THE YEAST OF THE SOIL. 27 



have any action on the bacteria. Lime is not necessary to the soil 

 unless it is acid, whether it has been treated or not treated; its 

 great office is to render soil slightly alkaline in which bacteria can 

 only grow. Acid soil is indicated by the growth of many kinds of 

 weeds, goldenrods for example, and if such conditions exist lime is 

 beneficial. 



William N. Craig enquired as to the amount of available plant 

 food in a ton of stable manure. 



The Lecturer replied that as nearly as he could determine it 

 roughly he would place the amount at fifty pounds, worth from 

 $3.00 to $4.00. The balance of the ton was chiefly straw, valuable 

 only as humus. 



Mr. Craig also asked which was better, commercial fertilizer or 

 barnyard manure; would our New England soil ^ield as well with 

 commercial fertilizers as with barnyard manure. 



Li reply to this inquiry the Lecturer said that commercial ferti- 

 lizers never will compete with barnyard manure under glass. That 

 for roses and other more delicate plants barnyard manure was 

 used more than commercial fertilizers. Commercial plant food 

 will never compete with stable manure, although good returns are 

 readily obtained from commercial fertilizers. In greenhouse culture 

 the man controls the conditions of warmth and moisture and where 

 he has stable manure he knows he will get certain results. He sup- 

 plies it under glass with those conditions and it is the best thing he 

 can use. It gives the right conditions to the humus of the soil. 

 Commercial fertilizers when used with stable manure help to bring 

 about the desired conditions quicker. 



As to outdoor conditions, that is another proposition. There 

 we do not control the weather, which is the greatest factor, and we 

 do not control other conditions, so some predigested plant food is 

 necessary. The most successful market gardeners in Arlington 

 and Concord are using stable manure and chemical fertilizers in 

 combination which bring about results that stable manure alone 

 would not accomplish, thus taking advantage of the humus of the 

 barnyard manure and the value of the chemical plant food. 



The question was asked if successful crops had been grown for a 

 series of years where commercial fertilizer had been alone used. 



The Lecturer replied that for a series of years with certain 



