Feb. 2$. 1918 



Humus in Mulched Basins 



515 



The color of the oranges on the trees mulched with alfalfa and bean 

 straw was distinctly more golden than the color of the oranges on the 

 trees mulched with the other organic substances. The foliage on the 

 bean-straw and alfalfa-mulched trees was considerably denser and 

 greener than that on the other trees. 



Table VIII. — Effect of different mulching materials in basins on orange production. 

 Experiment III. Picked May, igij 



Basin treatment. 



Yield of oranges corrected on ba- 

 sis of previous performance of 

 trees. 



Pounds 

 per tree. 



Oranges 

 per tree. 



Average 



weight per 



orange. 



Alfalfa hay 



Bean straw 



Manure 



Barley hay 



Sweet clover hay 

 Bur clover hay. . 

 Pine shavings. . . . 



308 

 289 

 261 

 202 

 217 

 216 

 163 



881 



744 

 611 



497 



584 



530 

 402 



Pounds. 



350 

 389 

 427 

 407 



372 

 408 

 406 



On comparing the results of the humus determinations shown in 

 Table IV with the fruit production shown in Table VIII it is evident 

 that the percentage of humus in the soil does not correlate with the fruit 

 production. There is, however, a correlation between the fruit produc- 

 tion and the ratio of the humus content in 191 6 to that in 191 5, but such 

 correlation is not evident in Experiments I and II. 



Closer examination of the picking records in Experiment III showed 

 that the bean-mulched trees produced more first-class fruit of the more 

 desirable sizes than the trees mulched with any of the other substances; 

 the alfalfa-mulched trees were second in this respect; manure third; 

 and barley fourth; while the trees mulched with sweet clover and pine 

 shavings produced the least number of fruits of the first quality. 



It may be that some toxic substance is formed in the decomposition 

 of the pine shavings which might account for the poor condition of the 

 trees and for the small yield obtained from them; also the shavings prob- 

 ably had a deleterious influence on nitrification. Redwood boxes for 

 use in germinating Citrus seedlings proved unsuitable, because, when 

 the root tips came in contact with the wood, they promptly died. 



Oranges from the trees in Experiments I, II, and III were analyzed, 

 the analyses being made by the branch office of the Citrus B3--products 

 Laboratory in Los Angeles. The analyses did not bring out any con- 

 sistent differences in the fruits from trees receiving different fertilizer 

 treatments. 



