LETTEK OF PEOFESSOE VOELCKER. 129 



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

 remarkably fertile soils resting on the old red sandstone formationj 

 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 Mm nedcr analysed defore soils 

 wMclh contained so much nitrogen^ nor do I find any records of soils 

 richer in nitrogen tlian 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 Oarse 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, j 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 quantity 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, contanis 

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

 86 lbs. 



" 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 Oarse soil It is this large amount of nitrogen, 



6* 



