Q&A with David Guerena of One Acre Fund


Published on Agrilinks 25.02.2015

In honor of the UN International Year of Soils, David Guerena, soil scientist and agriculture innovations manager at One Acre Fund spoke about how he fell in love with soil and shares his hopes for the field of soil science going forward.


David Guerena
Photo Credit: Hailey Tucker/One Acre Fund


Did you always know you were interested in soil science?

Not really, but I always enjoyed nature, plants and landscapes, and agriculture. I entered university as a crop science major. The second class of my first year was “introductory soil science.” I initially could not believe there was a whole class on soil – it sounded so boring. But the opening statement of the first lecture really caught my attention: “95 percent of all food and fiber comes from the soil; 99.9 percent of all fresh water passes through the soil; and most of the world’s antibiotics were isolated from organisms that live in the soil.” After that first lecture, I was hooked. I immediately added soil science as a major..

Tell us a little bit about your professional path.

Prior to joining One Acre Fund, I was a Ph.D. student at Cornell University, in the Department of Crop and Soil Science. I was also an International Research Fellow (2009 – 2014) with the World Agroforestry Center, and a Borlaug Fellow in International Food Security (2012 – 2014). Prior to Cornell, I managed a small organic vegetable farm and CSA (community-supported agriculture) in California while completing my bachelor degrees – one in soil science and one in crop science from California Polytechnic State University.

In my current role, I help develop strategies for One Acre Fund’s agricultural programs across all countries. I like to think of this as steering the agricultural ship to ensure our clients achieve harvests that exceed their expectations.

What are some exciting, soil-related projects you’re working on now?

There are quite a few actually! In Kenya, one thing we’re studying is soil acidity (in the coming weeks, you'll be able to view a full report on our soil acidity trials on One Acre Fund’s online library). Soils in Kenya can be highly acidic due to a combination of climate and geology. Acid soils dramatically reduce crop yields and the yield response of fertilizers. But while applying lime can improve soil acidity, most smallholder farmers in Africa don’t have access to it. The One Acre Fund agriculture innovations team in Kenya recently completed a large lime trial, and in 2015 we are planning an even larger trial to work out the “kinks” in the lime delivery system. The team is close to cracking the lime barrier, which is very exciting!

In Rwanda, we’re studying nitrogen fixation in bean varieties. Bean production is a major part of Rwandan agricultural systems. Beans and other legumes (e.g. soybean, cowpeas, and lentils) are unique in that they produce their own nitrogen fertilizer biologically. In theory, beans require less nitrogen fertilizer to have good yields due to their symbiotic relationship with the soil. The Rwandan innovations team, in partnership with N2Africa, provided farmers with low-cost microbial inoculants to boost nitrogen fixation. This essentially cut fertilizer use in half while maintaining yields. What’s great is that the inoculants cost around US$1 per farmer and results in a doubling of farmer profits and reduced reliance on chemical fertilizer. We are now using the Rwandan example to expand this program both within Rwanda and in other countries in East Africa.

Some people may think of soil science as boring or tangential. What would you say to those people?

Soil science is uniquely positioned to be at the forefront of some of the most important environmental and social issues of our day: Soil is the largest known reservoir of biodiversity on the planet. Soil ecologists are fundamentally changing the way we understand how our planet works and revolutionizing the medical sciences. Soils have a tremendous capacity to sequester carbon; globally soils hold over two times more carbon than is in the atmosphere (CO2) or in all plants and animals. Soils will play an important part in the most pressing environmental issue in human history, climate change.

For all the soil novices out there, what’s the most important thing to know?

Good question! There are a lot of interesting, little known facts about why soil matters. I’d like to direct you to this page on the Food and Agriculture Organization’s website. They’ve compiled some valuable material.

I’d actually like to use this opportunity to put in a plug for the field of soil science. The world needs more soil scientists, particularly woman soil scientists. Soil science programs at colleges and universities worldwide are disappearing, and enrollment numbers within the existing programs are plunging. Yet, the importance of healthy soils for society and our planet cannot be overstated. The world population is growing, and the future demands innovative solutions to climate change, antibiotics and antibiotic resistance, natural resource management, agricultural productivity, and water quality. Soil scientists are uniquely positioned to help provide the solutions. 

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