80 HARRINGTON MOORE Vol. Ill, No. I 



growth and weight were less than on the same soils without lime, but on 

 humus there was very little difference between the limed and unlimed (see 

 figure 5 and Tables 3 and 6). No matter how valuable experiments with 

 herbs are in studying environmental relations of forest trees, toxicity and 

 nutrition experiments in herbs must be applied to trees with caution. The 

 green and dry weight per plant of the wheat, exclusive of roots, are given 

 in Table 6. 



Table 6. Green and dry weight of wheat on heavily limed soils 



Green weight per plant. Dry weight per plant. 

 Soil grams grams 



Sand 028 .008 



Sand with humus 054 ,017 



Humus 344 .0786 



Light Application of Burnt Lime. — It is not possible to give an absolute 

 comparison of the influence of adding the small amount of burnt lime to the 

 three soils studied, because the mild lime series was sown on June 23, 15 days 

 after the others. Nevertheless some of the results are obviously due to differ- 

 ences in soil and are worth briefly considering. 



The effect seems to have been intermediate between strong lime and 

 absence of lime. On the coniferous trees, except cedar, the influence does 

 not appear to have been beneficial, nor particularly injurious. Height growth 

 throughout the season, always excepting cedar, was less than on the unlimed 

 soils at the corresponding age, though this may be due partly to the late start 

 as well as to the soil. Cedar found conditions more favorable on this series 

 than on either of the others : in spite of the later start, height growth on both 

 sand and on humus was nearly equal to that on unlimed soils by the end of 

 the season (see fig. 2) ; there was also fair growth on the mixture of sand 

 and humus, as compared with failure on this soil without lime. 



Jack pine and pitch on the mixture of sand and humus passed the sand 

 in height 3 to 5 days later than on unlimed soils. But red pine and cedar 

 on the mixture did not catch up with that on the sand until the end of the 

 season. By that time growth in height of all species on humus far surpassed 

 that of the strongly limed humus, and, in spite of the later start, that on sand 

 and on sand and humus equaled or surpassed that on the same soils with 

 stronger lime. 



Root growth was considerably less than on the unlimed series, probably 

 partly on account of time of start and partly on account of soil, but showed 

 greater length than on the more strongly limed series. Root area would un- 

 doubtedly have shown even greater superiority on the mild as against the 

 strong lime. 



In green weight there was not much difference between the lightly and 

 heavily limed sandy soils, in spite of the late start of the former, but there 



