ORCHARD TILLAGE, FERTILIZERS AND SHADE CROPS ii 
water causing sun scald. It is thought that reflection from a hot, 
baked soil may cause similar injuries. 
As has been noted before, Colorado soils are very deficient in de¬ 
caying vegetable matter and it is very rapidly dissipated when it is 
supplied. A summer cover will preform one of its most important 
functions in preventing, at least a portion of this loss. • 
Examine a moderately heavy soil in an orchard where a manurial 
crop is growing. The surface soil under the plants will be found to 
be cool, moist and friable, while adjacent unprotected land will be 
found to be hot, dry and compact. This difference is due not alone 
to the shade afforded by the plants but to the transpiration of im¬ 
mense quantities of water as well. It has been found, for instance 
that a grass plant will give off its own weight of water every 24 hours 
in hot, dry summer weather. To be sure it requires more water to irri¬ 
gate an orchard where any crop other than the trees is grown, but 
where sufficient water can be had for irrigation this feature need not 
be considered. 
It is a well known fact that our heavier soils, particularly if they 
are strongly alkaline, become so compact that it is almost impossible 
to cultivate them after the first irrigation in the spring. It is also true 
that continued clean cultivation, particularly if plowing is omitted, 
will make almost any of our soils compact. It is this condition that 
prevents the proper development of absorbing roots and the setting 
free of the native fertility of the soil. A few of our fruit growers 
have shown that green manures in combination with the necessary 
plowing, will work wonders with such soils as well as with the ap¬ 
pearance of the trees growing on them. 
Earth worms do damage in some orchards for the reason that they 
puddle the soil and much of the irrigation water seems to disappear 
through the channels, which they make deep in the ground. A supply 
of decaying organic matter should do much to overcome these effects. 
Soils are occasionally found which are so porous that water leaches 
down through them much like a seive. If fiber can be incorporated in 
such land by plowing under green crops this tendency will be over¬ 
come, to a certain extent at least. 
Many young trees are lost each year in the colder districts as 
a result of “freezing dry.” This term is used as a name for a condi¬ 
tion which may be induced in different ways. The usual cause is 
simply a lack of water in the soil during the winter. Trees give off 
water during cold weather from twigs and limbs, and if the supply is 
not replenished, death results. A similar effect is produced when a 
damp soil is frozen to such a depth that root action is suspended. The 
tops of such trees usually die after a feeble attempt at putting forth 
leaves has been made, while the roots are usually in perfect condition. 
The condition mentioned first, may be avoided by winter or late 
fall irrigation. The deep freezing of soil presents more of a problem 
but we believe that it may be prevented to a considerable extent by 
the use of shade crops. True, the system we propose contemplates 
plowing in the fall but eastern experience proves that as much pro- 
