HOW CROPS ARE BUILT UP. 131 



Natural manures of the organic kind that have been in 

 the growth of vegetable or animal life, such as rich soil 

 from swamps, &c., leaf mould, bush scrapings, stable, 

 stockyard, pig pen, and poultry yard stuff, offal, 

 sawdust, &c., &c., supply some of the ingredients 

 that plants live on, but in still more varying quantities 

 than crops take them. Hence the use of composting, so as 

 to supply in the heap such other materials as may be 

 necessary, and in such form as may mix thoroughly with 

 the others in less or greater quantity in the proportions 

 required. It is a further advantage in using natural 

 manures that as they are broken up and decay in the soil 

 they make room for the development or spread of root 

 growth, and add enormously to the good results got from 

 purchased manures. 



The sources of manures available for Australian 

 agricultural purposes include : 



Bone in Various Forms. By breaking and grinding, 

 bones are made more readily soluable for the use of plants. 

 Bones supply phosphates and lime, and small quantities of 

 the other food materials of drops. Raw bone is most 

 valuable, next cooked bone. Bone ash and burnt bone are 

 least valuable as manure. 



Boiling Down Stuff. This is the refuse material from 

 boiling-down works, and contains all the substance of 

 sheep, cattle, &c., except the tallow, which is of no value 

 for manure. 



Offal from Slaughter-houses. When this contains 

 blood material, it is rich in ammonia in addition to the 

 other substances of animal life. It is valuable in propor- 

 tion to the less quantity of moisture in it. 



Stable, Cow-pen, Piggery Stuff. The value is 

 proportionate to the feed of the animals, and whether it 

 lias been wasted by exposure to he weather. 



Fowl Yard Stuff. This is very valuable, rich in 

 ammonia and phosphates, and other sutetances in propor- 

 tion. 



Ashes. Wood ashes contain potash, lime, and various 

 other substances of plant life, the value being dependent 

 on the quantity of potash. 



