The Concept of Economic Efficiency 



29 



means of water application. A total absence of water would pre- 

 vent the seed from germinating and the inorganic salts in the 

 fertilizer from dissolving. A minimum rate of application of water 

 would be required for germination and plant nutrition. A higher 

 rate would affect the rate of plant nutrient assimilation, increasing 

 the physical yield. At some rate, a unit increase in the water input 

 would be attended by a maximum incremental response in physical 

 yield. Beyond that rate of application, higher rates of water input 

 would be attended by successively smaller increments in output, 

 until at some rate of application the soil fertility, seed, or physical 

 structure of the plants would provide the technical restraint to 

 any further increases in yields in response to increased rates of 



Z2 



Zo 



Xq Xi X2 X3 



FIGURE 5. The Production Function with One Factor Constant 



