20 
COLORADO EXPERIMENT STATION 
acts as an earth mulch and prevents the moisture rising above the 
bottom of the furrow. Unless rain comes, the ground that has been 
turned by the plow soon becomes so dry that plants will not live in 
it. It is a good system to thoroughly disk ground just before plowing. 
The surface turned under will then be fine and will better form a good 
connection with the soil below. 
Dry soil, clods, trash and coarse manure, when turned under by 
the plow, will make air spaces in the pulverized soil. The air in 
these spaces dries out the soil and increases the losses from evapora¬ 
tion. 
To retain the moisture in the pulverized soil, to bring it up from 
below to the roots of the plants and to drive out the excess of air, 
freshly plowed soil must be firmed until a compact but mellow con¬ 
dition is secured. The best implement so far devised with which to 
do this is the Sub Surface Packer originated by Mr. H. W. Campbell. 
The sub surface packer consists of a number of sharp rimmed iron 
wheels, twenty inches in diameter, placed five inches apart on a strong 
shaft mounted in a suitable frame. The packer follows the plow, going- 
lengthwise of the furrow. The sharp wheels fine the soil near the surface 
where the seed is planted and firmly packs the earth against the bottom of 
the furrowi and around the trash and manure,—just the condition needed 
for a good seed bed and for the best control of the moisture. 
The writer consideis the sub surface packer one of the most 
indispensable implements lor dry land farming, and would not attempt 
dry land operations without it. One hundred and sixty acres were 
plowed for wheat, eighty acres prepared as thoroughly as could be 
done by harrowing and eighty acres fitted by packing. The yield 
on the harrowed ground v/as eighteen bushels per acre, on the packed 
ground forty bushels. 
Whenever the soil is sufficiently moist to settle quickly, it is not 
necessary to use the packer, but it should be at hand for use when 
needed. It is heavy in draft, an eight-foot machine requiring four 
good horses. 
Sub surface packing can be fairly well done by setting the disks 
straight on a disc harrow and weighting the machine to cut deeply. 
