PHOSPHATES IN MASSACHUSETTS AGRICULTURE. 161 



received no such application. It may possibly be urged that this sulfur 

 has been beneficial. This of course is possible, although numerous other 

 hues of experiment carried on by the writer which afford opportunities for 

 comparison fail to demonstrate any necessity for the application of sulfur. 



Beneficial Secondary Effects from the Use of Soluble Phosphates. 



Among secondary effects which appear to be generally admitted to 

 follow apphcation of soluble phosphates may be named the following: 

 rapid early growth both of roots and tops, increase in tillering in grains 

 and grasses, earher and therefore often more perfect ripening, increase 

 of the availabihty of certain soil constituents, and larger acquisitions of 

 atmospheric nitrogen. 



1. Rapid Early Growth of Both Roots and Tops. — Many observers have 

 noticed the quick start which plants from seed make when dissolved 

 phosphates have been applied. Attention has been called to the differ- 

 ences in rate of development of the corn crop in the experiment comparing 

 different phosphates. ^ In numerous other experiments which have been 

 carried out here similar differences have been observed. Especially strik- 

 ing have been the results obtained with rape and cabbages both in field 

 and pot experiments. Differences about as great have been noted in the 

 case of soy beans and millet. 



The fact that the differences in early root development are perhaps 

 even more striking than in early top development has not been demon- 

 strated in our experiments, but Hall, ^ points out that Sir John Lawes 

 called attention to this effect more than sixty years ago. He refers to a 

 water culture which demonstrates it, and suggests that this effect ac- 

 counts for the extraordinary results often following even small applica- 

 tions of soluble phosphates. He states that an application of half a 

 hundred weight per acre of superphosphate in Australia to soils not sig- 

 nally deficient in phosphoric acid often doubles the yield of cereals, and 

 expresses his belief that the result is due to the stimulating action of the 

 phosphoric acid upon the young roots. He points out that this action is 

 particularly important in that semi-arid country because as a result the 

 plant quickly gets its roots down into the cooler and moister subsoil upon 

 which the yield of the crop largely depends. 



This stimulation of early root development must be a very great ben- 

 efit under the conditions of our agriculture and in our climate. The 

 crop wliich early develops an extensive root system — ■ both deep and 

 broad — can much better resist our frequent drouths than one whose 

 roots develop more tardily. It is apparent, also, since it is known that 

 roots by direct and intimate contact with soil particles exercise an impor- 

 tant influence in supplj'ing the plant with food, that the more extensive 

 the root development the more largely the plant will be able to utilize 

 the resources of the soil itself. 



1 See p. 154. 



■ "Fertilizers and Manures," p. 140. 



