4 BULLETIN -1277, U. S. DEPARTMENT OF AGRICULTURE 
A more serious limitation of " input requirements " is that the 
very concept denies the fundamental principle of diminishing re- 
turns, or " diminishing output '' as it is now sometimes called, and 
along with this, the principle of varying costs per unit of product. 
The principle of diminishing output states that beyond a certain 
point the output per unit of input varies inversely as the input of 
the cost element. Or stated conversely, as input increases, the input 
per unit of output increases. If this principle is true, then there 
can be no one definite requirement for each unit of product, but 
instead a different requirement per unit of product as the input 
changes. 1 As the requirements per unit of output change, so do 
the costs change, for costs are merely inputs expressed as values. 
Variations in Rate of Applying Fertilizer and Manure to Potatoes 
20 25 
DOLLARS 
Fig. 1. — Though some farmers applied $20 or $25 worth of fertilizer and manure per 
acre, more applied from $o to $10 worth than any other rate. This illustrates the 
wide differences in practices on farms in the same area. Data from Monroe County, 
N. T., for 1913 
The actual circumstances are that inputs vary a great deal. A 
simple case of this is the different quantities of the same kind of 
fertilizer applied to the same crop by different farmers. 
FEETILIZEE INPUTS FOE POTATOES 
Table 1 and Figure 1 illustrate fertilizer variations for potatoes 
in New York. 
1 No constant terminology has born used in presenting " input requirements " in cost-of- 
production bulletins. The nomenclature varies from " basic- cost formula " and " basic 
acre requirements " to " quantitative requirements for crop production." " Unit require- 
ments " is a clear-cut expression of what all of these phrases mean, namely, certain defi- 
nite physical quantities of each input factor required to produce a specified unit of output. 
The whole thesis of this bulletin is that there is actually no such thing as a definite unit 
requirement for a specified production. It. will appear from what follows that there is a 
range, frequently a. wide one. in the amounts of the cost elements which enter into a given 
product, it is necessary to have som<> k cm which expresses (he relation of input to out- 
put under any specific set of conditions, hut which does net imply that this is a fixed re- 
lation applying to ail conditions- The single term " input " will ordinarily he used, al- 
though ii does not sufficiently suggesl thai then is a definite relation between input and 
output, if occasionally th< expression ••input requirements" is used, the reader will 
■and that " requirements '' is added merely to suggest this definite relationship. 
