Our recent publication in Agriculture, Ecosystems and Environment examines nitrogen balances in smallholder maize systems in western Kenya. While other regions in the tropics have seen increases in food production over the past fifty years, per capita yields in sub-Saharan Africa (SSA) have stagnated or even declined. In response the African Green Revolution (AGR) marches forward, with the aim of giving farmers in SSA access to improved maize seed, mineral fertilizers, and legume rotation technologies. In theory, any of these inputs could in isolation, improve yields.
We used a combination of farmer interviews, on-farm harvests, and biomass modeling to calculate input-output balances on 24 working farms. We found that high yielding farms are more responsive to mineral N additions and low-yielding farms are more responsive to N added through legume rotations. This suggests that legume technologies are especially important for improving soil conditions to the point where they become responsive to mineral fertilizers and can support high yields.
Check out the full text publication on Kate's ResearchGate profile.
Last week I traveled to the University of Delaware extension office in Georgetown, DE to learn how to fly our new unmanned aerial vehicle (UAV, aka "the drone"). Born and raised in California's East Bay, I grew up playing with real sticks and not joysticks, so there was a rather steep learning curve when it came to landing the plane. James Adkins and Jarrod Miller were both naturals, of course, and will surely need to purchase a remote control plane "for practice." I don't think either one of them are too upset about that!
Ryan Baskette, from PrecisionHawk, came up from Raleigh, NC to train us to fly the plane over a soybean field near the Extension office. The fixed-wing plane can hold either a RGB camera or NIR camera depending on what we are interested in measuring - plant number, potential pests, nutrient status, etc. She is hand-launched (i.e. thrown gently) and then flies to altitude of 60m, where she creates a flight plan to survey a pre-selected area of interest. After only about 15 minutes, she comes in to land (this is where the remote control comes in), and she touches town gently (hopefully). Data can be immediately downloaded to a laptop and within an hour, we can see if the area was adequately captured.
We hope to use this technology to locate "problem" areas within farm fields and target management to these smaller areas rather than treat the field as a single unit (a practice known as precision agriculture). Such targeted practices will improve water, energy, and nutrient use efficiency benefitting both the environment and a farmer's bottom line.
Dr. Kate Tully
Kate is an Assistant Professor of Agroecology at the University of Maryland.
Dani is a PhD student in the AgroEcoLab and studies the effects of sea level rise on coastal farming communities and estuarine biogeochemistry.
Resham is a PhD student in the AgroEcoLab and studies how to improve water and nutrient use efficiency in cover crop systems.