Oversowing and Topdressing of Southern Hawkes Bay Hill Country

New Zealand Journal of Agriculture, Volume 87, Issue 6, 15 December 1953, Page 500

Oversowing and Topdressing of Southern Hawkes Bay Hill Country

MUCH of the hill country of southern Hawkes Bay has been grassed, but through deterioration, brought about largely by economic conditions, a great deal has reverted to low-fertility grasses and some scrub. Improvement depends on introducing better species, particularly clovers, into the swards, more general use of phosphatic fertiliser, and a better appreciation of stock management on such country. In this article L. H. Alsop, Fields Instructor, Department of Agriculture, Dannevirke, discusses application of these methods of improvement in the district.

OF the 900,000 acres in southern Hawkes Bay, consisting of Akitio, Weber, Dannevirke, Woodville, and Pahiatua Counties and the Porangahau portion of Patangata County, the greater part is hill country. This has wide variations in climate and soil fertility, the main divisions being as follows: 1. Easy rolling areas of reasonably good fertility: These respond well to topdressing and ' oversowing . of all species of clovers. The climate is usually favourable for the establishment and maintenance of pasture. 2. Easy rolling to steep areas of low fertility: For this country it is important to select the species of clover most suitable for the conditions. Particular care should be taken to sow at the correct time to ensure a good strike. An adequate supply of fertiliser must be provided over the first 2 years, with subsequent management to ensure establishment and reseeding to allow for further strikes if climatic conditions are adverse. • 3. Wet, cold gullies on steep faces with a southerly aspect: The chief requirements in this country are selection of suitable species, the application of fertiliser, ability to graze pasture down to the required length for oversowing, and good subsequent grazing management. Here a species demanding low fertility such as Lotus major can be used very successfully.

Climate The annual rainfall varies from 38 to 42in. along the coastal belt and on the lower hill country areas, and increases to 60 to 80in. on the foothills and the higher ranges. Distribution of rainfall is fairly even in late autumn, winter, and early spring, but long dry spells are not uncommon during summer and early autumn. Frosts along the coast do not cause concern, but those experienced during late autumn and early winter inland and on the higher areas can have an adverse effect on germinating clover. Importance of Clovers Many of the hill country swards consist of some crested dogstail, considerable sweet vernal, browntop, chewings fescue, and danthonia, and some ratstail, flat weeds, moss, fern, and scrub. Traces of volunteer white, suckling, striated, and clustered clovers are the only legumes. It is only by the introduction of higher-producing white, red, and subterranean clovers and Lotus species that improvement to the grasses can be achieved and phosphatic fertilisers utilised efficiently. The natural phosphate deficiency of the hill country is one of the most important factors limiting . pasture growth. Before increased production on these areas can be expected phosphates must be added so that the

clFancT o?survfv V al. & Althnll « b +bprp i<s nppd f nr n h n<! . hate on most of the hill disappointing results from topdressing have occurred too often, as the application of phosphates on grass alone is virtually wasted. Topdressing on hill country must accompany oversowing B’.. ensure more success for expenditure. When thriving clovers appear in any sward it is an indication that improvemenf j s taking place. K/fnd- SiiitahlA Snecies MOST ou raoie r On most soil types a welldistributed rainfall will contribute considerably toward the success of oversowing, but with variable climatic and fertility conditions consideration must be given to a choice of the most suitable pasture plants. Fortunately m most parts of southern Hawkes Bay j-t ts possible to introduce species such ag w^ te> Montgomery red> £ nd subterranean clovers, or Lotus major and Lotus hispidus. Over many areas these can be sown successfully in mixtures or as single species. To determine the right species a knowledge of the fertility and moisture requirements of the individual clovers is essential. These are as follows: —• ;

White Clover White clover, a perennial, is undoubtedly the most important clover in New Zealand. Given suitable treatment it can thrive under a wide range of conditions. Greatest value can be derived from it when it is grown on well-drained, high-fertility soils, but even under less favourable conditions it fills a very important place in New Zealand pastures. Factors limiting growth are dry conditions, lack of available phosphate and potash, overgrazing, lack of drainage, or too high soil acidity. White clover is the most prolific nitrogen-fixing legume in New Zealand pastures, and it will also derive the greatest benefit from an adequate supply of phosphate. Subterranean Clover Subterranean clover depends for its survival on its prolific reseeding. It thrives on free soils and produces the greatest amount of herbage of all the annual species. It should not always be looked on as the ultimate species in the sward, but should be regarded as a stepping stone to the establishment of white clover where there is enough moisture for this to remai-n permanent. In areas of low rainfall subterranean clover is best, and its annual habit makes it invaluable in areas of summer droughts. Red Clover Red clover is a perennial plant, but it will not stand up to hard grazing as well as white clover. Its fertility requirement is somewhat lower than that of white clover and its capacity to fix nitrogen is also less. The growth which this clover makes in late spring and early summer, however, makes it a valuable legume in hill country pastures. Lotus major Lotus major is a perennial the value of which is not generally recognised by farmers. It is a species demanding low fertility and thrives on cold, damp areas where other clovers will not produce efficiently. Once established it will persist and spread even without

regular phosphate dressings. Trials throughout southern Hawkes Bay have shown that it establishes slowly, ultipalely filling an important role in the improvement of those areas which are J°° cola and wet tor successful subterranean or white clover establishment. A k|;<-hm P n+ C'lnvorc . Trials in southern Hawkes Bay to determine the most suitable time for oversowing showed that autumn gave a more favourable response than spring. March proved to be the best month and April the next best. Of the spring sowings, that in September was comparable with late May sowings. It may, however, be possible or even advisable to sow in the colder, wetter districts during spring.

When the correct time to sow is being decided, consideration must be given to the climate. Sowings should not be made until regular autumn rains have begun, which will not only germinate the seed but also maintain the young, growing plants. Early autumn (February) sowings may be subject to light showers sufficient to germinate the seed, but the seedlings may succumb to following hot, dry weather or seed may be eaten by birds if left lying on the ground ungerminated for too long. Late autumn sowings go into the winter as small plants, and seedlings may be destroyed by frosts or pests. When oversowing is being done with subterranean clover in spring it must be remembered that this species is an annual which barely becomes established before summer

droughts, which may cause premature death, often without reseeding.

Seeding Rates In oversowings the losses in seed that does not germinate or is damaged and destroyed must, of course, be much greater than if the seed were sown on cultivated ground. It is very important that such factors as soil fertility, seed mixture, and temperature be considered when a seeding rate is being decided. The whole aim of the operation is to establish rapidly a suitable clover species in the pasture. On higher-fertility country 31b. of seed per acre is adequate, but when conditions are such that a 50 per cent, loss in establishment can be expected the seeding rate must be increased to aim at a germination comparable to approximately 31b. per acre.

Condition of Pasture at Oversowing Trial results have been sufficiently conclusive to show that the pasture should be grazed short before oversowing so that the seed can reach the soil surface and yet have enough cover to protect the establishing seedlings. A management programme to o up the bottom and to cut up tl soil should be carried out before sowing. Cattle are recommended in preference tc sheep, as the heavier animals will tend to stir the soil surface with sharp hooves, leaving’ a suitable bed for the germination of the seed. The following points are important to ensure that as many seeds as possible establish:—

The seed must be able to fall on or very close to the soil. The germinating plants must have light, air, and moisture to establish. . Sufficient cover to protect the plants in the cotyledon stage is desirable. Too much . cover will have a suppressing effect on the growing plants. Too much cover will also tend to force the plants to grow long stems, with the result that at the first grazing the plants are often eaten off below the crowns and do not recover. Management after Sowing It is advisable to remove all stock while the seeds are germinating, usually a period of from 4 to 6 weeks. After this little damage can be done

other than by extreme undergrazing or overgrazing. The rank growth often experienced during late autumn and early winter will do as much harm to the young clover seedlings as extremely close and continuous grazing. The first grazing should be carried out with a big mob of sheep so that the area can be grazed off quickly and then spelled again for a further 3 to 4 weeks. This type of management should be continued until the clover is well established with a vigorous appearance. At no stage should close grazing be permitted, as this will have a detrimental effect on root growth and development. The greater the root penetration and development that can be encouraged by on-and-off grazing and by not grazing too close to the soil surface, the greater will be the return from pasture production.

Selecting the Area Selecting the area to be improved is probably one of the most important yet least considered aspects of hill country improvement. Though it is good policy to encourage oversowing and topdressing, it is also sound to see that money spent on this aspect of development is not wasted. Farmers generally tend to oversow too large an area at once, often with the result that the management policy of that particular area becomes a problem in the over-all grazing of the farm.

. An important consideration is what area can be managed efficiently at a time and how much phosphate will be available to ensure that the area can receive dressings adequate for healthy and vigorous establishment. Management must allow for vigorous, wellrooted plants, and reseeding must also be allowed to obtain a high concentration of seeds in the ground. After this has been achieved there should be little cause for concern. However, it is only by selecting areas where stock _ movement at sowing, during establishment, and at . reseeding periods can be controlled that this can be achieved. Furthermore, an improvement programme should always concentrate on the better land first. To endeavour first to raise the level of the poorer country to that of the better areas is unsound. Rather should the better land be made to produce at a higher level before an attempt is made to increase production on poor back areas. Fertilising On the hill country the essential fertiliser is phosphate. The normal topdressing practice on the hill country is to sow l-l-cwt. per acre, but when clovers are being oversown this is not sufficient. A dressing of 3cwt. per acre at least is advised to establish a vigorous, high-producing clover on low-fertility areas, and it is important that regular applications be applied for not less than 2 years, When the supply of fertiliser and means of application are adequate, application of four 3cwt. dressings in

the first 2 years has proved advantageous. This is done by applying the first dressing with the seed, followed by a further application in spring, 3cwt. more the following autumn, and the fourth dressing 12 months later. This may appear to be somewhat expensive on poor hill country, but the aim of the operation is to create a fertility level capable of supporting the higher-producing clover species. Where finances are limited the farmer should endeavour to select a smaller area where a programme as described could be carried out rather than to reduce the rate of application. The frequency of phosphate application is most important and should receive careful thought. Many hill country farmers are attempting to

cover the whole of their properties with dressings of up to 2cwt. per acre as quickly as possible. Frequently this fertiliser is going on to ground either devoid of clovers or on areas containing only poor volunteer species. Liming With long hauls, high carting costs, and difficulties of spreading, liming has not received much support from farmers in many back country areas. Whenever it has been carried out, however, it has shown that most of the hill soils will benefit from a dressing of lOcwt. or 1 ton per acre. Whether to lime or not is mainly an individual problem based on locality, topography, availability of spreading equipment, and costs of application. Where it can be carried out economically it can well be recommended.

Grazing Management The improvement of all pastures is closely related to grazing management. Where lower-fertility conditions exist it is even more essential that this factor should receive careful consideration. Controlled grazing, in addition to oversowing and regular topdressing, will result in ' a substantial increase in over-all production on even the poorest of farms. Most farmers are familiar with the term “rotational grazing” and practise it to some degree, but often a more intensive system based on the pasture’s capability would give much greater returns. It is desirable that each paddock be assessed as to its ability to meet the demands of the feeding animal without damage to the existing sward. This can be done only by ascertaining how long a mob can be grazed on each area during the seasonal fluctuations. Paddocks vary considerably in herbage production and in their ability to recover after grazing by a large mob. Assessment based on size of paddocks is not always a sound method, but too often

it is the size of the area instead of the pasture’s capability that determines the carrying capacity. From this, overgrazing and undergrazing often result. Trial work has shown that a policy of on-and-off grazing, allowing for periodic spelling, gives greater production. A greater concentration of fertiliser, in a form readily available to plants is deposited by the animal. Selective grazing is kept to a minimum by the use of large mobs of animals, thus keeping down the tall, rank patches which indicate unproductiveness. A better control of clover growth is obtained through prevention of smothering or damage by too close grazing, both of which cause premature death. Example of Land Development The following example shows how by the application of these methods improvements can be achieved by topdressing and the introduction of suitable clovers. A farmer took over a property of 609 acres in March 1947. The carrying capacity at that time was 750 ewes, 184 hoggets, 13 rams, and 78 cattle; the wool weight for 1947 was 10,3321 b. The pasture consisted mainly of browntop, danthonia, crested dogstail, Yorkshire fog, sweet vernal, and some subterranean clover, with suckling clover predominating. Weeds in varying amounts were cudweed, field daisy, rushes, dandelion,. Scotch thistles, mouse-eared chickweed, fern, manuka, and moss. In 1947 a pasture-improvement programme was begun, the aim being first to build up fertility by topdressing and then to introduce -z suitable vigorous clovers. The programme from 1947 was as follows: —topdressed the whole farm with 2cwt. of phosphate.

1948 topdressed the whole farm with 2cwt. of phosphate. topdressed the whole farm and oversowed 80 acres with 21b. of white clover and 21b. of Mt. Barker subterranean clover per acre. 1950 topdressed 300 acres and oversowed 170 acres with 21b. of white clover and 21b. of subterranean clover per acre. 1951 topdressed all the farm and oversowed 180 acres with the same mixture. 1952 topdressed 60 acres and oversowed 60 acres. 1953 topdressed 60 acres and oversowed 60 acres. Carrying capacity and wool weights have responded as set out in the table below.

During the above periods there has been a marked improvement in carrying capacity with wool weights continuing to rise steadily, following the combining of. oversowing with top-, dressing. ■ It should be noted that the owner oversowed practically all his farm in 4 years. This is not usually advisable, but in this case the owner was able, through the original fertility build-up by topdressing and increased stocking, to make progress fairly rapidly. By maintaining a sound management policy of reseeding and mob stocking, and by watching closely that establishing plants were not grazed too

severely, the farmer carried out this progressive programme successfully.

Future Improvement Possibilities

Of the total area of southern Hawkes Bay, 750,000 acres could be classified as hill country capable of still further improvement. Of this, some areas are suited for improvement by cultivation; others are in the process of improvement by oversowing and topdressing but have not yet reached full potential production.

With the fluctuation in . seed prices and local. variations in cartage rates it is difficult to give figures that will be applicable in general, but the following example of -a complete programme carried out on 20 acres of a farm at Pongaroa, about 40 miles from Dannevirke, will serve as an indication of what it costs to develop land.

On the above costs the original seeding and two subsequent dressings would cost - £152 14s. 6d. or under £8 per acre. Farms closer to a railhead would be developed for less, depending on cartage costs. Further improvement to warrant expenditure could be computed as follows: — If it is assumed that untreated country would carry 1J sheep, treated country could be expected to carry at least 3 sheep, giving an increase of double the original carrying capacity. By careful management this state should be achieved after the completion of the oversowing and topdressing programme. Therefore, the first 3 to 4 years’ extra profit is taken up in paying for the original outlay. From this point, however, the added income is available for further improvement on other areas. Furthermore, with more stock a greater build-up .of fertility is taking place through the movement of stock from improved to unimproved areas. More and higherquality wool will be clipped, better lambing percentages can be looked for, and more lambs fattened. As further areas are made more productive an over-all increase in meat and wool will result.

Of more importance to the farmer, these methods will be the means of ensuring a better standard of living for him and his dependants, and he knows that when he retires he has left the land more fertile than it was when he began.

* The decrease in wool weight in 1950 occurred during - a change-over in flock management. t Estimate.

Dry Wool Year Ewes Hoggets sheep Cattle weight weight lb. 1947 . . 750 273 13 78 10,332 1948 . . 808 315 37 50 11,885 1949 . . 883 288 56 81 13,227 1950 . . 751 527 61 64 *11,639 1951 . . 868 390 90 56 14,063 1952 .. 908 440 13 115 14,724 1953 . . 950 570 20 153 1-15,000

£ s. d. d. 21b. of white clover per acre lib. of Mt. Barker subter8 0 0 ranean clover per acre . . 4 0 0 lib. of Tallarook subterranean clover per acre .. 5 10 0 3 tons of superphosphate at 3cwt. per acre 29 9 6 Cartage of 3 tons of superphosphate— . From Wanganui to Dannevirke at 28s. per ton .. From Dannevirke to 4 4 0 Pongaroa at 36s. per ton 8 0 Pongaroa at 36s. per ton 5 5 8 0 Spreading costs, approximately £ per ton 6 0 0 £62 11 6 Subsequent Topdressing Costs 3 tons of superphosphate .. 29 9 6 Cartage .. 9 12 0 Spreading .. 6 0 0 £45 1 6

Initial Oversowing Costs for 20 Acres