i83 



organic substances which are taken up from the soil by impoverished 

 spring water, which has a small oxygen content, but are deposited, on the 

 other hand, by the richly saturated river water. 



At a depth of 40 cm. during the colder seasons temperature observations 

 show that irrigated land is warmer by varying amounts, even up to 2.8°C. 

 To this increase in temperature may be ascribed the fact that in irrigated 

 meadows, growth begins earlier in the spring and continues later in the 

 autumn. 



Konig showed by an experiment in which he artificiallv mixed sewage 

 with the irrigation water, how quickly the subsoil shows its absorption 

 qualities, if the soil is not saturated and the irrigation water is heavily 

 charged with fertilizing matter. x\fter the water had been used once, it 

 could be proved that the soil had taken up 84.5 per cent, of the organic 

 substances; 74.2 per cent, of the ammonia; 81.6 per cent, of the potassium 

 and 86.8 per cent, of the phosphoric acid. After the same water had been 

 used twice again the presence of these substances in it could not be proved 

 at all. Of course these figures hold good only for this experiment and vary 

 according to the saturation of the soil and water; they have therefore, for 

 example, no value in irrigation with liquid manure, in which the soils must 

 become surcharged with nutritive substances in a comparatively short time. 

 Nevertheless, experiments show what varied advantages can be obtained 

 •with the right use of irrigation. The importance of watering the soil arti- 

 ficially is becoming more and more acknowledged. The best proof is found 

 in the transactions of the land cultivation division of the German Agricul- 

 tural Society' in which questions referring to the direct supplying of water, 

 raising of the ground water lez'el, have already been brought up. The sys- 

 tems known at present have been partially explained by means of illustra- 

 tions. The transactions have led to a direct commission from the Directors 

 of the society, "that they should take up the question of the watering of 

 land with the greatest possible energy." 



Cultivation of the Soil. 



At present, in large plots of land, it is possible only in the rarest cases 

 to provide for irrigation without considerable expense and therefore cheaper, 

 if less effective, means are more often utilized. Such resources are found 

 in working the soil. The breaking up of the soil is most advisable. Some 

 practical workers maintain that cultivating the field soil cannot possibly aid 

 in the retention of soil moisture, but that this manipulation must rather be 

 considered as the quicket way to remove more water from the soil. This 

 point of view is erroneous, as is shown by many experiments. The most 

 thorough are Wollny's", who has worked with control experiments and has 

 found that if the uppermost layers of the soil are broken up, they dry more 



1 Die Moglichkeit der Ackerbewasserung in Deutschland. Arbeiten d. Deutsch. 

 Liandwirtsch.-Ges., Part 97, 1904, p. 75. 



2 WoUny, Einfluss der Bearbeitung und Diingung auf die Wasserverdunstung 

 aus dem Boden. Oesterr. landw. Woclienbl. 1880, p. 151. 



