146 



SUCCESSFUL FARMING 



cent nitrogen, 8 per cent phosphoric acid and 4 per cent potash. In general, 



young trees are thought to require more nitrogen and a relatively smaller 



proportion of phosphoric acid and potash. 



In Florida there isa tendency to avoid so far as possible the use of 



organic manures, such as stable 

 manure, blood, cottonseed meal and 

 the like, owing to the effect such ma- 

 terials apparently have in the pro- 

 duction of the disease "die-back" or 

 exanthema. Sulphate of ammonia, 

 sulphate of potash and superphosphate 

 are very largely used. 



In California, on the contrary, 

 the tendency is to use organic sources 

 to supply the various elements so far 

 as possible. Experimental results in- 

 dicate that organic matter and nitrogen 

 are the most important elements to be 

 added in the fertilization of citrus 

 soils in California and minimize the 

 importance of potash and phosphoric 

 acid. Eight-year experiments show 

 no gain over checks by the use of 

 sulphate of potash with oranges and 

 very slight gains with lemons. Similar 

 experiments with superphosphate show 

 but slight gains over check plats, while 

 nitrogen plats give marked increase in 

 growth and yield. California growers 

 in general prefer stable manure to any 

 other fertilizer and are also using large 

 quantities of alfalfa hay and bean 

 straw, both plowed under and as a 

 mulch to supply nitrogen and organic 

 matter. 



The use of leguminous coveV crops 

 in citrus orchards to supply nitrogen 

 and organic matter is recognized as 

 good practice, both in California and 

 Florida (see above under " Cultiva- 

 tion"), and a considerable amount of 



the necessary nitrogen can be produced in this way at very slight expense. 



Pruning. Ordinarily orange trees are pruned very little beyond the 



moval of dead brush and water-sprouts, but this results in the formation 



a very dense tree with the fruit distributed over the surface. The inte- 



PRUNING AND ROOT TRIMMING OF CITRUS 

 TREE AT TIME OF PLANTING. 



