from blowing, thereby uncovering the grain roots. The plant food con- 

 tained in the coarser substance is not lost, but when plowed under, is 

 beneficial to the following crop, not only because of the plant food it 

 contains, but for the humus which it forms after it has become thor- 

 oughly rotted. 



Farmers who have top-dressed growing grain are very enthusiastic in 

 their praise of the system, many claiming that they obtained far better 

 results than when applied in any other way. 



Top-dressing growing corn and potatoes is also very beneficial. If, 

 however, the crops are to be cultivated after the application has been 

 made, the manure should be well rotted. It is especially beneficial to 

 potatoes after they have been cultivated once or twice, by preventing 

 the growth of weeds and the escape of moisture. Top-dressing pastures 

 and meadows always stimulates the growth. In a number of instances 

 the writer has seen the yield of hay doubled by the application of five 

 tons of manure to an acre. 



Green Manures 



Green manuring is growing on the land a crop and plowing it under. 

 This form of manuring adds no new inorganic plant food elements to the 

 soil, but when a crop is turned under all of the elements or compounds 

 consumed in the growth of the plant are returned to the soil. When 

 legumes (alfalfa, cow peas, clover, soy beans, vetch, etc.), are plowed 

 under, the nitrogen gathered from the air by the legumes is added to the 

 soil. After the crop is removed, the soil is much richer in nitrogen than 

 before the crop was planted, due to nitrogen in the roots and stubble. 



Vaelcker in England found that one acre of clover roots and stubble 

 contained one hundred pounds of nitrogen which had been gathered 

 from the atmosphere in excess of the amount removed in the crop and 

 the amount in the soil before the clover was planted. 



Weiske in Germany found one hundred and eighty pounds of nitrogen 

 in an acre of roots and stubble. 



Any green crop which is not taken off the land is beneficial to the soil, 

 both from a physical and chemical standpoint. Physically, the 

 improvement is due to the roots and stems which decay and become a 

 part of the soil. When the roots die and the plant decays, the entire 

 substance is finally resolved into humus, an essential factor in maintain- 

 ing soil bacteria and nitrogen. Humus thus formed assists in absorbing 

 and retaining moisture, and tends to make the soil mellow and friable. 



The necessity of renewing humus may be due to continued cropping, 

 hot winds and protracted droughts which deplete the soil of that essen- 

 tial substance very rapidly. 



Again, humus in time becomes dead, especially if thorough tillage is 

 not practiced; hence, the supply should be renewed as often as condi- 

 tions demand it, either by plowing under green crops or by applying 

 manure. 



86 



