20 USE or FELDSPATHIC ROCKS AS FERTILIZERS. 



the feldspar, even in large amounts, had little or no effect on the 

 growth of the plants. The investigator concluded that mica is, if 

 anvthinff, a better source of i^otash than feldspar, but that neither 

 of these minerals supplies a sufficient quantity to make them worth 

 the slightest consideration so far as plant growth is concerned. 

 The only criticism of these experiments that might be offered is that 

 80-mesh feldspar powder is far too coarse to be used in pot experi- 

 ments. This point will be taken up more fully later on. 



The most important researches which have ever been published 

 tending to show that under certain conditions finely ground feldspar 

 is worthless as a fertilizer are those of von Feilitzen." This experi- 

 menter, like Xilson, worked on Swedish moor soils. He concluded 

 that ground feldspar is almost worthless as a fertilizer. The results 

 and conclusions are best shown by abstracting from a translation 

 from von Feilitzen's publications : ^ 



Potash, as is well kuown. is one of the necessary constituents of plant food; 

 consequently, if it is absent in the soil or only there in insufficient quantities, a 

 normal development of the higher orders of plants is not possible. According 

 to the researches of plant physiologists, it is particularly instrumental in the 

 formation and transport of the carbohydrates (sugar, starch, etc.), for which 

 reason potash plays such a prominent part in the manuring of potatoes, turnips, 

 and other root crops, but it is also required for cereals and all the other culti- 

 vated plants. Of late, comprehensive experiments have been carried out by 

 Prof. Dr. H. Wilfarth at the experimental station at Bernburg, with the view 

 to ascertain in what way the want of one or several of the necessary constitu- 

 ents of plant food intluenced the development and appearance of plants. On 

 this occasion he found that the want of potash caused a defective growth of 

 some of the vegetative parts, the leaves of potatoes, tobacco, buckwheat, and 

 beetroots assuming a speckled appearance.^ Certain clearly defined ijortions, 

 especially at the borders of the leaves, grew yellowish-white and decayed, while 

 the other parts retained their original appearance. These marks are often 

 very much like those caused by fungi and insects, but if examined more closely 

 it becomes evident that they can not be due to such causes. 



• In 1003 we made quite similar observations, when experimenting with clover 

 and timothy grass, and, as it should be of interest, I shall describe in short the 

 observations made by us. In 1902 a series of experiments were prepared in 

 plots of soil of 1 square meter each (about 1 yard square), charged with 

 rather well-decayed reed grass turf, poor in potash, in order to investigate 

 whether the potash in a mineral fertilizer, prepared in Sweden, was of any 

 mauurial value. As, by analysis, this fertilizer turned out to be finely ground 

 feldspar, we were prepared for an unfavorable result at the very outset. 



The fineness of the ground feldspar is not given, but an analysis 

 showed that it contained 8.15 per cent of potash. The experimental 

 series was made up of two plats, each fertilized as shown in the fol- 

 lowing table, and in ^Sliiy, 1902, they were sown with a clover-grass 



a Exp. Sta. Record, U. S. Dept. Agriculture. 1904. 10. .30. 

 6 How Deficiency in Potash Affects Clover and Timothy. 

 c Jour, fiir Landw., 190.3, No. 11. 

 104 



