1919] SOILS FEETILIZERS. 421 



It is concluded that " when fresh manure is mixed with soil the resulting 

 reaction decreases the amount of water-soluble plant food, so that crops started 

 at that time might be retarded or at least not immediately benefited by the 

 manure. When the manure becomes well decomposed, it adds materially to 

 available plant food. Consequently, fresh manure should not be added to a 

 soil just prevhnis to or during the time a crop is growing. 



" If the soil is kept sufficiently open to the air, there should be no loss of nitro- 

 gen due to the addition of manure. Liberation of large amounts of CO2 in the 

 soil by rotting manure does not always greatly influence the composition of the 

 water extract of the soil." 



" Increase in water-soluble mineral matter after the addition of manure to 

 soil can be accounted for largely by that derived from the mineral matter of 

 the manure itself." 



Parallel forination of carbon dioxid, ammonia, and nitrate in soil, P. L. 

 Gainey [Soil ScL, 7 (WW), No. ^, pp. 293-Sll, fir/s. 8).— Studies of the parallel 

 formation of carbon dioxid, ammonia, and nitrate in a silt loam soil, conducted 

 at the Kansas Experiment Station, are reported. 



It was found that " there is a remarkable similarity and agreement between 

 the several carbon dioxid and ammonia curves when constructed from data 

 secured under anything like similar conditions. If conditions are favorable for 

 bacterial activity and cottonseed meal is added there is at first a very rapid 

 formation of carbon dioxid and ammonia, the maximum being reached during 

 the second 24 hours. After this the formation of both carbon dioxid and 

 ammonia decreased rapidly, the curves soon tending toward straight lines. 

 When dried blood was added to the soil the curves for both carbon dioxid and 

 ammonia were different. Formation during the first four days was very slow, 

 the maximum being reached between the sixth and eighth day analyses. The 

 formation of carbon dioxid from dried blood was never so rapid as from cotton- 

 seed meal. . . . 



" Insufficient moisture retards both carbon dioxid and ammonia formation, the 

 latter much more markedly. The minimum moisture for active carbon-dioxid 

 production is lower than for active ammonia production. For the soil used 

 ... 12 cc. of water per 100 gm. soil was near the minimum for vigorous 

 carbon dioxid production, and increasing the moisture beyond this point had 

 little effect upon the formation of carbon dioxid. A moisture content below 

 this results in a lowered carbon dioxid production. The moisture necessary for 

 optinuim ammonia formation is higher than that for carbon dioxid. 



" Insufficient aeration will also cause a depression or marked delay in carbon 

 dioxid and ammonia production. ... In no instance where the current of 

 air was not continuous was the production of cai'bon dioxid and ammonia 

 equally as rapid as where it was. In the case of carbon dioxid it appears to 

 be simply a delayed production, the total quantity soon reaching that produced 

 where aeration was abundant. The total ammonia produced imder limited 

 aeration did not, in most instances, reach the production where aeration was 

 abundant. So long as the current of air was continuous, increasing the volume 

 apparently had no effect. . . . 



" Nitrate production in all experiments was for some unknown reason excep- 

 tionally low for this particular soil. As a rule there was no accumulation 

 during the first few days. In fact, the small quantity of nitrate nitrogen 

 initially present usually disappeared completely before the first analysis. 

 Where aeration was insufficient, the beginning of accumulation was delayed 

 still more. Where the moisture content was varied, nitrate accumulation was 

 directly proportional to moisture content ; the maximum not being reached 

 until the maximum moisture that would be retained was reached. Where 



