172 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



yielded the least, while the li*rhtly i^runed trees have yielded the 

 lartjest crops of tlie best fruit. Tlie practical results of these experi- 

 nuMits have been to check, rather decidedly, the tendency among citrus 

 growers in California toward heavy pruning. 



The furrow system of applying organic fertilizers in citrus or- 

 cliards was introduced as a result of a study of similar methods at 

 Bahia, Brazil. This method consists substantially of placing stable 

 manure, alfalfa, bean straw, or such other organic material as may 

 be used for improving soil conditions in rather deep furrows that 

 are made a short distance from the trees and then covering it with 

 soil. In one plat of citrus trees where this investigation was carried 

 on, the trees in the section where stable manure was applied in fur- 

 rows at the rate of 10 cubic feet per tree, compared with others 

 Avhere a similar quantity w'as applied broadcast and plowed under 

 in the ordinary way, showed an improved physical condition which 

 was very striking and apparent to every observer, and these trees 

 produced in the year following the application more than four times 

 as much fruit as the trees to which the application was made in the 

 usual way. The results of the tests made along this line have been 

 so striking and so convincing to the growers that the furrow method 

 of using manure or other organic fertilizing material has now become 

 practically universal in southern California. The available evidence 

 demonstrates that 5 cubic feet of manure in the furroAV is as efficient 

 as twice that quantity when broadcasted and plowed under in the 

 usual way. During the year 1919 the saving of organic manures 

 in California citrus orchards was estimated by the fertilizer dis- 

 tributors in that State to have amounted to more than $1,000,000. 



There have been many commercial applications of the results of 

 this work. Growers in California are keeping tree-performance 

 records on more than 50,000 acres of citrus fruit. These records are 

 utilized by the growers for the purpose of locating superior trees 

 as sources of bud wood for propagation, for finding undesirable 

 trees of inferior strains for top-working, for systematically giving 

 the trees in the orchards individual care in regard to pruning, fumi- 

 gating, spraying, or other necessary attention and treatment, and for 

 determining the results of cultural practices, such as fertilization, 

 irrigating, and other factors of orchard -management. These records 

 are voluntarily turned over to the bureau representatives for their 

 use. 



NUT-PRODUCTION INVESTIGATIONS. 



Most of the work now in progress on pecans represents long-time 

 investigations. The activities include a continued study of varieties 

 and their relative merit and adaptability to different conditions and 

 certain important cultural studies, such as cover crops and other 

 means of soil improvement and maintenance, the use of fertilizers, 

 tillage, etc. Extended observations have also been made on the 

 premature shedding of the nuts, with a view to determining, if pos- 

 sible, the cause and prevention of this phenomenon. One experi- 

 mental plat in the vicinity of Putney, Ga., has been equipped for 

 irrigating, the object being to determine the influence of increased 

 water supply during periods of drought. However, since the in- 

 stallation of this irrigating system, there has been such an abundance 

 of rainfall as to make the application of water unnecessary. 



