POTASH IN AGRICULTURE.

Otago Witness, Issue 2892, 18 August 1909, Page 8

POTASH IN AGRICULTURE.

In the experiments carried out by tihe Irish Department of Agriculture for the past seven years in practically every county in Ireland and a variety of soils, moory, sandy, limestone, loamy, and medium and heavy clay, it has been -found on an average that the increased yield due to the application of potash tnamtxes on the ordinary farm crops has lapore than repaid the cost of the manures u&*d, while in the case of the flax crop the application of potash manure*, whether in the form, of kainit or sulphate or muriate of potash, has proved more remunerative than any other manure or combination of manures. Moreover, the application of potash manures to the flax crop was observed to effectively check the disease known as "yellowing" in flax. This striking effect of potash salts in checking the ravages of plant diseases has been recorded by many observers. Mr A. D- Hall, at Rothamsted, has observed that tho wheat on the potash-starved plots is always subject to rust, even in a good season, whei? little disease is to be seen on the other plots normally manured. The same observer records the fact that mangels manured heavily with nitrogenous manures are particularly susceptible 'to tho attack of a leaf spot fungus — tTromyees betas — wfoioh, however, is much less severe on the plots receiving an abundant supply ,of potash. In mangel plants attacked by Phoma betee some of the larger outer leaves droop, ac if from loss of water, then turn yellow partially or entirely, and wither away. The foliage leaves, young and old, eventually die, and the bulb loses its food-producing organs and rots completely. In experiments carried out in 1906-1907 by the Irish Department of Agriculture tinder the supervision of Mr Thomas Wade, ( in County Kildare, the county in which 'th« disease first Showed its appearance, it was found that the plots manured with kauri' 'x>ntained the largest percentage of sound roots, and in the plot in which salt was used instead of kainit, the mangels were x>mpletely rotten, which goes far to prove that sal£* in a manurial mixture for mangels does not produce the same vigorous, hardy plants that can be obtained by the use of kainit. Under some circumstances th< application of large quantities of potash has a tendency to retard the process of nitrification; but in oxperimenis conducted by F.<D. Chester, Bulletin No. 98, p. 57, Pennsylvania Department of Agriculture, the author claims that , tho action of potash salts is to combine with the humates of jfchesoil and form compounds which are feadily nitrifiable. Dumodt found that potash salts alone or mixed with carbonate of lime increased

nitrification in 6oile rich in humus. It has also been shown that nitrifying organisms cannot multiply except there are present, among other elements, lime, phosphoric acid, and potash. It therefore -follows that not only is potash an essential link in plant life, but in conjunction with phosphates, nitrogen, and lime is one of the fundamental factors in the process of Nature, when we consider the relationship that exists between man and the plant and animal kingdoms. Plants feed anknals, and both supply . food for man, while the former make use of ihe excreted products of the two latter, anamals emd roan exhaling carbonic acid, which through the agency of sunlight is decomposed by plarrta, Use carbon being retained by plants to build up their structure, and the oiyigen liberated fox the respiraiion of roan and animals. Sufficient has been said in support of the view that potash plays no small part in the dbamges that take place in plant and animal nutrition, 'but as the ultimate object of ali experiments is the appiicajbion of scientific truths to the particular industry on which they have the moat direct bearing:, it is zno3t fitting o consider briefly how far the British Isles compare with other countries in the practical recognition of tihe fertilising value that has wthin the last 20 years been ascribed to potash <n> agriculture. "

The following- table shows the consumption 'of pure potash for agricultural purposes, calculated in pounds .per 100 acres of arable land of the respective countries at ijhe beginning and close of the -last decade. It will' be seen that Holland heads •the list with a consuroiption in the yawr 1908 of 976.71b pear 100 acres of arable land, Ireland, in spite of its millions. of acres of moorland, which is spacdaHy benefited by applications of potash, ~*e t<-nth on the list, while the United States occupies the eJevembh position in ielati\«- onsuropiioh of potash foe manuring purposes: —

The increased oonsuinipiion in all countries within the last cfeoade is sulking. Bind clearly shows, thai ih& advantages, of potash manuring arc being more and mere appreciated every y-cer. — Extract f on- a lecture br Mr George , Bryce, 8.A., A.8.C.5., F.C.S., at the Conge-ess of Applied Chemistry.