20 



AUSTRALIAN AGRICULTURE. 



which affords an easily understood basis for calculation 

 and comparison : 



The Clay and Iron. Clay in soil, though not a plant 

 food, is useful to a certain degree, as giving closer texture 

 and capacity for retaining moisture. Iron may be healthy 

 for plant growth, or it may be injurious. Tests to get at 

 the state of the iron are very useful. 



Lime is present in all useful soils. It exerts marked 

 effects in preparing the food of plants. When it is almost 

 absent, or the proportion is low, say less than is represented 

 in the analysis as '2, that soil is very slow in yielding 

 crops, and the indigenous vegetation is poor. The applica- 



Soil analyses, and the analyses of water, plants, inilk, and sub- 

 stances generally of use in agricultural practices, including manures, 

 are dealt with fully in the author's work on " Helpful Chemistry for 

 Agriculturists," 4s., Batson and Co., Clarence-street, Sydney, and all 

 booksellers. 



t The standard 10 is a perfect soil for absorbin * and retaining 

 moisture. 



