Soil Flipping Pays

Dairy farmers near Westport have made remarkable gains by “flipping” their soils.

The process was started about 12 years ago by a farmer who was fed up with his cows up to their udders in mud. It involves digging into the sandy subsoil, breaking open the impervious iron pans that are typical features of these soils, and mixing in the peaty topsoil.

The soil isn’t actually inverted (flipped), but mixes the topsoil and subsoil sand, and the resulting soil mixture is a whole lot easier to use for dairy pastures.

Dr Craig Ross of Landcare Research and Richard Reynolds of Agriculture NZ, Greymouth, have been evaluating soil flipping on dairy farms at Cape Foulwind, near Westport. Dr Ross says that several farmers have “flipped” Pakihi soils in this particular area, using hydraulic excavators to aerate the poorly drained soils.

Flipping, topdressing and pasture resowing can double dairy cow carrying capacity and the cost is paid back within two years. The down-side to the process is loss of soil fertility, so high fertiliser rates are needed initially.

Farmers are applying 5-7 tonnes/ha of lime, a tonne of superphosphate and at least 100 kg/ha of urea at resowing, plus additional 500 kg/ha superphosphate, 600 kg/ha potassic sulphur superphosphate in three dressings, and up to six applications of 100 kg/ha urea in the first year after flipping.

By removing the main impediment – the iron pans – from these Pakihi soils, the farmers can look forward to much better drainage, according to Dr Ross. Water infiltration increases, on average, from 4 mm/hour on the untreated soil to over 50 mm/hour after 3 years on flipped soils – a much better rate to handle – even the West Coast rainfalls.

16th April 2003
Source: Dr Deric Charlton