Soil structure: its importance to resilient pastures in New Zealand (review)

Soil structure is critical to soil quality due to its influence on many soil processes and functions, including water storage and transport, the oxygen supply, the emission of greenhouse gases, and biological processes such as carbon and nitrogen mineralisation, nitrification and denitrification. These soil functions underpin key ecosystem services such as pasture production, nutrient cycling and mitigation of contaminant losses to receiving waters. The paper discusses key soil physical indicators relevant to pasture performance and the environment, including soil porosity, bulk density and hydraulic conductivity. In regions with robust programs for monitoring soil quality, e.g., Waikato, Canterbury, Auckland, Marlborough and Wellington, soil compaction is found to be widespread under pastoral land-use. The specific consequences of degraded soil quality on pasture production and financial implications remain unclear, at farm, regional and national levels. The range of impacts of soil structural damage on pasture yield, persistence, farm system response, and management practices that minimise or repair damage are presented. Knowledge gaps and further research needs are also summarised.