Combination of Compost and Mineral Fertilizers as an Option for Enhancing Maize (Zea mays L.) Yields and Mitigating Greenhouse Gas Emissions from a Nitisol in Ethiopia

Abstract

Combined application of organic and mineral fertilizers has been proposed as a measure for sustainable yield intensification and mitigation of greenhouse gas (GHG) emissions. However, fertilizer effects strongly depend on the soil type and still no precise information is available for Nitisols in Ethiopia. The study evaluated effects of different ratios of biowaste compost and mineral fertilizers (consisting of nitrogen (N), phosphorus (P), and sulphur (S)) on maize (Zea mays L. Bako-hybrid) yields in a two-year field trial. Soil samples from each treatment of the field trial were used to estimate emissions of nitrous oxide (N2O), carbon dioxide (CO2), methane (CH4), and microbial activity in a 28-day incubation experiment with two moisture levels (40% and 75% water-filled pore space, WFPS). The application of fertilizers corresponded to a N supply of about 100 kg ha−1, whereby the pure application of mineral fertilizers (100 min) was gradually replaced by compost. Maize yields were increased by 12 to 18% (p < 0.05) in the combined treatments of compost and mineral fertilizers compared to the 100 min treatment. The cumulative emissions of N2O and CO2 but not CH4 were affected by the fertilizer treatments and soil moisture levels (p < 0.05). At 75% WFPS, the N2O emissions in the 100 min treatment was with 16.3 g ha−1 more than twice as high as the treatment with 100% compost (6.4 g ha−1) and also considerably higher than in the 50% compost treatment (9.4 g ha−1). The results suggest that a compost application accounting for 40 to 70% of the N supply in the fertilizer combinations can be suitable to increase maize yields as well as to mitigate GHG emissions from Nitisols in Southwestern Ethiopia.

Fertilizer Management Strategy to Reduce Global Warming Potential and Improve Soil Fertility in a Nitisol in Southwestern Ethiopia

“…The influence of fertilizer type is clearly observed on the emissions of N2O and CO2 compared to Ch4. This indicates that the contribution of CH4 gas to GWP is not only influenced by fertilizer type but also soil moisture [9]. This study provides very useful insights for policymakers to design appropriate nutrient management strategies to reduce GWP from cereal production systems.…”

“…The two-year field experiment was conducted at the research station of Jimma University in Southwestern Ethiopia with latitude, 7 • 42 N; longitude 36 • 49 E. The research site is characterized as humid tropical climate with a minimum of 13 • C and a maximum of 28 • C [9]. The annual maximum and minimum precipitation in the area is around 1200 and 2400 mm, respectively.…”

“…This situation will be expected to contribute significantly to GWP. To minimize the future impact of fertilizer application on GWP without reducing the crop production in the country, applying the combined fertilizer at a rate of 30 or 50 kg N ha −1 of mineral fertilizer with biowaste compost (4.9 or 3.5 t ha -1 ) is a viable option, for smallholder farmers [9]. by 62.7% of GWP compared to the 100 min treatment in wet soil.…”

Soil Greenhouse Gas Emissions and Nitrogen Change for Wheat Field Application of Composted Sewage Sludge

“…According to Zerssa et al [28], N 2 O emissions were reduced when the mineral fertilizers were combined with compost. This can be explained by the replacement of the mineral N by organic N and, consequently, by an initial microbial immobilization of N [29] or slow release of N from the organic fertilizer.…”

Organic Waste Generation and Its Valorization Potential through Composting in Shashemene, Southern Ethiopia

“…Taking these requirements into account, recycling the nutrients from urban organic waste (including animal manure and human excreta) via thermophilic composting and using this compost as a fertilizer and soil amendment for agriculture could be a means of closing the loop of nutrients between urban and rural environments [31,[38][39][40]. Supplying the produced compost to smallholders could not only help to increase soil fertility and food security, but also tackle climate change by the concomitant humus build-up in soil [30,38,[41][42][43].…”