530 NATURE AND PROPERTIES OF SOILS 



that floats, if added in money values equal to acid phosphate, 

 should be about as satisfactory as a reinforcing material. 



304. Lime and manure. — Very often it would be a sav- 

 ing of labor to apply lime and manure to the soil at the same 

 time. This can readily be done with the carbonated forms. 

 Such lime may be mixed with the manure, either in the stable 

 or in the pile, without any danger of detrimental results. The 

 close union of the lime and manure may increase the effective- 

 ness of the former and at the same time promote a better type 

 of decomposition in the latter. If the soil is really in need of 

 calcium, however, a separate application of lime is much bet- 

 ter, as the amount of calcium added with the manure is never 

 large. Caustic compounds of lime such as calcium oxide 

 (CaO) and calcium hydroxide (Ca(OH) 2 ) must be kept from 

 manure. These forms readily react with the ammonium car- 

 bonate coming from the urea, and cause the liberation of 

 ammonia, which may be readily lost to the air : 



CON 2 H 4 + 2H 2 = (NHJ 2 C0 3 

 (NH 4 ) 2 C0 3 + Ca(OH) 2 = CaC0 3 + 2NH 4 OH 



A stable or shed containing manure may be at once deodor- 

 ized by the use of quicklime, but with the loss of much nitro- 

 gen. If the manure is to be worked into the surface soil, the 

 caustic lime may be applied some days before and if it is in 

 thorough contact with the soil, it will change to the carbonate 

 before the manure is added. When the manure is plowed 

 under, the lime is best added after the plowing and thor- 

 oughly harrowed in as the seed-bed is prepared. 



305. Manure and composting.— A compost is usually 

 made up of alternate layers of manure and some vegetable 

 matter that is to be decayed. Layers of sod or of soil high in 

 organic matter are often introduced. The manure supplies 

 the decay organisms and starts biological activities. The 

 foundation of such a compost is usually 'soil, and the pile is 

 preferably capped with earth. The mass should be kept 



