CALIFORNIA CITRUS CULTURE. 25 



FERTILIZATION. 



In the young orchards in all orchards a winter cover crop of vetch, 

 Canadian field peas, burr clover, or other vigorous legumes (vetch is 

 probably the best) is very desirable. This insures against washing of 

 the soil in case of heavy rainfall, supplies the needed humus, and also 

 adds to the soil the most expensive, and possibly the most deficient, soil 

 element nitrogen. The roots of this cover crop also liberate other 

 elements of fertility. The soil bacteria take the free nitrogen from the 

 air and combine it with the soil salts, when it is in form to be utilized 

 by the trees. This is emphatically the cheapest way to secure the 

 valuable and greatly needed nitrogen. We must have abundant water 

 for both the cover crop and the trees. This cover crop should be plowed 

 under not later than February, that it may be decomposed or converted 

 into humus in the early spring as the probable moisture at this season 

 promotes decomposition. To plow this under at so early a date and yet 

 permit the plant to reach its full development requires that the seed 

 of the cover crop be planted early not later than September. In case 

 of light rainfall in the autumn irrigation must be practiced, not only 

 as the seed is drilled in, but also when needed afterwards. In this case 

 broad, shallow furrows must be left so that irrigation can be accom- 

 plished whenever it is desired to water the plants. Some of our best 

 citrus growers advocate and practice the planting of cover crops in 

 summer, using at this season cowpeas. This may be wise in case one 

 has abundant water, especially in a young orchard, but in this case 

 we must be very careful that our trees are not robbed of the required 

 amount of water. I can but believe that this is a questionable practice. 

 The questionable practice of growing alfalfa in citrus groves is an 

 increasing one. This makes a heavy demand on the water supply. 

 Dr. E. W. Hilgard used to say that alfalfa hay was easily worth eight 

 dollars per ton to plow under as a fertilizer. Dr. C. G. Hopkins main- 

 tains that growing alfalfa, just to use to fertilize our orchards, is well 

 worth consideration. (See the Monthly Bulletin, Vol. I, No. 9, page 

 641.) 



Many utilize the space between the young trees by growing an extra 

 summer crop of some useful vegetable. In such case nothing is better 

 than beans, as these tend to make the soil loose and friable, and as these 

 are legumes, they really enrich the soil by adding nitrogen, as we have 

 already explained. Beans are also one of our most profitable field crops. 

 Many, however, grow no secondary crop, preferring to give the trees, 

 old or young, all the fertility that the soil possesses. 



As the grove reaches on toward maturity the presence of abundant 

 humus is more and more important, and so the cover crop must not be 



