Natural Deposits of Potash in Germany. 411 



impressed with tlie iraportauce of potash-salts in agriculture ; and 

 for this reason I speak quite as frankly of the uncertainty attaching 

 to the subject as I would gladly speak of any definite result. 



What we require for the present is an extensive series of experi- 

 ments with these potash-salts on the croj)S most likely to be 

 benefited by them — grown upon soils which do not, like clay, con- 

 tain, as a rule, a good deal of potash. I would suggest for practical 

 experiment the following crops, — turnips and swedes, and then potatoes 

 and clover. I would especially recommend potash-salts for light, 

 sandy soils. Those soils are generally deficient in potash ; and I am 

 not at all sure that a good deal of the disease in turnips, and root-crops 

 generally, is not due, in a measure at least, to the almost exclusive use 

 of superphosphate of lime as a manure on light land. The disease in 

 tm-nips is far less conspicuous in light land when only half a dressing 

 of superphosphate is used, and half a dressing of common farmyard 

 manure. In farmyard dung, and in liquid manure, we have a consider- 

 able quantity of j)otash ; and in light soils I believe potash must 

 be supplied in one way or other. It is on soils of that character 

 that clover frequently fails. I am not prepared to say that clover 

 sickness is in every instance caused by the absence of potash ; but 

 certain it is that potash must be present in the soil, or the crop will 

 not grow luxuriantly, Potatoes likewise require a considerable addi- 

 tion of potash on sandy soils. There is a greater chance of potash 

 being removed under the cultivation of potatoes than when corn-crops 

 are grown. 



In looking at the results which potash-salts have produced, I was 

 struck with some analyses of Dr. Grouven of Salzmunde, the director 

 of an agricultural experiment station, as we call establishments in 

 Germany similar to that of Mr. Lawes in England. Dr. Grouven 

 analysed, some years ago, the ash of sound clover and of diseased 

 clover. In 100 parts of the ash of sound clover he fomid potash 35'5, 

 or 35 T, and of soda 7 ; in 100 parts of the ash of diseased clover he 

 found 3'32— that is, in round numbers, only one-tenth as much potash 

 — and of soda 8"7. He likewise analysed the ash of sound, of partly 

 decayed, and of very rotten beetroot. In 100 parts of the ash of 

 sound beetroot he found 30-5 of potash, 2-23 of soda, and 1-76 of 

 magnesia : in the ash of that partly decayed he found 26'78 of potash, 

 •73 of soda, and 43 of magnesia. The ash of the diseased roots con- 

 tained only 19 per cent, of potash. Now from these interesting 

 analyses I think we may derive the useful lesson that, unless there 

 is potash present in the soil, our roots arc liable to get diseased: 

 and for this reason it is that I would especially suggest extensive trials 

 with potash-salts for root-crops. 



These, then, are the principal points which I intended to bring 

 under your notice to-day. I may observe, in conclusion, that some of 

 the crude salts are now on their way to England; and Mr. Frere 

 will no doubt, in due time, report upon the results which he hopes 

 to obtain from a number of experiments that he is about to try. I, 

 too, have instituted some experiments that I shall report upon at a 

 future time. 



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