EXPERIMENT STATION RECORD. 



Vol. XIII. No. 11. 



The bioloj^icjil activities of the soil, and their rehitions to soil fer- 

 tility and to the availability of soil constituents, have not yet received 

 the attention which their importance warrants. The study of main- 

 tenance of fertility and crop production has been confined too g-ener- 

 ally to supplying the necessary commercial fertilizers to meet the 

 temporary demands. This field has been experimented upon quite 

 thoroughly, and the limitations of fertilizer experiments are quite 

 keenly felt by some who have followed that line for a series of years. 



Little progress has as 3^et been made in studying availa])ility or the 

 conditions which influence or control it. It is now recognized as being 

 associated with the biological activities taking place within the soil, 

 and these in turn as influenced ])y a variet}^ of conditions such as tem- 

 perature, moisture, the atmosphere of the soil, etc. The process of 

 nitrification, for example, may be changed to denitritication by 

 unfavorable conditions of temperature and moisture, resulting in the 

 dissipation of the nitrogen which has been made availa))lc ])y the first 

 process. But the effect which different methods of tillage and soil 

 management have upon the available plant food in the soil is only 

 known to a very limited degree; for we have only slight knowledge 

 of the character of the changes which are taking place and of the 

 influences which favor or retard the desirable processes. 



A plea for investigation along this line, in addition to fertilizer 

 experiments, was made in a recent paper by W. Farrer before the 

 Australasian Association for the Advancement of Science.' In this 

 pap(M' Mr. Farrer points out that the transformation of potential plant 

 foods into available and assimilable forms is accomplished by the 

 chemical, physical, and biological activities which are constantly 

 occurring in the soil, and expresses the opinion that available materials 

 may be produced in increased quantitities l)v increasing and stinm- 

 lating these activities. He advocates making "such improvements iii 



^ The absolute dependence of ai;rieultnral progress upon experiments, and sugf^es- 

 tions in regard to some directinns in which experimental wurk should 1)e done for 

 the agriculture of Australia. Reprinted in Agr. Gaz. New .South Wales, lo (1902), 



pp. 20(3-214. 



lUOi) 



