96 Bulletin 174. 



2. They may lack humus or vegetahle Ttiould. — AVlien in native 

 conditions, in regions of sufficient rainfall, lands are covered with 

 vegetation. As this vegetation dies it becomes incorporated with 

 the soil as humus, making the soil mellow, dark-colored and rich. 

 It enables the soil to hold moisture, lessens extremes of temperature, 

 hastens chemical activities, and itself supplies plant-food. When 

 vegetable matter is withheld from the soil, the humus is not replen- 

 ished, and it is gradually used up. The soil then becomes hard, 

 " dead," very dry in dry weather and very muddy in wet weather, 

 and is subject to great extremes of temperature. If the original 

 basis of the soil is clay, the land bakes and becomes lumpy when 

 ploughed ; if sand, it becomes loose and leachy. See Part II, para- 

 graphs 5, 6. 



One great value of stable manure is to supply humus. Green- 

 cropping is also exceedingly useful. A rotation of crops in which 

 sod is one factor tends to maintain the supply of humus. Catch- 

 crops (sown between other crops) may be used to replenish the 

 humus ; also cover-crops (those sown in fall for a winter cover). 

 Long-continued cropping with one or with similar crops tends to 

 deprive the soil of humus. When the farmer does not properly 

 care for the land, nature tries to force him into another rotation 

 This is well illustrated in pastures and meadows in which daisies 

 and wild carrot force out the poor stand of grass. Most of the 

 depleted lands in ]^ew York are suffering more for humus than for 

 plant-food. 



To determine by experiment whether a soil has sufficient humus 

 is difficult, because the forms of available humus-producing materials 

 also contain plant-food. Ilumus may be supplied by muck, stable 

 manure, leaves or green-crops. All these contain the different 

 plant-foods, and also a large amount of vegetable matter. To test 

 whether a soil needs humus, apply these materials to several plats 

 of ground, leaving one or more without them for checks. Stable 

 manure might be applied to one plat, muck to another, a green- 

 crop of clover, barley, buckwheat, etc., turned under on another. 

 Nature uses leaves for making humus in the woods. 



3. They may need drairmig. — Under-draining lowers the water- 

 table (or the zone of standing water), causing the soil to become 



