376 ANNUAL REPORT OF THE Off. Doc. 



than dimiuished. Insoluble phosphoric acid can best be made avail- 

 able by thorough tillage of the soil combined with the use of farm 

 manures and with green manuring and cover crops. The wise prac- 

 tice, then, in using phosphate fertilizers of low grade of solubility, 

 but high in per cent, of phosphoric acid total, is to apply them to 

 some hardy, strong feeding cover crop, as rape or turnips, and always 

 sowing with the cover crop some rye if it is expected to let the land 

 remain unplowed during the winter. 



We warn the farmer against the use to any considerable extent of 

 insoluble phosphates. AYhile it is true that the plant food may in 

 time be made slow^lj- available, yet the conditions most favorable 

 for its use are not usually present. Moreover, the same conditions 

 which will render the plant food in insoluble phosphate fertilizers 

 available will also liberate phosphoric acid which is already con- 

 tained in most soils in liberal quantities. We recommend as the 

 wise practice the use of high grade phosphates for the purpose of 

 feeding the immediate crop, and that the soil be n \de to give up 

 some of its stores of plant food by means of thorough Lillage and the 

 use of cover crops and manures. 



The potash required for general farm crops may at present be 

 most economically secured from muriate of potash. This is a form 

 of potash very acceptable to jjlants, uniform in composition, and 

 may be used in all cases except for isome special crops, as tobacco, 

 where the sulphate seems best adai)ted. Those soils which are 

 formed as the result of glacial drift seem to be well supplied with 

 potash, and upon glacial drift soils intensive tillage apparently gives 

 more marked results than it does upon those soils which are largely 

 Hlluvial in character. 



It has, in times past, been the dream of some experimenters, that 

 they would be able in time to figure out a balanced ration for plants 

 the same as we do now for animals. But this idea is now held by 

 but few. Indeed field fertilizer experiments are not nearly so popu- 

 lar in experiment work as they formerly were. We cannot as the 

 result of our experiments lay down any general rules, and say that 

 corn should be fed in this way and wheat in that way, because there 

 is always an unknown and uncertain element which enters in, viz., 

 the soil. 



To learn then just what constitutes a balanced ration for plants 

 we must know the soil and its capabilities. Having determined this 

 we are then prex)ared to proceed intelligently along certain lines. 

 The science and art of feeding plants are not fixed and definite. He 

 who would acquire a knowledge of the subject must study the plants 

 as they grow and he must be so in touch with nature that he can 

 understand the language of plants a& the good feeder understands 

 the language of animals, 



