Effect of mineral N fertilizer and organic input on maize yield and soil water content for assessing optimal N and irrigation rates in Central Kenya

Field Crops Research

Cereal-Legume Mixed Residue Addition Increases Yield and Reduces Soil Greenhouse Gas Emissions from Fertilized Winter Wheat in the North China Plain

Agronomy

Incorporating crop residues into the soil is an effective method for improving soil carbon sequestration, fertility, and crop productivity. Such potential benefits, however, may be offset if residue addition leads to a substantial increase in soil greenhouse gas (GHG) emissions. This study aimed to quantify the effect of different crop residues with varying C/N ratios and different nitrogen (N) fertilizers on GHG emissions, yield, and yield-scaled emissions (GHGI) in winter wheat. The field experiment was conducted during the 2018–2019 winter wheat season, comprising of four residue treatments (no residue, maize residue, soybean residue, and maize-soybean mixed residue) and four fertilizer treatments (control, urea, manure, and manure + urea). The experiment followed a randomized split-plot design, with N treatments as the main plot factor and crop residue treatments as the sub-plot factor. Except for the control, all N treatments received 150 kg N ha−1 season−1. The results showed that soils from all treatments acted as a net source of N2O and CO2 fluxes but as a net sink of CH4 fluxes. Soybean residue significantly increased soil N2O emissions, while mixed residue had the lowest N2O emissions among the three residues. However, all residue amendments significantly increased soil CO2 emissions. Furthermore, soybean and mixed residues significantly increased grain yield by 24% and 21%, respectively, compared to no residue amendment. Both soybean and mixed residues reduced GHGI by 25% compared to maize residue. Additionally, the urea and manure + urea treatments exhibited higher N2O emissions among the N treatments, but they contributed to significantly higher grain yields and resulted in lower GHGI. Moreover, crop residue incorporation significantly altered soil N dynamics. In soybean residue-amended soil, both NH4+ and NO3− concentrations were significantly higher (p < 0.05). Conversely, soil NO3− content was notably lower in the maize-soybean mixed residue amendment. Overall, our findings contribute to a comprehensive understanding of how different residue additions from different cropping systems influence soil N dynamics and GHG emissions, offering valuable insights into effective agroecosystems management for long-term food security and soil sustainability while mitigating GHG emissions.

Soil greenhouse gas emissions, yield, and water-use efficiency affected by maize-soybean intercropping under long-term nitrogen fertilization

Field Crops Research

Combined Mineral and Organic Fertilizer Application Enhances Soil Organic Carbon and Maize Yield in Semi-Arid Kenya: A DNDC Model-Based Prediction

Agronomy

The application of mineral fertilizers can effectively enhance crop yields. However, this potential benefit may be diminished if the use of mineral fertilizers leads to a substantial decline in soil organic carbon (SOC) and an increase in soil greenhouse gas (GHG) emissions. This study aimed to determine the optimal fertilizer combinations and rates for improving SOC and maize yield while reducing GHG emissions in the semi-arid uplands of Kenya. Data were collected from five different fertilizer treatments (N50, N100, N150, N100+manure, and N100+straw) compared to a control (N0) in a long-term experimental field, which was used to run and validate the DNDC model before using it for long-term predictions. The results showed that the combination of mineral fertilizer and straw resulted in the highest SOC balance, followed by that of fertilizer and manure. All fertilized treatments had higher maize grain yields compared to low-fertilizer treatment (N50) and control (N0). Daily CO2 fluxes were highest in the treatment combining mineral fertilizer and manure, whereas there were no significant differences in N2O fluxes among the three tested treatments. The findings of this study indicate that the judicious application of mineral fertilizer, animal manure, and straw has great potential in enhancing SOC and maize yields while reducing GHG emissions, thereby providing practical farming management strategies in semi-arid Kenya.

Estimating food nitrogen and phosphorus footprints and budgeting nitrogen and phosphorus flows of Rwanda's agricultural food system during 1961–2020

The Science of The Total Environment

Maize-soybean intercropping reduces greenhouse gas emissions from the fertilized soil in the North China Plain

Journal of Soils and Sediments

Cereal-legume intercropping enhances the quality of feedstock for lignocellulosic bioethanol production by reducing the carbon: nitrogen ratio

Discover Agriculture

Maize production status and yield limiting factors of Kenya.

Zhongguo Shengtai Nongye Xuebao / Chinese Journal of Eco-Agriculture

Short‐Term Effects of Partial Substitution of Mineral Fertilisers With Compost and Biogas Slurry on Carbon Dioxide, Nitrous Oxide, and Nitrogen Emissions

Soil Use and Management

ABSTRACT Compost and biogas slurry are increasingly used as organic fertilisers, but existing studies on their application on soil N 2 O emissions have been contradictory, studies on soil N 2 emissions are lacking, and the mechanism of microbial control of gaseous N loss is unclear. This study investigated the effects of partially replacing mineral fertilisers with compost (30%) and biogas slurry (50%) on CO 2 , N 2 O, and N 2 emissions, alongside soil nitrogen‐cycling microbial communities in no nitrogen application (LN) and 600 kg N ha −1 year −1 fertilisation (HN) soils from China's North China Plain. Through controlled incubation experiments, gas flux measurements, and metagenomic analysis, we found that in the first 5 days of fertilised treatments, N 2 O emissions accounted for 85.26% and 94.18%, while N 2 emissions accounted for 71.25% and 68.78% of total emissions under LN and HN, respectively. Organic substitutions reduced soil mineral nitrogen (‐N) content by limiting exogenous nitrogen input and suppressing native organic matter mineralisation, thereby decreasing pulse emissions of N 2 O, N 2 , and CO 2 . While both substitutions promoted complete denitrification, biogas slurry at 50% substitution significantly enhanced nitrifying microbe abundance ( Nitrosospira , Nitrospira ) and nitrification‐related functional genes ( AmoC and Hao ), increasing nitrification‐driven N 2 O emissions compared to compost. For sustainable management, high‐fertility soils benefit from partial substitution of mineral fertiliser with compost, whereas low‐fertility soils require substitution ratios of biogas slurry for mineral fertiliser to boost microbial activity. These findings provide critical insights for optimising organic substitution strategies to balance productivity and environmental sustainability in intensive agricultural systems.