8 The Bulletin. 



dry as dust. This, then, is the explanation of the "souring" effect of 

 green manure as generally handled : The rain water goes rapidly down 

 through the soil and through the layer of vegetable matter and is stored 

 in quantities in the subsoil, but this bed of noncapillary vegetable 

 matter entirely cuts off the rise of this moisture from the subsoil to 

 supply that taken from the surface soil by evaporation and plant growth. 

 There has been a mechanical and not a chemical condition set up in the 

 soil that cuts oft" the water supply from the plants and causes them to 

 starve for Avater in spite of a normal rainfall. 



The remedy is apparent. See that the vegetable matter is cut fine 

 by the disc harrow before it is plowed under, and, when plowing, edge 

 the furrow slice and thus incorporate the vegetable matter with the soil 

 and have it uniformly distributed throughout the soil stratum from 

 top to bottom. The moisture can then move down and up in the soil 

 to meet the needs of the crop throughout the season. It is always 

 observed, on well-drained land, that the following year, when the land 

 has been plowed deeply again, the layer of vegetable matter torn up and 

 mixed with the soil, that the "souring" effect disappears, showing, if 

 rightly interpreted, that it was the localization of the vegetable matter 

 and not an excessive development of organic acid that produced the dele- 

 terious effect. 



Care must be taken not to turn under organic matter too deeply in 

 heavy soils, since the processes of decay go on very slowly below ten or 

 twelve inches. It has been found that the microflora, bacteria, etc., that 

 cause the organic matter of the soil to decay, and thus give rise to the 

 formation of the various nitrates in the soil, do not act freely below 

 nine or ten inches under the surface of heavy soils. 



It is also true that these all-important organisms cannot exist in the 

 first two or three inches of the surface soil on account of the too great 

 aeration and drying effect of the sun's heat. Their greatest activity, 

 therefore, is confined to that part of the soil stratum lying between three 

 and ten inches of the surface. 



InTow, these bacteria feed almost exclusively on organic matter. An 

 important by-product of cattle feeding is the manure produced, but the 

 principal produce of the feeding of the bacteria is the formation in the 

 soil of natural nitrates which are fundamental to crop production and 

 which are immediately available for the plant as soon as formed. If 

 we cut off the food supply from our cattle, they die, and the same is 

 true when we cut off the food supply from our soil bacteria. It will 

 be seen, moreover, that the proper feeding of the soil bacteria is thus 

 fundamental to the feeding of cattle or any other farm animals. 



PLOWING. 



Land intended for corn should generally be plowed in the fall and 

 sowed to some cover crop, as crimson clover, vetch, burr clover, or rye, 

 to be turned under in the spring for green manuring purposes. 



