146 Breaking up Flard-pan. 
under handily. In this practise the weed stems are not so 
woody, but they easily decay and act as a fertilizer, Where 
early plowing is practised, it is usual to plow again when the 
second growth of weeds reaches the proper state in the spring. 
When two plowings are given, the earth is usually thrown away 
from the trees in the first plowing, and returned toward 
the trees in the second plowing. But this order is sometimes 
reversed in situations where rainfall is heavy and the soil reten- 
tive, for the dead furrow between the rows often acts as a surface 
drain to carry off surplus water, which is thus prevented from 
standing around the tree roots. In all modes of plowing it is 
desirable that before the summer heat comes, the surface be 
leveled as completely as possible. 
Too much stress can not be Jaid upon the importance of 
plowing when the soil is in good condition and not otherwise. 
To disregard this is bad enough in all soils, but it is a grievous 
mistake to work any of the clayey soils when they are out of con- 
dition. If too wet, they are puddled by the plow and dry down 
in hard clods, impenetrable by air, and even resist water itself for 
a long time. When clods are thus formed, it may require long 
effort to bring the soil back to a good friable condition. The 
cultivation of adobe is one of the problems of California agri- 
culture. The more refractory it is, the more particular care is 
needed to take it when it is in proper condition to work. To 
work it when perfectly dry is simply impossible; and if it is 
plowed when too wet and sticky, it becomes hard, lumpy, and 
altogether unmanageable. The condition which favors best re- 
sults by tillage must be learned by experience. 
Another mistake, apt to be made where the orchard or vine- 
yard is but one of the branches of a mixed farm, is to put aside 
the plowing until all the field work is done, and in some seasons 
the soil in the orchard has become so dry that it turns up in large 
clods, which are afterwards partially reduced by the harrow, 
but never put in the fine tilth which should be secured for the 
retention of moisture and otherwise to encourage the growth and 
productiveness of the trees. 
Breaking up Hard-pan.—Those who advocate the use of the 
plow, claim several advantages for it. The chief is that more 
thorough tilth can be secured. In most, but not all soils, there 
is formed by cultivation an artificial hard-pan at whatever depth 
the implement attains, if this depth be kept the same for many 
successive cultivations. This hard-pan, in some soils at least, 
becomes impervious to water and is otherwise an injury to the 
growth of the trees. It occurs in irrigated and unirrigated land 
alike, but probably is more quickly formed by irrigation. When 
continuous summer cultivation is practised, the hard-pan will be 
