Growing Futures

Balancing the costs of burning

Balancing the costs of burning

Burning stubble provides benefits for crop rotation

One of the decisions cereal crop farmers need to make when preparing to establish the next crop, is what to do with the remnants of the old crop, or stubble, in the field. Burning the stubble is a traditional solution but when clean air is also a priority, is it still the best option?

When a grain crop is harvested, the straw residue that remains in the field is about the same as the amount of grain produced. New Zealand’s high crop yield - on average up to nine tonnes of wheat per hectare compared with three tonnes from low-rainfall Australian wheatfields, for example - leaves a very thick carpet of stubble, which makes it harder for farmers to establish crops with small seeds, like grass or clover, in these fields.

Research has identified that banning stubble-burning would increase the need for molluscicides (such as treatments for slugs and snails) and herbicides, which could increase resistance. It would also increase costs for tillage, particularly ploughing, which could negatively affect soil structure.

Over seven criteria, stubble burning ranked highest for establishing small seed crops in rotation, reducing production costs, enhancing productivity, and reducing pest and disease pressure. The net annual value of stubble-burning was calculated at $4.8 million annually.

The analysis provided evidence for Environment Canterbury’s decision to retain stubble-burning as an option for farmers under the proposed Canterbury Air Regional Plan.

The stubble burning expert review was commissioned by Environment Canterbury and led by the Foundation for Arable Research (FAR).

Created: September 2017

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