SOIL FERTILITY QUESTIONS.

New Zealand Herald, Volume XLVII, Issue 14511, 27 October 1910, Page 7

SOIL FERTILITY QUESTIONS .

EXHAUSTION AND CONSERVATION. NEW THEORIES DISCUSSED. There are many people who while sitting.rln ■ ; comfortable: armchairs, and; "enjoying .the ~ good things of this world are yet imbued- . with • a pessimistic view of ; the eventful future of the food supplies, of the world., -They, take : a telescopic glance .at far dis- .:■, tant/times, and shake, their heads-despond-i . ■ > ingly. .The days will come, say they, when. >:; the earth will refuse to bring forth her in- > ■■; ■.-.> crease,- when lean ■ crops 'will-be-:followed' v by still leaner, and gaunt famine will '■stalk • -. through the world. '■'[-.'./ ] t Their, gloomy views are,based on the argil- . ment that • the crops which are produced in the . world remove r :larger .quantities of. plant foods from the soil than ajre. replaced, and.':'" %% as these plant foods are absolutely essential for the production and sustenance of- crops,. ■ ;■■-■■■■;■ 4fc must logically follow that, sooner or later, ;■:■:'' the depleted land . will lose its productive r '.-; power. ■. . t .■.■.:..■■':"■'."■■'.■ -• ',_.'• : Such speculations-as to what may come ;to' pass, although* of no practical concern to/us "';ij to-day,. are interesting, especially as .wer *,'&? should consider ourselves in some wise as.-, '.*< the guardians of' the: coming \ generations,,''.';"•",;; and, therefore,; it is a matter of consolatiom '-,..\? '; to us to think that we do not share the , ; : : forebodings of, our pessimistic .friends. .'' ■ ■",..• ; : J .':.f They seem t» us to leave but of consideration the inherent capacity of the soil, and., still more the power of science-which will find a way '' to open' the earth's breast and- <[%. find precious food." - ; . •'' - t If ■we take any ordinary good soil and' calculate the quantity of plant;food in thai, .. ~„•;' top 6in, we find that it contains sufficient : ■-. phosphoric »!iid for about 170 crops, potash) ■ ■■'■'■>■■:■ for 250 crops, lime for more than 2000 crops, magnesia for more than ■ 1000 crops, and the \?'-): layer below' contains Estill - larger "'.'quantities): of the mineral plant foods. These substances . . are to a, very groat' extent inert, and aregradually brought into use by -the, cultivation.! of the soil. It seems to have been a. wise : ':/; dispensation of providence that the mineral - ; : constituents in the earth's crust should 'only be available slowly, and as the result 1 of man's labour, otherwise their too rapid use* ~ [:_ before science laid a governing hand 'pet 1:.. ."7 them, might have been attended with dan- '. ger. • '-' . ;■•; ■■• ' ' ,■ I It is argued that North Africa, Italy, ar.d g Egypt, once grain-producing , centres, have long ceased to be so, and this diminution ia attributed to 1 soil deterioration by . constant! . ; cropping; but may it not with more justice '"'.■'?. be set down to more pregnant causes which prevented proper cultivation. -North. iAfricai was devastated when Carthage was destroyed by the Romans. Agriculture in Italy ]'ellt .... into decay when the? Roman Empire vast'- ... ;;v>; broken up by Attila's German hordes; whan-' .7-1 corn could be grown -in Egypt when, the.;:-•';" Mu3s\ilmans were sweeping through tike land' with fire and .sword? ;. . ■ iAs well might a future historian say that: the land in England is. impoverished >;.by) ; : cropping because the acreage under wheafe' '■■. has decreased during the last three decades ; •; by more than .1,000,000 : acres.. ' Take a glance at : the soils ;of Europe 1generally. The European;, soils have beoii .:■■:£ occupied for agricultural purposes for 1000, ■■•■■■■:■:..••" years or more, arid during that period have* ~ , been regularly cropped for grain and other - '-- produce. What do we find ?l The soils are' . -. now producing larger crops than ever \before r - " ~;': in consequence of improved methods of cul- ■:■';'■* tivation. . < According to' an extract from a report;'; ":"■:■ connected with this, problem, "an exhaustive investigation has been made of soils for the L; last 18 years in certain countries of Northern Europe in which crop yields have been _■ increasing, and likewise the soils of : the United _'~"' States including the older soils of the Eastern States and the newer soils of th» ' ■{_ Western States. - The results-, of ■'.; these' :, -.% analyses, published side. by side, show-; . p no sienificant difference in chemical' .'/: composition between the older soils.- of: ji Europe and 5 the newer soils oE the United States. Microscopical examinations of the soils fail to , show that the .- g* longer occupation of the sods of Europe haar changed noticeably the mineralogical charac- ~ ter of the soils. In is reasonable to info* ; , : , from the work that has been done thM ' \~i within historic times the occupation of the scils for agricultural purposes his failed to* ', :. noticeably change the mineral character ; ofi • - l the soil material upon which ,the,future.life-"-;' ..' of the nation must ultimately depend. Th* '■ reasons for this and the laws lof Nature, : -yS3 which permit the soil thus to bo contihu- i . ously occupied and used for mankind ': as >;,'- freely as the air, are complicated and'difficult "to understand, and offer profitable field of research for our agricultural colleges, and experimental stations,'; ~ - ' : ; 'rh