Investigations at All Stations. 



89 



The relative development of the crops at the several stations at different 

 periods of growth is shown in plates 5 to 8. A summary of crop development 

 during 1921 is given in table 29, where the data of the preceding year are also 

 included. 



An examination of table 29 shows that the crops at Lincoln and PhilUpsburg 

 had as great, and in nearly every case a greater, height-growth in 1921 than 

 during the preceding season. At Burhngton the height-growth was the same 

 for oats during the two years, but less for the other cereals in 1921. The 

 average yield of dry matter at the several stations is not only in the same 

 sequence as during 1920, but the relative amounts are strikingly similar. 

 The working depth of roots is slightly less than during 1920, as is also, in 

 general, the maximum depth of penetration. 



Table 29. — Comparison of crop development, 1920 and 1921. 



Correlation of Crop Development with that of Native 



Vegetation. 



Native plants have the same general requirements as regards heat, hght, 

 water, etc., as cultivated crops. Since their growth is controlled by the same 

 physiological conditions, generally speaking, that hasten or retard the growth 

 of crops, the use of the native vegetation as an indicator of the possibiUties 

 of crop production and as a criterion of average yield in a given plant associa- 

 tion is patent. Different environments in agricultural regions should give, 

 broadly speaking, similar differences in relative growth, yield, etc., of crop 

 plants as of the native vegetation. Thus native plant-growth becomes a 

 measure of the effect of all the conditions which are favorable or unfavorable 

 for agriculture. Although conditions for growth, as indicated by a plant 

 association, can be brought out with sufficient clearness to predict with a fair 

 degree of certainty what will happen when crops are planted, the final test 

 is the success or failure of the crop when grown (c/. Shantz, 1911). It is 

 instinctive, therefore, to consider the correlation between crop development 

 and that of the native vegetation in the range of habitats under which these 

 investigations were made. 



