THE CHEMISTRY OF THE SOIL. 85 



nitrates thus formed in the summer, and depended upon whether the fallow 

 was succeeded by a wel or comparatively dry autumn. Should a wel autumn 

 and early winter succeed, the nitrates arc washed so far down into fche subsoil 



as fco he out of the reach of the crop, which then shows a very small return 

 for the previous summer fallow. 



The Etothamsted experiments also show that there is little or no nitrifica- 

 tion going on during the three months preceding harvest — that is during the 

 period of the plant's most active growth. The period of active nitrification 

 begins about midsummer, and continues with increased activity during late 

 summer and after the grain is harvested. The nitrates thus formed are 

 to a greater or less degree washed down into the subsoil during the rains of 

 autumn and the thaws and rains of late winter and early spring. Hence 

 the great importance of the use of nitrogenous manures in these countries. 

 The Etothamsted experiments show, further, that practically the whole of 

 the nitrogen supplied, as ammonium salts is nitrified during the season of' 

 growth of the wheat, and whatever is not removed by the plant gets washed 

 down as nitrate into the subsoil. 



\Vith us the condition of things is very different. During our mild winter 

 the wheat plant, once well started, is making steady and continuous growth 

 the whole time, from April or May, when the seed is sown, till December. 

 The months succeeding harvest are usually comparatively dry and warm, 

 and favourable to nitrification. The seed is thus sown, and the plant 

 germinates in land in which nitrates are abundantly present ; and as there 

 is practically no dormant period the plant gets the full benefit of this, at least 

 during the early stages of its growth, until it is well established. The 

 greater portion of the rain falls (at least in the principal wheat-growing 

 districts) during the winter months — June, July, and August — when it is of 

 the greatest benefit. If these months are dry, a failui'e in the harvest is 

 almost certain, unless rain falls in September or October. Nitrogenous 

 manuring alone is, therefore, of little benefit under our conditions. What 

 the wheat crop appears to need is an application of fertiliser to enable it to 

 make a vigorous growth at the outset, and to develop the root-system, which 

 latter property is possessed in a high degree by superphosphate, and this 

 is supplied by the application .of readily available phosphatic fertiliser 



The principle adopted by most of our farmers of applying with the seed a 

 small quantity of superphosphate is therefore a perfectly sound one, and 

 while applications of a complete manure may increase the yield as compared 

 with superphosphate alone, the value of the increase is not commensurate 

 with the additional expense involved in the other fertilisers. 



Other Cereals. 



Maize grows best on alluvial soils of good depth. Deep sandy or medium 

 loams with a clay subsoil retain moisture better than heavy soils, and are also 

 easier to cultivate. Heavy volcanic soils of basaltic origin are, however, 

 better than the lighter volcanic (granite) formations on account of their 

 greater fertility. 



Rye accommodates itself to lighter and drier soils — in fact, the poorest soil 

 is usually considered good enough for rye. 



Barley requires a light fertile soil, warm and friable, and grows most 

 strongly and produces the largest crops on land well tilled and heavily 

 manured. If, however, the grain is grown for malting purposes, the applica- 

 tion of excessive quantities of nitrogenous manures is to be avoided, as the 



