4 BULLETIN 705, U. S. DEPARTMENT OF -AGRICULTURE. 
Crop index. — The yielding power of the soil of a given farm or 
group of farms expressed as a percentage of the average yielding 
power of the soil of all farms in the community. 1 
Animal unit. — A mature horse or cow, or as many smaller animals 
as require the feed of a horse or cow, namely, 2 head of young cattle, 
2 colts, 5 hogs, 10 pigs, 7 sheep, 14 lambs, 7 goats, 14 kids, or 100 hens- 
Productive animal unit. — Includes all animal units except work 
horses. 
Receipts. — The gross income of the farms from all sources. 
Expenses. — The total amount necessary to conduct the farm busi- 
ness during the year. It includes, besides all cash outlay, deprecia- 
tion of equipment and buildings and all unpaid family labor (excepting 
that of the operator) used in conducting the farm business. 
Farm income. — The difference between the gross receipts and the 
expenses. It is the amount available to the farm family for living, 
saving, and paying debts after the expenses of conducting the farm 
business during the year have been paid. It does not include what 
the farm furnished directly toward the family living. 
Percentage farm income is of capital invested. — Farm income does 
not include the amount the farm furnishes the family in the way of 
food, fuel, and the use of the farm dwelling. Neither do the expenses 
include the value of the operator's labor and the cost of his board. 
These two amounts, that is, what the farm furnished the family and the 
value of the operator's labor and the cost of his board, were so nearly 
equal on the farms studied that percentage farm income is of capital 
invested is used in this discussion to measure the efficiency of farming. 
i The crop index may be defined as the crop yields of a particular farm expressed in percentage of the 
average crop yields of all the farms in the community. It is found as in the following example: 
A particular farm produces— 
2, 000 bushels of corn on 40 acres, 
1,200 bushels of wheat on 40 acres, 
900 bushels of oats on 30 acres, and 
120 tons of hay on 80 acres. 
Total 190 
The average yields of the above crops in the community are: Corn, 60 bushels; wheat, 32 bushels; oats, 
40 bushels; and hay, If tons per acre. Hence, on the average, the areas required to produce the above 
quantities of the products mentioned are— 
2, 000-^-60= 33. 3 acres of corn, 
1, 200-7-32= 37. 5 acres of wheat, 
900-7-40= 22. 5 acres of oats, and 
120-7-l|= 68. 6 acres of hay. 
Total* 161. 9 
Thus, it requires 190 acres on the farm in question to produce what 161.9 acres produces on the average. 
Hence, 1 acre produces on this farm 161.9-7-190, or 85.3 per cent as much as the average acre of the com- 
munity. 
