Problems In Managing Big Lucerne Areas

Press, Volume CIV, Issue 30763, 29 May 1965, Page 9

Problems In Managing Big Lucerne Areas

Reviewing some of the management problems involved in handling large areas of lucerne on light land farms in the 20 to 30 inch rainfall belt. Professor J. D. Stewart, professor of farm management at Lincoln College, told the farmers’ conference last week that these were quite complex, but it was believed that there would be high rewards for the innovating farmer as he could achieve stocking levels of four-and-a-half ewes to the acre quite comfortably, five ewes with a little less comfort and even six was not beyond the imagination. Dr. Stewart recalled that at Ashley Dene under experimental conditions with optimal grazing management, 75001 b of dry matter to the

acre had been produced consistently from lucerne whereas 45001 b could be expected from a pasture under similar conditions. If the 75001 b of dry matter from the lucerne could be harvested and utilised it would represent a theoretical carrying capacity of more than five ewes to the acre.

On the basis of a graph showing the possible variation in spring and summer production from lucerne at Ashley Dene, Dr. Stewart noted that only in an extremely dry year did the potential productivity of lucerne fall short of that required by four and a half ewes. And if the ewes were weaned two to three weeks earlier even this discrepancy would disappear.

Looking into the amount of lucerne that the light land farmer might aim for, Dr. Stewart said that the present

view, which was at this stage a fairly arbitrary one. was that an area of more than 70 per cent could lead to an imbalance. The sowing of the whole farm to lucerne was likely to create a number of management problems. The first was the pro- ! vision of standing room, par Iticularly in a wet winter. Lucerne paddocks did not provide a good platform so that there could be problems with sheep’s feet and others as well. There might also be problems in spelling paddocks adequately in rotation so that they would approach their potential productivity. And there was the likelihood 'of a depression and a delay in lambing due to a high oestrogen intake where ewes were fed entirely on lucerne before tupping. Greatest efficiency in utilisation of pasture plants required that the maximum amount be grazed where they grew. Wherever it was necessary to transfer use from one season to another there was a loss in technical efficiency, and this applied particularly to lucerne which was made into hay. It could generally be reckoned that there was a loss of 30 per cent of feeding value, even when the hay was moderately good. A comparison of the costs of wintering ewes on turnips and lucerne hay. Dr. Stewart said, lent some weight to the view that a low cost feeding system on light land would put more emphasis on turnips than on lucerne hay, though it was still recognised that reserves of hay conserved in good seasons remained the buffer against droughty seasons.

With 70 to 80 per cent of the farm in lucerne and some of the remainder under cultivation Dr. Stewart said that August became a critical month, it could be met by later lambing. An early to mid-September lambing would be more compatible with the pattern of production of lucerne, and since lucerne would grow on in November and December the role of early lambing was not as vital as with conventional pastures. There was also scope for oversowing lucerne with greenfeed cereals and Italian ryegrass in the autumn to provide pre-lambing feed in August, and as it was felt that a fairly rapid renewal programme would be desirable on a lucerne farm this would provide the opportunity for greenfeed in the first year of a renewal programme followed by turnips. ■** Dr. Stewart said that if it was to be sure of making 40 to 50 bales of hay to the acre from lucerne closed after mid-November on light land it would be possible to proceed with confidence on a high stocking rate policy. It would be possible to synchronise lambing for mid-Septem-

ber, stock up to capacity of September. October and early November production, draft and wean at eight to 10 weeks, tighten up the ewes and use late November, December and January production for lamb fattening and hay production. But it was rarely that it was possible to be assured of a reasonable cut of hay from lucerne closed in early November. Hay making was therefore a direct competitor with ewe carrying in the spring and early summer. It was, however, clear that there was scope for a stocking rate which was aimed at utilising a high proportion of the average lucerne production as it stood in the paddock, conserving hay from the surplus in good years and adjusting stock management in poor years. This implied a reliance on turnips as the basis of winter feeding, with hay providing the flexibility and balance of nutrition which was needed to supplement the turnips. . It was clear from work done by Mr C. E. Iversen, reader in agronomy at the college, that lucerne needed to be periodically and systematically spelled to get the most out of it, and past trials had shown that lamb growth rate was retarded by rotational grazing under moderate stocking rates. They were not certain, however, that this would be the case under high stocking rates on lucerne. Lucerne was able to provide for the increase in body-weight of ewes required in February and March, but there was the possibility of a depression of lambing performance due to the presence of oestrogens. This could be accepted as part of the cost of high lucerne farming to be measured against the benefits; or a special purpose flushing feed could be provided to avoid the oestrogen intake and allow the lucerne to be spelled and subsequenth ration grazed in the late autumn. Such a flushing croj was York Globe turnips sowr in November and fed in Fer ruary-March. The risks o. dessication were, of course quite high and it might be that such a policy would b( more likely to succeed when the rainfall was from 30 to 3. r inches than where it was from 25 to 30 inches. Answering a question, Dr Stewart said the Departmeni of Agriculture believed that there were some areas of MidCanterbury where lucerne did not establish and do satisfactorily., There seemed to be a line "above which lucerne did not do so well but below which it did well. When Dr. Stewart referred an inquiry about lucerne in irrigation pastures to Mr W. R. Lobb, superintendent of of the Winchmore irrigation research station, Mr Lobb said that under optimal treatment lucerne under irrigation produced half as much again as from conventional pastures.