68 Journal of the Department op agriculture. 



Caye Cross Phosphate is a material which has been put on the 

 market recently in limited quantities, and a good sample may contain 

 about 2 per cent, nitrogen and 22 to 23 per cent, phosphoric oxide, 

 both in a good form apparently. At the present market value of 

 bone-dust, this material is worth about <£10 per ton (if of good grade, 

 as above). 



(c) Potash Fertilizers. 



Karroo Sheejj Manure or Karroo Kraal Manure is the material 

 dug out of the old kraals in the sheep areas. Most of it is many years 

 old, so that a large part of the organic matter has decayed, and the 

 material left is generally mixed with more or less earthy matter. It 

 is much richer than ordinary farm manure, and contains on an 

 average 20 to 30 lb. nitrogen, 15 lb. phosphoric oxide, and 60 to 

 100 lb. potash per ton. It also contains a good deal of organic matter, 

 but iisually in a rather inactive form, in the case of very old kraals. 

 Karroo sheep manure is essentially a potash fertilizer, and still a 

 very cheap form of potash in spite of the fact that its price has 

 advanced considerably of late. It can be purchased to-day at £5 

 per truck load of about 8 tons f.o.r. at various Karroo stations, and 

 railage to stations near Capetown will cost about £4 to £5 per truck. 

 Thus it will cost the farmer at most 25s. per ton, which is probably 

 not more than the value of the nitrogen and phosphoric oxide alone, 

 even allowing a reduced value for nitrogen. This means that the 

 potash costs nothing. 



The coarse, lumpy material should be broken down to a finer 

 condition before applying to the soil. This will pay the farmer better 

 than purchasing fine sifted Karroo manure in bags. 



Kraal Ash is obtained by burning Karroo sheep manure. Most 

 of the organic matter and all the nitrogen is lost in burning, and the 

 ash remaining contains on an average 2 per cent, phosphoric oxide 

 and 12 per cent, potash, as well as a certain amount of carbonate of 

 lime. It seems to us that the burning of the manure is an unfor- 

 tunate practice, and one not to be recommended, for it amounts to a 

 deliberate destruction of a considerable portion of its plant-food 

 value. 



It is, however, an economical source of potash, as it costs only 

 £2 per ton f.o.r. at stations near Capetown. Thus the cost of the 

 potash, after allowing for the phosphoric oxide, is 2s. 3d. per unit. 

 Kraal ash is probably best used on acid soils. Its continued use on 

 soils well provided with lime may have a harmful effect in the end, 

 on account of the alkaline salts of potash and soda present. 



Sulphate of Potash, Muriate of Potash, and Kainit are potash 

 fertilizers obtaine'd from the huge salt deposit at Stassfurt, in 

 Germany. They contain respectively about 50 per cent., 45 per cent., 

 and 12 per cent, of readily available potash, but even at pre-war rates 

 are much more expensive forms of potash than our local products. 

 Of the three, the sulphate is the most preferred. 



[To be concluded in next month's Journal, when systems of 

 mgnuring, time and methods of applying manures, use of lime, and 

 manurial experiments in the vineyard will be discussed. — Editor.] 



