When Farming Gets Greener: New Index Reveals Hidden Sustainability Gains in UK Agriculture

British farming has quietly become more productive over the past three decades, but a new study argues that the familiar productivity statistics have been telling only half the story. Researchers have adapted an index developed for the OECD to UK agriculture, combining the market-based measure of total factor productivity with data on greenhouse-gas emissions and nutrient surpluses. The result is a single sustainability indicator that tracks both how much food the sector produces and the environmental pressures it generates, over the period from 1990 to 2023.

The conventional measure, total factor productivity or TFP, is the workhorse of agricultural policy analysis. It summarises the ratio of marketed outputs to marketed inputs: cereals, livestock, milk and other products on one side; fertiliser, fuel, machinery, labour and capital on the other. The UK’s Department for Environment, Food and Rural Affairs publishes an official TFP series built with chained Fisher index numbers, a transparent method consistent with national statistical practice. What this accounting deliberately excludes, however, are the non-market consequences of farming. Emissions can fall or nutrient pollution can shrink, and the official productivity index registers nothing at all.

The new study, published in Environmental and Sustainability Indicators by Jorge Campos-González, James Lowenberg-DeBoer and Dimitrios Papadas, borrows the Environmentally Sustainable Productivity Index framework to plug that gap. The idea is mathematically simple but consequential: alongside the good-output index and the market-input index, the researchers construct an environmental-pressure index combining three variables — agricultural greenhouse-gas emissions, nitrogen surplus and phosphorus surplus. A tuning parameter, alpha, controls how strongly the environmental component weighs on the final figure. When alpha equals zero, the new index collapses into conventional productivity; as alpha rises, environmental performance matters more.

The raw ingredients come entirely from public data. Market outputs and inputs are drawn from DEFRA’s agricultural productivity datasets, which the team carefully reconstructed to match the published series. The environmental pressures come from the UK territorial greenhouse-gas inventory and DEFRA’s soil nutrient balance statistics, which measure the difference between nutrients applied to farmland and those removed in crops and livestock. Because annual nutrient reporting only begins in 2000, the researchers interpolated the missing years of the 1990s and then tested whether that interpolation mattered — it turned out to shift the final result by less than half a percent.

The thorny problem is weighting. Emissions are measured in millions of tonnes of carbon dioxide equivalent, nutrient surpluses in thousands of tonnes; how do you combine them fairly when none has a market price? The researchers use data envelopment analysis, a non-parametric technique, as a weighting device. Each year is treated as a decision-making unit, and the method derives relative weights from the data itself. In the principal specification, greenhouse-gas emissions receive a weight of 0.550, nitrogen surplus 0.299 and phosphorus surplus 0.151. Crucially, the authors insist these are operational aggregation weights, not welfare-based estimates of environmental damage or implicit policy rankings.

The headline finding is striking. By 2023, market output was 4.8 percent above its 1990 level while aggregate market-input use had fallen 11.8 percent, pushing conventional productivity 18.9 percent higher. But the weighted environmental-pressure index had fallen 37.2 percent over the same period. When that decline is credited, the environmentally adjusted index climbs well beyond the conventional one: 24.0 percent above baseline for a mild environmental weighting, 34.8 percent for a moderate one, and 46.6 percent for the strongest weighting examined. In other words, British agriculture’s sustainability story looks considerably better than the standard statistics suggest — driven less by output growth than by falling input use and reduced environmental pressures.

The team did not stop at one number. They ran an unusually thorough battery of robustness checks: re-referencing the indices to different base years, rescaling variables, dropping each environmental pressure in turn, using equal weights instead of data-driven ones, perturbing every environmental observation by up to one percent a hundred times, and testing alternative solutions to the weighting model. The direction of the result proved remarkably persistent — the environmentally adjusted index stayed above conventional productivity at the 2023 endpoint in every deterministic specification — but its magnitude was genuinely sensitive to which variables were included. Excluding greenhouse-gas emissions pushed the moderate-weighting endpoint up more than ten percent, while excluding phosphorus pulled it down nearly five.

The study is equally candid about what the indicator cannot do. Chained Fisher indices provide a chronological record but not a globally path-independent multilateral index, so the measure is a national monitoring tool rather than an instrument for comparing arbitrary countries or periods. The alpha parameter is a sensitivity knob, not an estimated economic quantity. A directional distance-function analysis showed that frontier classifications depend heavily on how environmental pressures are represented, and the assembled data could not support a more structurally complete by-production model of pollution generation. Nor is the time series long enough to evaluate agricultural research investments, whose effects are known to materialise over decades. And the environmental block covers only three pressures; biodiversity, soil health, water quality and animal welfare remain outside the frame.

There is also policy context. The researchers descriptively compared three institutional periods marked by the 2016 EU referendum and the end of the transition period in 2020. Between 1990 and 2015, conventional productivity rose 19.5 percent while the environmentally adjusted measure rose 29.9 percent. Both dipped slightly between 2015 and 2020, and between 2020 and 2023 the environmentally adjusted index climbed 6.7 percent against just 2.1 percent for conventional productivity, driven by a 14.9 percent fall in the environmental-pressure index. The authors caution that with only three post-transition annual observations and substantial volatility, these patterns cannot be read as Brexit effects — but they illustrate exactly the kind of monitoring the indicator was designed to support.

The broader lesson is about measurement. A higher environmentally adjusted productivity figure does not mean every aspect of farming’s environmental footprint improved at once, and it says nothing about how performance varies between individual farms. What the framework delivers instead is an architecture: market output, input use and environmental pressures remain separately visible within a common index, so policymakers can see where progress comes from and where it stalls. As UK agricultural policy increasingly ties payments to climate mitigation, nutrient management and public goods, a measure that credits genuine environmental improvement — while being honest about the assumptions behind it — could become an essential companion to the productivity statistics that have long dominated the debate.

Subject of Research: Environmentally adjusted productivity measurement in UK agriculture combining TFP with greenhouse-gas emissions and nutrient surpluses, 1990–2023

Article Title: Integrating productivity and environmental pressures in UK agriculture: an ESPI-based sustainability indicator

Article References: Campos-González, J., Lowenberg-DeBoer, J., & Papadas, D. (2026). Integrating productivity and environmental pressures in UK agriculture: an ESPI-based sustainability indicator. Environmental and Sustainability Indicators, 32, Article 101559. https://doi.org/10.1016/j.indic.2026.101559

Image Credits: AI Generated

DOI: 10.1016/j.indic.2026.101559

Keywords: UK agriculture, total factor productivity, sustainability indicators, ESPI, greenhouse-gas emissions, nitrogen surplus, phosphorus surplus, data envelopment analysis, Fisher index, DEFRA, environmental policy, nutrient management