46 PARA RUBBER. 



Herbaceous Plants. 



Herbaceous plants can be best grown from the first to the fourth 

 year on account of the abundance of light which they are able to 

 obtain and the relative freedom of the soil particles from the roots of 

 other plants. The plants which can be used are Crotalaria striata, 

 D.C., C. laburnifolia, L., C. incana, L., Cajanus indicus, Spreng, 

 and species of Indigofera and Cassia. These plants are shrubby in 

 habit, grow to a height of one to five feet, and will stand pruning at 

 intervals of four to six months. Trailing or creeping plants such as 

 the groundnut and species of Vigna can be successfully grown and 

 also the sensitive plant. All these plants give a good cover to 

 the soil and help to keep the weeds in check and produce large 

 quantities of organic matter rich in plant food. Space forbids a full 

 account of this subject, but the following facts are of interest as 

 showing the weight of green material obtainable and the composi- 

 tion of several species : — 



Weight of Organic Time between Sowing 

 Name of Plant, Matter per Acre. and Uprooting. 



Crotalaria striata . . 20,244 lb. . . Ten months. 



Vigna. . . 12,092 ., . . Four months. 



Pondicherry groundnut . . 4,692 „ .. Five months. 



Composition of Various Green Plants, in the^Fresh State. 



Nitrogen. Potash. Phosphoric Acid Lime. 

 Name of Plant, Per Cent. Per Cent. Per Cent. Per Cent. 



Crotalaria striata ..0-7 to 1-0.. 0-47 .. 0-154 .. 0-210 



Vigna ..0-6 .. 0-738 .. 0-177 . . 0-727 



Pondicherry groundnut 0-914 .. 0-493 .. 0-155 .. 0-242 



It is interesting to work out what the equivalent of 15, 000 lb. 

 of green manure of Crotalaria striata is from a purely theortiical 

 standpoint. 



According to the above analyses it is approximately equal to 

 a manure of the following composition : — 



lb 



Castor cake . . 

 Blood meal 

 Nitrate of soda 

 Basic slag . . 

 Potassium sulphate 



500 

 500 

 140 

 115 

 140 



If the whole of the material is to be used, it should be buried with 

 lime or basic slag around the trees or forked in, as previously 

 explained. During its decomposition it leads to the liberation of 

 large quantities of plant food, which would otherwise remain in a 

 latent stage for many years. 



