FARMERS' INSTITUTES. 25 



MAINTAINING FERTILITY WITH GREEN MANURES. 



PROF. J. D. TOWAR, AGRICULTURAL COLLEGE. 



A fertile soil is one rich in the elements of plant food and fnll of 

 'Organic matter. To restore an exhausted soil to a condition of fertility, 

 or maintain and improve the crop-producing- quality of a fertile soil, 

 we should first see that its supply of humus is kept at the normal. We 

 are coming more and more to value the virgin humus, now it is gone, 

 and our agricultural papers are crowded with articles on obtaining and 

 maintaining this valuable material. It keeps the soil open for the 

 admission of air and the free distribution of roots, it helps to hold mois- 

 ture and it favors bacterial growth. By the slow decay of humus, car- 

 bonic acid is formed and brought in contact with the undissolved mate- 

 rials which contain the needed food of growing crops. Humus further 

 aids in lightening heavy clays and in binding the shifting sands. In 

 extreme hot weather it serves to regulate the temperature of the soil. 



Soils may be rich and productive in the absence of humus, but ideal 

 conditions which hold moisture, conserve and develop fertility and favor 

 growth are not insured in the absence of a normal supply of organic 

 matter. Time was when the summer fallow was a seeming necessity, 

 and in truth it has produced the wheat crops that have lifted many a 

 mortgage in our State. Yet, though it lifted the money mortgage, it 

 planted on those fallowed acres a mortgage on the fertility, secured by 

 the unwise deeds of our fathers, that only the best intelligence and 

 shrewdest managers of the present generation can eradicate. The sum- 

 mer fallow, and the- winter fallow as well, invariably increase the yield 

 of the succeeding crop. But good agriculture rebels against such heroic 

 means of treating the soil, and I verily believe that the exliausted con- 

 dition of many of our older Michigan farms are largely due to these 

 severe practices. How then is the supply of humus to be maintained, 

 and what are the sources upon which w^e ma^'^ draw? First, The roots 

 and stubbles of plants. Second, Coarse manure produced on the farm. 

 Third, Green manuring. Observe that green manuring is placed last, 

 and it is there that it belongs, because it is only a process to supplement 

 the other natural sources of organic matter. It is not a practice that 

 takes sides by itself and alone, though we might suggest a system of 

 rotation which by means of green manuring and grain farming the fer- 

 tility of the farm might be maintained and yet produce profitable re- 

 turns. But this sort of practice would not obtain favor where so intense 

 an agriculture is jpracticed as we have in this State. It is in connection 

 with mixed farming, live stock, and even fruit and vegetable farming, 

 that green manuring comes in for its greatest share of credit and recog- 

 nition. 



W^e may say that green manuring as a definite practice is not a com- 

 mon one, though in realitj^ we are continually turning under green 

 growth, while our best rotations involve green manuring methods in the 

 highest degree. 



For convenience let us assume that crops. are grown for commercial 

 and for soil improvement purposes, and to the credit of the practice of 

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