Agriculture and Food Systems - Research Publications

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    Next-generation enhanced-efficiency fertilizers for sustained food security
    Lam, SK ; Wille, U ; Hu, H-W ; Caruso, F ; Mumford, K ; Liang, X ; Pan, B ; Malcolm, B ; Roessner, U ; Suter, H ; Stevens, G ; Walker, C ; Tang, C ; He, J-Z ; Chen, D (NATURE PORTFOLIO, 2022-07-21)
    Nitrogen losses in agricultural systems can be reduced through enhanced-efficiency fertilizers (EEFs), which control the physicochemical release from fertilizers and biological nitrogen transformations in soils. The adoption of EEFs by farmers requires evidence of consistent performance across soils, crops and climates, paired with information on the economic advantages. Here we show that the benefits of EEFs due to avoided social costs of nitrogen pollution considerably outweigh their costs—and must be incorporated in fertilizer policies. We outline new approaches to the design of EEFs using enzyme inhibitors with modifiable chemical structures and engineered, biodegradable coatings that respond to plant rhizosphere signalling molecules.
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    Elevated CO2 negates O-3 impacts on terrestrial carbon and nitrogen cycles
    Xia, L ; Lam, SK ; Kiese, R ; Chen, D ; Luo, Y ; van Groenigen, KJ ; Ainsworth, EA ; Chen, J ; Liu, S ; Ma, L ; Zhu, Y ; Butterbach-Bahl, K (ELSEVIER, 2021-12-17)
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    Soil bacterial communities triggered by organic matter inputs associates with a high-yielding pear production
    Wang, L ; Ye, X ; Hu, H ; Du, J ; Xi, Y ; Shen, Z ; Lin, J ; Chen, D (COPERNICUS GESELLSCHAFT MBH, 2022-05-05)
    Abstract. The roles of microorganisms in enhancing crop production have been demonstrated for a range of cropping systems. Most studies to date, however, have been confined to a limited number of locations, making it difficult to identify general soil biotic and abiotic characteristics underpinning the yield-promotion across various locations. This knowledge gap limits our capacity to harness soil microbiome to improve crop production. Here we used high-throughput amplicon sequencing to investigate the common features of bacterial community composition, ecological networks and physicochemical properties in six yield-invigorating and adjacent yield-debilitating orchards. We found that yield-invigorating soils exhibited higher contents of organic matter than yield-debilitating soils and harbored unique bacterial communities. Greater alpha diversity and higher relative abundances of Planctomycetota and Chloroflexota were observed in yield-debilitating soils. Co-occurrence network analysis revealed that yield-invigorating soils displayed a greater number of functionally interrelated modules (meta-modules) and a higher proportion of negative links to positive links. Chloroflexota was recognized as a keystone taxon in manipulating the interaction of bacterial communities in yield-invigorating soils. Altogether, we provide evidence that yield-invigorating soils across a range of locations appear to share common features, including accumulation of soil organic matter, higher microbial diversity, enrichment of key taxa like Chloroflexota and maintaining a competitive network. These findings have implications for science-based guidance for sustainable food production.
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    Surface modification of coal tailings by thermal air oxidation for ammonia capture
    Zhang, W ; Han, B ; Wille, U ; Butterly, C ; He, JZ ; Chen, D (Elsevier, 2022-08-15)
    Utilization of coal tailings (CTs) to enable ammonia (NH3) capture is of interest from pollution control and waste management perspectives. In this work, CTs were surface modified by air oxidation at different temperatures and varying duration to increase the uptake of NH3. The CTs treated at 300 and 250 °C for 5 h achieved an NH3 uptake of 52.5 and 45.3 mg g−1, respectively, which was significantly higher than that of the untreated CT (2.1 mg g−1). A linear relationship between NH3 uptake and concentration of acidic surface functional groups was found (R2 = 0.99). Spectroscopic analysis showed that NH3 can be retained on the oxidized CT through chemisorption involving carboxylic groups, leading to the formation of amides. Kinetic studies in the temperature range of 200–300 °C revealed an activation energy of 50.2 kJ mol−1 for the formation of acidic surface functional groups on CTs. These comparably mild conditions for the oxidative surface modification make CTs versatile and readily available materials for reducing agricultural NH3 emissions.
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    Mitigating soil greenhouse-gas emissions from land-use change in tropical peatlands
    Lam, SK ; Goodrich, JP ; Liang, X ; Zhang, Y ; Pan, B ; Schipper, LA ; Sulaeman, Y ; Nelson, L ; Chen, D (WILEY, 2022-04-18)
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    Effects of organic amendments on soil properties and growth characteristics of melon (Cucumis melo l.) under saline irrigation
    Elbashier, MMA ; Shao, Y ; Wang, L ; Chen, D ; Zhong, H (International Journal of Agricultural and Biological Engineering (IJABE), 2021-01-01)
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    Decreasing ammonia loss from an Australian pasture with the use of enhanced efficiency fertilizers
    Lam, SK ; Suter, H ; Bai, M ; Walker, C ; Mosier, AR ; van Grinsven, H ; Chen, D (Elsevier BV, 2019-11)
    Mitigating ammonia (NH3) volatilization from intensive pasture systems is critical for environmental sustainability. However, field-scale evaluation on the potential of enhanced efficiency fertilizers (e.g. urease inhibitors and controlled-release fertilizers) in mitigating NH3 volatilization is limited. Using a micrometeorological technique, we conducted two field trials to investigate the effects of Green UreaNV® (urea coated with the urease inhibitor N-(n-butyl)thiophosphoric triamide, NBPT) and polymer-coated urea (a controlled-release fertilizer) on NH3 volatilization from an intensive rainfed pasture in southern Australia. We found that NH3 volatilization from urea was 5.8 and 5.6 kg N ha–1, respectively, in the autumn and spring trials, equivalent to 11–12% of the applied urea in each season. The use of Green UreaNV® and polymer-coated urea decreased the cumulative NH3 volatilization by 45–55% and 80%, respectively. Taking into consideration the high environmental damage cost of NH3 as found in the European Union, we hypothesize that both Green UreaNV® and polymer-coated urea can be cost-effective in mitigating NH3 loss from this pasture. Our findings suggest that the extra cost of using these enhanced efficiency fertilizers for farmers is not compensated by the fertilizer N value of decreased NH3 loss. However, from a societal perspective the extra cost for Green UreaNV® is likely outweighed by reduced environmental cost of NH3. New fertilizer technology should be developed to improve the cost-effectiveness of polymer-coated urea to the farmers.
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    Predicting the Ratio of Nitrification to Immobilization to Reflect the Potential Risk of Nitrogen Loss Worldwide
    Zhang, Y ; Pan, B ; Lam, SK ; Bai, E ; Hou, P ; Chen, D (AMER CHEMICAL SOC, 2021-05-11)
    Nitrification and immobilization compete for soil ammonium (NH4+); the relative dominance of these two processes has been suggested to reflect the potential risk of nitrogen loss from soils. Here, we compiled a database and developed a stochastic gradient boosting model to predict the global potential risk of nitrogen loss based on the ratio of nitrification to immobilization (N/I). We then conducted a meta-analysis to evaluate the effects of common management practices on the N/I ratio. The results showed that the soil N/I ratio varied with climate zones and land use. Soil total carbon, total nitrogen, pH, fertilizer nitrogen application rate, mean annual temperature, and mean annual precipitation are important factors of soil N/I ratio. Meta-analysis indicated that biochar, straw, and nitrification inhibitor application reduced the soil N/I ratio by 67, 64, and 78%, respectively. Returning plantation to forest and cropland to grassland decreased the soil N/I ratio by 88 and 45%, respectively. However, fertilizer nitrogen application increased the soil N/I ratio by 92%. Our study showed that the soil N/I ratio and its associated risk level of nitrogen loss were highly related to long-term soil and environmental properties with high spatial heterogeneity.
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    A global synthesis of soil denitrification: Driving factors and mitigation strategies
    Pan, B ; Xia, L ; Wang, E ; Zhang, Y ; Mosier, A ; Chen, D ; Lam, SK (ELSEVIER, 2022-04-01)
    Dinitrogen (N2) and nitrous oxide (N2O) produced via denitrification may represent major nitrogen (N) loss in terrestrial ecosystems. A global assessment of soil denitrification rate, N2O/(N2O+N2) ratio, and their driving factors and mitigation strategies is lacking. We conducted a global synthesis using 225 studies (3367 observations) to fill this knowledge gap. We found that daily N loss through soil denitrification varied with ecosystems and averaged 0.25 kg N ha−1. The average emission factor of denitrification (EFD) was 4.8%. The average N2O/(N2O+N2) ratio from soil denitrification was 0.33. Soil denitrification rate was positively related to soil water-filled pore space (WFPS) (p < 0.01), nitrate (NO3-) content (p < 0.05) and soil temperature (p < 0.01), and decreased with higher soil oxygen content (p < 0.01). N2 emissions increased with latitude (p < 0.05), WFPS (p < 0.01) and soil mineral N (p < 0.05) but decreased with soil oxygen content (p < 0.05). The N2O/(N2O+N2) ratio increased with soil oxygen content (p < 0.01) but decreased with organic carbon (C) (p < 0.05), C/N ratio (p < 0.01), soil pH (p < 0.05) and WFPS (p < 0.01). We also found that optimizing N application rates, using ammonium-based fertilizers compared to nitrate-based fertilizers, biochar amendment, and application of nitrification inhibitors could effectively reduce soil denitrification rate and associated N2 emissions. These findings highlight that N loss via soil denitrification and N2 emissions cannot be neglected, and that mitigation strategies should be adopted to reduce N loss and improve N use efficiency. Our study presents a comprehensive data synthesis for large-scale estimations of denitrification and the refinement of relevant parameters used in the submodels of denitrification in process-based models.
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    Degradation of the Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate in Soils: Indication of Chemical Pathways
    Sidhu, PK ; Taggert, BI ; Chen, D ; Wille, U (American Chemical Society (ACS), 2021-10-18)
    Nitrogen fertilizers amended with nitrification inhibitors (NIs) are used to increase nitrogen use efficiencies in agricultural systems. 3,4-Dimethylpyrazole phosphate (DMPP) is the most successful commercial NI to date but has a highly variable efficacy. To explore whether degradation could contribute to its inconsistent performance, incubation studies were performed with DMPP and 3,4-dimethylpyrazole glycolate (DMPG) in two alkaline clay soils that were treated with the fertilizer ammonium sulfate ((NH4)2SO4). Analysis of the soil extracts revealed a qualitative correlation between the amount of NI present in the soil and inhibition efficiency as well as several degradation products resulting from the oxidation of a methyl side chain and dimerization. A similar outcome was obtained for the degradation in sterilized soil and in accelerated weathering studies in the absence of soil. Our data suggest that chemical and not microbiological pathways are primarily responsible for the degradation of this inhibitor, which could potentially be initiated by reactive oxygen species (ROS) resulting from both biotic and abiotic processes in soils.