Performance of Nui ryegrass

Press, 20 April 1979, Page 6

Performance of Nui ryegrass

Under a high level of irrigation Grasslands Nui perennial ryegrass has outyielded Grasslands Ruanui by about 10 per cent in dry matter production at Winchmore irrigation research station, according to Mr J. M. (John) Hayman, a scientist at the station. And the indications are that this season the margin in favour of Nui will be greater still. This season production from Nui has already exceeded '14,000 kg of dry matter per ha and there will be one more cut before the end of the year at the end of May, whereas Ruanui has been running at about 12,000 kg.

Nui, which is a selection from an old perennial ryegrass pasture near Mangere, Auckland, has been in a grazing trial at Winchmore for the last three years at. three different levels of irrigation. It has been compared with Ruanui and also Grasslands Ariki.

To date, when given no. irrigation at all or under a low level of irrigation — such as when it is watered only when the soil moisture falls to wilting point — there has been no difference in production compared with

Ruanui. but the new grass has come into its own on an annual production basis when compared with Ruanui under a high level of irrigation, such as when water is applied at about 19 per cent soil moisture or when about half of the available soil moisture has been used. But Mr Hayman observes that the annual figures disguise some differences in seasonal production. Thus Nui tends to be superior in summer and particularly autumn production, but if anything it is slightly slower than Ruanui in the early spring. In the autumn of last year under dryland conditions where wet, mild conditions in the autumn followed a dry summer and early autumn the new grass responded particularly well to the autumn rains when they came.

A feature of the new grass that has emerged from the trials is that it competes vigorously with weeds and other grasses so that it forms a higher percentage of the sward. While Mr Hayman said it was difficult to say what the situation was as far as clovers in conbination with it were con-

cerned. there was good evidence that the proportion of these was less than with the other grasses.

. Nui seems to stand hard grazing well and there was some evidence that it needed this sort of treatment in the spring to prevent it going to seed. This could be a reflection of the fact that there was more ryegrass in the sward and that this was less palatable to stock than clovers and many of the weeds.

Mr Hayman said that they had attempted to measure liveweight gain on the different grasses running the same number of sheep and shifting them at the same time. In the spring where the stock were grazed laxly the liveweight gain on Nui was less than on Ruanui, but where the grazing pressure had been more severe there had been no difference. Again this might simply be a reflection of the ability' of stock to be more selective of the more palatable species under light grazing and so had eaten more of these species in the Ruanui pasture.

All of these observations, Mr Hayman emphasised, applied on Lismore

soils of only limited fertility, and the situation might be very different ini soil of better fertility.

The recommendation was that for farmers for whom autumn production! was of prime Nui would be a valuable grass, but if spring growth l was of prime importance Nui would not be superior to Ruanui.

Where a farmer did not want to take a seed crop from his pastures Mr Hayman said he would recommend sowing a mixed sward of the two varieties because the grass which suited the particular environment on a farm and the management that was applied to it would eventually dominate. He was sure that ryegrass pastures adapted to the sort of management that was applied to them. So the better the range of genetic material in the pasture the better the chance there was of developing a pasture that suited the environment and the management fac-i tors applying to a particular farm. Mr Hayman said that sowing rates as for other pastures would be quite adequate — about 20kg per ha together with white clover.

In cutting trials withi Pitau white clover no advantage over Huia had been found under theif conditions. It was in fact, however, bred for use in areas with a milder win* ter.

There were also two new cocksfoots from the Department of Scientific and Industrial Research which showed substantially greater production than Grasslands Apanui under a cutting system and these would have to be put into grazing trials to confirm whether the advantage was carried through under these conditions.