A decline in soil fertility resulting in decreased land productivity is a problem that many small-scale farmers in Tanzania face. Simeo Marco Sumuni learned about this issue in dialogue with farmers when he attended the Workshop for Participatory Research Design (WPRD) organized by SAT. He therefore decided to dedicate his Bachelor thesis in Agronomy at Sokoine University of Agriculture in Morogoro to this widespread challenge. Focusing on Tanzanian staple foods – maize and common beans – Simeo wants to enable farmers to increase the yield potential of these crops by improving soil fertility and by choosing favorable seeds and an elaborate intercropping system.
Simeos research project investigates how different cropping patterns influence nodulation in different common bean seed qualities (Lyamungu 90 and Soya Njano). Soya Njano is a local seed variety that is used by many small-scale farmers in Tanzania while Lyamungu 90 is an improved hybrid variety. Through a process called Biological Nitrogen Fixation (nodulation) plants form and develop roots called nodules that fix atmospheric nitrogen. Nitrogen is an essential nutrient for plant growth which is why low nitrogen availability inthe soil results in low yields and poor quality of crop produce.
The experiment set-up looks like the following: In a total of 15 experimental plots (5 treatments, 3 replications), Simeo has either planted sole Maize, Lyamungu 90 beans (hybrid) or Soya Njano beans (local) or an intercropping of Maize with either Lyamungu 90 beans or Soya Njano beans at a ratio of 1:1. Results have shown that germination of the bean seeds, plant height and the ability of nodulation didn’t vary significantly with the cropping system and different bean varieties. Simeo attributes this partly to the good quality of the seeds and the climatic conditions during the research term. Also, even though he was able to observe many nodules, and also active ones, in sole Lyamungu 90, this was not a statistically significant variation. As a conclusion, Simeo summarizes that Lyamungu 90, the improved variety, performs better when it comes to growth and yield potential. But the results have to be taken with a pinch of salt, as local weather conditions and other factors, like excessive rainfall or shading effect through intercropping, can have a rather big impact on these outputs.
Simeo therefore recommends that smallholder farmers, which usually prefer to grow the local Soya Njano variety, also test the improved Lyamungu 90 variety, which potentially is more resistant to drought, disease and pests. By testing its performance throughout the rainy seasons and in successive years, farmers will eventually be able to decide which variety and cropping system suits them best and yields the most productive and, of course, environment friendly results. Organic agriculture is about trial and error, being flexible and adapting to environment instead of oppressing it with chemicals. This research is proof of that, once again.