152 The Principles of Fruit-growing. 
should be slight. Nothing could be better calculated 
to dry out a potato field or a corn field than throw- 
ing the ground up in high ridges, leaving a large 
surface exposed to the action of sun and wind. 
In fruit plantations which are in a proper state of 
cultivation, a small-toothed or even spike-toothed 
cultivator will be found sufficient to maintain the 
surface mulch. 
The roller, in its relation to soil moisture, is an 
implement whose value depends largely upon local 
conditions. There is no tool which requires more 
judgment as to its proper use. On light, loose, 
sandy or gravelly soils, where every effort must be 
made to solidify and pack the particles closely to- 
gether, the roller must be used repeatedly. The 
difficulty with such soils is that the spaces between 
the grains are so large that the water is permitted 
to pass through freely, and is lost by percolation. 
The capillary openings are so large that there is 
very feeble rise of the water to take the place of 
that used by plants and lost by evaporation. The 
roller lessens the size of these pores in solidifying 
the soil, and the capillary force is then strong 
enough to draw the water to the surface. If, now, 
the soil is left in this condition, it has been put 
in the best possible form for parting with its 
moisture into the atmosphere, and it will take ad- 
vantage of the opportunity unless prevented by 
establishing a surface mulch. In seeding land in a 
dry time, the soil should be rolled in order to bring 
sufficient moisture to the seeds to insure germina- 
