Dr Fekremariam Mihretie1, Dr Julianne Lilley1, Dr David Deery1, Dr Di He1, Dr John Kirkegaard1, Dr Andrew Fletcher2, Dr Roger Lawes2, Dr Xiaoxi Li1
1Agriculture and Food, Canberra, Australia, 2Agriculture and Food, Townsville, Australia
Biography:
Fekremariam, a CERC Postdoc fellow at AGRICULTURE and FOOD, investigates the ecological and economic potential of legume-based mixed cropping systems using APSIM. Previously, he explored the impact of water stress on stomatal conductance and photosynthesis in crops as a Postdoctoral Fellow at Soka University and the National Institute of Environmental Studies (NIES) in Japan. He also contributed to research in Ethiopia, focusing on generating agroecologically based agronomic practices to enhance productivity, profitability, and sustainability of major crops (Teff, Wheat, Rice, Maize). Additionally, he served as the national coordinator of a watershed project at ICARDA in Ethiopia.
Abstract:
A simulation study using APSIM was conducted to assess the impacts of different crop rotation and nitrogen rate scenarios on crop yields, soil health, and resource use efficiency at four contrasting study sites (Boorowa, Cootamundra, Ardlethan, and Condobolin) in southeastern Australia. The study evaluated four crop rotations and five nitrogen rates (0, 50, 100, 150, and 200 kg N/ha) to determine their effects on long-term crop yields, profitability, and resource use efficiency. The crop rotation scenarios were: 1. Canola-wheat-wheat (C-W-W); 2. Lucerne-canola-wheat (L-L-L-C-W-W); 3. Faba bean-barley-oat-canola-lupin-wheat (F-B-O-C-LP-W); 4. Faba bean-canola-wheat-barley-faba bean-wheat (F-C-W-B-F-W). Results showed that without fertilizer, wheat yields ranked as L-L-L-C-W-W > F-C-W-B-F-W > F-B-O-C-LP-W > C-W-W across all locations. At 50 kg N/ha, yields were ordered as F-C-W-B-F-W > L-L-L-C-W-W > C-W-W > F-B-O-C-LP-W. For nitrogen rates of 100, 150, and 200 kg N/ha, yields ranked as F-C-W-B-F-W > C-W-W > L-L-L-C-W-W > F-B-O-C-LP-W. Regarding soil organic carbon (SOC), without fertilizer, the order was L-L-L-C-W-W > F-C-W-B-F-W > F-B-O-C-LP-W > C-W-W consistently across all study sites. A similar pattern was observed at 50 kg N/ha. However, at nitrogen rates of 100, 150, and 200 kg N/ha, the C-W-W rotation became superior in SOC compared to other systems. In comparison to the conventional cropping system (C-W-W), the L-L-L-C-W-W, F-B-O-C-LP-W, and F-C-W-B-F-W systems reduced nitrogen fertilizer application by 90%, -2%, and 55%, respectively, while achieving optimum wheat yields in the long term.