40 BULLETIN 316, U. S. DEPARTMENT OF AGRICULTURE. 
branchy. In 1913 the contractors received $1.50 to $2 per cord for 
the willows loaded on barges, and at this price they were in some 
instances able to make wagon hauls of a mile and still operate at a 
profit. 
The first cutting is sometimes 10 or 12 years old, although willows 
8 or 9 years old are most commonly used. On cut-over land the new 
crop is ready in 7 years, and in several places in lower Missouri three 
crops including the original seedlings have been grown and cut off 
in 25 years' time. The average yield of fully stocked stands (and 
most of the stands are fully stocked) is 40 cords per acre, although 
it may range 10 cords above or below this figure on small areas. 
The original seedlings at this rate produce an average of 4 cords per 
acre per annum; and the sprout growth, between 5 and 6 cords per 
acre per annum. These figures represent the maximum capacity of 
the land, complete utilization, and a low solid content per cord. It 
is doubtful whether the trees at this age reach their maximum pro- 
duction, but the increased production obtained by a longer rotation 
would be offset by the less close utilization that would be necessary 
if the material went into cord wood for excelsior, pulp, or fuel. 
The land on which these willows are found is usually a rich sandy 
silt, although here and there occur patches of less fertile sands on 
which the growth is not so vigorous. This land, fertilized by a 
deposit of sediment each year, is rich enough to produce a relatively 
high yield of any kind of crop if it could be farmed. On poorer 
land, even if moisture conditions were favorable, it is doubtful 
whether more than one-half to two-thirds of this yield could be 
obtained. 
The use of willows by the Army engineers has so far been for the 
manufacture of channel, pocket, and facine mattresses. To make 
these mats, they have developed especially built machinery and 
barges, so that in recent years the cost has been much reduced. 
The mats are usually 1,000 feet long, 250 feet wide, and 12 to 14 
inches thick. The dimensions, however, vary considerably in 
accordance with the requirements of the situation. After sinking 
the mat along the bank, the upper portion approximately at low- 
water mark, the bank is graded with a hydraulic grader to a slope 
of 1 to 3 and paved with rock varying in size from 4 to 100 pounds. 
(See PI. VII, fig. 2.) The cost of making the mat varies consid- 
erably, but on the average is from $4 to $8 per square (a square is 
100 square feet), or $10 to $20 per linear foot. The completed 
work, including the mattress, grading, and paving, costs $20 to 
$30 per linear foot. The mats will last for 30 years, or longer under 
favorable conditions. Portions of the mat exposed at intervals of 
low water have a tendency to disintegrate very quickly unless buried 
