October 21, 1910] 



SCIENCE 



537 



There are other features of marked in- 

 terest which explain many of the common 

 observations of cereal cropping. I can 

 note only a few of these which might 

 amount to an explanation of difficulties 

 met with in our efiforts at crop betterment 

 and of the benefits which accrue from 

 those methods Avhich are recognized. 



Farmers have noticed that where fresh 

 barnyard manures have been spread upon 

 their soils preceding wheat, a compara- 

 tively small amount has resulted in what 

 they have called over fertility. My obser- 

 vations and experiments show that this is 

 not necessarily over fertility, but increased 

 soil infection coming from the excess of 

 fungi due to cultures developed in the old 

 straw and manure made from bedding 

 straw drawn from diseased fields. Such 

 straw introduced on the newest land im- 

 mediately results in the production of 

 shrivelled grain and in general crop de- 

 terioration in following years. In the case 

 of flax my own experiments have been 

 many times confirmed by the farmers. If 

 barnyard manures which have been made 

 by stock fed or bedded with flax straw are 

 used, the soil may be ruined for the growth 

 of flax by one application, even though no 

 flax has ever been grown there before. 

 This applies equally to wheat, barley and 

 oats, when bedding made from sick straw 

 of such crops is used, though apparently 

 not so markedly destructive because of the 

 fibrous method of rooting of these cereals. 



We have all observed and advocated that 

 the best possible preparation of a soil for 

 the production of either wheat or flax is 

 that which comes from a properly culti- 

 vated corn field, which is not again plowed 

 before the grain is seeded, but which re- 

 ceives only shallow or surface cultivation. 

 We have all observed that the expected 

 better yields do not always follow, and 

 that instead of getting plump wheat or 



good flax there may be much wilt in the 

 flax or the wheat may not produce the big 

 yield of plump grains. This in cases of 

 wheat is analogous with the results on new 

 lands, previously cited. There are two 

 reasons why we may not of necessity ex- 

 pect better results on the corn crop ground. 

 If that be a small piece of ground sur- 

 rounded by old wheat stubble lands, the 

 drifting or blowing of the diseases from 

 these lands throughout the season may 

 readily keep the corn ground thoroughly 

 infected, while the cultivation sets free a 

 larger and more available food supply and 

 the crop grows ranker and more succulent, 

 only to be destroyed by its parasitic ene- 

 mies. If the fleld be sufficiently large so 

 as not to be thus injured by the surround- 

 ing areas, or if there are no surrounding 

 areas, the labor on that new well-worked 

 land may be largely lost by the use of in- 

 fected seed taken from old lands. 



It is a well-known fact that quack-grass 

 {Agropyron repens) is the most destruc- 

 tive weed known to cereal agriculture. It 

 has been a wonder to most farmers and 

 many experimenters why wheat is able to 

 make so little progress against this weed 

 even after the greatest efforts are made to 

 prepare the seed bed. Usually we have as- 

 sumed that the heavy rooting capacity of 

 the quack-grass allows it to rapidly take 

 charge of the ground, exhaust the moisture 

 and thus overcome the cereals seeded over 

 the quack-grass area. Our late observa- 

 tions and cross inoculations convince us 

 that the quack-grass has a great advantage 

 over the cultivated wheat. Not iincom- 

 monly the roots of the quack-grass, and es- 

 pecially the hea^y underground stocks, are 

 thoroughly attacked by several of these 

 wheat-destroying diseases which fruit 

 freely upon the dead and dying under- 

 ground masses of quack-grass. The young 

 wheat plants placed over such a center of 



