FARM EXTENSION SERVICE

Manawatu Standard, Volume L, Issue 195, 16 July 1930, Page 4

FARM EXTENSION SERVICE

“THE BEARING OF DRAINAGE ON GRASS FARMING.”

In general an important primary objective of tire farmer to-day is to induce grass to grow at a more rapid rate during the seasons when the rate of growth is relatively, low. The more the rate of grass growth is raised during periods naturally marked by slow growth, the more easy does it become. to carry stock through the critical seasons that are a source of-so much worry. During July, August and September, the rate of grass growth ordinarily is low, not so much because of low fertility but because of low temperature in the soil. It follows that the most effective way of inducing more rapid growth at this stage is often not the provision of more plant food but the provision of more soil warmth. Frequently, the best means towards improvement in warmth is improvement to drainage. The connection between soil warmth and soil drainage lies in the fact that the amount of heat absorbed in raising the temperature of a body of water to a certain extent would raise to an equal extent of five times that weight of dry soil. In other words, it takes much more heat to raise the temperature of water than that of dry soil. Hence the more water in soil in the spring, the colder will be that soil, and removal of excessive water by drainage will make a soil warmer and earlier in the .spring. Drainage, however, does much more than make a soil earlier’ in this direct fashion; it has a markedly beneficial effect on the influence of the herbage. "With improved drainage, weedy species such as spurrey, sedges, pennyroyal and buttercups become less prominent and replaced by more valuable species. Perennial ryegrass in particular, valuable because of its spring growth under favourable conditions, is very sensitive to' the soil moisture supply. It will not' persist under continuously saturated soil conditions, when soil drainage is poor, ryegrass is low in vigour; when the drainage is bad, the ryegress disappears. Provision of fertility by freely topdressing does not constitute a remedy. Fields/that have been ploughed in narrow “leads” in such a way that the “finishes” . give a certain amount of surface drainage sometime? well illustrate the influence of good drainage on the character of the vegetation. On the slightly raised crowns of the leads will be found at times vigorous ryegrass and clover; the lowest, most poorly drained portions, produce merely such species as Creeping Bent and Yorkshire, while in an intermediate position occur these inferior species together with ryegrass of low vigour and productivity. Further, better drainage fits pastures and other crops better to endure drought conditions. At first this may seem strange, but consideration will make it quite clear why it should be so. In general, the root system of our important crops will penetrate only into aerated soil, and in badly drained soil the air that would normally be

(Contributed by Fields Division and Plant Research Station.)

present is displaced by moisture. In such soil, the root system of a crop is restricted in its development to the surface. Heavy, badly-drained soils usually dry out completely and rapidly when drought occurs. Then the vegetation which they carry’ with its shallow root system i| in a precarious position, whereas on a well drained soil the roots enter to a greater depth and so the crops are much more drought resistant. Therefore, paradoxical as it may seem, drainage at. times counteracts drought. Only some of tire benefits coming from drainage have been mentioned, but they will suffice to indicate the great value of drainage in the production of grass as well as in. the production of other crops. In remarks founded on ill-formed or careless thought, it is often implied that while good drainage may be necessary in the production of annual and other special forage crops, such as lucerne, it is of little moment in the production of grass. The present tendency is to rely more, and ever more, on grassland, and in reality the more self-sufficing becomes our grassland the greater grows the urgency of proper drainage of that grassland. Hence, the farmer who hopes to depend, more and more on his grassland requires to give greater rather than less attention to proper drainage. This is well illustrated in the actual practice of those who are achieving the greatest success with their grassland in districts naturally characterised by poor drainage. In such districts, both in dairying and in sheep-farming, good results and good drainage frequently go hand-in-hand. In view of all this, it may. well be asked why do so many refrain from carrying out drainage in circumstances under which it would prove profitable.. A partial answer lies in the misconceptions that occur in respect to drainage —misconceptions in regard to its value, its cost, and its permanence. Herein the complete system of tile drainage will be omitted from consideration. Mole drainage, which will be of great service over large areas, may be done by contract; at a cost in the vicinity of 25s to 27s 6d an acre a contractor will do all the work attached to providing mole drains nine feet apart and 18 inches deep. Should the farmer be prepared to provide his own power, using, .say. a tractor, then the cost will be considerably less. This is well illustrated by cost accounts kept by Mr W. J. McCulloch in respect to the recent drainage of an area of 35 acres. The cost of this work was:

On the basis of these figures the cost of . the drainage was 9s BJd an

acre. It is noteworthy that in this work the drains were" placed not the customary nine feet apart, but six feet apart, so that the work done was 50 per cent more than in the mole drainage ordinarily carried out. Incidentally, the cost allowed against the tractor has been questioned as being too high. Mole draining is unquestionably effective, and much more lasting in its influence than many seem to believe. The data in respect to cost which have been given indicate that it is not beyond the financial resources of many farmers whose land would benefit materially from drainage. Probably the most important financial consideration in respect to drainage is that it does not ordinarily involve a recurring outlay of any magnitude. The annual charges to be set against drhinage are the relatively small ones of interest and maintenance. In this respect it may well be compared with top-dress-ing. Some farmers go on top-dressing poorly drained land year after year. In doing this they are very probably adopting a practice quite sound economically, but at the same time the likelihood is that the top-dressing could he made much more financially attractive by expenditure on drainage. This is the point of importance—often it is not a matter of attending to drainage rather than to top-dressing or ’ vice versa, but of attending to drainage in order to make profitable top-dress-ing still more profitable. In a similar wav the potential value of . suitable good seeds will at times be fully realised only when drainage has received attention. When drainage is the weak link, as it often is, in the chain of factors giving fertility, then any substantial upward movement in production in general will come economically only from rectifying the drainage position. Vigorous green leafy pasture growth in the early part of the season has been proclaimed as an indication that good pastures are being well managed. Such growth will be found only when drainage conditions are good. • | Summed up, adequate drainage has an important bearing on grassland farming because: i- (a) It begets warmer soil conditions in the spring which favour earlier growth- of all the common pasture species, and so it begets greater growth at a critical time. (b) It begets greater total annual growth because it favours the more productive pasture species such as ryegrass and clovers. (c) It results in greater net returns from the use of fertilisers and highclass seed.

(d) It is an auxiliary rather than an alternative to top-dressing. Only tho important effects of ago on grass production have as yet been considered. Drainage has equally important effects on the health of live stock with which grass-farming is so intimately and directly concerned. The stock are the living agents which deal with the grass produced. The efficient production of grass is only one-half of the task of the grass farmer. Efficient utilisation is the other half. Efficient utilisation is impossible without healthy, thriving stock. Poorly drained farm conditions directly favour the ravages of disease. This applies both to dairying and to sheepfarming. Among the disorders which are lessened by good drainage are such

serious ones as trouble of the udder, foot rot, fluke, parasitic worms, tuberculosis and calving troubles. Hence, from the stock viewpoint as equally as from the crop viewpoint, drainage deserves attention.

This is the recognised time of the year for giving attention to drainage. Apart from the actual work of constructing new drains there are other important matters which frequently call for attention. For instance, open drains should be kept clear. Mole and tile drain lines and outlets should be inspected after heavy rains in order to detect and locate any trouble in the working of the drains. All indications of want of drainage should be noted. Knowledge of such indications often is of value when any comprehensive drainage work is being undertaken. Every opportunity should be taken to study the natural fall of the farm. Sometimes, much drainage work is rendered ineffective or unduly costly because the natural fall of the land was not properly understood when the work was being started. For instance, the running of mole drains across saucer-shaped depressions is likely to give eventual trouble even though tho drains function for some time at least. It could usually be avoided by a complete knowledge of the lie of the land. Again, it is not advisable that the fall of a drain become less as the outlet is approached. Yet because the general fall was not fully considered in the beginning this is sometimes allowed to happen when it could bo avoided, i Finally, emphasis may fittingly be placed on tho need in drainage for sound planning and thorough work right from the start; if weakness creeps in it frequently is not easy to locate, and almost always is costly to rectify. The fact that a greater part of a drainage system is invisible makes it relatively difficult to estimate whether it is acting as efficiently as it naturally should. From all this it follows that care, thought and thoroughness should characterise drainage work throughout. WHAT TO DO WHEN DRAINAGE IS NOT PRACTICABLE. At times circumstances may make it impracticable to carry out drainage at a cost which will secure economical returns. When this is the case, it is not always necessary to leave the land in the occupation of the weeds and poor grasses which are encouraged by a water-logged condition of the soil. Experiments have shown that correct manuring may reduce the number of poor plants it is necessary to endure due to wetness of grassland. This arises from the fact that a superior pasture species may be struggling for a foothold against adverse conditions, both 'of drainage and of fertility, and manuring, by’ increasing fertility, enables it to establish itself. This is often the case with such valuable plants for wet conditions as Meadow foxtail, Poa trivialis, and Timothy. At times there is failure to obtain satisfactory results with these under moisture conditions which are suitable to them because the fertility is too low to he suitable.

Further, manuring, by increasing the amount of growth produced, helps to a considerable degree in bringing about drier soil conditions because of

the extra water drawn off by the more productive grass covering. A further valuable means of bringing about satisfactory grass production on poorly drained land is the use of certain high-class species which will tolerate much wetter conditions than will such pasture plants as cocksfoot, ryegrass and clovers. Among the plants that are suitable for this purpose are Floating sweet grass (Glyceria fluitans) and Poa aquatica for the wettest conditions; Lotus major for conditions not quite so wet; Paspalum, which is widely suitable north of New Plymouth and Gisborne, and which can also be used with good results on much North Island coastal country south of these places. Meadow foxtail, Poa trivialis and Timothy will tolerate not so much moisture as the species just mentioned, but moister * conditions than will such plants as ryegrass and cocksfoot. They require relatively high fertility, a fact which at times is overlooked with consequent poor results. Alsike will serve under conditions where these three species should be used better than will any other member of the valuable clover family. It may advantageously be recalled at this point that the pasture in which perennial ryegrass and white clover are permanently the dominant species is the ideal pasture to be sought after v if it can be obtained economically. >The use of the species just mentioned, such as Meadow foxtail, Lotus major and Alsike, will not give such good pastures as ryegrass-white clover combination. Their use under such circumstances is an important instance of a fundamental principle of efficient grassland management. This principle, briefly stated, is use the species which best suit the circumstances when the circumstances cannot be made to suit the best ;pecies. The adverse influence of bad drainage is not confined to its direct effect on the character and productivity of the herbage. In the winter and spring poorly-drained land suffers so severely from* treading by stock that at times substantial portions of the turf are lost by being buried. Even this does not cover all damage; for the bare spaces which result from it form a suitable starting point for weeds, such as the daisy, buttercup and docks, which freely avail themselves of the opportunity provided to establish themselves. It is easier to point out the damage which results in this respect than to suggest generally practicable ways of avoiding it when drainage cannot be carried out. On some farms the damage is apt to be so bad that it, rather than the year’s feed production, becomes the limiting factor in respect to carrying capacity. When this is the case, what might be considered radical measures may be justified. These include such practices as the grazing of stock off the farm during the period when the worst damage would be inflicted on the pasture, or the heavy feeding of such forages as hay, ensilage and roots on a very restricted portion of the farm so that damage to the remainder by “poaching” may be avoided. The position of drainage in grassland farming, as has been outlined, is: (1) The farmer should strain to drain, because drainage, apart from its intrinsic value, affects the efficiency of other important profitable measures. (2) Sound planning and thoroughness should characterise all drainage carried out. . (3) When drainage is economically impracticable, adopt suitable alternatives along the lines discussed.

Driving and labour 50 hours at Is 10Jd per hour £4 13 9 Benzine, 64 gallons at Is 6id a gallon 4 17 4 Oil 1 4 0 Interest, repairs and depreciation, on a £400 tractor at :2s 6d an hour 6 5 0 Total £17 0 1