Mitigation and best practice options

Simple steps to minimise the effects on water quality and mahinga kai.

Here are some simple steps to minimise the effects on water quality and mahinga kai.

Reduce leaching

Nutrient losses, especially leaching of nitrates from soils in winter, can be reduced by up to 50% by reducing cultivation and changing the time of cultivation. Cover crops grown over winter will prevent excessive leaching when rainfall is high. Avoid leaving pasture that is ploughed in autumn to lie fallow over winter.

Increase soil organic matter

Employ measures to build up soil organic matter content in the cultivated layer by adding bulky, organic material, retaining crop residues, or using green manures. Altering crop rotations to give a higher proportion of crops that require little tillage and, in particular, using a grass crop or pasture in rotation will help improve soil's organic content.

Maintain soil structure

Cultivating at the correct moisture content allows for adequate decomposition of the pasture/crop residues before planting the next crop. On continuously cropped soils, stubble can be mulched after harvest and left on the paddock if it is to be direct-drilled the next season. If it is to be cultivated, mulched stubble can be incorporated into topsoil, in the course of cultivation. Partial ground cover of mulch protects soil from being lifted by wind or runoff until the new crop emerges.

Minimise tillage

Avoid excessive tillage and don’t plough too deep. Minimise the number of cultivations and avoid cultivating when the soil is wet. Reduce the number of cultivation passes before sowing to reduce topsoil loss, erosion and fertility depletion. Consider direct drilling and time of cultivation.

Fencing of waterways

Maintain a riparian buffer or vegetated strip adjacent to waterways and don’t cultivate land right to the water's edge. Add fish-friendly culverts and/or build bridges where there is a requirement to cross waterways.