Focus on cleaner water
I have been fortunate to chair the Doubtless Bay Catchment Group (DBCG) over the last two years. Much work had been done before then, but this year we finalised the DB Catchment Plan, which identifies the water quality issues and lists a range of regulatory and nonregulatory methods to achieve the improvements listed in the plan.
Two non-regulatory approaches promote the use of natural fertilisers and improved soil health to reduce sediment discharges and nutrient losses to water.
The group wants to trial biological fertilisers to increase biological soil activity, to reduce overland erosion and nutrient leaching on gently sloping pastures, currently managed with conventional fertiliser, and commissioned a report from Landcare Research to investigate the impact of this.
An earlier Niwa study into the Mangōnui Harbour sediment sources showed that sediment generated from pasture dominated samples in five of 19 sub-catchments. The hypothesis was that biological fertilisers, particularly slow-release rock dusts, will increase root growth, increase beneficial microorganisms, and decrease nutrient leaching and surficial erosion.
We were delighted when the report confirmed this, cementing this approach with sound research into the toolkit available to farmers and other land users to better protect their land, water and bottom line.
Soil science is incredibly complex, as is the way by which a plant can uptake nutrients. A cubic inch of healthy soil is home to more than a billion micro-organisms, and some synthetic fertilisers can diminish this microscopic community that is so essential for plant and animal health. Natural fertilisers, on the other hand, improve soil structure, increase root depth and mass, which makes the plant more drought-resistant and provides better nutrition for stock.
Building organic matter in soil increases its water-holding capacity and decreases nutrient leaching to waterways. Plants also benefit by the increase in mycorrhizal fungi, which can boost roots’ reach by up to 700 per cent, which can release previously unavailable phosphorus to the plant.
It is important to note that erosion and leaching reduction on pastures cannot be achieved just by changing the type of fertiliser. Farm plans look at additional erosion measures like riparian plantings and fencing, along with a raft of other measures. The NRC has boosted its farm planning staff to increase support to farmers across the region. If you are a farmer, please consider using this free service.
Hill country farmers face additional erosion issues, which can be also addressed and supported by farm plans. Farm forestry, be it exotic, indigenous or a mix, is currently getting lots of support from both local and central government, and now is the perfect time to investigate how to profitably incorporate it into a sustainable farm management plant. If you would like a copy of the Landcare Research report please email me.
"Building organic matter in soil increases its waterholding capacity and decreases nutrient leaching to waterways."