TOP-DRESSING

Waikato Independent, Volume XXIX, Issue 3100, 20 June 1929, Page 3

TOP-DRESSING

VALUE IN GRASSLAND FABMING. WINTER FARM .SCHOOL LECTURE. At the Winter Farm School at Cambridge on Tuesday, in the course of a lecture prepared by Mr. P. W. Smallfield (fields superintendent of the Agricultural Department) and read by Mr. J. W. Woodcock (Waikato instructor), the interesting subject of top-dressing was dealt with as follows:--A great "deal of interest is at present being taken with regard to the nitrogenous manuring of grassland, and the successive Application of nitrogenous fertilisers to pastures throughout the year is an important phase of the European system of rotational grazing. I propose soon to deal with certain phases of our experimental work in connection with nitrogenous manuring, but I first wish to stress the absolute importance of phosphatic manuring as the basis of our grassland fafming. Go in for adequate phosphating of all your grassland and improved methods of utilisation before attempting to further increase grass growth by the extensive use of nitrogen and potash, the economic value of which is still somewhat obscure.

A great advance has recently been made in the methods of phosphatic topdressing in the fairly wide adoption of the practice of applying the fertilisers twice a year—usually 2ewt in the autumn and 2cwt in the spring. I look on the early autumn top-dressing in March and April as being of great importance. Early autumn top-dressing increases the ryegrass growth in the late autumn and early winter, and this helps to increase the winter carrying capacity of grassland. The spring dressing of phosphates is usually applied in August and September, but I am inclined to think that a later application would be more beneficial. Experimental work conducted last season at Marton showed that November applications of phosphates carried growth on through the dry summer weather, and experiments have now been started in the Waikato to test this point out for our local conditions.

There are a number of phosphatic fertilisers used for top-dressing, the principal ones being superphosphate, slag, and rock phosphates. For general Waikato conditions, superphosphate is probably the most satisfactory fertiliser. The average soil is light, and on light soils the response from slag and rock phosphate is not as quick as it is on heavy soils. Superphosphate is quick in action, and when applied in March or April it produces a flush of grass while the weather conditions are suitable, and early autumn topdressing with super is important for securing an increased winter growth of grass. On pastures that are not in good condition, and where fog and weeds are present to a considerable extent, super may bring on a big rank growth of fog, which is neglected by stock, and on such land slag, or a mixture of slag and super, would be preferable so as to encourage a good, white clover growth.

On the heavy lands of .North Auckland, where the primary aim is pasture improvement rather than the quick stimulation, of grass, slag is probably the most efficient fertiliser to use.

The main aim in the use of nitrogenous fertilisers is to increase the early spring production of grass. Early calving is essential in order, to obtain a high-producing, long lactation: period from dairy cowSj and early calving is only satisfactory if cows can be adequately fed in the spring. The autumn and early winter production of grass can be increased by the autumn topdressing of pastures with phosphates, and early autumn top-dressing is now a feature* of dairy farm management. On ryegrass pastures the autumn and early winter growing period usually extends to the end of June, while July, August, and early September are months of normally poor growth of, ryegrass. If dairy cows are to have a long, highproducing lactation period, they must calve in July or early August, and the provision of young grass for earlycalving cows from mid-July to mid-Sep-tember is an important problem in dairy farm management.

Grass from mid-July to mid-August can generally bo obtained by shutting up some fields in June, catching the last of the winter growth of ryegrass, and holding this till the cows calve. Young grass from mid-August to midSeptember can be obtained by the use of nitrogenous fertilisers, but whether the extended use of these for providing early winter feed is payable, has not yet been definitely decided. In experimental work conducted during the past season the increase in the production of early spring grass from winter applications of nitrogenous fertilisers has been sufficiently satisfactory to warrant dairy farmers trying theni out on a small scale. The value of nitrogenous fertilisers in producing early spring feed can be best judged by shutting up two small fields in the winter, both of which hate had the same phosphate treatment, and one in addition a dress-

ng of nitrogen

The efficacy of nitrogen in producing eariy spring feed varies considerably, depending on the type of pasture-and moisture and shelter conditions of the field, and it is most efficient on wellsheltered and drained fields the pasture of which is dominantly ryegrass. The best time to apply nitrogenous manures in the winter has not yet been definitely determined, but it'should be carefully borne in mind that there is no hope of the use of nitrogenous manures being a payable proposition unless the whole of the extra grass produced by them is turned into buttcrfat. Ryegrass pastures shut up in June will provide feed for cows calving in July, and applications, of nitrogenous fertilisers to the fields shut up at this time will only be warranted if sufficient cows calve to use the whole of the extra grass-growth for milk production. The average farm is shortest of pasture feed from midAugust to mid-September. Applications of nitrogen in July will increase somewhat the grass growth at that period, and at present July would appear to bo the most suitable month for the general application of nitrogenous manures. However, if the use of nitrogenous fertilisers in the winter is latershown to be a, payable proposition, then the ability of the dairy farmer to use them extensively for the stimulation of the early spring growth of grass will lead to earlier calving herds; hence the need for earlier applications of nitrogen, and June may be shown to be the month when the first winter applications should be made. Farmers should now remember that the use of nitrogenous fertilisers is still in the experimental stage.