By John Clarke
The 2016 Climate Change Projections for NZ predict that the eastern half of Northland will experience hotter, drier summers with less winter rain and frosts. Droughts will become more common, as will extreme weather events. Relative humidity will decrease and evapotranspiration will increase. I believe that planning our landscapes to meet these changes will increase our chances of successfully localising our food supply.
Recently there has been interest in developing a tropical fruit industry in Northland. I suggest that by adopting mixed plantings of alley crops on contour with appropriate soil building techniques (such as the Yeoman’s plough on contour), water harvesting techniques (such as swales and vetiver grass), and minimisation of soil cultivation through direct reseeding, I believe that we can reduce risks while maximising production, minimising input costs, maximising soil water absorption, minimising evapotranspiration, and reduce stress on aquifers (from pollution and overuse).
For instance, monoculture banana plantations are decimated by extreme weather events. The world’s main banana crop, the Cavendish, is under threat from the Panama disease fungus which already exists in Australia and there is no known treatment. Therefore, developing a banana monoculture industry would seem high risk. An alternative would be to form landscapes that maximise water collection at swales and on-farm dams (whenever we resort to aquifers for irrigating, we engage in an ultimately unsustainable agriculture). Landscape resilience could be increased by alley cropping a mixture of bananas on contour with an Alan Savory style livestock grazing system and further refine that with multi-species grazing. This would build soil organic matter rapidly and even more so with annual use of a Yeoman’s plough. Nutrient, microbe and water holding capacity of the soil could be enhanced by the addition of biochar and avoidance of soil cultivation.
To increase the protection of the banana crops to strong winds and evapotranspiration, alternate alleys could be planted with trees crops, and banana alleys could be interspersed with nitrogen fixing trees such as honey locust. The bananas (which would ideally be planted in the damper ground below swales) could be planted with taro, and probably within 5 years, with ginger and turmeric.
A mixed cropping landscape would increase food security by better enabling a yield in years of extreme weather.
The photograph of Mike Shepherd’s New Forest Farm below, is an example of the way a farm can be designed to withstand climate change and extreme weather while providing a wide range of yields.