110 STATE BOARD OF HORTICULTURE. 



In regard to the implements to be used, the orchardist must 

 exercise his best judgment and consider the nature of the soil to 

 be worked. There are a large number of good cultivators on the 

 market, some adapted to heavy, others to light, and others to 

 gravelly soil. The orchardist should ascertain those best suited 

 to the re(|uirements of his particular work, and secure them. 



CULTIVATION AND IRRIGATION.* 



The orange tree is a native of tropical forests, where it 

 obtains warm soil and abundant moisture within easy reach. 

 Its successful culture in the countries like California, which 

 lack summer rains and moisture-laden atmosphere, is neces- 

 sarily to some degree artificial and a notable triumph of modern 

 horticulture. In order to achieve the highest results, it becomes 

 more and more essential that the grower shall keep the soil in 

 the most perfect condition, shall apply all needed water and 

 plant-food in sufScient but not in excessive amounts, and shall 

 pay especial attention to keeping the feeding roots as low as 

 practicable and to preventing the formation of what is called 

 "hardpan," but is only the well-known "plow-sole," aggra- 

 vated by shallow irrigation. 



"Hardpan," some growers say, appears now where it was 

 never before known. The fibrous roots of orange trees run 

 along its surface, and thus are subject to every vicissitude. It 

 often happens that what orchardists call " hardpan" is only 

 the firm layer of soil caused by uniform cultivation, or plow- 

 ing, whether deep or shallow. The depth to which soil is 

 stirred should vary from year to year; eight inches, twelve 

 inches, ten inches, fourteen inches, and then eight inches again, 

 would put an end to much of the present outcry against 

 " hardpan." Cultivator teeth should also be kept sharp, and 

 should be "set down" to various depths so as to prevent the 

 formation of " plow-sole" of any description, and to assist in 

 breaking up that which former neglect has caused. 



Very few orange groves have been planted upon true "hard- 

 pan," and if so planted have seldom succeeded. Only a few 

 trees, such as our native oaks, are capable of thrusting roots 

 through the iron-like layer of natural subsoil that is properly 

 termed " hardpan." AVhen found to exist, it should be deemed 

 sulficient to delmr citrus culture, unless so thin that, by boring 



*.T, W. Mills, in University (jf California Bulletin No. 138. 



