219 



But we must go beyond mere tillage. I was m Cali- 

 fornia this summer and took the time to make myself ac- 

 ({uainted with the methods used in the growing of citrus 

 iruit. I talked to many of the orange growers, and they 

 <'(mfessed to me that one of the big problems in California 

 is the maintenance of humus, the maintenance of organic 

 liiatter. Several of them admitted to me that in spite of 

 the use of green manures, they were not able to maintain a 

 .sufficient amount of vegetable matter in their soils. AVe 

 can understand why that should be so. because these irri- 

 gated soils are rich in soluble salts, they are rich in lime. 

 The temperatures are nniform, and when the irrigation 

 water is put on a certain type of soil, the bacteria which 

 Vv'ould destroy the fibre cellulose becomes so prominent that 

 the vegetable matter passes out as if burned in a furnace. 

 I\rr. McBeth has isolated a large number of these cellulose 

 destroying bacteria, and it is remarkable how fast they will 

 destroy the most resistant type of woody fibre. They are 

 active and prominent in these California soils under their 

 conditions. 



A brother of mine who is connected with the University 

 of California said, " I have been advising the citrus growers 

 in California for some time now not to depend on cover crops 

 plone, because cover crops are not going to maintain the 

 humus in their soils. I have been advising them to buy 

 cheap straw; they can buy wheat straw or second grade al- 

 falfa for a very few dollars a ton ; they can buy alfalfa as 

 low as $7. a ton and put that on a cover crop and plow the 

 v^7hole mass under." Ihdess they do that very thing, they 

 will not be able to maintain the organic matter in the soils. 



Changes in our hunuis here are not as far reaching, but 

 they go on just the same and the organic matter disappears 

 and the more thorough our tillage, the more rapid the dis- 

 appearance of the vegetable matter, and as soon as we cease 

 to maintain a sufficient supply of vegetable matter in our 

 soils, then we slow down the machinery which is responsible 

 lor the making available of plant food, and the crop then 



