TIIIRTY-FOrRTH FRUIT-GROWERS ' CONVENTION. 



133 



fertilizers can not have their full effect, and may even cause some injury 

 in puddling or causing- the soil to run together, as well as burning it out, 

 often leaving it worse off than before. To offset this effect of com- 

 mercial fertilizers, or to retain the fertility of the orchard or vineyard 

 witliout them, the incorporation of organic matter, or humus, in the 

 soil becomes a necessity. To do this, and at the same time increase the 

 iiitrogen content, the growing and plowing under of green manure, or 

 leguminous crops, has proved by far the most efficient means. However, 

 the application of barnyard manure has been highly satisfactory for 

 the purpose of increasing the humus in soils, as well as improving 

 its general tilth. The action of this increase in humus in the soils, 

 by either plowing under green manure crops or the. application of 

 barnyard manure, is seen in the improved tilth of the soil, and most 

 especially in the increased capacity of the soil to imbibe and retain the 

 optimum water content, the quantity of water necessary for best crop 

 production. This improvement in the water carrying capacity of 

 the soil in turn tends to render more soluble, or available, the plant food 

 already there, and to replace from below the (piantities removed from 

 the top soil by the plant. 



In the Avork of growing green manure crops in orchards, the citrus 

 growers of Southern California have made astonishing and most grati- 

 fying prcigress. I believe I am correct in stating that they have 

 found that the most satisfactory and conclusive benefits in orchard 

 fertilization have been obtained from the growing of green manure, 

 or legume crops, and the application of barnyard manure. The 

 benefits, however, are out of all proportion to the actual quantity of 

 plant foods added to the soil by either. This may be explained by 

 the fact that the increase of humus increases the availability of the 

 plant foods already in the soil, and at the same time retains them 

 near the surface, where the feeding roots of trees secure their supply 

 of plant food. 



It is apparently true that few soils are actually so rich that the 

 aj)plication of a complete fertilizer to the citrus orchard is not either 

 beneficial or necessary. In conjunction with this practice it will 

 always be found that the increase of hianus by the growing of green 

 manure crops, and the application of barnyard manure, will render 

 such commercial fertilizers much more effective, and at the same time 

 remove any evil effects they may have upon the soil. 



:\m. JAMES MILLS. I will ask Mr. Koethen to say a few words 

 on this subject. 



^IR. KOETHEN. Professor Mackie has given us a very good resume 

 of the subject. There are some things that have been said in which 

 I, for one, do not agree with him. I do not believe that the heavy 

 soils are not well adapted to the growing of citrus fruits. I believe 

 I will be borne out by the testimony of some who are here. We all 

 know that the early premiums that were taken for citrus fruits were 

 taken by trees grown on heav}^ soils. What we call the red adobe soil, 

 such as you find in Redlands, is recognized by most citrus growers as 

 the best for a citrus orchard. I believe that is uncontroverted, and 

 that is probably one of the stiffest soils we have — stiff red claj^ 



