Grasses Play Their Part; But Management Counts Most

New Zealand Journal of Agriculture, Volume 62, Issue 2, 15 February 1941, Page 91

Grasses Play Their Part; But Management Counts Most

Continuing his article in the January issue, the author points out that while soil, climate and topographical

conditions must necessarily affect production, it will usually be found that the most important factor is management.

JUDICIOUS topdressing will do much to pave the way for the introduction and maintenance of ryegrass, but if ryegrass is effectively to replace much of the inferior grasses and rubbish found on second-rate dairying pastures, and if its remarkable capacity for production is to be fully exploited, then the system of grazing management to be followed must also be adapted to the special requirements of the ryegrass. It should be properly understood that throughout by far the greater part of the typical dairying land of New Zealand the type of pasture to be found on any field will in the long run depend mainly on management, and will owe but little either to good luck or to bad luck. Most of the dairying land is capable of carrying ryegrass, and if the management, like the fertility, is raised to the ryegrass standard, this will ultimately lead to a dominantly ryegrass type of pasture sward. Leaf Surface Affects Rate of Growth In the endeavour to encourage speedy growth, attention is very commonly confined to raising the soil fertility by topdressing, on the assumption that the food of the plant is obtained through the roots, and that the rate of growth is therefore entirely a matter of soil fertility. That the plant does obtain much of its food through the root system is obviously true, but it may ; surprise many to learn that more than half of the material ' comprising the dry weight of any plant is obtained

s’” ■■ ■ 11111111 ii By

P. S. SYME,

| Instructor in Agriculture, j i Warkworth. | iiiiiiiiimiiiiiitii iiiiimiiiiiiiiiiiiaii mini ■ ii?

not through its roots but through its leaves. Analysis shows that the chief dry matter constituent of plants is carbon. This carbon is obtained from the carbon dioxide in the atmosphere, and the capacity of a plant to absorb it is to some extent proportionate to the area of the leaf which it can present to the sunlight. This obviously means that each time a plant is . closely defoliated by grazing, normal growth ceases and cannot possibly . recommence until the plant is again able to expose a new leaf surface.

As the majority of grasses have been developed under natural grazing conditions, they have acquired also the ability to transfer food reserves from the roots to form new leaves. This, of course, weakens the root system, but the sacrifice enables the plant to make the. necessary • fresh growth of green leaf by which it can again absorb carbon and so recommence growth in the normal manner. It will be obvious, therefore, - that persistent close grazing which does not permit sufficient time for recuperation must exert a weakening effect on the plant; and when it is considered that repeated defoliation is, in essence, the very method commonly recommended for destroying many noxious weeds, it will be readily appreciated how quickly faulty grazing can cause deterioration even of the most vigor-

ous pasture. This also .helps to explain the baneful effects of persistent overstocking, and why this practice may actually reduce the rate of growth arid ■ lead to a vicious circle which penalises both stock and pasture. A consideration of the foregoing suggests that growth will be speeded up if the routine management of the pasture is designed to enable the plants to develop a fair amount of leaf surface between each successive grazing, If, in addition, the grazing can be rapidly performed and care is taken not to graze tod close, the weakening effect of the repeated defoliations on the root system over a period will be reduced to a minimum. Value of Rotational Grazing In actual farm practice these various requirements can be adequately met only by intensive subdivision and a system of rotational grazing. If properly planned, such a system provides for the necessary concentration of stock to permit of quick, even grazing and at the same time allows a suffi-

cient interval for recuperation between successive grazing periods. That, in this instance, theory has withstood the exacting test of actual field practice has been the general experience of the majority of those farmers who have gone in for intensive rotational grazing, and it can be definitely asserted that the adoption of

this system has been a major factor in the phenomenal increase in production shown in recent years on a wide variety of farms throughout the main dairying districts of New Zealand. Importance of Generous Food Reserve While stock may be depended on

to provide adequate control of pasture growth throughout the greater part of the year, the natural seasonal production is so ill-balanced during the flush periods as to necessitate the extensive use of the mower. As about twothirds' of the annual growth is normally produced in about one-third of the year, it is evident that a proper balance can be secured only by conserving a generous portion of this surplus for the hungry winter months when growth is at its lowest ebb. If the winter management of the pastures is to conduce to the build ing up of a high-producing ryegrass type of sward, an adequate reserve of supplementary feed is highly necessary to permit of lenient winter grazing. For this reason, every effort should be made to conserve the maximum practicable amount of surplus growth either as hay or silage. Fodder in this form, if properly protected, will keep, and even in the heyday of plenty it must not be forgotten that the weather over a period tends to average out normal, so that a season which is abnormally good is quite liable to be succeeded by one which is just abnormally bad. The effect of cutting for hay or silage, and the transfer of fertility involved when this is fed out, can have an important bearing on the composition of the sward, and this should be kept in mind when planning the general scheme of farm operations.

Topping Is Important As already mentioned,. large leaf surface has a bearing on the rate of plant growth. If allowed to grow beyond a certain stage and to produce seed, however, much harm may result. Nature abhors waste, and the ripening process involves the transfer of nutriment from the leaves and stems into the seeds, so that once a pasture has begun to seed the feed quickly becomes tough and fibrous and of lowered nutritive value.

Where paspalum is present in a ryewhite clover pasture, topping is sometimes of particular importance. Apart from the food wastage caused by seeding, rank paspalum is 'somewhat liable to exert a smothering effect on the clovers, and once the clovers are suppressed the fertility quickly falls below the ryegrass level. Although the paspalum itself can still survive, the lowering of the fertility is quickly reflected in the reduced yield, and the tendency is for the pasture to revert ultimately to an almost pure sward of sod-bound paspalum capable of giving only a rather moderate production through the summer and early autumn, and producing a negligible quantity of feed for the remainder of the year.. Under good management, however, considering its length of season and yield, the rye-white clover-paspalum association approaches the limits of perfection. It should be noted that topping aims at the prevention of seeding, and that once the seed heads have been allowed to develop, the plant makes little further growth, so that topping then loses much of its value. Winter Management Can Make or Mar a Sward Contrary to what one might expect, the treatment which a pasture receives during the dormant winter period has a very important bearing on its productive capacity. Correct management during the winter will work wonders with even a poo? sward, and faulty

management at this time will produce a rapid deterioration of even the most perfect sward. Mention has already been made of the importance of applying the autumn topdressing while the soil is still warm and conditions are still favourable for active growth. This on many farms is an unsuspected critical period, as there is a tendency to graze the pastures too hard because of a natural reluctance to break into the winter feed. Herein lies one of the main advantages of a generous reserve. Like money, supplementary feed should not be squandered, but also like money, it should not be hoarded. If properly utilised at this period, supplementary feeding can very advantageously reduce the drain on pastures and prevent the very serious over-grazing which results in the pastures being eaten down too close towards the end of the autumn. If grazed too close at this time, recovery is very slow, and the winter growth is almost negligible. If, however, a number of selected fields can be closed up while grow ing conditions are still favourable, this flying start enables the pasture to produce an appreciable quantity of valuable winter feed. In utilising this growth, rationing and the free use of hay will enable it to go a surprisingly long way, as the selected fields can each be used in rotation. The herbage should not be allowed to exceed about eight inches before grazing, and it should not be eaten down below about three inches, so that its recovery and subsequent growth should be as rapid as possible. In addition to providing considerably more winter growth, this lenient controlled grazing results in much quicker spring growth, and yields considerably earlier crops of silage or hay. Hard Winter Grazing Penalises the Ryegrass When a pasture is consistently hard grazed during the slow-growing winter months, it is only too obvious that the brunt of this will fall on the ryegrass. The poor ■< winter-growing species will be defoliated only once; grasses such as ryegrass, which do endeavour to make winter growth, will be persistently eaten down right through the winter, .and with low temperatures and limited sunlight retarding growth, little opportunity is afforded for recuperation; so that much of the growth which the : plant does make is made at the

expense of the root system. When a measure of relief comes in the spring, much of the ryegrass is already so enfeebled that it is in no condition to compete with weeds and winterdormant grasses, which, after their winter rest, can resume vigorous and aggressive growth. While hard winter grazing punishes the ryegrass, it definitely favours the white clover. Because of its prostrate habit, this clover withstands hard grazing well, and this, by preventing shading and weakening the competing ryegrass, rather tends to encourage white clover growth. For this reason, it is very often found that hard winter grazing combined with generous topdressing results in severe spring bloating. For this, the clover usually acts the, part of scapegoat, although, in strict justice, the winter management and the actual method of utilising the clovery sward should also carry their share of the blame. As lenient, spelled winter grazing tends to favour the ryegrass and hard winter grazing favours the clover, judicious planning of the winter management in this respect can do much to correct any ill-balance. With insufficient clover, the high fertility demanding grasses produce but poorly.

while too much clover may result in serious trouble from bloat. Where the clover is becoming too thick, this generally implies that the ryegrass element is becoming correspondingly thin. Because of the rapid increase in the supply of clover nitrogen, the consequent rise in fertility, assisted by a spell of lenient controlled grazing, quickly promotes vigorous grass growth and tends to restore the ryegrass dominance. Management Matters Most As farms in general tend to be as distinctly different and individualistic as their owners, it is impossible to prescribe any exact standard of management as suitable for universal application. The experience of many thousands of farmers, however, goes to show that, while soil, climate, and topographical conditions must necessarily affect production in a varying degree, in the long run it will usually be found that the most important factor of all is management. The farmer counts for more than the farm.

nikiiiiiiiiiiiiiii iiiinmi hi iiiiiiiimiiiiiiiiiniiiiiimiiii i nun iiiiiiiini i niiiiiiiimiiiimiiimiimiiiiillinU To Farmers’ Wives j and Daughters j Have you read our new Women’s j Section— “ The Good Neighbour,” | by Mary —at the. back of the | “ Journal ”? | Here are some of the items in this | month’s issue: Care of Silk Stockings, | Beauty Hints, Household Hints, Tasty | Recipes, Short Story and Competitions. I . ■ S __ ____.______. ; > , J