363 



MAIZE 



CHAP. 

 VIII. 



and it is likely that chemical action eventually takes place which 

 renders a part at least of their phosphate insoluble and there- 

 fore of no value as plant-food {Holm, i). 



Steamed bone flour is more readily soluble than bone-meal. 



334. Basic Slag Alone. — At Koedoespoort, Pretoria, on 

 sandy soils poor in lime, Prof. Watt found that a dressing 

 of basic slag was beneficial to the leguminose crop grown in 

 rotation with the maize {Watt, R. D., 2 J. At Potchefstroom 

 the average yield for three years with the use of basic slag was 



Fig. 125. — Effect of basic slag on maize (cf. Fig. 126). 



8 muids 106 lbs. per acre, and the net gain 17s. 5d per acre 

 {Holm, I). 



335. Nitrate of Soda Alone. — This is a very soluble manure 

 and is apt to leach out in the drainage, so that in some climates 

 there is little or none left for the following year ; but with the 

 dry winters of South Africa some residual value may remain 

 for the succeeding crop. Though an important element of 

 plant-food, experiments show that the application of this 

 manure is not always profitable. As it is one of the most 



