PASTURE PROBLEMS

New Zealand Herald, Volume LXXII, Issue 22172, 27 July 1935, Page 22

PASTURE PROBLEMS

GJiA/JSd AMI SPELLING I ROTATIONAL SYSTEM | EFFECTS AND THEIR CAUSES ! M »««•}• A yri cultural CvUvgt- Bullet is} No. JJ. While different bjwiee and >■ trains of plants differ in the rapidity with which they recover after being defoliated it obvious that frequent and severe iivfuliklion is a series j faetor to production. 'J'lie reason for this is fairly obvious when it is remembered that the lea \e*. oi plant® aire a* e»i*Miti»J to their growth as vbc are,' The leaves may lie viewed as the ''Manufacturing: workshop* " <»i Ib< plant wherein Xature'a raw material# are convened., with ahe aid of sunlight, into the complex substances of which the plant consists and on v hich auimak feed. Removaj of the leaves means reduced ability to build up raw materials into plant material. Severe defoliation results, in the limitation i>i root development. *J his is clearly dunvn by iiivestiiiaiions carried out at the Jmjierial (.'heniical Industries I.tesuarch Station at Jealotts Hill in England. Five different pasture type* were subjected, one portion of each to severe defoliation and the other portion u> more lenient treatment. Defoliation was carried out either by cutting or by grazing. A i ter a season oi such treatment the root systems to a depth of si?: inches were examined, resulting in the finding that the less severely defoliated swards had an average. for the five types, of 63 per cent jijore roots by weight than the severely defoliated ones. Salient Points Hence the salient facts presented are: — 1 1; Pasture herbage up to three or four weeks of age is a highlynutritious food; <-/ close grazing limits the production of a pasture; (J) the more frequently pasture herbage is defoliated the lower its. production will be, becauH« reduction in leaf growth causes reduction in root development. Consequently, spelling of pasture to aliou a certain amount oi leafage to accumulate is essential to high production and tilling systematically involves a .system oi intermittent sjielbng and grazing, or w hat is commonly called rotational grazing, fact (1) indicates thai jiastures may be spelled for three to four weeks without appreciable loss in the nutritive value of the herbage. Fact (3) points definitely to the desirability of resting pastures for at least three or four weeks from the poinx of view oi increasing their productivity. Unfortunately, however, practical considerations set a limit to the length of spelling which can be adopted for grazed pastures. Where cattle are beam grazed it may be possible to allow about three-weekly resting periods ui the spring and early summer and still get efficient utilisation of the herbage produced. Disastrous Results

With, sheep, however, and especially in the Case of ewes and iambs, putting them on to a three-week spring-flush, would, under typical North Island conditions meet with disastrous results. Fouling of the pasture under heavy stocking and consequent poor utilisa tion would be certain, to say nothing of the effect on the stock themselves. Consequently, while long spelling jieriods are desirable from the point of view of greater production of herbage, the inability to utilise it efficiently would more than offset the advantages of such greater production.

Obviously an ideal system of rotational grazing from the point of view of maximum production of herbage is not necessarily the ideal from the point of view of the maximum returns from stock. It is obvious, too, that it is impossible to lay down hard and fast rules regarding spelling jieriods under rotational grazing. These, must necessarily vary from farm to farm and will be governed materially by seasonal and climatic conditions.

The position may he summed up as follows: Under a system of rotational grazing, pastures should be spelled as long as possible between grazings, consistent with .good utilisation by the stock. And keeping in mind fact C2) the necessity for providing supplementary feed in tJie form of hay, silage, roots, or green-feed crops is fully apparent, to obviate too close grazing during low leaf production jieriods. Knowledge of Conditions

Sound common-sense and a knowledge oi : local conditions are necessary as adjuncts to the most effective application of the principles embodied in good pasture-management. There are practically no dairy fanners at the present time who are not carrying out some form of rotational grazing. Unfortunately, however, this does not .necessarily mean that good management is being achieved. The evidence of overgrazing in the early spring—a critical time in the life of a pasture —and the prevalence of need heads and rough patches on pastures in the summer, hear testimony to abundant examples of had or indifferent management. Those who object to a more systematic rotational grazing on the score of the expense of subdivision should examine the possibilities of better management under existing subdivision. An example of how Mr. J. Spall, of Whakarongo, increased his production of butter-fat by more careful management was quoted by Mr. R. I'. Connell at the New Zealand Grasslands' Association Conference in 1931. Increased Production

In two years Mr. Spall, on a. 60-acre farm, increased his butter-fat production from 16Mb. an acre to 2101b. an acre without any change in his topdressing programme. The increase was due to systematic rotational grazing, which was assisted by an additional 12 chains of fencing. Stock was changed into a new paddock every day or every two days ho that over-grazing of pastures and punishment of stock were avoided and seed stalks and rough patches wen; kept down by the use of the mowing machine, resulting in the herbage being maintained in a leafy and digestible condition. Spellings between grazing* were in some cases as short as seven to eight days during rapid growth periods. In t)i is connection it, should be emphasised that the periods of spelling that should be adopted must be governed by the rate of growth of herbage. Harrowing to spread droppings was carried out two or three times a year. Although an ideal system of pasture utilisation entails close subdivision, good results can be achieved with from eight to 12 paddocks and it hoped that the fads presented will assist in a better understanding of the reasons for. (1) Keeping pasture in a leafy condition. 12) The advantages of resting periods between graaings. 13) The serums coimeijuenoflß of too severe and close grazing.