Lysimeter Experiments 31 



ments, and the evapo-transpiration ratios should be wider. In order 

 to institute a comparison between the figures obtained in the present 

 experiments and those obtained under controlled conditions, the unit 

 water requirements fovmd by a number of investigators are given in 

 table 13. 



Comparison of the figures in tables 12 and 13 shows that both maize 

 and oats had wider ratios in all the experiments quoted than in the mini- 

 mum requirements as found by the writers, and that clover also had a 

 wider ratio than was found to be the case here. 



I Other experiments on water utilization hy plants in lysimeters 



Not many data are available on water utilization by plants raised 

 in lysimeters. Gerlach (1912) reports that in experiments with ten 

 lysimeters, each containing 4 cubic meters of soil and in which there 

 were five soil types, the utilization of water, including evaporation, for 

 six crops averaged from 500 to 700 grams for one gram of dry matter 

 produced. The crops raised were potatoes, oats, rye, oats. This agrees 

 fairly with the average figure of 1:580 found in these experiments 

 for the same factor. The average annual rainfall at Bromberg was 

 538 millimeters, as compared with 791 millimeters at Ithaca. 



As the result of a previous experiment Gerlach (1911) reports the utiliza- 

 tion of from 416 to 1149 parts of water to one part of dry matter in a 

 rotation of potatoes, oats, rye, oats, on unfertilized soil, and from 359 

 to 632 parts of water to one part of dry matter in the same rotation on 

 the same kind of soil to which a complete fertilizer had been applied. 



In reporting further experiments at Bromberg, Kriiger (1911) states 

 that in the growth of rye 488 parts of water was required to produce 

 one part of dry matter from October to June, while from April to June 

 only 348 parts of water was required. 

 1^ On the lysimeters at Jonkoping it was found by Von Feilitzen, Lugner, 

 and Hjerstedt (1912) that an vmfertilized soil produced oats, potatoes, 

 turnips, and grass with an average evapo-transpiration of 511 parts of 

 water to oix? part of dry matter. On the same muck soil with complete 

 fertilizer only 311 parts of water was required. For each crop the water 

 requirement per part of dry matter produced was as follows: On un- 

 fertilized soil: oats, 410 parts; potatoes, 401 parts; turnips, 715 parts; 

 grass, 518 parts. On well-fertilized soil: oats 244 parts; potatoes 149 



31 



