The World’s Biggest Field Experiment

A new paper (another summary) in Nature reports on what is perhaps the world’s biggest field experiment which has successfully shown how to, at scale, increase crop yields and reduce fertilizer usage in China. The scope of the 10 year experiment is astounding. The researchers first conducted thousands of field experiments all over China to discover and validate best practices:

A total of 13,123 site years of field trials were conducted from 2005 to
2015 for the three crops (n=6,089 for maize, 3,300 for rice and 3,734 for wheat), with sites spread across all agro-ecological zones…Each field trial included two types of management: conventional farmers’ practice (control) and ISSM-based recommendations (treatment; developed specifically for a given area). The recommended practices were discussed with local experts and participating farmers. Adjustments were made when necessary. Finally, the agreed-upon management technologies were implemented in the fields by the farmer; the collaborators provided guidance on-site during key operations, such
as sowing, fertilization, irrigation and harvest. Campaign collaborators recorded fertilizer rate, pesticide and energy use, and calculated nutrient application rate. At maturity, grain yield and above ground biomass were sampled by the collaborators for plots with a size of 6m^2 for wheat and rice, and 10m^2 for maize. Plant samples were dried at 70 °C in a forced-draft oven to constant weight, and grain yield was standardized at 14% moisture for all crops.

With validated best practices in hand the researchers and tens of thousands of collaborators then fanned out across the country to convince farmers to adopt the best practices.

During the campaign, about 14,000 training workshops, 21,000 field days, and more than 6,000 site demonstrations were organized by campaign staff; more than 337,000 pamphlets were distributed….During the campaign, we also encountered barriers and experienced challenges.  For example, we observed that some farmers appeared indifferent during some  outreach events. We later learned that it was mainly, because they could not comprehend the scientific content that we were trying to deliver. We solved the problem by having local (county or township) agents acting as an on-site ‘interpreter’ in  ways that speaks/connects with those farmers.

This was amusing:

It is also worth noting that the interests of agribusinesses do not always align with those of our campaign staff. For example, one of our main strategies used in the campaign was to select a site (for example, a village) for a given area, establish the base with field demonstrations of ISSM-based practices, then attract and engage more farmers from the same as well as neighbouring villages, creating  a snowballing and lasting effect. But sometimes, our partners in the private sector were more interested in changing sites so as to reach more farmer-clients. Vigorous  debates and discussion ensued. Eventually, the private sector personnel conformed to our reasoned schemes while using the established sites as demonstrations for  visitors from other areas.

Outputs and inputs among the treatment and control farmers were then measured (here I would have liked more information about the randomization. A lot can go wrong or be mismeasured at this stage.).

Farmers conducted all field operations. Campaign collaborators and/or extension agents were responsible for information and data collection. Typically, 10–30 farmers were randomly selected per ISSM-adopting site; another group of randomly selected 10–30 farmers from a nearby village without ISSM intervention served as a control/comparison. From the selected pool of farmers (roughly 14,600 paired data points), information on key management practices were obtained through a questionnaire survey, including crop varieties, planting densities, planting dates, fertilizer rates and harvest dates. For some sites, grain yields were directly measured in the same way as the field trials (see ‘Field trials’) for the selected 10–30 farmers. Yield and nitrogen rate were then averaged for each site.

The results were impressive.

Aggregated 10-year data showed an overall yield improvement of 10.8–11.5% and a reduction in the use of nitrogen fertilizers of 14.7–18.1%, when comparing ISSM-based interventions and the prevailing practices of the farmers. This led to a net increase of 33 Mt grains and a decrease of 1.2 Mt nitrogen fertilizer use during the 10-year period, equivalent to US$12.2 billion.

The entire experiment cost on the order of $56 million and generating $12.2 billion dollars of increased output, not including any environmental gains.

As if this weren’t enough the researchers then surveyed over 8 million smallholder farmers in China to estimate how much output could increase if the intervention were fully scaled.

What’s especially encouraging about this project is that no new technologies, seeds or infrastructure was involved–just basic science and a tremendous outreach campaign. Moreover, since the campaign increased profits it may continue to generate gains in the future even without further intervention as the practices spread. Repeated interventions will be necessary as climate changes, however. Information technology may makes this easier. China can be intimidating.


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