12 BULLETIX 633, U. S. DEPARTMENT OF AGRICULTURE. 
into camp near the fields for the few weeks when there is a rush of 
work of this kind. The amount of labor required for harvesting 
the crop is therefore not really a limiting factor in the acreage that 
the farmer can grow. The limit is represented rather by the area 
which he and his family can tend at times other than harvest. 
MAINTENANCE OF SOIL FERTILITY. 
The systems of farming which prevail generally in this region are 
not such as to maintain satisfactorily the fertility of the soil. As a 
result the yields on most farms are low. The three more important 
factors in maintaining crop yields are the use of manure, the plow- 
ing under of sod crops or green manure crops, and the use of com- 
mercial fertilizers. On most of these farms the amount of live stock 
kept is small compared with that kept on farms farther north. The 
amount of manure produced on the farm is not sufficient to maintain 
the fertility of the soil at a satisfactory level. Furthermore, on ac- 
count of the general mildness of the climate, farm animals are not 
kept indoors much of the time, and a good part of the manure thus is 
not available for distribution on the tilled fields. Farmers therefore 
get relatively little from the manure actually produced on the farm. 
In order to determine the results actually obtained from manure the 
farms in this survey were divided into two equal groups, the first 
consisting of those farms having less live stock than the average per 
hundred acres of crops, and the second of those having more than the 
average. A comparison was then made between these two groups of 
farms with respect to the average yield of each of the more important 
crops. The difference in favor of the farms having the more live 
stock was as follows: Corn, 1J bushels per acre; wheat, 0.6 bushel; 
oats, 2.5 bushels ; hay, 0.1 ton. 
When the relative acreage of these crops and the average price of 
their products for the last 10 years are taken into account this 
difference in yield in favor of the farms having more live stock than 
the average amounts to $5.14 per year for each animal found on the 
farms having most live stock over and above those found on farms 
having least live stock. In other words, under the average condi- 
tions which prevail in this locality the farmer, on the average, ac- 
tually gets in crop returns $5.14 from the manure of each 1,000- 
pound animal or its equivalent in smaller animals. This is a very 
low valuation for manure, a fact which undoubtedly is due largely 
to the small proportion of the manure that is actually applied to the 
fields. By taking the best possible care of manure, by distributing 
this manure in the fall of the year on land that is to be devoted to 
corn the next year, and either disking it into the land or plowing 
