THE SOIL AS A FACTOR 23 



for us, we must observe certain conditions essential to their well- 

 being. The compost heap must contain an abundant supply of 

 decomposing organic matter. The decomposition in this material 

 must not be allowed to take the form of acid fermentation; in 

 other words, sufficient lime must be incorporated into the com- 

 .post heap to keep the process of fermentation and decomposition 

 from becoming acid. Heat is also necessary in order to stimulate 

 action of these little organisms. Under normal growing conditions, 

 however, the heat generated from decomposition and fermentation 

 is sufficient for the high development of the organisms, provided 

 there is moisture in the soil at all times. Heat and lack of moisture 

 are not congenial ; heat and excessive moisture are not congenial ; 

 and the right amount of moisture without sufficient heat is not 

 productive of good results. Under normal conditions the heat, as 

 has already been suggested, will come from natural sources and 

 will be generated in the process of decomposition and fermenta- 

 tion. The moisture and lime must be applied as occasion requires. 

 The gardener should at all times keep a close watch upon the 

 compost heap to see that it does not become excessively dry, as 

 bacteria cannot work to good advantage in dry heaps. Decompo- 

 sition is arrested by either excessive drought or excessive moisture. 

 All these factors accomplish their greatest good during the normal 

 growing period of the year. Cold weather checks all activity, so 

 that it is necessary to have the compost heap constructed at a time 

 when it will be possible to take advantage of the benefits of the 

 season in accomplishing the desired results. The compost heap 

 should, therefore, be constructed during the fall, early winter, or 

 very early spring so as to be in condition to allow the greatest 

 activity of these beneficial organisms during the summer months. 

 If the compost can be made a year in advance of the time it 

 is to be used, it will be all the better. As none of these natural 

 operations progress rapidly, time is important. 



Soil sterilization. In garden operations it is quite as important 

 to treat the soil so as to resist certain injurious forms of life as it is 

 to supply food for others. Soil sterilization has for its direct object 

 the treatment of soil in such a way as to render it free from injuri- 

 ous enemies, chief among which are eelworms, or nematodes. As a 

 consequence of sterilization the soil is freed of spores of injurious 



