188 



USE OF MANURE. 



It is the prevailing opinion of chemists as well as practical men that 

 -where it is practicable it is best to apply manure and urine to the soil 

 in the freshest possible condition. The fertilising constituents of well- 

 rotted manure, as already explained, are more quickly available to 

 plants; the manure itself is less bulky, easier to distribute, and affords 

 a] good breeding place for organisms which promote nitrification* in 

 the soil; and is less likely to promote rank growth than fresh manure. 

 On the other hand, fresh manure mixed with the soil readily under- 

 goes a fermentation which not only increases the availability of its 

 own fertilising constituents, but also assists in rendering soluble the 

 hitherto insoluble fertilising constituents of the soil. In fact, even 

 with special precautions to prevent injurious fermentation under the 

 feet of the animals and in the heap, the greatest return is likely to be 

 gotten from manure applied in the fresh condition. 



The form in which manure should be applied (whether fresh or 

 rotted) is determined largely by the soil on which it is to be used. If 

 improvement of the mechanical condition is the main object sought, 

 the best results will be obtained by applying the fresh manure to the 

 heavy clay soils, and the well-rotted manure to the light soils. If, how- 

 ever, the prompt action of the fertilising constituents of the manure is 

 desired, light soils, in a favourable season, are likery to utilise coarse 

 manure to better advantage than heavy soils. Decomposition takes 

 place slowly in heavy soils and the constituents of the fresh manure 

 become available very slowly. In light soils, on the other hand, unless 

 the season is dry, the conditions are such that the manure decomposes 

 readily, and the fertilising constituents are probably rendered available 

 as fast as the plant needs them. There is also considerable danger on 

 this class of soils that some of the soluble constituents will be carried 

 away in the drainage if well-rotted manure is applied. For this reason 

 such manure should be applied to light soils shortly before it is likely 

 to be needed by the crop. Small applications at frequent intervals is 

 a safe rule to follow on these soils. In general, it may be said that for 

 spring application the more readily available rotted manure is prefer- 

 able to the fresh unrotted material. 



On clay soils it often happens that manure produces no effect what- 

 ever during the first year on account of slowness of decomposition, 

 but since the clay possesses very powerful absorptive properties the 

 manure is not lost. The fertilising constituents are retained in the 

 soil and are finally utilised by the crop. There is therefore no danger 

 in applying to clay soils large quantities of manure a long while in 

 advance of the planting of the crop. During dry seasons the manure 

 may produce little effect, but with a sufficient amount of moisture its 

 aetion is likely to be considerable. The application to such soils of 

 large quantities of manure improves their physical condition, and by 

 the addition of humus renders more porous those which are too compact. 



The behavior of calcareous soils toward manure is very variable, 

 depending upon the compactness of the soil. In those which are suffi- 



* Nitrification is the process by which the highly available nitrates are formed 

 from the less active nitrogen of organic matter, ammonia salts, etc. It is due to 

 the action of minute microscopic organisms which develop only in the presence of 

 air, moisture, and a basic substance such as lime or an alkaline carbonate. 



