N0EMAL DAY'S WOEK FOE VAEIOUS FAKM OPERATIONS. 3 
be obtained. From such data the principles and relationships for 
wise investment can be worked out, which might possibly be recog- 
nized by the occasional individual, but which must at best be appre- 
hended only vaguely by the majority, if they are not quite without 
the purview of the man confined to the duties and experience of one 
farm. 
SEASONAL OPERATING FACTORS. 
Under practical farm conditions, work can be planned intelligently 
and successfully executed only when allowance is made for rainy 
days and other climatic conditions which interrupt the various opera- 
tions in their respective seasons. Conclusive data of this character 
for any region can be secured only by long-continued observations of 
the weather in connection with its interfering effect on farm work. 
However, approximate seasonal factors for farm operations can often 
be calculated for any locality from the current practice with any 
crop. 1 
i In the southern part of the corn belt one man with a 2-horse team can plow, harrow three times, and 
plant 40 acres in corn from about March 10 to May 10. What "fraction of this period is available for field 
work? 
A man can plow 1.75 acres, harrow 10 acres, or plant 11 acres per day. Hence, to plow, harrow three 
times, and plant 1 acre will require — 
(r^+^+rr) day. To do 40 acres will require 40 ( r^^+^+r-- ) davs. 
\1. io 10 11/ " \1. to 10 11/ 
Another expression for this number of days may be found as follows: The whole number of days from 
March 10 to May 10 is 61; if F represents the fraction of this period available for field work, then Fx61 is 
the number of available days. Thus, Ave have two expressions for the number of days available for field 
work, and these two expressions may therefore be equated. This gives us the equation— 
Solving this equation, we find F equals 0.631. That is, 63.1 per cent of the period is available for field 
work. 
The following more general formula, based on the above considerations, is useful in many ways: 
/t t' t" \ 
(a + b + c+- ; 
FS. 
In this formula A stands for the number of acres of land involved; t, t', t", etc., represent the number of 
times the various operations are performed; a, b, c, etc., represent the area covered in a day in each of the 
various operations performed; F is the fraction of time available for field work; and S is the number of 
days in the season during which the work must be done. 
Another use to which this formula may be put is illustrated in the following problem: Assuming that 
during March one day in two is available; during April and May, two days in three; that oat land is 
plowed, harrowed once, and drilled; that corn land is plowed, harrowed three times, and planted; that 
a day's work is plowing 1.75 acres, harrowing 10 acres, drilling 8 acres, or planting 11 acres of corn; and 
that the rotation used calls for equal areas of corn and oats; what area of each of these two crops can one 
man put in between March 1 and May 10? Our formula now becomes— 
/I 1 ' 1\ . / 1 3 1x1,2,, 
Vl75 + T0 + 8) + A (uTS+lO+ll) = 2 X31+ 3 X4 °- 
From this we find A equals 24 acres. That is, one man can plant. 24 acres each of corn and oats. 
If in the foregoing problem we omit the plowing and harrowing for the oats and simply drill them in 
the old corn stubble by means of a disk drill, as many farmers do, how many acres can the man put in of 
each of these crops? For this problem the formula now becomes — 
G) +A (rrs+fo+n) 4 X31 +I>< 40 - 
