THIRTY-FOURTH FRUIT-GROWERS^ CONVENTION. 



IGl 



liave been withdrawn from the soil by plants in their growth are 

 returned to it by their death." In the case of the forest lands, the 

 original fertility of the soil has not only been maintained, but vastly 

 increased by the deca}^ of leaf mold and other vegetation, and the sub- 

 sequent formation of humus in the soil. Here, then, we perceive the 

 working of a natural law of replenishment or restoration. This law, 

 ordained by the Maker of the Universe and observed in nature's own 

 processes, must be obeyed by man. We must restore to the soil those 

 elements that we remove from it in crops, or, failing to do this, we 

 shall bring poverty upon ourselves and upon those who are to follow us. 



All these facts are perfectly familiar to us. There is no need, 

 before an audience like this, to make any argument to emphasize the 

 necessity of fertilization of our soils. We recognize the necessity; we 

 are willing and even anxious to obe}' the law of restoration ; but Avhen 

 we fertilize our farms and our orchards, we desire to do it wisely and 

 intelligently; and we find the subject hedged about with some diffi- 

 culties, and containing problems still unsolved. 



It is an interesting fact that it was only about one hundred years 

 ago that the sources of plant food began to be correctly understood. 

 Professor Snyder says, in the introduction to his admirable book, 

 that, while manures had been used from the earliest times, and their 

 beneficial effects recognized, their action \\;is nvi^arded as mysterious, 

 so much so that the alchemists preached a theory that so-called "spirits" 

 left the decaying manures and entered into the plant, thus accounting 

 for its more vigorous growth. Continuing, he says that among the 

 first to see the relation between chemistry and agriculture was Sir 

 Humphrey Davy, who published a treatise on the subject in 1813. 

 Since that date vast strides have been made in the proper understand- 

 ing of the composition of plants, and of the sources and composition 

 of plant food. Years of study and investigation have been given 

 to the subject by eminent men of many countries, and through the 

 investigations and extensive field experiments carried on" by such 

 scientists as . Von Liebig, in Germany, and Lawes and Gilbert, in 

 England, the world at large attained much of its enlightenment which 

 forms the basis of our present day knowledge of these subjects. 



Coming down to our own time, and to the present day, I think it 

 may be confidently said that a . distinct advance has been made in our 

 orchard practice by us farmers here in Southern California, during 

 the past twenty years. Fertilization is practiced much more wisely 

 and intelligently, I feel sure, than it was fifteen or twenty 3^ears ago. 

 In no respect is this more true than in the general awakening to the 

 value and importance of humus. 



HUMUS. 



Humus has been aptly described as the "life of the soil," and this 

 is true in a very literal sense, for it is the home of the bacteria of 

 the soil, those wonderful little organisms which convert the inert ferti- 

 lizing elements into forms which are available as plant food. When 

 the humus of a soil becomes exhausted, or burned out, these micro- 

 organisms cease to do their work ; and under these conditions our trees 

 may be insufficiently fed even though a plentiful supply of fertilizers 



11 — FGC 



