STRONG MANURES.

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sawdust, &c. This addition tends to check their too !rapid decay, and prevents the great loss which ensueswhen manure ferments, or becomes hot from the effects jof its own decomposition; and at the same time thevegetable matters added are gradually brought into astate of decay, which renders them also a most valuableaddition to the soil. i

421. Strong animal manures are doubly valuable, |for not only do they contain abundance of those matters jwhich constitute the food of plants, but they also assist

in rendering useful, materials which would withoutthem be of far less service. Whether these manures areemployed in the liquid or in the solid form, some meansshould be adopted to retain the ammonia, either by the jaddition of acids, or by some other method. ;

422. These remarks are far less applicable to animal !manures, such as fatty substances, horn, wool, bones, •;&c., which decay but slowly. These substances for themost part act slowly and gradually, and in a verydifferent manner from the softer parts of animals. Ingeneral the strength or value of animal manures is inproportion to the quantity of nitrogen which they jcontain ; those which contain much of that element jdecay rapidly, and evolve a considerable quantity of 1ammonia; whilst those containing little or no nitrogendecay slowly, and, though valuable, and perhaps morelasting in their effects as manures, are far less powerful jfor the time.

423. Wool, and horn, contain less nitrogen than flesh '