162 THE MONTHLY BULLETIN. 



matter but also nitrogen, and furthermore, because the experience in 

 growing legumes in orchards and with other crops indicates that there 

 is no detrimental effect produced by associating these plants together. 



Doth Doctors Kelley and McBetli have emphasized the great import- 

 ance of cover crops. When we have a good thing, we must continue to 

 emphasize it. I find some people opposed to cover crops, and here and 

 there one meets a grower who has failed to get a good crop with the 

 Melilotus clover. It is our experience that wherever a man knows how 

 to plant and use the Melilotus, he is very certain to get good results, and 

 when a man comes to me and says, "It is impossible on my soil to grow 

 a crop of Melilotus," I can not but feel that he has not used the right 

 method and possibly that we might help him to find the correct one. 

 Certainly, it is a fact that in the great majority of soils Melilotus can be 

 grown very successfully. 



It is true that Melilotus at the present time is not altogether what we 

 want, although it is the best thing we have. We really want something 

 better than INIelilotus. and this is one problem for the plant breeder. 

 Melilotus is slow growing in the fall and winter, and it is only when the 

 spring opens that it makes a good rapid growth. It may be possible, 

 and probably will be, for us to breed a type of this clover that will grow 

 more rapidly in the early winter season, thus producing a considerable 

 crop in the early part of the season. This would make it a very much 

 better winter cover crop than it now is. 



Aside from Melilotus clover, we have emphasized purple vetch to be 

 very good, and you may see samples of it at the Orange Show in con- 

 nection with our Station exhibit. We are not certain that purple vetch 

 is superior, or even equal, to the bitter clover or Melilotus, but it is a 

 rapid grower in the fall and early winter and gets ahead of the weeds. 

 It is a cover crop that should be tried out very thoroughly here and 

 there all over the State. 



In considering the use of winter cover crops, we should remember a 

 point brought out by Doctor McBeth in regard to their fixing and hold- 

 ing the nitrogen until the spring months come and the danger of leach- 

 ing away is past. This is another of the fundamental reasons for using 

 winter cover crops of this kind. 



Of the various plant food elements that are usually applied as fertil- 

 izers, nitrogen in California soils is by far the most important. From 

 what source the nitrogen should be taken at present would seem largely 

 to be a question of economy only. The one exception to be made to this 

 statement at present is in the use of nitrate of soda. The experiments 

 at the Citrus Experiment Station that have been under way for nine 

 years show clearly an accumulating injury from the continued use of 

 this material. Plats fertilized with nitrate of soda for several years 

 gave excellent results but later became badly mottled and began to fail. 

 After nine years their condition has become serious, no fruit of any 

 value being produced. It may be that the use of certain other materials 

 along Avith the nitrate of soda would have retarded this injury, but in 

 a region where the soils are practically all in some degree alkaline, it 

 would not seem a wise policy to add continually still larger quantities 

 of sodium. As nitrate of soda contains a dangerous element, its use in 

 the fertilization of citrus trees in California should be discontinued, 

 particularly as many other sources of nitrogen are available at as reason- 

 able a cost, such as dried blood, tankage, sulphate of ammonia, and 



