I'l, \.\T TdNINS. 441 



The writer coiihl |)roceed to deal with the vast amount of 

 evidence jnit forward In- Hopkins. Kin<i, Hall. Hilgard and 

 Russell to rel)ut this theory of Whitney and Cameron's; but 

 since his intentinn was to only outline the theory so that the 

 hearing- of what is presently to follow will he aj^parent, the reader 

 IS sim|:)ly referred to the writings of those authorities. 



To come to the observation which it is desired to ])\'dcc on 

 record, the writer was, some time a,<ii\ enqao^ed in soil survey 

 work on the farm Ziunmielkfontein. in the i^'dliot District, when 

 he came across a virgin land that had refused to give a crop of 

 oats the first year it was under cultivation, and maize the second 

 year, excei)t where it w-as manured. The soil was an acid, grey 

 sandy loam, and o<i a tyjje that is known thronghout the district 

 for its poverty. Similar soils usually give out after about three 

 years' crop]>ing, l)ui they resjxjnd well to phosi)hatic manuring 

 wdiether applied as superphosphate, basic slag or bone meal. 



Knowing the soil to be po<^r. the farmer sowed it, in the tirs-t 

 instance, to <:)ats. As has already been stated, no crop was 

 reai>ed. 



The farmer then thought he would experiment. He 

 accordingly planted the land the next year with maize in three 

 w'ays, i-c, without any manure, with lime, and wdth bonemeal. 

 Unfortunately the farmer kept no records of quantities; but the 

 amounts of fertilizer ajjplied would itrobaldy l)e about 300 lbs. 

 per acre of lime aiul 200 to 250 ll)s. of rather coarse bonemeal 

 per acre. 



Where nothing was a])i)lied, the crop was an absolute 

 failure : likewise where lime was ai)plied. In both ca.ses the 

 plants urew to an average height of about 18 inches. Here and 

 there a plant tried to jn-oduce a cob: l)Ut none of them bore any 

 grain. 



Where. ht)wever, bonemeal was a])plied the plants grew 

 to an average of 5 feet in height, a:id bore rather small cobs, 

 wdiich were well covered with grain. It should be stated that 

 both lime and bonemeal were applied through the planter. 



The failure of the lime to eltect any improvement whatever 

 W'Ould seem to show that the acidity of the soil was not the 

 principal limiting (factor ; wdiile the action of the Ijonemeal. taken 

 in conjunction with the experience of the district that any kind 

 of phosphate would give increased vields on this type of soil, 

 would make it ap])ear tolerably certain that the bonemeal acted 

 through its pho.sphoric acid, and not through its nitrogen. The 

 analysis of this soil showed that it was deficient in nothing 

 except carbonate of calcium and phosphoric oxide. Of the 

 former it contained a mere trace, of the latter 0.035 pcr cent, 

 only, wdiich also furnishes further evidence that the bonemeal 

 acted through furnishing phos])horus as a i)lant-food. 



Attached hereto is a photograph ( ['late 10) which the writer 

 took of a portion of the held when the crop was ripe but un- 

 touched. Ooi the left-hand side, wdiere the man is standing, 



B 



