The Improvement of Permanent Pastures and Rough Grazings
We are here concerned with the improvement of pastures and grazings that for one reason or another are unlikely to be brought under the plough. This is a large acreage, but it cannot be accurately estimated. With the non-ploughable but improvable rough grazings it is probably something like seven and a half million acres for England and Wales. Both 'ploughable' and 'ought-to-be-ploughed' are relative terms, because with increasing knowledge and the constant introduction of both new types of implements and improved models of those already in general use our standards of what is possible and what is economic have to be constantly modified. Again, as regrassing is carried over an ever-increasing area of the ought-to-be-ploughed acreage, so will farmers come to appreciate ever more keenly the value of grass as a crop. The ultimate fate of our permanent grass and rough grazings will, however, be determined by the pattern of our national policy. If a prosperous rural Britain is to be woven into that pattern then the appropriateness of the measures taken to ensure a healthy and productive agricultural industry will be reflected in the smallness of our acreage in permanent grass and rough grazings and in the attention that is given to what remains.
We have three main classes of permanent grass and rough grazing to consider:
(a) those which are rough and under-grazed and which consist predominantly of more or less worthless grasses and of weeds, with little or no clover;
(b) fields which have long been used as meadows without the support of adequate manuring and which have consequently been reduced to a state of exceedingly low fertility, accompanied by excessive weediness;
(c) fields which have been grazed for generations and which have been robbed of essential minerals (lime and phosphates, for example) in the milk of dairy cows, or in the bone and carcass of young growing animals.
The methods of improvement appropriate to the rough and under-grazed swards are precisely similar to those we have described when discussing pretreatment.
In view of the shortages of phosphates it is, however, only in very exceptional circumstances that phosphates should now be employed on the not-to-be-ploughed grazings, while on many of these great improvement can be effected without any dragging or cultivating.
Areas on peat, or peaty soils, in Molinia with rush can be improved out of all recognition merely by burning off the coarse vegetation, following up with the mowing machine, and applying heavy dressings of lime in the form of ground limestone. It is only necessary in addition to sow the seeds of wild white clover with some amount of crested dogstail and supported by the pasture strains of timothy (e.g. Aberystwyth S. 48 and S. 50), rapidly to create an entirely different type of sward and one with vastly increased carrying capacity and a greatly extended grazing season.
The process will be hastened if dressings of a soluble nitrogenous fertilizer are added from time to time, and the results will be speeded up in proportion as the grazing is heavy. Almost all types of rough grazings can be greatly improved by generous applications of limestone, the sowing of wild white clover and heavy grazing. The tendency always will be for Agrostis (not present in large amount in Molinia, Nardus and fescue pastures) rapidly to gain on the ground, and this mingling with the introduced white clover will lead to the formation of an Agrostis-white clover pasture which will represent an entirely different level of grazing value to the more completely natural pasture which it will have replaced. On these very poor rough grazings on acidic soils Davies has shown that the results produced only by lime and the introduction of wild white when supported by heavy grazing are truly remarkable and have shown themselves as greatly increased yields of herbage nitrogen, phosphates and lime, the yields of these ingredients on the limed and grazed plots being frequently from four to ten times as heavy as on the grazed plots receiving no lime. It would appear, however, from these experiments, that except on the Molinia pastures the application of limestone has not effected an increase in the amount of readily available phosphate in the soil. The greatly increased yield of herbage phosphate is probably, therefore, in large measure due to the important effect of calcium on the root system in these lime-deficient soils; it is also possible that the limestone may have increased the concentration of soil phosphorus which the herbage can slowly utilize.
We have alluded to these extreme cases because they serve to emphasize the great value of liming pastures where the lime requirements are high. It is always best to drag in the ground limestone, but this is hardly necessary on wet Molinia swards, where it is also difficult of achievement, while many hill sides are too steep or too rocky to permit of the intervention even of dragging implements. We have also referred to these Welsh experiments because they illustrate so convincingly the importance of the grazing animal in connection with pasture improvement. A heavy concentration of the grazing animal is an absolute essential in the improvement of all types of rough grazing, and perhaps particularly those on soils markedly deficient in lime. It is generally supposed that without fencing it is impossible to effect concentrated grazing. Actually the animals will always follow the mowing machine -- they will follow, too, areas that have been dressed with limestone and nitrogen. Consequently on the open hills and in large enclosures such as occur in subdivided sheep walks and generally on parks and fields of fifty acres and upwards great improvements can be effected by mowing-over, liming, and applying nitrogen on blocks of but moderate size. The animals will automatically concentrate on the blocks so treated, while the blocks neglected will come in their turn for treatment. In the meantime the untreated blocks will often grow on into a tolerable hay crop frequently well worth harvesting as such. When the treatment will have covered the whole enclosure, or the greater part of an improvable area, then the stock-carrying capacity of the total acreage will have been greatly increased, but even so, the grazing can be quite appreciably controlled by mowing over in large strips, starting say in May, and mowing a fresh strip each week until the whole paddock has been mowed over. This mowing over would be rotated year by year in such a way that no block would be mowed over at the same relative date two years in succession. It is true that many swards are too rough to mow over, hence, for one reason, the necessity of pitchpoling to remove ant-hills. No operation is, however, more necessary than the mowover on swards that have been long under-grazed and which have a tendency to rank growth, just as no operation is more necessary on swards so luxuriant that the herbage is always growing away from the animals. The mow-over too is an excellent means of keeping a number of weeds in check. Pastures full of buttercups, which are prodigious seeders, should be mowed over when the buttercups are in full flower and before the seed has set, and again when a second crop of flowers develops. A late mow-over when weeds like thistles, hogweed and hard-heads are in an advanced state of growth is always markedly efficacious. The mow-over in all cases should, however, be followed almost immediately by heavy grazing. Early and hard spring grazing, which greatly favours the spread of white clover and is inimical to weeds like hard-heads, followed by a relatively late mow-over is a sure way of decreasing weeds on inferior pastures. To conclude these remarks about the virtues of the mow-over we need only say that perhaps the best-managed pasture fields that have come under our notice have been those grazed on the 'on' and 'off' basis and where the mowing machine has followed the animals after each period of grazing.
There is a huge acreage of very poor permanent grass on ordinary farm fields, a large proportion of such grass is not densely matted nor is the vegetation rank or coarse -- the main trouble, as we have said, is loss of fertility. Ideally all deficiencies in terms of lime, phosphates and potash should be immediately rectified, but under present circumstances where such fields are in the not-to-be-ploughed class the farmer must do the best he can by resort only to lime and nitrogen, and by good management. Where there is a lime deficiency this should be immediately rectified, by adequate dressing of ground limestone well-dragged in with an implement of the strength of the Aitkenhead 'Grass-Ripper'. If it was always a standard practice heavily to harrow in ground limestone on grassland and to apply nitro-chalk after the lime had been so harrowed in, immediate results would be obtained, and the maximum biochemical benefits from lime would be achieved without any prolonged period of depression in yield or of absence of any apparent result.
If clover is absent, or only present in small quantity, the seed of wild white should be sown. By feeding out silage or hay during the winter it is sometimes possible to subject a field to such intensive hoof cultivation that if this is followed up by drastic pitchpoling it is possible to get a completely earthy tilth, when a full seeds mixture may be sown and complete renovation effected within a few weeks, or at most a few months.
Old meadows inadequately manured for decades present a difficult problem: wherever possible these are fields that should be brought under cultivation. Such fields are always full of weeds of which yellow rattle is often the most plentiful. Yellow rattle is an annual and early seeding plant which is favoured by late hay harvests and is essentially a weed of meadows. The correct procedure would be to use the not-to-be-ploughed meadows as pastures for a run of years. Hay should be obtained from new hay-leys coming into the rotation on the ploughable fields. Lime must be applied wbere there is a lime requirement, and in order to obtain as much grass as possible and to hold as many stock as possible to the sward nitrogen should be applied judiciously and on a regular plan. During the present food crisis the farmer must obtain all the feed he can from his permanent grass, and therefore a somewhat extravagant use of nitrogen is justified, even if by adopting this course he will make further drains on the already depleted supplies of phosphates and potash in the soil. He will do less harm by grazing than by the continued taking of hay, and if he will attend to lime he can further safeguard himself. As supplies of phosphates and potash again become plentiful, he must make good not only what he will have taken out of the soil with his eyes open as a contribution to food production, but also what had been steadily removed year after year for generations.
Old worn-out pastures present a problem almost more difficult than the meadows. In many cases a change-over to hay would be the best thing for the fields, but only if it were possible adequately to manure for the hay crop, and neither phosphates nor dung should be permitted on the not-to-be-ploughed. If the farmer has not got hay-leys coming into production there is, however, a case for using certain types of old pastures for hay or at least for silage, when he must look wholly to nitrogen for his production, and as with the old meadows rectify exaggerated phosphate and potash deficiency. Fields full of thistles are a case in point. To let grass and thistles grow up together and to encourage a lusty growth of thistles by nitrogen and then regularly to cut the crop (grass and thistles together) as for silage is to make some use of the thistles and also to wage very effective war upon them. Pasture fields put up to hay, although they would not as a rule produce heavy crops, would develop a herby hay which if cut early would be of relatively high protein equivalent, and therefore of great value to-day. The cutting at the early hay stage would greatly weaken the thistles, and provided the field was heavily grazed during the aftermath period, and limed if lime-deficient; on the balance such treatment would be better for the sward than to continue the grazing-only management. Where the grazing has been consistently too hard for many years the silage or early-hay plan is to be definitely recommended. Where fields have been consistently under-grazed, then it would be better to intensify the grazing and to occasion some control by mowing over in terms of separate blocks at different dates, as recommended for large enclosures.
Finally, the farmer must be reminded that he can do much for his not-to-be-ploughed permanent pastures by attending to ditches and water-courses. Let him follow this up by liming and dragging, the intelligent use of the mowing machine and with the judicious aid of nitrogen, and he will be able to make even the poorest of them contribute to the food production effort.
DAVIES, R. 0. (1941).'The Effect of Grazing and Cutting on the Yield, Botanical and Chemical Composition of Natural Hill Pastures. 11. Chemical Section.' Journ. Ecology. Vol. 29.