18 



CITRUS FRUITS IN CALIFORNIA: 



lost, as loose, cloddy soil will dry out 

 almost as fast as though uncultivated. 

 The deeper and finer the top soil is 

 stirred the less water the tree will re- 

 quire. We strongly recommend the 

 thorough cultivation of citrus trees to 

 a depth of from 4 to 6 inches where it 

 is possible and that the orchard be 

 cultivated from four to eight times 

 between each irrigation. It is at times 

 impossible to cultivate more than two 

 or four inches deeo the first time after 

 an irrigation withou turning up mud, 

 but by setting the cultivator a little 

 deeper each time the ground is gone 

 over, a depth of five or eight inches 

 can be attained in six or seven culti- 

 vations. It is not best to do all the 

 cultivating at once as it should be 

 distributed over the interval between 

 the irrigations and in this way helps 

 to conserve the moisture in the sub- 

 soil which prevents the tree from suf- 

 fering. 



Fertilizers and Fertilization. 



It is best to begin the study of soil 

 fertility early as it is far better to 

 feed the soil before it is exhausted. 

 How best this can be done is a ques- 

 tion that has been puzzling our best 

 orchardists for a number of years, 

 and it will, no doubt, continue to do 

 so for years to come as there are so 

 many different soil conditions to con- 

 tend with that it is impossible to lay 

 down any rule that will apply in all 

 cases. 



It is a well known fact that nitro- 

 gen, phosphoric acid and potash are 

 the three chemicals required in the 

 soil to produce and sustain plant life, 

 and chemists have figured out just 

 how much -of each of these are re- 

 quired for the different plants and 

 trees, and how much the different 

 crops will take from the soil, yet, 

 when it comes to analyzing the soil 

 it will be found that most of the soil 

 contains a sufficient amount of all 

 these ingredients to produce crops, 

 and yet the tree may show that some- 

 thing is lacking. This is accounted 

 for by the fact that any analysis of 

 the soil will show what it contains, 

 but does not tell whether the plant 

 food is available, and unless it is in 

 such form that the roots can feed 

 upon it, it is useless and other plant 

 food will have to be furnished. For 

 this reason, the question of fertiliza- 

 tion can only be determined bv the 

 growth of the trees; at the same time 



it is not advisable to let the 4 orchard 

 go without any fertilization until it 

 begins to show a starved condition. 

 By applying about the same amount 

 of plant food that the tree takes from 

 the ground each year, it should pre- 

 vent the soil from becoming exhaust- 

 ed. Then if the tree shows by its 

 growth a lack of certain ingredients, 

 it can be supplied accordingly. It 

 has been our observation that barn- 

 yard manure applied in liberal quanti- 

 ties is one of the best fertilizers for 

 the promotion of growth, as it not 

 only supplies considerable plant food 

 but assists in making that already in 

 the ground more available by its ac- 

 tion in loosening up the soil. 



Cover crops of legumes, such as 

 peas, vetch, fenugreek and burr clover, 

 are also quite generally used and are 

 giving good results. They are sown 

 in the late summer or early fall, and 

 allowed to grow during the fall and 

 winter and are then plowed under in 

 the spring. The value of a cover 

 crop depends largely on the amount 

 of growth it makes and the manner in 

 which it is turned under. To get the 

 best results a legume should be se- 

 lected that will make a heavy growth 

 and then thoroughly turned under in 

 the spring. No cover crop, fertilizer 

 or manure, is of any particular value 

 on top of the ground. It must be 

 turned 'under or placed in the ground 

 where the rootlets of the tree can 

 feed upon it. 



Commercial fertilizers are used 

 quite extensively and with good re- 

 sults, but on account of the cost, a 

 good many growers do not use 

 enough per tree to get the best re- 

 sults. It is necessary to use some 

 commercial fertilizer in connection 

 with the use of barnyard manure or 

 cover crops in order to supply all the 

 ingredients necessary to properly 

 feed the tree. 



The planter should bear in mind 

 that no matter what form of fertiliza- 

 tion is used, satisfactory results Can- 

 not be obtained unless the soil is 

 properly cultivated as the rootlets of 

 the tree cannot take up the plant food 

 unless the soil is kept in condition 

 so that these feeders can continue un- 

 disturbed in quest of it. 



The Time to Plant. 



Citrus trees being evergreen they 

 can be planted at all seasons of the 

 year, although the months of March, 



