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Chapter 14
The Management of the LeyThe manner in which a ley is managed is just as important as the details of seeds mixture or manuring. Indeed, it would almost be true to say that management of the ley, and especially during the first eighteen months, is the most important single factor making for success or failure. The very best management that can be given to an establishing sward is to graze it on the 'off-and-on' principle, ideally to put as many stock as possible to graze for as long as is necessary to eat the young grass, and then to move on the stock. Follow by resting the young seeds and bring the stock back again as soon as there is keep to hold them. Given three or four such grazing periods in succession during the first few months of the life of an establishing young ley, and that ley may be regarded as pretty well fully established and its management need not after that time be so exacting.
Nurse Crops
The question of whether or not to sow a ley with a cereal cover crop is one of general practical interest. There is no doubt that during the first few weeks after sowing, and particularly in dry spring weather, seeds sown under a cereal come away well. Once, however, the corn crop becomes tall and has developed excess of 'flag', the cereal hinders rather than helps the development of the seeds. This hindrance may be caused by a number of factors; for example, the leafy corn crop cuts away the light from the young grass and clover plants. In an excessively dry season the corn crop competes with the establishing ley for soil moisture, and it is the corn crop which wins, with the result that take of seeds is depressed. In wet seasons the corn makes excessive leafage, and may be laid, thus smothering out the young seeds and again resulting in bad, often patchy, takes of seeds. Because of these adverse influences following upon sowing in a grain crop designed to go to maturity, the mass of evidence at our disposal leads us to say that long-duration leys should not be sown under cereals unless that cereal is to be grazed or made into silage. Young developing seedlings can stand being smothered over by the 'nurse' for some eight to ten weeks after sowing, but after that the 'nurse' crop reduces establishment of both grasses and clovers. It will be argued that the ley recovers subsequently. To a degree, this is true, but only in so far as (1) seedlings whose growth has been delayed by the corn crop are able to live and begin full development after the corn is harvested, and (2) there may be considerable delayed germination, especially in white clover and in some of the more persistent strains of grasses.
Grass a Farm Crop
We would stress the fact that grass is a crop, which ought, therefore, to be farmed as is any other farm crop. The temporary ley, whether of short duration (one to three years) or of longer duration, is an extremely valuable crop, whose output of animal food will outyield that from any cereal and will at least be equal to that of roots or kale. When these yields are transcribed into units of human food, the temporary ley still compares favourably with most arable crops. It is common sense to say that everything should be done to make the most of that crop. If the ley is to be left down for a number of years it is unwise to jeopardize it by under-sowing in a competitive cereal. Rather than sow in the cereal crop in spring, we would suggest sowing in the disked-up and well-consolidated stubble in the autumn. This would be particularly applicable in the eastern and southern districts of England, where the harvest is early and the stubbles normally clean. Doing it in this way, the seeds should be sown as early as possible, and as soon as the corn is off the field. A field designed for regrassing in this manner should be the first to be cleared of corn, so that it could straightaway be cultivated and resown. In years when the harvest is late, the ryegrasses could be sown in the autumn and the sowing of clovers, timothy and cocksfoot might be deferred until the spring. It is the clovers which do not over-winter well in the seedling stages, and mixtures containing clovers should, in general, not be sown after the middle of August. Sowings made after this date often result in good takes of grasses but in poor takes of clover, and especially if there is a good germination of the autumn-sown clover. Better that the clovers should lie dormant in the soil until the following spring than that they should germinate in the late autumn and the seedlings be killed off during winter. Where, however, the sowing is done early enough in the autumn, the grasses and clovers get away quickly and can be stocked during the autumn. Once such fields have been grazed and the surface well-consolidated by the grazing animal, there is then less danger of loss of take through the winter months. It is not cold and frost which kill the clovers as much as the repeated heaving of the surface soil during periods of alternate frost and thaw. This was well exemplified during the winter of 1940-1 at the Grassland Improvement Station. Young seeds sown in August 1940, on heavy clay, received no rain until October 1940. Partial germination then took place, but it was too late, so that the seedlings of both grasses and clovers made no further growth. The autumn was wet and followed by continued frosts all through January and to the middle of February 1941. There was, however, practically no killing off of the young seedlings until after these heavy frosts. From the middle of February until the middle of March 1941, we experienced a period of alternating frost and thaw, with relatively very mild spells. It was during this period of frost and thaw in which the young seedlings were killed off. They were literally heaved out of the ground, resulting in an almost complete kill of all clovers, while the death-rate in grasses was also high. This evidence is in conformity with the evidence based on critical trials at Aberystwyth. In Wales and the West of England generally the winters are milder than in the Midlands and the East, but frosty weather in the West is more often represented by prolonged periods of frost and thaw, and it is the frost and thaw which do the damage to autumn-sown seeds. This, coupled with high moisture content in the soil, makes the winter climate of western Britain the more hazardous one for young establishing (autumn-sown) seeds. The practical point is that everywhere, whether in the west or east spring sowings are to be preferred, and especially with regard to long-duration leys. Sowing of grass and clover seeds can be done throughout the months of May, June and July with reasonable safety in the west and north. The evidence before us suggests that July-August sowings are normally also highly successful in eastern and southern districts. The seeds (preferably drilled to a depth of about one inch in spring and half an inch in summer) must be placed in contact with the moisture. If the cultivations have been well done, and no hollowness is left between plough furrow and subsoil -- an important point, emphasized elsewhere with regard to direct reseeding on the upturned sod -- the seedlings come right away and will be ready for grazing within six weeks after sowing.
The grazing animal should be brought to bear upon the new ley as soon as ever possible. When leys are sown in corn, they should be stocked as soon as the corn is off the field. If the ley is sown without a cover crop or under rape or with Italian ryegrass, the field should be grazed from the outset and as soon as keep is available. It is far better to graze too early than too late. Young developing seeds require well-consolidated ground, and the consolidation they demand is afforded by the hoof of the grazing animal. At the first grazings, sheep are better than cattle, because of the more even treading over the whole surface but even so, cattle or horses can be satisfactorily used. There are, in fact, plenty of instances where cattle have been the only grazers from the start and where highly successful leys have been quickly established.
Not only does the young ley require to be consolidated and kept firm, but the grazing animal, by clipping off the young grasses and clovers, causes them to tiller and the sward rapidly thickens out in consequence. The fear is often expressed that putting the animals in too soon on a new ley results in excessive uprooting of the young seedlings. It is true that a certain amount of uprooting takes place. In one trial field at Aberystwyth, as much as one-sixth of the seedling population was uprooted when sheep were put on very young seeds, but the end result was a first-class ley, superior to comparable areas left too late before being grazed off. The superiority was reflected not only in the young, nutritious herbage (and no crop produces feed of higher nutritive value than does maiden grass) but in the number of plants per acre that were fully established by the end of summer.
The influence of the grazing animal on the developing ley is threefold. The surface is consolidated and thereby brought into better condition for growth, the grazing causes the plants to tiller and cover the ground quickly, and the animal dung and urine add to the fertility of the surface soil. Dung and urine from animals grazing upon highly nutritious grass are correspondingly rich in immediately available plant food. Because of its ability to make rapid growth, the young ley draws heavily upon the available fertility in the soil. Maiden grass is, therefore, a high fertility demanding crop. If the leys are grazed and the excrement of the animals returned immediately to the soil, this is taken up by the plant and the cycle of plant development-food availability goes on at an increasingly rapid pace.
The trend of events as to fertility in relation to the young developing ley is of tremendous importance where old grassland is being reseeded directly. As is well recognized, old pasture, whether derelict or not, carries an immense reserve of plant foods. A large proportion of these plant foods is, however, locked up in the old roots (=the fibre), herbage and roughage. This herbage and this fibre have to rot down before plant foods become available to the new crop. The agents which carry out this rotting process are the bacteria and other micro-organisms present in the great majority of soils in sufficient quantities to do all that is wanted of them. These bacteria, however, cannot do their work unless there is a liberal quantity of easily available plant food in the soil. That is why, even where the best of old pastures are ploughed up and regrassed, it is essential to ensure that adequate supplies of phosphates, nitrogen, potash and calcium are available. The soil bacteria are particularly responsive to phosphates and lime, while in the early stages of the process of rotting, they must be equipped with adequate supplies of nitrogen. This is one very important reason why fields that are to be regrassed should receive enough lime, slag and soluble nitrogen (preferably nitrochalk on acid soils) at or about the date of sowing the seeds mixture.
The young ley is a high fertility demander, but it is also a fertility upbuilder. The grazing ley in particular will by full of clover, which, in itself, adds fertility to the soil. The grazing animal consumes the nutritious herbage and excretes correspondingly rich residues. The whole habitat is one of intense biological activity, both in the soil itself (where root action as well as bacterial action proceeds at a rapid rate) and on the surface, where leafy growth goes on apace. The movement of plant foods is rapid from soil to plant, from plant to animal, and from animal back to the soil. Think of this in terms of the molecule of phosphorus (the basic element of our phosphatic manures). In the grazing ley, this molecule would proceed from soil, through plant and animal and back to the soil within perhaps a few days, or, at most, weeks. If that same molecule were taken up by an oat crop and passed into the yard-made dung of animals, it would take at least twelve months for it to complete its cycle from soil and back to soil. The same molecule of plant food on poor and under-stocked permanent grassland, and where roughage accumulates year after year, might take many a year to complete its cycle from soil and back to soil.The Management of the Fully Established Ley
The botanical composition of the ley should be maintained at a level set by the composition of the seeds mixture that has been employed. The ley is a mixed crop, whose ingredients each make their own demand upon the environment as well as reacting the one upon the other. The grasses, to be at their best, must have clovers co-habiting with them. The clovers are light-demanders, and will not tolerate long-continued shading by the grasses. If the pasture is allowed to grow rank for lengthy periods of time, therefore, the clovers are weakened. On the other hand, continued hard grazing depletes the grasses and the ley becomes too thick with white clover or tends to become foul with weeds. To keep the proper balance of grasses and clovers, therefore, the best possible management of a grazing ley is one that entails alternate grazing and resting of the sward. Certain of the rest periods may be prolonged to a silage crop or to a light hay crop. Even the taking of a reasonably heavy crop in occasional years does not necessarily do undue damage, so long as the period during which the hay crop is growing is not a prolonged one. On fertile soils, a two-ton per acre hay crop may grow after no more than four to six weeks during the months of April, May and June. If the ley be carefully grazed in the period that follows, the balance of species can recover and no great harm will have been done.
The most harmful procedure would be to take a series of heavy hay crops combined with an overgrowth of aftermath. In general, it is better to alternate the management on any particular ley not only within the season but from season to season. Thus, if hay is taken in one year, this should be followed by grazing throughout in the year which follows. Conversely, if the ley is grazed consistently hard in any year (not on the 'off-and-on' basis) then it should be rested either for light hay or for a silage cut in the following season. Repeating the same management year after year results in rapid sward deterioration, with consequent loss in production. Thus, hay every year causes loss of vigour, and so also does continuous hard grazing year after year.
The whole question of the management of leys is closely linked with the proper rotation of leys. Good quality hay must always be an important feature of ley farming, and therefore a portion of the leys should be explicitly designed for hay production. Hard grazing in the spring months, when keep is short, is generally a necessity. Therefore, certain leys must be designed to stand up to severe grazing in winter and spring. Short leys are particularly productive, but too oft-repeated on the same field is only to invite clover sickness. The thesis, then, is to rotate leys of different types -- to follow a hay ley by a grazing ley, to follow a short-term ley with a long-duration ley, and so on.
The proper management of leys raises the whole question of extending the grazing season at both ends. The call for early bite is insistent. Early bite can be achieved in a number of ways. Thus, a ley in its first and second harvest years may be liberally manured in February in order to provide early keep in March and April. This early keep, largely contributed to by the ryegrasses, is not only very succulent, but is extremely rich in nutrients. Animals coming off dry feed or off winter grazings on to such excessively rich herbage tend to scour badly, and once they have tasted the new grass, it is difficult to get them to take other foods. The quantity of early bite that can be so grown is limited, and in practice is not sufficient to carry the stock right through to the period until normal spring growth starts all over the farm.
Another and very useful method of providing early bite is to lay up certain of the leys in late August or September. Dressed with 1-2 cwt. per acre of nitrogenous manure, fully established leys will produce a lot of herbage in the autumn, and this will overwinter in situ. Where the seeds mixture is based on winter-green and leafy strains of the grasses, the amount of 'burned' leafage is reduced to a minimum, and the product is wholly palatable in the months of February, March and April. Treating fields in this way at Aberystwyth, we obtained a product containing some 14-15 per cent protein in March, and when sheep were grazed on the fields there was no suggestion of scouring, even where the animals had come off very bare winter pastures. On one three-acre ley rested from September to March, grazing, sufficient to maintain five sheep to the acre was obtained from about the middle of March to early May. This result was achieved on the same field in two successive spring periods, and this on a thin, shallow soil under conditions where the May-July peak of growth would not be expected to provide for more than about four sheep to the acre.
The practice of autumn-winter resting for the explicit purpose of providing early spring keep is one that deserves further explanation. It is an old practice in parts of Wales, and in the north of England. If carried out on the same sward year after year, cocksfoot and other coarse grasses and weeds tend to dominate, but there is no reason why the practice should not be taken from field to field in rotation. The ryegrass-cocksfoot ley, once properly established, can produce a large quantity of winter 'foggage', and fields might be specially sown out for the explicit purpose of producing such 'foggage'. This raises the whole question of special leys designed for winter-spring bite. The pasture strains of timothy (as the Aberystwyth S. 48) remain very winter-green. If timothy leys be liberally manured with nitrogen in August, they would provide an abundance of growth which would remain green, palatable and nutritious into the following spring. Predominantly cocksfoot leys put up in August could, on suitable soils, provide December-January grazing and still provide an early bite of new growth in March and early April. It is all a matter of the composition of the ley and of maintaining vigour as well as of rotating this type of autumn-winter-spring management around as many ley fields as possible.
Once ley farming has become an intimate practice on the farm, the next step will be to provide leys designed for specific purposes: leys designed especially to produce heavy hay crops -- special hay leys of two to three years' duration; other leys designed for grazing with no more than incidental hay crops being taken from them. The basis of the hay leys will be red clover (with emphasis on the late-flowering strains) with either ryegrass or cocksfoot or timothy, whereas white clover will provide the basis of the longer duration grazing ley. In some districts, lucerne and/or sainfoin will form the basis of the three to four year hay ley.The Mowing Machine on Pastures
In seasons of lush growth it is essential that the mowing machine be used on leys that are being grazed. It must be realized that leys in full production and on fertile soils may carry two or more dairy cows to the acre during the months of April to August. During wet spells in the summer period leys often get out of hand, and it is here that the mowing machine becomes essential. The difficulty is partly overcome by shutting-up some of the grazing fields to a light leafy hay or silage crop. The mowing machine should, however, be run over every grazing ley so as to deal with overgrown patches not eaten down by the stock. The mowing-over can be done with the stock actually in the field -- the animals will often follow the mower to eat the freshly cut herbage and stems. Frequent harrowing of the pastures to spread and to dry out animal droppings helps materially in preventing patchiness on the fields and induces more even grazing in general.
Next: 15. The Choice of Varieties of Cereals and other crops
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