Harry F. Clements 469 



discontinued, the tensiometers are removed from the field, and the 

 sheath moisture is used as the guide to further irrigations. Such a crop 

 would not be irrigated until the moisture level dropped to approximately 

 79 per cent. An irrigation would be applied and a new, lower level set 

 up, say 76 per cent. Obviously, if the moisture level of a crop is low 

 throughout the second season, this crop has been ripening already and 

 would call for a much-reduced ripening period. In any event, when 

 the final moisture level of 73 per cent is reached, the crop is harvested. 

 While the moisture level is dropping, the nitrogen level drops and the 

 primary index rises. However, the dominant criterion of ripened cane 

 is the moisture level of 73 per cent. This must be arrived at gradually. 

 Ripening is not effected if the crop is simply dried out. 



Now, as should be the case, if the crop log enables us to follow the 

 welfare of the crop, it should enable us to focus our attention on the 

 needs of a crop, and therefore should result in increasing yields. In 

 some cases we have saved substantial outlays in fertilizers. In other 

 cases, however, we have used more fertilizer. The important thing, 

 however, is that we have not only increased the tonnage of cane pro- 

 duced but have improved the quality of that cane with a resulting 

 increase in tons of sugar produced per acre per month. 



Finally, we are learning from the crop log that if we maintain the 

 moisture levels where they should be through proper timing of irriga- 

 tion as well as fertilization and weed control we approach more closely 

 each time the maximum production possible for the atmospheric energy 

 available to us. 



REFERENCES 



1. Clements, H. F., Hawaiian Planters' Record, 44:201 (1940). 



2. , Hawaii Agr. Expt. Sta., Biennial Rpt., 34 (1944-46). 



3. , Rpt. Hawaiian Sugar Techn., 6th Annual Meeting (1948). 



4. , Akamine, E. K., Shigeura, G., and Isobe, M., Hawaii Agr. 



Expt. Sta., Biennial Rpt., 108 (1944-46). 



5. , and Kubota, T., Hawaiian Planters' Record, 46:17 (1942). 



6. , and Kubota, T., Hawaiian Planters' Record, 47:257 (1943). 



7. , and Moriguchi, S., Hawaiian Planters' Record, 46:163 (1942). 



8. , Shigeura, G., and Akamine, E. K., Hawaii Agr. Expt. Sta., 



Biennial Rpt., 120 (1946-48). 



9. Richards, L. A., and Weaver, L. R., /. Agr. Research, 69:215 (1944). 



