39 



IV. — How to use Barnyard Manure. 



We have now reached the difficult part of the matter. The most 

 economical use of barnyard manure is seldom made, largely be- 

 cause of our ignorance of the exact needs of the plant, in the 

 particular soil used. Some general rules, however, may be laid 

 down. 



The farmer should strive to place the manure at the disposition 

 of the growing crop just at that moment when the most nitrate 

 has been formed and before any has been destroyed. The most 

 favorable conditions are obtained when fresh manure is packed as 

 tightly as possible, away from the air, and kept in that condition 

 until half-rotted, and then ploughed under just before planting or 

 sowing. Under these circumstances, although the third class of 

 bacteria have in the rotting of the litter made soluble food of one 

 kind for the " nitrate destroyers," the latter have been deprived of 

 their necessary food, the nitrates, for none could be formed in the 

 tightly packed mass, and they have remained harmless. But the 

 heap has become half rotted even without them. After the manure 

 is ploughed in, the " nitrogen formers," now having plenty of air 

 rapidly produce nitrates which are beyond the reach of the de- 

 stroyers ; for by this time all their soluble non-nitrogenous food 

 has been decomposed and has gone into the air, leaving them to 

 die. The growing plants in the mean time absorb the nitrates. 



If fresh manure is ploughed in directly before seeding, a poor 

 result is obtained, for the nitrates are not formed until after the 

 plants have passed their growing period, and they consequently 

 starve. As might be supposed, winter crops fare better with this 

 procedure than spring crops. By ploughing in fresh manure several 

 months before seeding, a much better result is obtained because 

 the nitrates are on hand and are being formed at the growing period 

 of the crops. Experience has abundantly proven that it is better 

 to plough manure into the soil and allow it to lie there rather than 

 in the pile. Whether it is better to leave manure spread on the 

 surface of the land rather than to plough it in or leave in pile, de- 

 pends chiefly on the amount of loss caused by surface drainage. 

 This may be small, but, if the ground is frozen, the surface in- 

 clined and the manure half rotted or more, the loss will be con- 

 siderable. The nitrate-destroying bacteria are of several species, 

 and have thus far been found in straw and various other litter, in 

 soils and in the dung of herbivorous animals. They have not been 

 found in human excrement, or that of the carnivora or birds. 



When barnyard manures are made with bedding devoid of much 

 decomposable organic matter, the nitrate destroying bacteria can- 



