Food Prodiiciion: Problems and Prospects 7 



yield growth contributing 40 percent of production expansion for 

 the whole period and 80 percent in the last subperiod of 1965-71. 

 Wheat yields per unit of land in five countries from the begin- 

 ning of the century are depicted in figure 1.2. It is interesting to 

 note that the differences between the yield levels of Japan, the 

 United States, and India were quite small at the beginning of the 

 period. Although Japanese yields were already increasing in 1900, 

 American wheat yields, as was the case in Europe, did not start 

 their upswing until the mid-1930s. Indian yields were completely 

 stagnant until the mid-1960s, when the introduction of new Mex- 

 ican wheat varieties ushered in the Green Revolution.^ 



Productivity Changes 



Recent developments in agriculture have been characterized not 

 only by increased use of resources— land, fertilizers, water, and 

 machinery — but also by increasing productivity. From the same 

 set of inputs farmers have been receiving increasing amounts of 

 output. These productivity gains are due to improved quality of 

 the factors of production, better knowledge, and better infrastruc- 

 ture and institutional arrangements. Chapter 5 presents empirical 

 estimates of productivity changes in thirty-six countries for the 

 period 1955-68. These estimates are part of production function 

 estimates reported in detail in that chapter. In this section other 

 estimates of total factor productivity in agriculture are reviewed. 



Conventional calculations of total factor productivity are essen- 

 tially based on measuring inputs and outputs at constant prices 

 and attributing the increases of the differences between these 

 measures to productivity.-^ Figure 1.3 exemplifies this method 

 with Israeli data; the two factors— labor and capital — and the 

 product (value added) are measured and depicted in the figure at 

 constant prices. The difference between the measures of the ag- 

 gregate input and the product is attributed to productivity. 



Rates of growth of output and productivity and share of con- 

 ventional inputs in explaining output growth for several countries 



2. A more detailed discussion of Indian yields and productivity trends is pre- 

 sented in chapter 6. 



3. For further discussion and refinement see, among others, Jorgenson and 

 Griliches(1967). 



