How Farmers in Cambodia are Using Conservation Agriculture to Grow Vegetables
Setting the context
A dynamic duo from North Carolina Agricultural and Technical State University—Professor Manuel Reyes and Don Immanuel Edralin, a post-doctoral researcher—have helped farmers in many countries use conservation agriculture practices to improve their soil while growing crops, in partnership with Feed the Future Innovation Labs and the U.S. Agency for International Development.
In 2013, they began a partnership with the Horticulture Innovation Lab to use conservation agriculture with vegetable farmers in Cambodia. Because conservation agriculture is more commonly used with field crops such as maize, millet and soy, they first tested these methods for vegetable crops on small plots in North Carolina. They found that conservation agriculture practices—minimum soil disturbance (no tillage), continuous mulch cover, and diverse cropping (intercropping and crop rotation)—when combined with drip irrigation offered many benefits to vegetable farming.
For this Horticulture Innovation Lab project in Cambodia, they added drip irrigation to conservation agriculture practices for small-scale vegetable farmers, mostly women. This research sought to find whether combining these practices could reduce labor needs and drudgery, increase yield and income, and ultimately be adopted by vegetable farmers in Cambodia.
What did the researchers find?
For field trials in Cambodia, women farmers grew a variety of vegetables, including string beans, cucumber, Chinese cabbage, Chinese kale, cauliflower, tomatoes and eggplant.
Usually when beginning to use conservation agriculture with field crops like maize and soybean, there can be some lowered yields during the first few seasons. But this trial with vegetables found no significant differences in yields or income between the various treatments in the first and second growing seasons. In fact, by the third growing season, some vegetables under conservation agriculture had higher yields than the traditional system. And by the fourth growing season, all yields were higher in conservation agriculture plots compared with traditional, tilled plots.
In addition there was a significant change with the new practices on farmers’ drudgery and labor. The researchers estimate that growing vegetables on small plots (100 meters square) with traditional methods and hand watering requires hauling about 1,300 pounds of water per day during the dry season — and twice as much during very dry seasons. Drip irrigation freed the women farmers from 65 percent of the heavy labor related to watering. Conservation agriculture practices also reduced labor when it came to repairing vegetable beds and weeding.
Furthermore, the soil also benefited. Soil erosion was controlled, eliminating threats of productivity loss from land degradation. Soil moisture was higher, prolonging water availability to the crops.
Many of the women farmers were so pleased with the new practices that they asked to end the experiment early, to avoid the extra labor of tilling, hand-watering and weeding required to maintain the field tests.
Reyes sees himself as a tailor when it comes to applying conservation agriculture practices to new communities—and in this case, new crops.
“The three principles are the same, but you tailor-fit each conservation agriculture practice such as it will be accepted socially and locally, using materials that can be managed easily wherever it is that you are,” he said. “These combinations vary from community to community, so it is best to start small, experiment on small plots with the community’s input, and then scale up.”
Reyes has outlined the most basic steps to combining drip irrigation with conservation agriculture in a recent blog post: 14 Steps to Growing Vegetables with Conservation Agriculture and Drip Irrigation. He notes that mulch materials need to be readily available or easily grown, and sometimes additional fertilizer applications such as nitrogen, phosphorous or lime may be needed when first beginning to use these practices. Some of the most common errors he has corrected with farmers are not using enough mulch (2.5 inches minimum), installing the drip irrigation on top of the mulch instead of under it where the mulch can protect the drip hardware from sun damage, and overwatering because mulched systems need less water than the traditional.
The next step? Reyes is now working with these Cambodian women farmers on a new Horticulture Innovation Lab project, this time focused on providing market incentives for women farmers who are adopting conservation agriculture, by building a local niche brand. The new brand is intended to support higher prices because the vegetables are produced sustainably, locally, and with the least amount of artificial chemicals as possible.
His team is also developing a mobile app, iFarmCA, for saving and sharing data between users of conservation agriculture, to build a global network of local best practices for conservation agriculture.