The War May Mean A Shortage Of Fertilisers

New Zealand Journal of Agriculture, Volume 61, Issue 1, 15 July 1940, Page 11

The War May Mean A Shortage Of Fertilisers

By—

C. R. TAYLOR,

Fields Instructor, Whakatane.

But Your Stock Provide Tons Of Free Manure Waiting To Be Spread With The Harrows

Under modern wartime conditions shortages inevitably occur in a country so dependent on imported necessities for full production from farms, and it becomes essential to adjust methods to secure the maximum results from available supplies. This is particularly necessary in the case of fertilisers, which have become so important a factor in grassland farming, and one of the immediate adjustments required is to ensure maximum production from supplies now in sight and possibly becoming less in the future.

HOW is this to be achieved? In the first place, refrain from topdressing pastures which do not pay a material dividend for this outlay. All farmers know that certain pastures, say, of the reyegrass-cocksfoot-white clover type, respond well to topdressing, but there are others of a brown-top-vernal character lacking in a fair measure of. clover growth which do not respond sufficiently to cover the cost of the fertiliser used. In the latter circumstances it is clearly uneconomic to topdress such pastures at any time, but in time of war it amounts to nothing more or less than criminal waste. Far better would it be for the farmer and the country if such unresponsive pastures were either renovated by severe harrowing and oversown with productive species or else ploughed and resown to permanent pasture or cropped for a period. In no other way can real benefit result from the topdressing applied.

Use of Harrow

Another method of effecting economy in topdressing is by the use of the grass harrow in the regular spreading of animal excreta. Both the urine and solid material contain significant

amounts of available plant food in the way of nitrogen, phosphoric acid, and potash, to say nothing of the important trace elements, and when these are evenly distributed at regular intervals over the entire paddock great assistance is rendered to the pasture plants in their ' efforts to produce growth. ' I'g

Every farmer knows this to be perfectly true, for has he not observed the phenomenal vigour of plants in the vicinity of dung patches and the areas* which stock have urinated? Surely such observation tells its own story in indicating the vast potentialities for achievements in a wholly costless product. Why not make more

use of it, especially at a time like the present?

Great Value of Animal Deposits

If still a little more persuasion is required to make farmers generally realise the . great value of the voided products of livestock it may be stated that scientists- have estimated that in one ton of cow manure there is phosphoric acid . equivalent to 281 b of superphosphate or slag, potassium equal to 251 b of kainit (potash)', and nitrogen to the value of 201 b of . sulphate of ammonia. ' \

Assuming, therefore, that a mature cattle beast voids 10 tons of material a year, which is a very fair average, and that the average carrying capacity of a farm is, say, two acres to a cow, then the return to the soil per acre of costless plant food in the equivalents mentioned above is as follows: Superphosphate l{cwt. Kainit lj-cwt. Sulphate of ammonia .. lcwt. Where, on the better-class country, carrying capacity is higher than that referred to, the return of plant food is, of course, also correspondingly greater. .

Maintenance of Fertility

In addition to the actual minerals supplied to a soil (superphosphate, potash, and other plant foods) through the conscientious use of the harrow on grassland, it must also be remembered that a huge quantity of humusforming material’ is also made available for the maintenance of the soil fertility in the broadest sense. This is vitally important, as humus encourages essential bacteria, retains soil moisture at an optimum level where drainage is satisfactory, and also makes possible the best utilisation of the artificial fertilisers used.

To bring home to farmers more fully the significance of this- statement one might mention that the Sahara Desert is a soil from , a geological point of view and yet it is sterile, that is, it will grow nothing. Why? Not merely because it is a waterless waste (although moisture is, of course, vital), not merely because it lacks applications of artificial manures (for all the manure of this type in the world