186 EXPERIMENTS UPON GKASS LAND 



12-51- 



10 



7-5 



Plot 



4-2 3 II 14 



FIG. 39. Percentage of Centaurea nigra in the Herbage of the Grass Plots. 

 First Crop, Season 1903. 



Unmanured* 



Minerals only. 

 4-1. Superphosphate. 

 8. No Potash. 

 7. Complete. 



Nitrogen only. 



5. Aram. -salts. 



17. Nitrate Soda. 



Nitrogen and Minerals. 

 4-2. No Potash 



9. Complete .. 



11. Excess N. J ' 

 14. Complete; Nit. Soda. 



