Irrigation hopes for light land

Press, 9 November 1984, Page 18

Irrigation hopes for light land

Farmers on poor producing, light, stony soils can take heart from new results in irrigation research. Trials run by the Templeton research station of the M.A.F. have shown that under adequate irrigation, some light, stony soils will produce as much pasture as many irrigated, deep, stonefree soils.

Presenting a paper on this research at the Grassland Association’s annual conference in Timaru Mr John Hayman, a scientist at Templeton said irrigation not only reduced the variation in pasture production between seasons but also reduced the variation between soils. In two series of trials, covering 12 Canterbury soils and eight seasons, irrigated pasture production was similar on eight soils. These eight soils included a stone-free Wakanui clayloam, a Chertsey silt-loam, both stony and stone-free S silt-loam, stony ore and a very stony Balmoral silt-loam at Culverden.

Two very stony soils - a Lismore and a Ruapuna - failed to match the others, while a deep, well-drained Wakanui clay-loam and a

Chertsey silt-loam were superior. These trials also compared pasture and lucerne production, with and without irrigation.

Reporting on the results, Mr Hayman said that in average and high rainfall years, lucerne lived up to its reputation of producing more herbage than pasture in the absence of irrigation. However, in two exceptional years (1981-82, 198283) when the drought began in spring, lucerne produced less than pasture. Under irrigation, lucerne out-produced pasture on the same site for 2 to 3 years, but by the fifth year its yield was less than pasture. Trial results also gave some guidelines to farmers facing restrictions in summer water supplies for irrigation border-dyked pasture.

The results indicated that maximum pasture production on farms in this situation would most likely be obtained by spreading the water over all border-dyked pasture, even if this meant extending the irrigation interval to up to 28 days on low. water-holding capacity soils and up to 34 days on deep soils.