66 VEGETABLE FORCING 



(10) It has some effect in binding sandy soils, but this 

 function is of no practical value in relation to greenhouse 

 soils. 



The yields of greenhouse crops are often materially 

 increased by the application of lime, and every commer- 

 cial grower should conduct simple experiments to 

 determine its full value. It is improbable that any harm 

 can result from the use of reasonable amounts. 



Commercial fertilizers. As previously stated, commer- 

 cial fertilizers are not used extensively by the market 

 growers of vegetables under glass. In the chapters relat- 

 ing to the various classes of vegetables, experiments will 

 be cited in which fertilizers have been used advan- 

 tageously. There is a strong impression among growers, 

 however, that little if anything is to be gained by the use 

 of chemicals, and the statement "that more harm than 

 good has been done by the use of fertilizers in vegetable 

 forcing" is very likely a truthful assertion. 



As early as 1892, Prof. W. J. Green of the Ohio station, 

 after conducting some careful experiments, reported the 

 following in Bulletin 43 of that station : 



"It may be urged that no results could reasonably be expected 

 from the use of any fertilizing ingredient upon a soil already well 

 supplied with plant food. The persistency with which the virtues 

 of nitrate of soda for garden crops have been urged has led many 

 to believe that it can be used with profit, even upon soils already 

 full of fertility. 



"This experiment does not show that nitrate of soda, or any other 

 fertilizer, cannot be used to advantage in any case, but rather that 

 the limitations to their use are narrower than is commonly sup- 

 posed. The soil used in this experiment was a clay loam. To fit 

 such a soil for use in the greenhouse the best method is to compost 

 it with stable manure, and such is the course generally followed by 

 gardeners. The case would be different with a sandy soil, as the 

 addition of stable manure, in order to make it friable and to prevent 

 baking, is not so essential as with clay. Less stable manure would 

 be needed with a sandy soil than with clay, and the deficiency in 

 plant food could be made up with commercial fertilizers, and no 

 doubt at a profit. A clay soil could be made friable by the addition 



