Pastures based on perennial ryegrass and white clover grow well on most fertile, drought-free soils in moderate climates, but the east coasts of the North and South islands tend to suffer from summer droughts, which affect the pastures. In these regions, legumes that grow during winter and early spring, such as subterranean clover, often produce more animal feed than white clover, which is more productive in summer.
Deep-rooted grasses such as tall fescue and cocksfoot tolerate drought better than perennial ryegrass, and so are more productive in these regions.
Drilling the soil
Most seeds are sown after the soil has been cultivated and a fine seed bed produced. Another method, called direct drilling, is to kill the previous pasture by spraying with herbicide and then sow the seeds into grooves in the soil made by a special drill. This helps conserve soil moisture.
The South Island’s inland high country has cold winters and summer droughts. Sowing native tussock grassland with clover seed and sulphur-superphosphate fertiliser can produce a striking change to a clover-dominant cover. This may persist for a few years, but if it is not well grazed during this time the clover will disappear and the pasture revert to its original condition, perhaps with some poorer grasses such as Yorkshire fog and browntop.
Tooth and hoof cultivation
On hill country, machinery cannot be used to cultivate the soil before sowing seed. One alternative is to graze the area with a large number of sheep or cattle, so that bare ground is exposed. The seed is sown into this seed bed and stock may be used to trample it in.
Western and southern South Island
The West Coast receives high rainfall levels (up to 6 metres annually) but is almost frost-free, so perennial ryegrass and timothy thrive under these conditions.
Grasses such as timothy, grazing brome and prairie grass grow well in the southern South Island, where summers are cool and moist, and winters are colder. Summer growth here is strong but winter growth is slow.