Importance of resilient pastures for New Zealand’s agricultural soil carbon stocks

Abstract

New Zealand’s agricultural pastures contain significant soil carbon (C) stocks that are susceptible to change when impacted by management and natural processes (e.g., climate). Inputs of C to these pastoral soils is through photosynthetic uptake of atmospheric CO2 either on-site or elsewhere. Changes in soil C stocks are in response to the management of the system that alters the input-output balance. Increasing the resilience of pastures to climatic events such as hot and dry summers or cool and wet winters can increase inputs of C to the soil while sustaining above-ground production and so provide an opportunity for C sequestration. Furthermore, increased pasture for grazing can reduce the need for management practices identified as detrimental for soil C stocks such as irrigation or the production of cropped supplemental feed. A reduction in the need for renewal and its associated soil C losses, and the establishment of a more diverse sward, especially if deeper-rooting species are included, has the potential for increasing soil C stocks provided the diversity can be maintained. From a soil C perspective, a resilient pasture maximises CO2 uptake to ensure adequate above- and below-ground inputs to maintain or increase soil C stocks and minimise the need for management activities detrimental to soil C.

Improving Human Diets and Welfare through Using Herbivore-Based Foods: 1. Human and Animal Perspectives

“…Associated with negative impacts of warmer, drier climate on pasture growth rates, the longevity of the traditional perennial ryegrass-white clover pasture type is also expected to decline resulting in higher rates of pasture replacement [156]. Indeed, the latter impact is already evident across the upper North Island of New Zealand [157] bringing higher costs of production but, importantly, also increased risk of nitrate leaching [158] and high rates of loss of soil C [159]. Adaptation will be required but the R&D response is lagging as pasture research now sits well down the list of Government and industry stakeholder priorities [160].…”

Organising Committee Chair's address: Resilient pastures

“…Soil physical (Houlbrooke et al 2021) and biological (Shi et al 2021) properties are significant contributors and require further attention. Whilst short-term annual or Italian ryegrasses can be used to, in effect, avoid the persistence problem, this strategy involves frequent soil disturbance and carries increased risk of soil organic matter depletion (Wall et al 2021) and therefore may not result in true resilience.…”