10 BULLETIN 757, U. S. DEPARTMENT OF AGRICULTURE. 
and days when it is too wet for field work. This available time is . 
distributed as follows: 
Days. Days. 
ATONE ec ey Sa ee AT RUS (a Ose ee a 22 
May —__ oe ds SS be Ae EEE 22) |S Septemberai i: is) Seyi a eee) 
June sue aot teal So ee | OCOD eR 2 = ee 22 
Sulyaen ja es 2 | NO Vembpers. 2s Wali so. Ue ee 2 
FACTORS THAT CONTROL COST OF PRODUCTION. 
Several important items enter into the cost of production of crops, 
each of which has a bearing on the profitableness of the various farm 
enterprises. In general, as each of these items increases in amount 
above a normal average the profits decrease. There are, however, one 
or two exceptions, such as the cost of twine and of thrashing, which 
are directly in proportion to the yield. 
USE OF LAND. 
The value of agricultural land, in general, is determined largely by 
its average productivity. Security of investment, profits from ex- 
pected advances in value, and risk in production are other influenc- 
ing factors. The earning value or productive value of land in North 
Dakota, however, is not always in proportion to its market value. 
The payment to capital for the use of the land in older farming 
communities is usually equivalent to the current rate of cash rent 
for such land, less taxes and upkeep of buildings. In North Dakota 
scarcely any land is operated on a cash rent basis. In the rare cases, 
where obtainable, cash rent usually amounts to from 3.5 to 4 per cent 
on the investment. It was found in eastern North Dakota, where 
the average selling value of land is approximately $50 per acre, that, 
in general, when a: farmer buys land, paying one-half the cost price 
in cash, the remaining $25 per acre is liquidated in about 15 years, 
interest being allowed at 6 per cent, indicating that he has made a 
net income of at least $2.50 per acre per year. 
For purposes of calculation, if 6 per cent on the value of the land 
is assumed for use of land, no serious error will be made. In the 
Red River Valley this interest amounts to $2.97 per acre; in east- 
central North Dakota, $2.42; in west-central, $1.77; and in the west- 
ern part, $1.34 per acre. 
LABOR ON CROPS. 
Man labor is one of the important factors of production. The 
amount required per farm was indicated on page 9. The amount 
required per acre for the leading crops under normal yields is shown 
in Table I. 
