USE OF EARTH SATURATED WITH .MANURE. 145 



roots, all the cereal plants, other conditions being the 

 same, should attain the same height, and each ear yield 

 the same number and weight of grains. 



In the short, rotten farm-yard manure, the nutritive sub- 

 stances are much more uniformly distributed than in the 

 fresh straw manure ; and the agricultiurist effects a still 

 more uniform diffusion by mixing the dung with earth, 

 and turning it into so-called compost. As dung and all 

 other manuring agents act only through the medium of the 

 eaHhy particles that have become saturated with the nutri- 

 tive substances contained in the manure, it is, under certain 

 circimistances, advantageous for the farmer to prepare a 

 saturated earth, by help of his farm-yard manure, and to 

 use this composition, wliich may of course be made ou 

 the field itself. If, in accordance with Voelker's valuable 

 experiments, we assume one cubic metre ( = 35 cubic 

 feet) of farm-yard manure (500 kilogrammes or 1000 

 pounds) to contain 660 pounds of water, 6 pounds of 

 potash, and 12 pounds of ammonia ; and if this were 

 mixed with 1 cubic metre of earth, of which 1 cubic 

 decimetre (= 61 cubic inches) absorbs 3000 milli- 

 grammes (=46 "2 grs.) of potash, and 6000 milligrammes 

 ( = 92-4 grs.) of ammonia ; then, after the complete decay 

 of organic matter in the manure (about 25 per cent, of 

 its weight), and the evaporation of one-half of the water, 

 the result would be 1| cubic metre of earth fully saturated 

 with all the nutritive substances in the manure. Soils 

 that will absorb the stated amount of potash and 

 ammonia are evei'}^vhere to be found, and the farmer 

 will have no difficulty in choosing the earth most suitable 

 for his compost heaps. 



It is well known that dung exercises a mechanical 

 action also, tending to diminish the cohesion of a com])act 

 soil, or to make a heavy soil hghter and more porous. 



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