New findings on agricultural productivity

The American Journal of Agricultural Economics has recently published several new and important papers on agricultural productivity.  Whether agriculture is becoming more or less productive is a critical question as it relates to sustainability (are we getting more while using less?), food security (can food production outpace population growth?), and consumer well-being (are food prices expected to rise or fall?). 

These papers focus on "total" or "multifactor" productivity rather than just yield.  Yield is a partial measure of productivity - it is the amount of output per unit of one input: land.  One can increase yield by adding more of other inputs such as water, fertilizer, labor, etc.  What we want is a measure of how much output has increased once we have accounted for uses of all inputs, and this is total or multifactor productivity.

The first paper by Matthew Andersen, Julian Alston, Phi Pardey, and Aaron Smith is worrisome.  They write:

In this paper we have used a range of data and methods to test for a slowdown in U.S. farm productivity growth, and the evidence is compelling. The results all confirm the existence of a surge and a slowdown in productivity but with some variation in timing, size, and statistical significance of the shifts. ... Over the most recent 10 to 20 years of our data, the annual average rate of MFP [multifactor productivity] growth was half the rate that had been sustained for much of the twentieth century. More subtly, and of equal importance, the past century (and more) of statistics assembled here suggest the relatively rapid rates of productivity growth experienced during the 1960s, 1970s, and 1980s could be construed as aberrations (along with the relative rapid rates of growth experienced during a period spanning WWII), with the post-1990 rates of productivity growth now below the longer-run trend rate of growth.

The second paper by Alejandro Plastina and Sergio Lence provides a deeper understanding behind the causes of productivity growth.  They present a straightforward way to decompose multifactor productivity into six different factors: technical change, technical efficiency, allocative efficiency, returns to scale, output price markup, and the input price effect.    They write:

Technical change is the major driver of TFP growth over the long run, and there is evidence that technical progress in the 1990s and 2000s was much slower than in the 1970s. This is a relevant result for policy makers, and begs the question of what is actually causing the slowdown in technical change. This is the first study to show technical regress in the agricultural sector during the farm crisis of the 1980s.

Another novel result is that annual changes in TFP bear no significant correlation with annual rates of technical change but instead are highly correlated with the markup effect, followed by the returns to scale component and allocative efficiency change. These findings suggest that evaluating the effects of research, extension, and other variables on each of the components of our measure of TFP change (rather than solely on an aggregate TFP index) can shed light on the actual channels through which those variables affect agricultural productivity growth in the United States and therefore contribute to policy design.

Finally, there is Julian Alston's fellow's address from last year's AAEA meetings.  In addition to providing an excellent literature review, he makes several important points.  He argues that agricultural research is significantly under-funded relative to the benefits it provides in increased productivity:

Evidence of remarkably high sustained rates of social payoffs to both private and public investments in agricultural R&D testify to a significant failure of government to fully address the underinvestment problems caused by the market failure. Moreover, if anything, in high-income countries like the United States, agricultural R&D policies seem to be trending in the wrong direction, making matters worse.


a reasonable first step would be to double U.S. public investment in agricultural R&D—an increase of, say, $4 billion over recent annual expenditures.4 A conservatively low benefit-cost ratio of 10:1 implies that having failed to spend that additional $4 billion per year on public agricultural R&D imposes a net social cost of $36 billion per year—an order of magnitude greater than the annual $1–5 billion social cost of $20 billion in farm subsidies.

Alston also points out that the main beneficiaries of productivity growth are consumers, and the farmers may or may not benefit.  He writes:

It seems inescapable that the agricultural innovations that made food much more abundant and cheaper for consumers did so to some extent at the expense of farmers as a whole—more than offsetting the effects of growth in demand for output from the sector. This finding is reinforced when we pay attention to the details of the timing. Specifically, the periods of the most rapid decline (or slowest growth) in [net farm income] seem to coincide with the periods of most rapid increase in farm productivity—the 1940s to 1980s, especially 1950–1980, as identified by Andersen et al. (2018)—consistent with the hypothesis that agricultural innovations have reduced net incomes for U.S. farmers as a group.

This suggests something of a paradox.  Farmer groups have often been some of the biggest supporters of agricultural research and are proponents of productivity growth, while consumers have been skeptical if not hostile toward many productivity-enhancing technologies on the farm.  Yet, it is likely food consumers that have received the lion's share of the benefits from increases in agricultural productivity through greater food security and lower food prices.