stance and when dissolved in water imparts to it the pronounced al- 

 kaline properties of 'lime-water'. Warington and Win"grad.sky have 

 each sho«'n that concentrated lime water destroys the nitrifying bac- 

 teria, and that these organisms only flourish when their surroundings 

 are feebly alkaline in character. 



Many a farmer has found that the application of 3 or 4 tons of 

 slaked lime per acre has had a depressing effect on the crop immedia- 

 diately following the application So large a dressing as this applied 

 in the spring of the year is practically certiin to have a markedly in- 

 jurious effect on the soil-bacteria and to prevent their free growth and 

 activity until the alkaliuity of the lime has been destroyed by the 

 carbonic acid and vegetable acids derived from the humus of the soil. 

 The following and subsequent seasons, however, will yield gratifying 

 proof of the benefits of lituing, provided the soil was one really in need 

 of sucli treatment It is rarely wise to apply more than a toti per acre 

 at a time, and this is best applied in temperate climates in the winter 

 when nitrification is practically suspended. Excellent results have 

 followed the use of such moderat; dressings as 6 or 8 cwt. per acre; 

 the German Agricultural Society, for instance, found in their field ex- 

 periments with sulphaie of ammonia which were conducted at many 

 different centres under the direction of Professor Maercker, that the 

 application of half a ton of lime per acre to the soil before ap dying a 

 dressing of sulphate of ammonia yielde I an increased crop averaging 

 over 2 cwt. of corn in the case of harley and oats* 



Chalk or marl is often obtainable at small cost and although at least 

 four times as much is required to equal the effect produced by lime, 

 there is no risk of injury to the soil or crop. 



D. — Moisture. 



When soil is dust-dry, nitrification ceases Schloesing found, for in- 

 stance, that provided the soil was not water logged and fre; aeration 

 was secured, the rate of nitrification increased with the proportion of 

 moisture in the soil. In one series of experiments he obtained the fol- 

 lowing results : — 



Per centage of moisture in soil 9.3 14.6 16.0 20.0 

 Pounds of nitric acid produced 



per acre in 13 months 157 lbs. 172 397 478 



Greneriilly speiking, nitrification is appreciable in a soil containing 

 4 per cent, of moisture, and is at its maximum when the soil contains 

 about half the total quantity of moisture which it is capable of retain- 



ing 



From the point of view of practice, nitrification is thus §een to have 

 a close connection with the accidental variations of season, other con- 

 ditions being the same. A season of intermittent and fairly liberal 

 rainfall is most favourable f r nitrification. Excessive wetness, how- 

 ever, depresses this activity by reducing the temperature of the soil 

 and overloading it with moisture. It is important to note that culti- 

 vation is of great service in promoting and maintaining the progress 



* Jahrbuch der Deutschen Laiidw. Gesellschaft, 1880, p. 450. 



