Surface runoff on farms up to 5 times higher when hill soils are poorly drained

Embargoed until: Publicly released: 2022-06-21 03:00

New Zealand

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Hill country farms cover more than 60% of NZ's farm landmass, but the sloping landscapes they're on means that when it rains, the surface runoff can move sediment and nutrients like nitrogen and phosphorus into streams and lakes, too much of which leads to declining water quality. Kiwi researchers compared nutrient and sediment losses in surface runoff when cattle were fed winter hay supplement on two hill country sub-catchments that had different kinds of soil. The catchment with poorly-drained soil had nearly five times more surface runoff - and 4.5 times more total nitrogen - than the area with well-drained soil. The authors say carefully choosing where cattle are fed in winter, such as in areas with better-drained soil, could reduce nutrient and sediment loss at no cost to farmers.