96 TALKS ON MANIRES. 



Why this difference ? ll will not du to say iliat more nitrog* 

 was applied in the farm-yard lainure than was needed. M> 

 Lawes says : " For sume years, an ainounl of aniinouia-salls, cou 

 tainiiig 82 lbs. of nitrogen, was apidied to one series of plots (oi 

 barley), but this was found to be too much, tbc crop generally 

 being too heavy and laid. Yet prob.ibly alxiut 200 lbs. of uitrogec 

 was annually supplied in the dung, but with it there was no over- 

 luxuriance, and uo more crop, than where 41 lbs. of nitrogen was 

 supplied in the form of ammonia or nitric acid." 



It would seem that there can be but one explanation of these 

 accurately-ascertained facts. The nitrogenous matter in the ma- 

 nure is not in an available condition. It Ls in the manure, l)Ul the 

 plants can not take it up until it is decomposed and rendered sol- 

 ul)le. Dr. VcDlcker analyzed " perfectly fresh horse-dung," and 

 found that of fne ammonia there w as not mure than one pound 

 in \~i tons ! And yet these 15 tons contained nitrogen enough to 

 furnish 140 lbs. of ammonia. 



" But," it may be a.skcd, " will nut this fresh manure decompose 

 in the soil, and furnisli ammonia ? " In liglit, sandy soil, 1 pre- 

 sume it will do so to a consi Icrablc extent. We know that clay 

 mixed with manure retards fermentatio;i, but sand mixed with 

 manure accelerates fermentation. This, at any rate, is the case 

 when sand is added in sm dl quantities to a heap of fermenting 

 manure. But I do not suppose- it would have the siime cfTect when 

 a small quantity of manure is mixed with a large amount of sand, 

 as is the ca.se when manure is applied to land, and plowed under. 

 At any rate, practical farmers, with almost entire unanimity, think 

 well-rotted manure is better for sandy land than fre.sh manure. 



As to how rapidly, or rather how slowly, manure decomposes 

 in a rather heavy loamy soil, the above -experiments of Mr. Lawes 

 afford very cunclusive, but at the sime time very disrouracring 

 evidence. During the 19 years, 3,^00 His. of nitrogen, and 1G,4!»2 

 lbs. of mineral matter, in the form of farm-yard manure, were ap- 

 plied to an acre of land, and tlie 19 crops of barley in irrain and 

 straw removed only 3,724 lbs. of mineral matter, and 1,001 ll)s. of 

 nilr.)gen. The soil now contains, unless it has drained away, 

 1,7;JG lbs. more nitrogen per acre tlian it did when the experiments 

 comnipnced. And yet 41 lbs. of nitrogen in an ava'Iahle mndlt'on 

 is sufficient to produce a good large crop of liarley, and S2 lbs. per 

 acre fnrnislied more than the plants could <ir>raiiize. 



" Those are very interesting experiments," said the Doctor, " ani 

 show why it is that our farmers can afford to jiay a hlLMicr priic 

 for nitrogen and phosphoric acid in superphosphate, and other ar 



