TOP-DRESSING OF NORTH AUCKLAND HILL LANDS.

New Zealand Journal of Agriculture, Volume XXXVI, Issue 2, 20 February 1928, Page 103

TOP-DRESSING OF NORTH AUCKLAND HILL LANDS.

SOME EXPERIMENTAL RESULTS ON SANDSTONE COUNTRY.

C. J. Hamblyn,

B.Ag., Instructor in Agriculture, Whangarei

During the past two seasons manurial top-dressing trials have been carried out under the direction of the writer on an area of more or less deteriorated hill land on the property of Mr. R. F. Ellis, near Kaipara Flats. The 'experiment was designed somewhat on the lines set out in an article in the Journal for November, 1926, dealing with the topdressing of King-country hill lands. Accurate records were kept of the cost of application of the fertilizer and of the stocking of each paddock top-dressed, as well as of an area adjoining which was not treated in the first season. The area selected for the trials consists of some 90 acres of typical sandstone hill land representative of large areas of similar country throughout the North Auckland Peninsula. Originally carrying good mixed bush, and sown to English grasses from twenty to forty and more years ago, the deterioration has varied according to the management and the type of stock carried, until at the present time there is a wide variation in the type of pasture and second growth on these lands. However, whether brown-top, danthonia, or paspalum have come in to form a sward and prevent a covering of bracken fern, hard fern, or manuka, or whether the reversion has been to these forms of secondary growth, the results as far as the stock carried is concerned have been the same —a replacement of breeding-ewes by mature cattle and sheep, and a considerable reduction in the number of stock carried. In the case in question the carrying-capacity, as shown by the records of a 50-acre block with a general southerly and westerly aspect, was not more than one-third of a sheep and one-sixth of . a cattle beast per acre, and the owner found it extremely difficult to make any impression on the heavy growth of bracken fern without severely punishing the cattle. The top-dressing was carried out on two adjoining paddocks, each of 20 acres, No. 1 being treated with superphosphate and No. 2 with basic slag. paddock no. 1. This area slopes generally to the north and west, and the pasture consists mainly of danthonia, with cocksfoot still persisting among the growth of bracken fern which covered about half the paddock. Blackberry was also bad in places. In the first season this area was top-dressed at the end of September, 1925, with 3 cwt. of superphosphate per acre, and stocked alternately with sheep and cattle throughout the year. The total cost, including freight, cartage to the farm and paddock, and application by hand, worked out at £1 4s. rod. per acre. The carrying-capacity of the paddock for the year ending 30th September, 1926, as shown by the records of stocking, was four-fifths of a sheep and two-fifths of a cattle beast per acre*

The paddock was again top-dressed at the end of June, 1926, with 11 cwt. super per acre, and the records of stocking were kept until the end of September, 1927, when the carrying-capacity for the year worked out at two sheep and one-eighth of a cattle beast per acre. The considerable decrease in the proportion of cattle was due partly to difficulty in securing sufficient stock, and to the fact that the combination of top-dressing. and heavier stocking in the previous season had cleaned up the paddock sufficiently to allow of the cattle on the farm being used on new areas. However, there is no doubt that the proportion of cattle to sheep could have been increased with benefit to the paddock and little reduction in the number of sheep carried.

In addition to the increased carrying-capacity, the benefits of the top-dressing were most marked in improvement of the pasture sward, the better wintering of the stock, and (it was held) the increased wool

return per sheep. Moreover, most of the sheep-stocking during the spring and summer was done with ewes and lambs. Perhaps one of the most interesting items noted towards the end of the second year was the manner in which the blackberry had been prevented from seeding through being kept closely grazed by the sheep, and by the choking effect of the -Stronger growth of paspalum and danthonia around the crowns. . PADDOCK NO. 2. This area, also of 20 acres, slopes generally to the south and west, and the, pasture consists mainly of brown-top, with paspalum and danthonia on the drier slopes. A considerable portion of the paddock was covered with a dense growth of bracken, together with patches of hard fern and manuka. [blackberry had taken charge in some

of the steeper gullies. This was cut and burned, and grass-seed sown before the paddock was top-dressed. The fire got away in places, and an area of several acres on the ridges was also burnt off.

The paddock was top-dressed with 3 cwt. per acre of basic slag in August, 1925, and the carrying-capacity for the year worked out at nine-tenths of a sheep and one-fifth of a cattle beast per acre. The ground was again top-dressed at the rate of i| cwt. of slag in June, 1926, and the carrying-capacity increased for the year ending 31st August, 1927, .to two sheep per acre, while the number of . cattle carried was reduced to only one-twenty-fourth of a beast. Here again shortage of cattle affected the good results, which would have been much better as far as the pasture was concerned had more cattle been used. Though the fern-growth was reduced to scattered patches during the winter of 1926, the reduction of the cattle carried allowed it to get away somewhat during the' following spring, but the improvement in the grass sward prevented anything, like the spring growth of previous seasons, and Mr. Ellis is confident that he can deal with it without detriment to the stock. . 50-ACRE BLOCK. The 50-acre block already mentioned was top-dressed in June, 1926, with 11 cwt. of fertilizer per acre, half being treated with superphosphate and half with basic slag. Little improvement was noted in the pasture until the following autumn, but the carrying-capacity was improved from one-third of a sheep and one-sixth of a cattle beast to i T % sheep and one-ninth of a cattle beast, while the stock dealt more effectively with the growth of fern than they had previously been able to. . GENERAL. The cost of applying the fertilizer per acre in 1925, using 3 cwt., worked out at £1 4s. rod. in the case of the superphosphate, and £1 4s. 6d. for the slag. With the reduction in freight on the railway, and a reduction in the cost in Auckland of £1 10s. per ton for super and of £1 per ton for slag, the top-dressing with i| cwt. in 1926 cost 10s. yd. and ns. 2d. per acre respectively. This makes an average of between 17s. and 18s. per acre for the .two seasons. • *, ’ Though the foregoing results may not appear to be altogether encouraging, there is no doubt that considerable interest in the trials has been created in the district, and those farmers who have attended field-days on the area or visited it at different- times are confident that top-dressing combined with better stocking is infinitely better than the old system of continually burning off or depending on cattle alone in the endeavour to get rid of or control the bracken fern. Both the 20-acre paddocks have again been top-dressed at the rate of 3 cwt. per acre, making a total of y| cwt. in three years, or an average top-dressing of 2| cwt. per year. The idea of this last dressing is to see if a still further increase in the carrying-capacity can be made ; it is also an endeavour to clean up the paddocks so that they can be easily maintained in good order. Records will be kept of the stocking for the next two or three years —-when probably no top-dressing will be done in order to observe the after or residual effects of the fertilizers and the rate of deterioration in the two paddocks.

From general observations made during the last two seasons the writer is of the opinion that at least 2 cwt. per acre is necessary for obtaining immediate results ; that where fern is at all bad 3 cwt. per acre in the first year, followed by i| cwt. in the second, is. better than 2 cwt. to 2| cwt. each year ; ■ and that it is more economical to top-dress one area in two successive seasons than to proceed from one paddock to another each year.

Note. —The fertilizers for these trials were supplied by the Auckland Fertilizer Manufacturers’ Association and Auckland Manure Merchants’ Association, who provided the superphosphate and basic slag respectively, and the assistance thereby rendered is duly acknowledged. Thanks are also due Mr. Ellis for the efficient manner in which he kept the records, and for the interest taken by him in organizing field-days and showing visitors over the area.