34 THE WEED FACTOR IX THE CULTIVATION OF CORN. 



land only once and secure large yields. Studies are being conducted 

 on this problem of adapting cropping systems to weed control, and 

 more data will be at band at a later date. 



Just what implements are best to destroy weeds when present and 

 just what rotations should be practiced to control them are largely 

 local problems. Each State or agricultural region will have its 

 own answer. In those cases where a soil mulch may be desirable it 

 will undoubtedly be true that any tillage implements designed 

 primarily to kill weeds wiU incidentally produce a sufficient soil 

 mulch to answer all requirements in this respect. 



The writers interpret the results here presented to mean that 

 weeds are in the main the enemy which makes cultivation necessary. 

 The exceptions should be deter min ed by farther work. Weeds can 

 be fought from two standpoints: (1) With tillage implements 

 specially designed to kill these pests instead of to stir the soil and 

 make a niulch and (2) from the standpoint of rotations especially 

 designed to overcome the weeds of the particular locality. It is 

 believed that by adopting methods in conformity with this point of 

 ,iew the weed problem will be simplified and in all probability the 

 cost of cultivation will at the same time be greatly decreased. 



SUMMARY. 



A number of tests made at several agricultural experiment stations 

 seem to indicate that it is the weed factor that makes the cultivation 

 of corn necessary, or. stating the proposition conversely, that culti- 

 vation is not beneficial to the corn plant except in so far as removing 

 the weeds is concerned. 



The subject of weed control is recognized as a fundamental one 

 in tillage philosophy. It was therefore determined to carry on. over 

 a wide range of climatic and soil conditions, a large number of tests 

 of the relative yields of corn produced by supposedly optimum cul- 

 tivation as compared with mere weed elimination. 



The experiments were made by having two plats or sets of plats, 

 one of which received no cultivation after planting, the weeds being 

 kept down by a horizontal stroke of a sharp hoe at the surface of the 

 soil, particular care being taken not to disturb the soil or to form a 

 soil mulch: the other set of plats received the usual cultivation. 



This work was carried on by the Department of Agriculture for 

 six years (1906 to 1911) in cooperation with several State agricultural 

 experiment stations and with farmers, many of whom were gradu- 

 ates of agricultural colleges. The results of 125 experiments are 

 recorded in this bulletin, including the early experiment-station tests. 

 The seven years' work in Utah is given separate discussion. Of the 

 125 experiments 124 record grain yields and 55 give fodder yields. 



257 



