Page:The Olive Its Culture in Theory and Practice.djvu/63

Absorbtion is greater by night than by day. and recently cultivated ground is the most receptive, as it exposes the greater number of particles to the action of the air.

As the earth grows dry. its capacity to absorb moisture diminishes. So we observe that ground frequently and thoroughly cultivated retains moisture the longest.

THE DRYING QUALITY OF SOILS.

Of 100 parts
of water.

Silicious sand in four hours evaporates	88.4
Calcareous	75.9
Gypsum	71.7
Dry chalk	52.0
Earthy	45.7
Clayey soil	34.6
Clay	31.9
Carbonate of lime in four hours evaporates	28.9
Manure	20.5
Magnesia	10.8
Garden earth	24.3
Arable hand	32.0

These figures indicate what we see in practice, that the more sandy the soil, the sooner it dries. Some soils when they dry, actually diminish in volume, and through splits and cracks expose the roots of the tree. Sandy, limey and gypsum soils do not have this drawback; the others vary in the following degrees.

Of 1000 parts.

Carbonate of lime soils loses	50
Dry chalk	60
Earthy	89
Clayey soil	114
Clay	183
Magnesia	154
Manure	200
Garden earth	149
Arable land	95