234 EXPERIMENT STATION RECORD. [Vol.36 



must cooperate in their action, and that the effect of both is influenced and 

 controlled by the individuality of the type of cane and its accumulated energy. 



Chemical changes during the ripening of sugar cane, J. Mieasol y Jison 

 (Philippine Agr. and Forester, 4 (1915), No. 5-€, pp. 101-108). — A study of the 

 chemical changes occurring in ripening sugar cane is reported, and the results 

 of experiments with local Philippine varieties are presented. The analytical 

 data are given in tables. 



It was determined that during the ripening period a point is reached when 

 the purity is very high, the sucrose content at its maximum, and the reducing 

 sugar at its minimum, and that sugar made from the juice at this stage is of 

 high grade. It was observed that after this point is reached and maintained 

 for a length of time depending on the variety, the soil, and climatic conditions, 

 the purity and sucrose content of the cane decrease and the reducing sugar 

 increases. The upper third of the cane was found to contain the least sucrose 

 and the most reducing sugar, together with a low degree of purity. It is stated 

 that the sugar produced from a given area of Los Banos White cane by a 

 modern mill is of more than twice the value of sugar obtained from the same 

 area by native processes. 



A comparison of annual cropping, biennial cropping, and green manures 

 on the yield of wheat, B. A. Madson (California Sta. Bui. 270 (1916), pp. 3-U, 

 fig^ ^)_ — This bulletin is an amplification of the results obtained from cereal 

 investigations reported in Bulletin 211 (E. S. R., 24, p. 637). A study is made 

 of the effect of continuous cropping, alternate cropping, and fallow and green 

 manuring on the yield of wheat and on the soil. 



Continuous cropping rapidly decreased the yield of wheat to a point below 

 profitable production. Fallow was found to be the most effective means of 

 maintaining the productiveness of semiarid soils, although the use of green 

 manure crops increased the yield above that of continuous cropping. A decided 

 difference was noted in the effect of different cover crops upon wheat production, 

 the outstanding feature being that a cereal should not be used as a green manure 

 in a cereal rotation. 



The organic matter added to the soil from a green-manure crop seems to be 

 lost through oxidation the following summer, and the humus content of the soil, 

 or the humus nitrogen content, does not appear to be increased. The favorable 

 effects of green-manure crops must therefore be attributed to other causes than 

 the increase of humus in the soil. Frequent fallowing will probably deplete the 

 humus content of the soil, although it greatly stimulates production. 



The irrigation of wheat, F. S. Hakris (Utah Sta. Bui. U6 (1916), pp. S-32, 

 figs. 22). — This bulletin gives the results of irrigation experiments with wheat 

 extending over a period of four years. The general literature on the subject 

 is reviewed, together with 17 bulletins published by the Utah Station dealing 

 with the irrigation of wheat. The experiments were divided into two groups : 



(1) The plats to which varying quantities of water were added weekly, and 



(2) the plats receiving a uniform amount of water at each of four fixed stages 

 in the growth of the crop. These stages were (1) when five leaves had de- 

 veloped, (2) when the plants were just preparing to head out, (3) when most 

 of the plants were in bloom, and (4) the dough stage. Some of the more strik- 

 ing results are as follows : 



The highest yields were obtained with three irrigations of 5 in. each applied 

 at the first, second, and third stages of growth. Irrigation water applied after 

 the grain was planted but before it was up and that applied after the dough 

 stage decreased the yield. If only one irrigation is to be given it should be 

 applied at the first stage of growth. The date of maturity of wheat was 

 retarded by excessive irrigation. Economy in water was increased by the use 



