24 TRUCK-FAKMItfG AT THE SOUTH. 



food; while in the darkness and under the shelter from 

 winds, nitrates are formed and absorbed. It will be seen 

 that the increase of fertility is greater than could be ex- 

 pected from all the manurial agents in the pea vines. 



Clay soils, being more retentive of moisture and pos- 

 sessed of greater power of absorption, are less benefited 

 by the mulch than those of a sandy character. 



Like the questions of deep and shallow plowing and 

 deep and surface manuring, that of plowing under the 

 green vines, or allowing them to dry and partly rot upon 

 the surface, will depend upon circumstances. They will 

 contain and convey to the soil in the green state a greater 

 quantity of fertilizing material and will decompose more 

 rapidly. If intended to benefit a crop to be put in soon 

 after they have reached a proper stage of growth, they 

 must, of course, be plowed under green. Four weeks 

 should elapse between turning under the vines and sow- 

 ing or planting the crop, in order to allow a sufficient 

 time for the most active decomposition to have passed, 

 lest the heat evolved by the great mass of decaying green 

 vegetable matter might be detrimental. For a spring 

 crop, however, the vines should be left to die, and mulch the 

 soil throughout the winter, unless indeed a second green 

 crop, as of rye, is contemplated; because a bare fallow 

 would be wasteful of the fertility supplied by the pea 

 vines. It is an error that the bare soil deteriorates dur- 

 ing summer only, for it is a common experience that a 

 field of light soil, left bare after a late crop of sweet 

 potatoes, shows a want of fertility the ensuing spring. 



Two crops of pea vines may be grown in a season; but 

 after an interval of three or four weeks. To turn under 

 a heavy growth properly, it must first be pressed down by 

 a field roller or by dragging over it a heavy harrow with 

 the teeth turned up; and it requires a good two-horse 

 plow with a large sharp revolving coulter attached. To 

 draw the vines into the furrows, a heavy chain with suf- 



