298 DRY FARMING 



ing to recognize the purpose of plowing that leads to the 

 belief that its efficiency increases with its depth, even 

 though that depth be extended below all practical limits 

 of cost and effort. Plowing does not increase the water- 

 holding capacity of the soil, nor the area in which roots 

 may develop, or from which the plants may obtain food. 

 Plowing removes from the surface either green or dry 

 material that may encumber it, provides a surface in 

 which planting implements may cover the seed, and re- 

 moves or delays the competition of weeds or plants other 

 than those intended to grow, and in some cases, 'by loosen- 

 ing and roughening the immediate surface checks the 

 run-off of rain water. All these objects are accomplished 

 as well by plowing to ordinary depths as by subsoil ing, 

 dynamiting, or deep tilling by any other method. There 

 is little basis, therefore, for the expectation of increased 

 yields from these practices, and the results of these ex- 

 periments show that they have been generally ineffective. 

 (Journal of Agricultural Research, Vol. XIV, No. 11 

 p. 484). 



The quite general popular belief in the efficiency of 

 deep tillage as a means of overcoming drouth or of in- 

 creasing yields has little foundation in fact, but is based 

 on misconceptions and lack of knowledge of the form and 

 extent of the root systems of plants and of the behaviour 

 and movement of water in the soil. (loc. cit. p. 521). 



245a. Green Manuring. Green manuring has not usu- 

 ally given as high yields of spring wheat, winter wheat, 

 oats or barley as has summer tillage. It has yielded but 

 little if any higher than disked corn ground with any of 

 these crops. It is much more expensive even than sum- 

 mer tillage. There is not yet any apparent cumulative 

 effect of the addition of humus to the soil, although it has 



