46 
WATER REQUIREMENT OF PLANTS. 
Table XXXIV.— Effect of various fertilizers on the water requirement of oats and 
wheat at Gottingen, Germany, according to different investigators. 
Crop. 
Soil. 
Soil moisture. 
Water requirement with- 
Notes. 
K N P KNP Check KN KP PN 
Oatsi... 
Do!.. 
Wheat * 
Dos. 
Kilograms. 
/Clay, 9.16.. 
1 Sand, 11.7.. 
Earth, 20.... 
Earth, 11.... 
Loam, 12 
Loam,20(?) 
2.21 kilograms... 
1.74 kilograms... 
3 pots. 
..do... 
344±9 311±L270±7 
313±8194±2 307±5 
49 to 54 3. 
59 to 64 3 . 
64 to 74 3. 
Low water con- 
tent. 
High water con- 
tent. 
/45 3. 
\70-3. 
1 plantper 
pot. 
5 plants 
per pot. 
1 plant per 
pot. 
Splants 
per pot. 
4 pots . 
do. 
290 
291 
302 
291 
542 
229 
269 
467 
Mean water requirement « . 
277 
3114 
314 
268 
290 
283 
255 
584 
197 
240 
405 
368 
173 ±3 
178 ±1 
225 
237 
232 
258 
403 
222 
233 
349 ±9 
332 ±7 
259 297 
23 S 
319± 
192 ±2 
227 
225 
222 
277 
350 
217 
225 
259 
264±2 
299±6 
247 
291 
306 
249 
535 
197 
261 
344 
177±2 
192 ±1 
236 
220 
216 
254 
457 
211 
237 
1 Liebscher, 1895, p. 211. 
2 Von Seelhorst, 1899, p. 372. 
3 Percentage of moisture-holding capacity. 
* Von Seelhorst and Biinger, 1907, p. 247. 
6 Ohlmer, 1908, p. 157. 
6 Mean for all determinations except Von Seelhorst and Biinger ? s high water content series. 
wimmer' s experiments. 
Wimmer (1908) published the results of extended experiments con- 
ducted by a large number of collaborators. The data on the effect 
of potash and nitrogen on the water requirement are given in Tables 
XXXV and XXXVI. 
Glass pots 33 centimeters high with an upper diameter of 21 centi- 
meters and a lower diameter of 19 centimeters were used. These pots 
were left open and the combined transpiration and evaporation 
determined. Apparently no attempt was made to correct for evapo- 
ration from the soil surface. The plants were grown to maturity. 
Many details of the experiment are given in the tables and need not 
be repeated here. 
The effect of potash (Table XXXV) is much less evident than in 
the work of Wilfarth and Wimmer (1902), already discussed (p. 39). 
Even in the soils showing the lowest content of potash the addition of 
potash did not lower the water requirement. None of the soils were 
poor in potash. 
The addition of nitrogen (Table XXXVI) lowered the water require- 
ment with most plants. In Juetrichau sand the high probable error, 
as well as the small amount of dry matter produced, lead one to disre- 
gard these data in discussing the results as a whole. 
285 
