LETTER OF PKOFESSOK VOELCKEK. 129 



me about a month ago. At the same time I enclose copies of two 

 remarkably fertile soils resting on the old red sandstone formation, 

 as analysed by myself some time ago, and also a series of soil analy- 

 ses made some years ago by Professor Anderson at request of the 

 Highland Agricultural Society of Scotland. 



" You will not fail to recognise a general similarity in the com- 

 position of your soils, and observe that they all contain large quan- 

 tities of potash, no doubt in the state of easily decomposable silicate 

 of potash. With the exception of No. 2, they also contain silicate 

 of lime, which in No. 2 appears to be entirely replaced by silicate 

 of magnesia. 



" The soils are not very rich in phosphoric acid, but still there is 

 amply sufficient to meet all the requirements of plants usually cul- 

 tivated on the farm. However, I cannot help thinking that phos- 

 phatic manures, especially for root crops, should be used liberally 

 on your soils, and guano and other ammoniacal manures more spar- 

 ingly, for you will perceive that all four soils are very rich in nitro- 

 genised organic matter. Indeed, I have never analysed before soils 

 which contained so much nitrogen, nor do I find any records of soils 

 richer in nitrogen than yours. 



" In No. 2 the proportion of nitrogen is smaller than in the three 

 other soils, which might have been expected, since there is not so 

 much organic matter. 



" In the soil from the Carse of Gowrie Dr. Anderson found 2 

 per cent, of nitrogen, which he considers a large proportion. Dr. 

 Anderson, referring to this constituent, says, 'The actually large 

 amount of this quantity may not be apparent when it is expressed 

 in fractions of a per cent. ; we must bear in mind that the weight 

 of the soil ten inches deep on an acre is, in round numbers, about a 

 thousand tons, and that quantitj will contain about two tons of ni- 

 trogen. It will further serve to illustrate its abundance to mention 

 that a crop of wheat, amounting to 36 bushels, with straw, contains 

 about 52 Ibs. of nitrogen, and a crop of Swedish turnips only about 

 86 Ibs. 



" In the least fertile of your four soils, and I consider No. 2 the 

 least fertile, in a purely chemical point of view, there is more nitro- 

 gen than in the Carse soil. It is this large amount of nitrogen, 

 6* 



