Sixteen Year Field Trial Shows Organic Corn Outcompetes Chemical-Intensive Fields in Kenya

In a sixteen-year field trial based in Central Kenya, researchers have found higher crop yield stability in low-input organic systems with previously degraded soil than in high-input organic and nonorganic agricultural systems.

One of the agrichemical industry-fed arguments against organic production is the false belief that, if all agricultural production went organic, then it would lead to a crisis of food security. Proponents of transitioning to organic continually push back, given the steady flow of evidence, backed by decades-long field trials, that organic can compete and even outcompete conventional systems after a transitional period.

Background and Methodology

This long-term field trial, published this year in European Journal of Agronomy, was conducted at two sites in Central Kenya Chuka (lower soil fertility) and Kandara (higher soil fertility) between 2007 and 2022.  Both Chuka and Kandara share bimodal rainfall (two wet seasons split up with distinct dry seasons) and consist of two growing seasons in a given calendar year. There were six crop rotation cycles for the maize, which included various legumes, vegetables, and root crops depending on the input level and farming system.

The experimental design was a randomized complete block design in agricultural plots, with the fields split up into four farming systems: organic high input (Org-High), conventional high input (Conv-High), organic low input (Org-Low), and conventional low input (Conv-Low). High versus low inputs refer to the quantity and types of soil inputs, mulch, irrigation, and pest management tools (pesticides). Mulch was only applied in organic systems. Organic systems were fed natural forms of soil supplements (i.e., compost) and rain-fed, while conventional systems were sprayed with synthetic pesticides and fertilizers and supplemented with irrigation. Using statistical analysis tools, the researchers measured plant growth through the height and stem diameter of ten randomly selected plants across all plots; for yield, the crop was harvested from the center of each plot to ensure robust data results.

The researchers of this study are based at Switzerland-based Research Institute of Organic Agriculture (FiBL) and International Centre of Insect Physiology and Ecology in Nairobi, Kenya. The authors declared that “they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.” Funding for this research was provided by Biovision Foundation for Ecological Development, the Coop Sustainability Fund, the Liechtenstein Development Service (LED), and the Swiss Agency for Development and Cooperation (SDC).

Discussion and Results

“Based on the findings of our study, organic farming systems have the potential to achieve yields that match or exceed those of conventional farming systems, particularly in the long term when given adequate time for soil adaptation and improvement in soil fertility,” the authors write in the conclusion of their study.

Some additional key findings from this field trial include:

• Organic systems show steady improvement in fertility over time, with Org-High yields matching Conv-High yields, especially in less fertile soils in the Kandara site;
• At Kandara, Org-Low had the most stable yields out of the four farming systems; and
• Low-input systems have more consistent crop yields across all seasons of the trial, with authors noting this to be a particular feature of organically managed systems.