196 THE SYSTEM OF FARM- YARD MANURING. 



ok the additional portion of K converted into straw- 

 constituents ; then the alteration in the produce may 

 be expressed as follows : 



Corn. Straw. 



(K - ak) + (oK S* + ak st) ; 



that is, the produce of straw increases, while that of 

 grain diminishes. It is also evident, that where the St 

 constituents are in excess and the amount of K constitu- 

 ents is increased, then if K is proportionately deficient 

 there will be an increase in the produce of straw, and if 

 K is proportionately increased there will be a larger 

 produce both of corn and straw. 



As the constituents of K, with the exception of nitro- 

 gen and phosphoric acid, are also constituents of S, this 

 accession of produce in the field under consideration 

 will be also effected either by a supply of phosphoric 

 acid, or of nitrogen, or both together. 



If by this supply the closeness of the K particles in 

 the ground, or of the phosphoric acid and ammonia par- 

 ticles, is doubled, then under the most favourable cir- 

 cumstances the harvest may be doubled by the supply 

 ofK. 



If, on the other hand, the soil is deficient in St con- 

 stituents, any increase of nitrogen or phosphoric acid in 

 the ground will fail to exercise the slightest influence 

 upon the crop. 



It results from this, as a matter of course, that the 

 absolute or relative amount of straw, given by a field in 

 a crop of corn, will furnish no proof of the St constituents 

 in the soil : since, though two fields may be equally rich 

 in these constituents, the produce of straw depends upon 

 the quantity of K constituents in the ground : hence 

 the field which is richer in K, will, under like circum- 

 stances, give a larger crop of straw. 



The fact, therefore, that the fields at Cunnersdorf 

 and Oberbobritzsch yielded a like amount of straw, 

 cannot lead to the inference that these fields contained 

 an equal quantity of St constituents, since the corn 

 crops show that the quantities of K were unequal. The 

 harvests exhibited the following proportions : 



