in] ECONOMISING POTASH 31 



about 16 Ibs of potash. Thus, in the ordinary way of farming 

 the amount of potash sold off is very small, only the potato crop 

 taking away any considerable amount. The bulk of potash is in 

 the crops which are fed on the farm, and it is not retained by the 

 animal, but passes out in the liquid excretions. 



It is therefore imperative that the liquid should be saved. 

 This is dealt with on p. 14. 



Root residues. When grass land or clover leys are ploughed 

 up decay sets in, and the potash in their roots, stems, leaves, etc. 

 becomes liberated. No exact estimate is possible of the amount, 

 but it is certainly considerable. A crop grown on ploughed up 

 ley or grass land, therefore, needs less potash than usual. 



The reserves of potash in the soil. 



Although potassic fertilisers are easily soluble in water, they 

 do not readily wash out from the soil, because they are absorbed or 

 "fixed" by some of the soil constituents. Wherever high farming 

 has been practised the amount of potash supplied in the imported 

 fertilisers, stable manure, or feeding stuffs may well have been 

 greater than the amount removed. There has therefore been 

 some accumulation in the soil, which can now be treated as a 

 reserve, and drawn upon for the needs of the crop. There are 

 two ways of doing this: 



1. Salt or sulphate of soda may be applied. 



2. The land may be limed. 



Salt. On any land known to benefit by kainit it is advisable 

 to try dressings of salt. The most suitable crops are mangolds, 

 cereals and grass land. 



Mangolds gave the following results at Woburn 1 : 



No 1 cwt 2 cwts 4 cwts 6 cwts 



Unmanured salt salt salt salt salt 

 Mean of 4 varieties, 



tons per acre 27-0 30-9 30-6 34-3 34-6 36-3 



All plots except the unmanured received 1 cwt nitrate of soda 

 per acre. 



1 Journ. Ray. Agric. Soc. 1908, 69, 355. 



