WATER UTILIZATION BY SPRING WHEAT, 23 
COMPARISON OF CULTURAL METHODS. 
The conservation and use of moisture in plats on which different 
cultural practices have been employed, are sufficiently comparable 
at the different stations to allow definite deductions to be made. 
For the average of all stations, plats A and B show no notable 
differences in the quantity of moisture conserved. The differences at 
individual stations are only minor. In the northern section of the 
Great Plains the advantage of one or the other at the stations where 
one is superior favors plat A. This is without doubt due to the fact 
that in most years there is a better opportunity to obtain moisture by 
holding the winter snow than by conserving the moisture that falls 
after harvest. The soil at harvest has been shown to be dry approxi- 
mately 90 per cent of the time; therefore, cultivation at that time 
usually conserves no moisture, because none is present. By pre- 
venting weed growth, fall plowing is better able than spring plowing 
to conserve the moisture that falls between harvest and winter. How- 
ever, the moisture that falls after harvest is not usually all used up 
on land not fall cultivated. The season between harvest and freezing 
is not long, and the demand of plants for moisture at that time is not 
high. Where there is sufficient precipitation after harvest to induce 
weed growth, there is usually enough so that the moisture supply 
is not exhausted by the time freezing kills the weeds. 
In years with a heavy precipitation after harvest, plat B usually 
conserves more moisture than plat A. The greater number of times 
that plat A possesses the higher moisture content in the spring shows 
the superiority of catching snow over retaining fall precipitation in 
conserving moisture at the northern stations. 
At the southern stations the difference between the two methods 
in conserving moisture when a difference exists has been in favor of 
plat B. In this region there is little snow ; consequently, the superi- 
or^ of plat A in catching snow is of little importance. There is 
also an earlier harvest and a later fall than at the northern stations. 
This gives plat B a longer period for moisture storage and also gives 
the weeds on plat A a greater chance to remove the moisture that 
falls after harvest. In spite of this, the difference between the two 
plats in the quantity of moisture stored has generally been small. 
That the greater depth of plowing practiced on plat B has not 
increased the root development of this plat over that of plat A is 
indicated by the fact that the two plats have been practically dupli- 
cates in the utilization of the moisture present. 
Unfortunately, the slight superiority of one plat over the other in 
moisture storage in different sections of the Great Plains is such that 
it is not possible to benefit greatly from it in farm practice. The 
southern stations, where plat B has conserved more moisture than 
plat A, are particularly subject to soil blowing during the winter 
months. This operates against the use of fall cultivation on an ex- 
tended scale. 
At the northern stations, where plat A has been slightly superior to 
plat B, there is a practical limit to the spring work that can be done 
without unduly delaying seeding. In that region the earlier seeding 
that may be practiced on fall plowing frequently more than makes 
up for any superiority of spring plowing in the quantity of moisture 
conserved. 
