamal Howes

Doctor of Philosophy, (Soil Science)
Study Completed: 2019
College of Sciences


Thesis Title
Targeted Duration Controlled Grazing – The Effects of Timing of Grazing on Nitrate Leaching and Treading Damage

Nitrogen (N) leaching and treading damage to soils and pasture are two major challenges facing New Zealand dairy farmers. Duration controlled (DC) grazing can be used to mitigate these problems but there are a number of questions related to DC grazing management. Mr Howes used a targeted form of DC grazing to reduce N leaching from pasture grazed by dairy cows. He identified the critical soil moisture content that farmers on fine textured soils can use to schedule grazings that avoid pasture and soil damage. He found that grazing very wet soils for four hours resulted in relatively small reductions in annual pasture growth. However, this damage can reduce grass growth in early lactation. This research demonstrated that the need to occasionally graze wet soils in order to maintain pasture quality does not undermine the overall advantages of the DC system.

Professor David Horne
Professor Michael Hedley
Dr James Hanly