Agriculture has a substantial spillover that affects the Earth’s ecosystems, resulting in an ‘ecological footprint’ of food: negative environmental impacts per diner. Addressing this is no easy matter, but the Good Agricultural Practice (GAP) agreement of the World Trade Organization might provide a mechanism.

Authors: Meine van Noordwijk and Lijbert Brussaard. Source: Agroforestry World

It could be argued that food production that doesn’t adhere to GAP – for example, the system polluted soil and water or was a result of unnecessary conversion of natural habitat – enjoyed a form of domestic subsidy in the exporting country and could be taxed accordingly at an international border. This might help persuade producers to improve their practices and help reduce agriculture’s ecological footprint.

It’s not an impossible scenario. The global trade in agricultural commodities has generally responded quickly to market-based opportunities to increase the cost efficiency of food production through supporting low-cost producers in developing countries. But the trade has had mixed effects on globally aggregated yield and resource-use-efficiency gaps, which are important concepts linked to agriculture’s ecological footprint.

With continuously increasing demand from a growing population with rising incomes and shifting diets, the urgency of closing yield gaps is widely acknowledged. GAP could help do so.

Can one GAP reconcile two other gaps 2The concept of ‘yield gap’ has been around for a long time. It refers to the difference in production between what is deemed to be feasible and what is actually achieved in terms of crop yield. It is an indicator of the inefficient use of land. Resource-use efficiency is generically defined as the amount of targeted output achieved per unit of input. In the case of agriculture, that means how much food we get compared to what effort and resources – such as labour, fertilizers, herbicides and pesticides – we put in.

We can see these gaps at play in a classical argument of agricultural economics, challenged by some, that ‘economically optimum’ levels of agricultural inputs – such as labour, fertilizers, pesticides, irrigation – do not achieve maximum yields and thus do not fully close the yield gap or, conversely, that fully closing yield gaps is not (micro-) economically efficient and justifiable. These arguments materialize in the long tradition of publicly financed subsidies of inputs where micro-economic rationality on the farm does not match the macro-economic goals of the district or national capital and where there is a counter-argument for taxing, say, the use of fertilizers and irrigation water where micro-economic decisions lead to low resource-use efficiency and loss of natural capital.

To complicate matters further, the ratio of output to input at an ‘accounting border’ changes with the scale of the production system, mostly owing to the (ecological) internalization of external inputs.

For example, while nitrogen-use efficiency (NUE) in a crop field can be higher with inorganic rather than organic fertilizers, the NUE of a whole farm is generally increased if there is no waste and all residues and by-products are recycled.

Correspondingly, the efficiency of an entire agricultural sector is increased if all manure and food-processing waste is re-utilized. For example, while the yield gap was progressively closed for Dutch dairy farming, farm-gate NUE decreased between 1950 and 1985 from 46% to 16%. Farming specialization with the concomitant loss of mixed farming systems, along with removing biological nitrogen fixation (which wasn’t counted as an input) and replacing it with fertilizers (which was counted as an input) in an attempt to close the yield gap, increased the efficiency gap as defined at this accounting scale.

Subsequent concerted research efforts raised farmgate NUE to 72% in prototype (mixed) farms while reducing losses to the environment. The segregation of livestock and crop production, while reducing farmgate yield gaps, dramatically increased the resource-use efficiency gap in The Netherlands while ‘nutrient mining’ in areas exporting large volumes of animal feed continues.

Computer simulation models suggest that closing yield gaps by 50% for crops and 25% for livestock by 2050 would decrease greenhouse-gas emissions from agricultural and land-use change by 8% overall and by 12% per calorie produced. The options for efficiency increase if crop and livestock systems remain or return to integration – avoiding depletion in areas mined and excesses elsewhere – will need to be further assessed but are likely to be considerable.

The difference between best and worst mode of production of a single commodity, evaluated from a given perspective, has been termed the ‘management swing potential’. This indicates the scope, within existing production systems, for closing the efficiency gap. The GAP rules could be used to make the worst production systems less attractive and swing management in a more environmentally direction, at least for international trade.

GAP rules make it important to quantify yield and efficiency gaps under GAP conditions, as nationally defined. To our knowledge, such a study has not yet been carried out and could result in an effective mechanism. With a higher target of Best Management Practices, and acknowledging that there is considerable site- and climate-related variability in best-practice articulation, intermediate intensities of land use that don’t fully close the yield gap appear to be environmentally superior.


Further reading: van Noordwijk, Meine and Brussaard, Lijbert: Minimizing the ecological footprint of food: closing yield and efficiency gaps simultaneously? Current Opinion in Environmental Sustainability Vol 8, June 2014, Pages 62–70

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