Oct. IS, 1914 



Water Requirement of Plants 



the plants had become well established. In practice it was found con- 

 venient to make up a large quantity of the fertilizer solution of such 

 concentration that 2 liters contained one-fourth of the total quantity 

 required for one pot. The addition of this quantity to each pot was 

 followed immediately by 2 liters of water. 



To test the influence of the fertilizer, one standard set of six pots of 

 Kubanka wheat was grown without fertilizer at Akron, for comparison 

 with the fertilized sets. The detailed results are given in Table II. The 

 water requirement of the unfertilized set was 4±2 per cent below that of 

 the fertilized set when based on the production of dry matter, and i ±4 

 per cent above, when based on grain production. The results therefore 

 indicate that the additional plant food was not needed at this station, 

 the water requirement of the two sets agreeing (within the errors of the 

 experiment) whether based on the production of dry matter or on the 

 production of grain. In 191 1 the water requirement of the unfertilized 

 set ^ at Akron was 6±3 per cent above the fertilized set when compared 

 on the basis of dry matter, although the ratios based on grain production 

 were the same. 



T.\BLE II. — Effect of fertilizer on the water requirement of wheat at Akron, Colo., in IQ12 



CLIMATIC FACTORS 



The instrumental equipment for the measurement of climatic factors 

 included maximum and minimum thermometers and an air thermo- 

 graph exposed in a standard shelter 4 feet above the ground surface, an 

 anemometer, a psychrometer, a rain gauge, and an evaporation tank. 



' Based on pots i to 6, unfertilized, wliich had tlie same exposure as pots 7 to 12, fertilized. 



