SEASONAL NOTES.

New Zealand Journal of Agriculture, Volume 46, Issue 3, 20 March 1933, Page 171

SEASONAL NOTES.

THE FARM.

Pasture Top-dressing Considerations.

Tn general the top-dressing of the past was credited with having caused much less benefit than it actually did cause. If the farming community had possessed an accurate knowledge of the past profits from judicious topdressing many farmers would have adopted more extensive programmes, and some who did no top-dressing would assuredly have considered it worthy of a place in their farm practice. The recent regrettable reduction in top-dressing is largely due to this past failure to measure accurately its true function in our farming.

While, unfortunately, it must be admitted that some, because of their financial position, are not top-dressing as extensively as they believe they should, it is known that others could profitably spend more on topdressing than they are spending, but refrain from doing this because they erroneously believe that the extra expenditure would not result in enough benefit to justify it.

Confused thinking frequently underlies unduly restricted expenditure on top-dressing. . Some, for instance, would readily affirm that top-dressing would increase their production substantially, but at the same time they contend that they would be unwise to seek an increased production in view of the fact that they are already losing money on each pound of butterfat or on each lamb they produce. In certain circumstances such thinking may be sound ; more often it is unsound. This is because an increased production due to top-dressing is frequently associated with a cost of production lowered to such an extent that a working loss is turned into a profit, or at least lessened. Judicious top-dressing has at times been the primary cause of increases of 25 per cent, to 50 per cent, in production. How such happenings may affect unprofitable farming is indicated by the fact that it is better to lose i|d. a pound on an output of 15,000 lb. of butterfat than 2d. a pound on an output of 12,000 lb., and it is also better to lose id. a pound on 18,000 lb. of butterfat than i|d. a pound on 15,000 lb. These figures indicate that even when a farm is being run at a loss top-dressing may directly affect production in such a way as to be well justified. Normally when a farm is being run at a profit the justification for top-dressing becomes more readily obvious.

It is confused thinking also to look upon top-dressing merely as a means of bringing about increased production ; on thousands of farms it is the essential means of avoiding decreased production. Hence, a farmer who does not seek to increase his production may still need to top-dress more freely than he plans. Top-dressing viewed as a maintenance measure is of special moment this season to those who, having top-dressed for some seasons, carried it out on a reduced scale last season. Under normal grazing much of our grassland if not top-dressed suitably at regular intervals would steadily deteriorate. An important feature of the process of deterioration is that it is at times insidious, and hence may go unnoticed until costly damage has occurred. The farmer who sees his pastures every day is not always well equipped by training or experience to note the relatively insignificant gradual changes in them, which, taken over a year or two, amount to serious deterioration. The residual influence of previous top-dressing is particularly apt to create in farmers who have reduced their programme an unfortunate belief that their grassland is not being detrimentally affected by discontinuance of top-dressing. At times farmers

who had been regularly applying liberal dressings of superphosphate or of other phosphates have discontinued top-dressing for a season, and for that season the carrying-capacity has not always' been ■ greatly affected ; but the immediate effect on the carrying-capacity does not necessarily, or even probably, reflect the ultimate effect of not top-dressing grassland the quality of which has been built up partially- by earlier top-dressing. The earlier top-dressing has created reserves of fertility which represent part of the current capital value of the farm, and a type of management which does not provide for the replacement, of these reserves simply means utilizing capital instead of income.

From these considerations it follows that a farmer in deciding upon his top-dressing programme should often be interested not so much in the extent to which a given amount of top-dressing will increase next season’s production over that of last season’s, but in how much the production two seasons hence will decline if top-dressing is not carried out.

It is well to bear in mind that top-dressing does not require to be more effective in order to be profitable now that produce brings lower prices.' This is largely due to the fact that top-dressing has not remained a fixed charge in face of the . decline on ■ farm-produce values. As superphosphate is of outstanding importance in top-dressing it is of some interest that about a dozen years ago when butterfat was returning from is. 2d. to is. 3d. a pound super cost £8 15s. a ton on trucks. This is not substantially different from butterfat at 8d. a pound and super at £4 a ton. On the basis of these figures it will be found that there is to-day no necessity that top-dressing shall produce very remarkable results in order .to be effective enough to be worth while. Dairying ; well exemplifies . this. Increases of over 40 lb. of butterfat an acre, due primarily to top-dressing at the rate of 2 cwt. to 3 cwt. an acre, are far from uncommon. To-day an increase of 40 lb. of butterfat an acre, due to the dressing specified, costs about 12s. an acre. At 8d. a pound for butterfat it returns £1 6s. 8d. an acre. An increase of 20 lb. of fat an acre for an expenditure of 12s. would return 13s. 4d. an acre. If a suitable dressing of 2 to 3 cwt. an acre does not result in an increase in production of 20 lb. of fat an acre and at the same time obviate deterioration of the pastures, then, provided the management is reasonably efficient, the land probably should not be devoted to dairying to-day.

When financial factors prohibit the carrying-out of a full top-dressing programme it is advisable to do as much as can be financed instead of eliminating • it altogether, and when only a portion of a farm is to be treated it is advisable, as a rule, to top-dress the fields supporting the better ; swards ; then the influence of the fertilizer is exerted on a greater number of the more valuable pasture plants, which have a greater capacity of responding usefully to improved fertility than have the inferior plants and weeds which are more prominent on the poorer swards.

In general, the first result to be sought in top-dressing is increase in the supply of phosphates. Successful results in the field have well justified the very general use of superphosphate. It has been stated previously in these notes that super does not cause any permanent increase in soil-acidity, and this view is authoritatively confirmed in the following statement in “ Artificial Fertilizers in Modern Agriculture,” published in 1931, and written by Sir John Russell, Director of Rothamsted and of the. Imperial Bureau of Soil Science : The old statement that superphosphate tended to exhaust the lime and to make the soil acid is incorrect . . . Shortly after its. application it may act like any other neutral salt in intensifying the effects of soil-acidity ,. . . but the ultimate effect is very small, and may even be in the direction of reducing the acidity.”

Over wide areas with fairly heavy rainfall slag is known to give good results, and in districts of good rainfall African and similar phosphates

may be expected to prove satisfactory, but, instead of using these latter phosphates alone, when a quick result from top-dressing is desired it is usually advisable to employ a mixture consisting of equal weights of one of them and of super. In a few districts official field trials have given evidence of benefit from the use of potash on grassland, and in such districts farmers are justified in fairly extensive trial use of „this fertilizer. The available evidence indicates that the use of potash should be linked with the use of phosphates, for in the soils of the districts concerned there is apparently a deficiency both of phosphates and of potash, and if the phosphate position is not improved the use of potash alone may be expected to be unsatisfactory. Apart from the particular districts to which reference has been made, the evidence available does not justify a general recommendation to use potash in top-dressing. The material known as 30-per-cent. potash salt is, as a rule, the most economical source of potash for grassland.

On farms in which a shortage of winter feed for dairy animals is expected it may prove profitable to apply a soluble mitrogenous manure, such as sulphate of ammonia or nitrate of soda, in late March or April, at the rate of about 1 cwt. an acre, as a means of increasing the supply of feed. The use of such nitrogenous fertilizers alone is seldom satisfactory, and to get satisfactory results phosphates should be applied at the same time as, or shortly before, the nitrogenous material. The best results from nitrogenous manures follow their application to vigorous well-drained pastures in which rye-grass is prominent.

Liming.

Those who desire to reduce their expenditure on top-dressing are inclined at times to resort to liming as a cheap substitute for phosphates. Unfortunately, this may be expected almost always to prove a very unsatisfactory substitute, for while there is a considerable area on which a mixture of lime and superphosphate gives attractive results the area on which satisfactory results from lime alone are evident is very restricted.

The results from liming in New Zealand are so variable that money should be spent cautiously on it in those areas which do not present reliable conclusive evidence that liming is profitable. If land does not respond satisfactorily to standard dressings of phosphates, then lime is well worth a trial in association with the phosphates. Apart from field trials, no methods of ascertaining the amount of lime that may profitably be applied to land have been shown to be reliable.

Autumn Management of Pastures.

Wherever top-dressing is known to be beneficial a special effort should be made to dress newly established . grass. At times young pastures deteriorate rapidly because of a slight initial lack of fertility, and, as a rule, it is better to prevent this by timely suitable top-dressing than later on to renew or repair deteriorated swards.

Autumn harrowing of pastures is widely advisable, and should be done thoroughly enough to bring about even distribution of droppings, which, when so treated, have a considerable fertilizing value, and which if left undisturbed bring about deterioration instead of improvement of the sward.

Seed Treatments of Cereals.

Commonly occurring smuts of wheat, oats, and barley may be controlled effectively by suitable treatment of the seed prior to sowing, and yet these smuts annually cause substantial losses in the crops of the Dominion.

Stinking smut of wheat is spread by minute parts of the parasite, causing it being deposited on the outside of the grains to be used as seed. Hence seed from a healthy crop may become contaminated with

the disease by contact with sacks or machinery which have held a diseased crop, and so, to be on the safe side, even when using seed from a healthy crop, it is usually worth while suitably to treat the seed against smut. The dry-dusting of wheat seed with fine copper carbonate powder as a means of controlling stinking smut has been widely recommended not only in New Zealand, but in leading overseas wheat-growing countries. In.favour of the. copper-carbonate treatment it may be pointed out that it is very effective, it involves no danger of injury to the seed, it may be done at any convenient time and at a considerable interval prior to sowing if desired, and it favourably compares in point of expense with other methods of treatment. The harmful effect of inhaling the powdered carbonate in any considerable quantity cannot be overlooked, and on this account farmers should use a proper dustproof mixing-apparatus for treating seed or should obtain treated seed from merchants. (Certain materials which are prepared for the dry-dusting of wheat seed, and which are sold under trade names such as Ceresan, are referred to in a separate article in this issue by the Field Mycologist.)

When the dry-dusting treatment is not to be employed formalin may be used with good result. An effective way is as follows : Add i pint of good formalin to 60 gallons of water ; wet the seed thoroughly with the solution by sprinking the seed and then shovelling it about on a clean floor. Then pile the seed into a heap, cover the heap with sacks soaked in formalin solution of the strength already mentioned, and leave the heap covered with the sacks overnight. The seed should be sown while still damp ; if it dries out a considerable loss in germination may result. To avoid reinfection with the smut put the treated seed in sacks which have been soaked in the formalin solution.

Another effective way of treating seed wheat is the following : Add i pint of good formalin to 40 gallons of water. Have sacks one-third full of seed and preferably sewn instead of tied. For ten minutes immerse each sack in the formalin solution, keeping the grain in the sack well agitated by lifting one corner after another. Then place the sacks on ground where there is no danger of freezing and spread the grain evenly by flattening out the sacks. Seed treated thus overnight is ready for sowing the next morning, and cannot be kept long without injury. This method of treatment may be employed successfully for the control of smut in barley and oats, for which dusting with copper carbonate is not satisfactory.

General Cropping Work.

In the main South Island wheat-growing districts autumn and early winter form the ideal sowing season for wheat, which fares best on a fine firm seed-bed. Experience has shown that over a wide range of country wheat responds well to a dressing of 1 cwt. of superphosphate to the acre.

For winter and spring feed, oats (which may .possibly be utilized for grain or chaff), should be sown not later than April or early May. Generally they respond profitably to 1 to 2 cwt. an acre of manure in which superphosphate is prominent. If the land has been under cultivation for a considerable period some nitrogenous fertilizer such as sulphate of ammonia may prove profitable as a supplement to the phosphate.

Any available green maize or millet should be turned into silage or hay before the first frosts occur. If a weight of green material sufficient to avoid undue loss in saving is on hand, silage is to be preferred to hay.

At times the growth made by lucerne during . the latter part of the season is grazed. The trampling resulting from such grazing favours grass, and so as a rule the grazing is inimical to the lucerne. This is especially so in districts of good rainfall, in which grasses often are the worst weeds troubling lucerne.

— R. P. Connell,

Fields Division, Palmerston North.