552 



REPORT OK OKFICE oF KXPKRIMKNT SPATIONS. 



by droiiiilils. Ivcliitivc lo llii' latter point, the ohscrv ations hroiijrht 

 out clearly (liat tlu' cll'oct.s ol" droiiolits on (Miltivatcd t rcc.'^ ai'c nion' 

 aj)i)an'iit the .succeeding' sea.son tlian durinji- the dry yeai- itself, 

 I*i()l"es.M)r \N'hitten's ol).sei-\ utions and nHMi.sureinents indicate that "a 

 mai'ked fallinji" otl' in heit^hl, ijfi-owth. and a generally de\italized con- 

 dition oi" the trees may he looked lor in uncultivated oichai'ds for a 

 year or two followiiiif an excessive autunui dioiioht." \lv holds that 

 in a dry sunnnei- cultivation should he continued until th<' crop of fruit 

 is mature or rain comes. In a wet summer and autumn, cultivation 

 should cease in that State al)out Aujj^ust I. 



The actual leni>th of time to continue cultivation in the orchard 

 will, of course, vary w'ith diti'erent conditions. In North Dakota, for 

 instance, where the winters are colder, the growing sea.son shorter, 

 and the rainfall less than in eastern United States, Professor Waldron 

 states* that cultivation should be continued much later in the season 

 to preserve all the moisture in the soil possible, since in soils lacking in 

 moisture the trees winterkill. Mulching the trees in late fall to main- 

 tain moisture during the winter in that State has been found of the 

 greatest importance. 



The reason why severe freezing injures appie roots and trees more 

 in dry soils than in moist ones has not been detinitely settled. Pro- 

 fessor P^nierson'" suggests, as the result of experiments along this line, 

 that it may l)e on account of the more pronounced freezing and thaw- 

 ing in such soils. Professor Bailey,'' on the other hand, points out 

 that there is evaporation of moisture from trees during the winter 

 season and, if the ground is very dr}', this loss can not be readily met 

 and the trees thereby "" freeze dry,'' a condition generally fatal. 



The amount of moisture in clean, cultivated orchard soils as com- 

 pared with the moisture content of the soil of orchards in grass is 

 contrasted in the table herewitli: 



Moisture content of soils in cultivated and uncultivated orchards. 



a Kansas Sta. Bui. 106. 

 & Nebraska Sta. Bui. 39. 

 « Nebraska Sta. Bui. 79. 



^Illinois Sta. Bui. 52. 



e New York Cornell Sta. Bui. 198. 



/New York Cornell Sta. Bui. 72. 

 ffUn tilled. 



A study of the data in the tal)le shows that in dr\' seasons clean cul- 

 tivation has a remarkable eti'cct in conserving soil moisture. An 



«Missonri Sta. Bui. 49. 

 ''Nc.rtli Dakota Sta. Bui. 49. 



'"Nebraska Sta. Bnl. 79. 



''New York Cornell Sta. Bill. 117. 



