Landscape-based nutrient application in wheat and teff mixed farming systems of Ethiopia: farmer and extension agent demand driven approach

Introduction: Adapting fertilizer use is crucial if smallholder agroecosystems are to attain the sustainable development goals of zero hunger and agroecosystem resilience. Poor soil health and nutrient variability characterize the smallholder farming systems. However, the current research at the field scale does not account for nutrient variability across landscape positions, posing significant challenges for targeted nutrient management interventions. The purpose of this research was to create a demand-driven and co-development approach for diagnosing farmer nutrient management practices and determining landscape-specific (hillslope, mid-slope, and foot slope) fertilizer applications for teff and wheat. Method: A landscape segmentation approach was aimed to address gaps in farm-scale nutrient management research as well as the limitations of blanket recommendations to meet local nutrient requirements. This approach incorporates the concept of interconnected socio-technical systems as well as the concepts and procedures of co-development. A smart mobile app was used by extension agents to generate crop-specific decision rules at the landscape scale and forward the specific fertilizer applications to target farmers through SMS messages or print formats. Results and discussion: The findings reveal that farmers apply more fertilizer to hillslopes and less to mid- and foot slopes. However, landscape-specific fertilizer application guided by crop-specific decision rules via mobile applications resulted in much higher yield improvements, 23% and 56% at foot slopes and 21% and 6.5% at mid slopes for wheat and teff, respectively. The optimized net benefit per hectare increase over the current extension recommendation was $176 and$333 at foot slopes and $159 and$64 at mid slopes for wheat and teff (average of $90 and$107 for wheat and teff), respectively. The results of the net benefit-to-cost ratio (BCR) demonstrated that applying landscape-targeted fertilizer resulted in an optimum return on investment ($10.0 net profit per$1.0 investment) while also enhancing nutrient use efficiency across the three landscape positions. Farmers are now cognizant of the need to reduce fertilizer rates on hillslopes while increasing them on parcels at mid- and foot-slope landscapes, which have higher responses and profits. As a result, applying digital advisory to optimize landscape-targeted fertilizer management gives agronomic, economic, and environmental benefits. The outcomes results of the innovation also contribute to overcoming site-specific yield gaps and low nutrient use efficiency, they have the potential to be scaled if complementing innovations and scaling factors are integrated

Validated fertilizer use at landscape scale: demand driven approach in sorghum, wheat and teff mixed farming systems in Ethiopia: A Technical Report

Soil nutrient management is very critical to maximize crop yield and to maintain soil health for a sustainable productivity. Decline in soil fertility and soil quality, among other factors, are major constraints to the agricultural productivity and disfunction of environmental services (Bahr, 2015). In Ethiopia, soil nutrient mining and very less replenishment of organic and inorganic resources are the recurrent problems that resulted in soil nutrient depletion. Besides, severe topsoil erosion associated with steep slope cultivation made the country one of the highest nutrient depletion rates in Africa with 41, 6 and 26 kg ha-1yr-1 of nitrogen, phosphorus and potassium, respectively (Stoorvogel and Smaling, 1990). Soil nutrient balance assessments in central Ethiopia showed that nutrient losses even worsen and reached an amount of 122 kg N, 13 kg P and 82 kg K ha-1 per year-(Haileslassie et al., 2005). In addition to the poor nutrient and organic matter status, aluminum toxicity and phosphorous fixation are other constraints in Ethiopian soils apparent in pH less than 5.5 which enhances nutrient limitations and toxicity (Agegnehu and Amede, 2017; Agegnehu et al., 2006). The state of nutrient depletion entails context specific nutrient management and fertilizer applications