A new article by Tufts University’s Steven Block in Oxford Economic Papers explores why African yields have fallen from 1960 until 1980, then risen back to their initial, post-independence levels from 1980 until 2000:
In this paper new estimates are presented for the path of TFP growth in African crop agriculture. With adjustment for the quality of inputs TFP growth rates declined from a rate of 1.5% per annum in the early 1960s to less than 0.5% per annum by the late 1970s. Since then the growth rate has risen steadily so by the early 2000s it was close to the levels achieved at the beginning of the period. These results follow from using a novel semi-parametric econometric approach to estimating TFP. Recent advances in panel econometrics are used to show the heterogeneity of TFP growth rates across countries. Expenditures on agricultural R&D, along with the reform of macroeconomic and sectoral policies have played a substantial role in explaining this pattern of TFP growth.