60 Gardening 
under only in autumn. Special pains should be taken 
to pulverize thoroughly all the soil to the depth spaded. 
If it turns over in large lumps, these should be broken 
up by hammer-like blows of the fork or with the rake. 
It pays to do this work well. 
Plowing or spading in autumn, as well as in spring, 
is advisable for all soils that tend to be compact or to be 
lumpy. The soil is left in the rough, with no attempt to 
take or level it down to a smooth surface. The action 
of the frost on the exposed lumps gives a finer crumb 
structure. 
The gardener can also improve the physical condition 
of soils by the addition of certain materials. Heavy 
clay soils are benefited by addition of coarse vegetable 
matter, as poorly rotted manure, leaves, and grass clip- 
pings. It is well to add these in autumn so that the till- 
age in the following spring will mix them well with the 
soil. The addition of sand or lime will also make com- 
pact and lumpy soils more finely granular. Sandy 
soils tend to be so loose that they dry out too readily ; 
this condition is improved by the addition of well-rotted 
humus and manure. 
Careful treatment required for clay soil. Clay soils 
tend to become compact and to break up into coarse 
granules or clods when tilled. If such a soil is too dry 
when spaded, it is lumpy. If it is too wet, it will be 
made lumpy. No soil should be spaded except when it is 
dry enough to crumble readily when rolled in the hands. 
‘An easy way to test this is to squeeze a small handful of 
the soil into the form of a ball, quite as one makes a 
snowball (Fig. 39). If it sticks together in a ball and 
