PHOSPHORUS, ITS SOURCES AND USE IN PLANT FEEDING 69 



used on the wheat crop, we never failed to get large returns in the luxuriant 

 stands of clover that followed, though the effect on the wheat crop direct was 

 not so apparent as when the acid phosphate was used. But we invariably had 

 more difficulty in getting a good stand of clover after the use of the acid phos- 

 phate than we did after the use of the insoluble phosphoric acid. In our case 

 stock and stock food was the chief interest, and the wheat was only regarded 

 as a means for paying the expense of getting the land in clover. Where im- 

 mediate results only are sought it may be best to use the dissolved phosphate, 

 but where final results in the clover and grass are of more importance, then 

 it will be far cheaper and perhaps better to use simply the pulverized rock, 

 or what is known as "floats." As we have often said, where one can afford 

 to wait for the results he can get them with less expenditure of money in the 

 use of pulverized rock than in the dissolved article. This experience has 

 been verified by some experiments made at the Maryland Agricultural 

 Experiment Station and published in a recent bulletin of that Station. They 

 state that the best results were obtained, in the long run at least, from the 

 use of the insoluble phosphates. Not having this bulletin at hand we cannot 

 quote from it direct, but believe that we have given the sum of their results. 

 The fact is that no chemist can discover just what is taking place in the soil, 

 even with what may be put there in what he calls a perfectly soluble state. 

 The soil is a wonderful laboratory, in which the forces of nature are always 

 at work, making new combinations and bringing about changes in what we 

 put there. The carbonic acid of the rain water is nature's great breaker up of 

 combinations and former of new ones, and what exists in the soil in one state 

 today may be in a very different one tomorrow. It is always safe, then, for 

 the farmer to question his soil and to accept the results it gives him, for he 

 can find thus, for himself, things that no chemist can discover. In certain 

 sections of Eastern North Carolina observant farmers have long since found 

 that they got no results for the use of phosphoric acid in any form, but that 

 nitrogen and potash always gave them good results. Subsequent investiga- 

 tions by the Department of Agriculture have demonstrated that these farmers 

 are right, and that on their lands the chief need is for nitrogen and potash. 

 Then, since by good farming with the legumes they can get all the nitrogen 

 they need, the farmers on lands where phosphatic marls and rocks are found, 

 are in that happy condition where they need to purchase but a single form of 

 plant food in order to make and keep their lands perennially productive. 

 There may be other sections North and South, where similar conditions pre- 

 vail, and this makes it all the more important that farmers should experiment 

 to determine the manurial needs of their soils. How this is done we have 

 tried to explain elsewhere. 



