PROCEEDINGS OF THIRTY-THIRD FRUIT-GROWERS ' CONVENTION. 255 



careful selection, varieties better adapted even to California and Ari- 

 zona conditions, and even in southern Texas, than all but a very few of 

 the imported varieties would give us. 



Last Tuesday I addressed a farmers' institute under the auspices of 

 the California Experiment Station, conducted by Professor Neff — a 

 gathering of people who were very enthusiastic on matters pertaining 

 to the Coahuila Valley. We distributed about eight thousand seed- 

 lings last spring and great quantities of date seeds, so that in the near 

 future we may hope to add to the wonderful resources of California 

 this further industry, of date-producing — in this country that is so hot 

 and so dry that it bids fair to give success to this work. 



MR. JUDD. We have with us other professors, and I would like to 

 hear from Professor Stubenrauch and Professor Mackie. 



PROFESSOR MACKIE. Mr. Chairman, and Ladies and Gentlemen : 

 I have scarcely prepared anything for this meeting except a very 

 receptive ear, which has been filled with very many good things. In 

 regard to my own work, it follows very closely that which was outlined 

 in the excellent paper read by Mr. Mills last evening, and a great deal 

 of it would simply be a repetition of what Mr. Mills has placed before us. 

 There is, perhaps, just one little matter which I wish to add to 

 what Mr. Mills said, and which interested me personally a great 

 deal, and that is in regard to the addition of humus to the soil 

 in California. It is my province to classify the soils of California, 

 get them into various groups and certain correlations, and in regard 

 to the humus of the soil the State is divided into two or three 

 groups. The soils of the southern portion of the State, as Mr. 

 Mills has told you, are deficient in humus. There are certain soils 

 throughout the San Joaquin Valley also in that class. The Sacramento 

 Valley soils have very little sand in them; sandy loam is about the 

 lightest soil we have, except where the rivers wash. In the Sacra- 

 mento Valley the humus problem is not quite so great as it is in the 

 southern portion of the State. The main problem in all these places is 

 to get a certain amount of humus to carry food to the plants, and two 

 ways are provided of supplying nitrogen to the plants. One, as we all 

 know, is by the cover-crop method, or getting it into the soil by means 

 of the bacteria on legumes. The other is by another set of bacteria 

 which also live in the soil and produce nitrates by direct oxygenation 

 of the hydrogen in the air. These can exist only where humus is 

 found in the soil in a healthy state; that is, free from improper sub- 

 stances which will destroy the action of the bacteria. It may be said 

 that the nitrates of the soil exist only where humus exists. That 

 means that wherever we can extend the humus in the soil we can 

 extend these two sorts of bacteria which form nitrates; and the growing 



