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Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities

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A special issue of Agronomy (ISSN 2073-4395). This special issue belongs to the section "Farming Sustainability".

Deadline for manuscript submissions: closed (31 October 2023) | Viewed by 20366

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Dr. Bing Gao

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1. Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, 1799, Jimei Road, Xiamen 361021, China
2. Xiamen Key Lab of Urban Metabolism, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
Interests: urban metabolism and environmental effects; carbon and nitrogen transformation and environmental effects; organic solid waste utilization and pollutants; carbon reduction
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Dear Colleagues,

Nitrogen (N) is an essential and irreplaceable element, which sustains food production and the global population after it is converted into reactive N (Nr) species. However, the imbalances and overuses of N in agriculture activities have caused large Nr losses to the environment, resulting in a cascade of negative effects on natural resources and environmental quality. At the same time, agricultural soil accounts for 8%–10% of the soil C pool in terrestrial ecosystems, which plays a significant role in the global C budget. Technical practices sequestering more C into agricultural soils globally can serve as an effective measure to slow down the rising levels of atmospheric CO₂. Under the context of carbon peak and carbon neutralization all over the world, the study of the environmental impacts and carbon-nitrogen transformations in different agricultural activities is necessary for the green and low-carbon sustainable development of agriculture around the world.

Dr. Bing Gao
Guest Editor

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Keywords

carbon sequestration
carbon dioxide emission
nitrous oxide
methane
carbon-nitrogen transformation
global warming potential
carbon peak and carbon neutralization
nitrogen losses
nitrate leaching
ammonia volatilization

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Research

16 pages, 5246 KiB

Open AccessArticle

Responses of Soil Respiration to the Interactive Effects of Warming and Drought in Alfalfa Grassland on the Loess Plateau

by Jiaxuan Li, Jingui Zhang, Tao Ma, Wenqiang Lv, Yuying Shen, Qian Yang, Xianzhi Wang, Ruobing Wang, Qian Xiang, Long Lv, Jianjun Zhang and Jingyong Ma

Agronomy 2023, 13(12), 2992; https://doi.org/10.3390/agronomy13122992 - 5 Dec 2023

Viewed by 1470

Abstract

Elevated temperature and frequent drought events under global climate change may seriously affect soil respiration. However, the underlying mechanism of the effects of warming and drought on soil respiration is not fully understood in the context of the Loess Plateau. This study examined the response of soil respiration (Rs) to multiple factors, including warming (W), drought (P), and their interaction (WP), in the semi-arid grassland of the Loess Plateau in Northwest China. The research period was from May to November 2022, with an open-top heating box used for warming and a rain shelter used for drought. The results showed the following: (1) Rs ranged from 1.67 μmol m⁻² s⁻¹ to 4.77 μmol m⁻² s⁻¹, with an average of 3.36 ± 0.07 μmol m⁻² s⁻¹. The cumulative soil carbon flux ranged from 500.97 g C·m⁻² to 566.97 g C·m⁻², and the average cumulative soil respiration was 535.28 ± 35.44 g C·m⁻². (2) Warming increased Rs by 5.04 ± 3.11%, but drought inhibited Rs by 3.40 ± 3.14%, and the interaction between warming and drought significantly reduced soil respiration by 11.27 ± 3.89%. (3) The content of particulate organic carbon (POC), dissolved organic carbon (DOC), soil organic carbon (SOC), and readily oxidized carbon (ROC) decreased with the increased soil depth. ROC after W and WP treatments was significantly higher than that of the control, and POC after P treatment was significantly higher than CK (p < 0.05). (4) The seasonal variation of soil respiration was positively correlated with soil temperature, soil water content, plant height, and leaf area index (p < 0.05), but the response rules differed during different regeneration periods. Soil water content; soil water content and leaf area index; and soil water content, soil temperature, and leaf area index were the factors that regulated the variation in soil respiration in the first, second, and third regeneration periods, respectively. These results clearly showed the limiting effect of drought stress on the coupling between temperature and soil respiration, especially in semi-arid regions. Collectively, the variations in soil respiration under warming, drought, and their interactions were further regulated by different biotic and abiotic factors. Considering future warming, when coupled with increased drought, our findings indicate the importance of considering the interactive effects of climate change on soil respiration and its components in arid and semi-arid regions over the next decade. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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20 pages, 5405 KiB

Open AccessArticle

Regional-Scale Virtual Nitrogen, Phosphorus, and Potassium Factors of Potato Production in China

by Xuejuan Fang, Dongliang Zhong, Weijun Zhou, Mohammad Jawad Alami, Shenghui Cui, Bing Gao and Wei Huang

Agronomy 2023, 13(9), 2430; https://doi.org/10.3390/agronomy13092430 - 20 Sep 2023

Viewed by 1299

Abstract

Improving yield in potato production with minimal environmental impact is of great significance for China’s potato staple food policy. Previous research has been limited by the absence of regional-scale parameters to evaluate the environmental costs of regional potato production. To address this gap, we utilized the input–output analysis method to offer a thorough estimation of nitrogen (N), phosphorus (P), and potassium (K) inputs and outputs in the potato production stage at a regional scale, leveraging a meta-analysis dataset from plenty of the literature. On this basis, we calculated the virtual N, P, and K factors (VNFs, VPFs, and VKFs) for different potato production regions, under both conventional and optimal management practices. China’s potato production suffered from excessive N and P inputs, while K inputs remained insufficient. Significant spatial heterogeneities were observed for the VNFs, VPFs, and VKFs across different potato production regions. Northeast China and northwest China emerged as the most suitable potato cultivation regions because they demonstrated high potato yields with relatively low inputs and, consequently, lower VNFs and VPFs. Southwest China was the most vital region where targeted efforts could lead to reducing VNF and VPF, thus significantly mitigating environmental N and P losses. In addition to reducing fertilizer inputs, site-specific and whole optimization measures are proposed to lower the environmental costs and promote the sustainable development of potato production. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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18 pages, 2491 KiB

Open AccessArticle

Improvement of Active Organic Carbon Distribution and Soil Quality with the Combination of Deep Tillage and No-Tillage Straw Returning Mode

by Zhihui Zhao, Peng Geng, Xiao Wang, Xiao Li, Peixuan Cai, Xiumei Zhan and Xiaori Han

Agronomy 2023, 13(9), 2398; https://doi.org/10.3390/agronomy13092398 - 17 Sep 2023

Cited by 1 | Viewed by 2070

Abstract

During the initial period of straw return, a suitable straw return technology can lay the foundation for long-term soil fertility improvement. This study focused on the issues of backward straw return technology and blind fertilizer application in the southern part of the maize-producing area in the Northeast Plain of China. In this study, two straw return modes (2-year no-tillage straw cover + 1-year deep loosening and burying straw returning mode, NPT; 3-year rotary tillage and burying straw returning mode, RT), with RT mode as a control, were combined with different N fertilizer application rates (0, 192, 240 kg/ha). The changes in soil organic carbon (SOC) and its active components (MBC, DOC, and LOC) in the 0–40 cm soil layer were analyzed, and the carbon stratification rate, carbon pool index (CPI), SOC storages of each component, and maize yield were calculated to evaluate the short-term (3-year) differences in soil organic carbon quantity and quality in order to find suitable straw return methods and nitrogen application rate combinations. The results showed that the NPT mode increased the SOC and MBC content in the 20–30 cm soil layer, with an increase of 16.2% to 37.8% and 23.0% to 50.3%, respectively, compared with the RT mode. Under the NPT mode, the carbon pool stability was higher after nitrogen fertilizer addition, with a CPI value of 10.2% to 37.8% higher in the 20–40 cm soil layer compared with the RT mode. The differences in maize yield were not significant (p < 0.05) between the nitrogen application rates of 192 kg/ha and 240 kg/ha, but the SOC storages did not show significant changes. The MBC storage had the highest value under the nitrogen application rate of 192 kg/ha. Therefore, we thought that, in the early stage of straw return, the organic carbon priming effect caused by increased microbial activity was higher under the nitrogen application rate of 192 kg/ha. Considering the aspects of not affecting maize yield and improving SOC stability, it is recommended to use the NPT mode with the application of a 240 kg/ha nitrogen fertilizer rate for straw return. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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17 pages, 3384 KiB

Open AccessArticle

Combined Application of Biochar and Pruned Tea Plant Litter Benefits Nitrogen Availability for Tea and Alters Microbial Community Structure

by Yi Luo, Yongli Zhang, Yejun Wang, Yulong Sun, Xianjiang Xia, Youjian Su and Wanyou Liao

Agronomy 2023, 13(6), 1465; https://doi.org/10.3390/agronomy13061465 - 25 May 2023

Cited by 2 | Viewed by 1574

Abstract

The application of biochar is one of the promising management practices to alleviate soil acidification and improve soil fertility. However, it has been found to reduce the content of ammonium nitrogen (

{NH}_{4}^{+}

−N) in the soil, which is the most [...] Read more.

{NH}_{4}^{+}

−N) in the soil, which is the most important form of nitrogen (N) for tea tree growth. To investigate the response of soil

{NH}_{4}^{+}

−N content to the combined application of biochar and pruned tea plant litter, a pot trial was performed with three treatments: control (CK); biochar (BC); biochar + tea plant litter (BC + L). Soil chemistry properties and ammonification rates were determined, and the microbial community composition was analyzed by high-throughput sequencing. The results showed that the

{NH}_{4}^{+}

−N content in BC + L treatment was 1.7–9.5 fold higher than CK and BC treatments after 15 days of application, with no difference in the proportion of ammonia oxidation phyla such as Nitrospirae. The proportion of soil fungus Ascomycota was strongly correlated with the content of soil available nitrogen (p = 0.032), and the relationship was well described by a linear equation (R² = 0.876, p = 0.01). Further redundancy analysis revealed that soil pH, soil organic carbon (SOC), the ratio of SOC to total nitrogen and the ratio of SOC to alkaline hydrolyzable nitrogen appeared to be important factors influencing the separation of BC + L from CK and BC groups. In summary, the addition of biochar and pruned tea plant litter alters soil properties and may influence the composition of microorganisms with various trophic groups, thus affecting ecosystem function. Our results also highlight the importance of returning pruned materials with biochar application in tea plantation ecosystems. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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9 pages, 1587 KiB

Open AccessArticle

Intensification of Pasture-Based Animal Production System Has Little Short-Term Effect on Soil Carbon Stock in the Southern Brazilian Highland

by Pedro Antonio Garzón Camacho, Cassiano Eduardo Pinto, Cássio Felipe Lopes, Daniela Tomazelli, Simone Silmara Werner, Fábio Cervo Garagorry, Tiago Celso Baldissera, Janquieli Schirmann and André Fischer Sbrissia

Agronomy 2023, 13(3), 850; https://doi.org/10.3390/agronomy13030850 - 14 Mar 2023

Cited by 2 | Viewed by 2073

Abstract

Pastures are of central importance in food production and provide multiple ecosystem services. The objective of this paper was to determine whether the intensification of pasture-based animal production systems, through practices such as fertilization and improved pasture species, has a higher capacity in the short-term (five years) to sequester carbon in the soil compared to (1) natural grassland without anthropogenic interactions, (2) natural grassland fertilized and overseeded with exotic species, and (3) annual pastures with frequent soil disturbance. The study assessed the organic carbon stock (OCS), total organic carbon (TOC), particle size, porosity, and density at different soil strata, as well as the root system and forage production. Forage dry matter (DM) production varied significantly with means ranging from 6615 to 13,000 kg ha^–1 year^–1 for natural grassland (NG) and permanent pasture (PP), respectively. Improved natural grassland (ING) and NG presented a higher density and root diameter than PP and annual pasture (AP). Forage systems significantly influenced soil porosity and density, with NG and ING showing lower soil densities and higher soil porosities. The OCS (0–100 cm) was similar between NG (270 Mg ha^–1), ING (255 Mg ha^–1), PP (274 Mg ha^–1), and AP systems (256 Mg ha^–1). Over a period of five years, the intensification of pasture-based animal production systems did not have a significant impact on OCS in the soils of a Brazilian subtropical highland. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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18 pages, 2608 KiB

Open AccessFeature PaperArticle

Investigation of Soil Microbial Communities Involved in N Cycling as Affected by the Long-Term Use of the N Stabilizers DMPP and NBPT

by Wei Zhang, Yan Ma, Xuan Yang, Xiuchun Xu, Bang Ni, Rui Liu and Fanqiao Meng

Agronomy 2023, 13(3), 659; https://doi.org/10.3390/agronomy13030659 - 24 Feb 2023

Cited by 4 | Viewed by 1992

Abstract

Both, 3,4-dimethylpyrazole phosphate (DMPP) and N-(n-butyl) thiophosphoric triamide (NBPT) are commonly used as nitrogen (N) stabilizers, and are often used in agriculture to reduce nitrogen (N) loss from soils by inhibiting soil nitrification and by slowing down urea hydrolysis, respectively. The current knowledge gap concerns how soil microbial communities involved in N cycling are affected by the long-term use of DMPP and NBPT. The present field study explored the inter-annual variation of nitrous oxide (N₂O) emissions and the responses of ammonia oxidizers (AOA, AOB encoded by the amoA gene), nitrite-oxidizing bacteria (NOB, encoded by the nxrA and nxrB genes), and denitrifier (encoded by the narG and nosZ genes) populations following a long-term (8 years) addition of DMPP and NBPT. The results showed that the reduction in N₂O emissions by DMPP and NBPT increased year on year. The AOB population diversity significantly increased (p < 0.05) after a long-term urea application but decreased after DMPP addition. The long-term application of urea increased the potential nitrification rate (PNR) by the enrichment of the genera with a high ammonia oxidation capacity in the AOB population. In contrast, DMPP addition weakened this effect and formed a population with a low ammonia oxidation capacity. Variations in the NOB population were mainly associated with fertilizer-induced changes in substrate NO₂⁻, whereas DMPP and NBPT had minor impacts on the NOB population. Additionally, the change in the denitrification population was indirectly affected by the soil ammonium (NH₄⁺) content with a long-term N stabilizer application. These findings provide a new interpretation related to the response mechanisms of the nitrifier and denitrifier populations for the long-term use of N stabilizers in soils. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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16 pages, 4766 KiB

Open AccessArticle

Methane Uptake and Nitrous Oxide Emission in Saline Soil Showed High Sensitivity to Nitrogen Fertilization Addition

by Wenzhu Yang, Youlin Hu, Mingde Yang, Huiyang Wen and Yan Jiao

Agronomy 2023, 13(2), 473; https://doi.org/10.3390/agronomy13020473 - 5 Feb 2023

Cited by 8 | Viewed by 1855

Abstract

Saline soils can significantly affect methane (CH₄) and nitrous oxide (N₂O) in atmospheric greenhouse gases (GHGs). However, the coupling effect of nitrogen fertilization addition and saline soils on CH₄ uptake and N₂O emissions has rarely been examined under various salinity conditions of soil. In this study, the effects of nitrogen fertilization addition on CH₄ and N₂O fluxes under different salinity conditions of soil in Hetao Irrigation District, Inner Mongolia, were investigated by on-site static chamber gas chromatography. A slightly saline soil (S₁) (Electrical Conductivity: 0.74 dS m⁻¹) and a strongly saline soil (S2) (EC: 2.60 dS m⁻¹) were treated at three levels of nitrogen fertilization: a high fertilization rate of 350 kg N ha⁻¹ (H), a low fertilization rate of 175 kg N ha⁻¹ (L), and no fertilizer (control treatment, referred to as CK). Nitrogen application was the important factor affecting N₂O emissions and CH₄ uptake in saline soil. The CK, L, and H treatments exhibited a cumulative CH₄ uptake of 156.8–171.9, 119.7–142.0, and 86.7–104.8 mg m⁻² in S1, 139.3–176.0, 109.6–110.6, and 68.5–75.4 mg m⁻² in S2, respectively. The cumulative N₂O emissions under the L and H treatments in S2 were 44.1–44.7%, and 74.1–91.1% higher than those in S1. Nitrogen fertilizer application to saline soils reduced CH₄ uptake and promoted N₂O emission in the Hetao Plain, Inner Mongolia. Our results indicate that mitigating soil salinity and adopting appropriated fertilizer amounts may help to cope with global climate change. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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16 pages, 1602 KiB

Open AccessArticle

Virtual New Nitrogen, Phosphorus, Water Input, and Greenhouse Gas Emission Indicators for the Potatoes Consumed in China

by Bing Gao, Dongliang Zhong, Xuejuan Fang, Wei Huang, Su Xu and Shenghui Cui

Agronomy 2022, 12(12), 3169; https://doi.org/10.3390/agronomy12123169 - 14 Dec 2022

Cited by 1 | Viewed by 1583

Abstract

Based on China’s potato staple food policy, we chose potatoes as a study case to analyze the following indicators—the virtual new nitrogen factor (VNNF), the virtual new phosphorus factor (VNPF), the virtual irrigation-water (IW) factor (VIWF), the virtual total water (IW + precipitation) factor (VTWF), and the virtual greenhouse gas (GHG) emission factor (VCF) of the potatoes consumed by households in the six potato cultivation regions—by reviewing 220 publications from 2000 to 2020. The results showed that the VNNF ranged between 17.8 ± 7.8 and 30.1 ± 17.0 kg N kg⁻¹ N in the consumed potato, the VNPF ranged between 8.4 ± 5.0 and 18.8 ± 11.3 kg P kg⁻¹ P in the consumed potato, the VIWF ranged between 0.3 ± 1.0 and 1.8 ± 1.4 m³ IW kg⁻¹ for the consumed standard yield (except in the three mainly rainfed potato regions), the VTWF ranged between 4.8 ± 2.2 and 9.3 ± 3.7 m³ total water kg⁻¹ for the consumed standard yield, and the VCF ranged between 3.4 ± 1.5 and 5.9 ± 2.4 kg CO₂ equivalent kg⁻¹ for the consumed standard yield, under the conventional practice in the six potato cultivation regions. The normalization score results indicate that the northeast, northwest, southwest, and south of China are relatively more suitable regions in which to plant potatoes, based on the VNNF, VNPF, VIWF or VTWF, and VCF indicators. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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14 pages, 1480 KiB

Open AccessArticle

Influence of Reduced Tillage, Fertilizer Placement, and Soil Afforestation on CO₂ Emission from Arable Sandy Soils

by Tomasz Sosulski, Tomasz Niedziński, Tamara Jadczyszyn and Magdalena Szymańska

Agronomy 2022, 12(12), 3102; https://doi.org/10.3390/agronomy12123102 - 7 Dec 2022

Cited by 3 | Viewed by 1995

Abstract

Extreme meteorological phenomena resulting from climate change caused by anthropogenic emissions of greenhouse gases (GHG) require the implementation of CO₂ mitigation practices from various industries, including agriculture. Owing to varying soil, climatic, and agrotechnical characteristics, they may have different efficiencies in mitigating soil CO₂ emissions. The aim of this study was to evaluate the impact of three mitigation practices (reduced tillage, deep fertilizer placement, and soil afforestation) on CO₂ emissions from sandy soils in Central and Eastern Europe allowing the prediction of the mitigation effectiveness of these methods. The average soil CO₂-C flux under a moldboard plow system ranged from 218.4 ± 108.4 to 263.7 ± 176.6 mg CO₂-C m⁻² h⁻¹ and under a reduced tillage system ranged from 169.7 ± 118.7 to 163.6 ± 115.2 mg CO₂-C m⁻² h⁻¹ in a year with normal meteorological conditions and under extreme drought conditions, respectively. In the dry growing season, similar amounts of CO₂-C were released from the soil fertilized to the soil surface and after mineral fertilizers application at a depth of 10 cm and 20 cm (133.7 ± 155.8, 132.0 ± 147.5 and 131.0 ± 148.1 mg CO₂-C m⁻² h⁻¹, respectively). Meanwhile, from the forest soil, the average CO₂-C emission in the dry growing season was 123.3 ± 79 mg CO₂-C m⁻² h⁻¹. The obtained results revealed that reduced tillage on sandy soil allowed for reduced CO₂ emissions from the soil by 28.7–61.2% in normal and drought weather, respectively. Under drought conditions, deep fertilizer placement did not reduce CO₂ emissions from sandy soil, and CO₂ emissions from forest soils were even higher than from arable soils. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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12 pages, 1788 KiB

Open AccessArticle

Extracellular Enzyme Patterns Provide New Insights Regarding Nitrogen Transformation Induced by Alkaline Amendment of Acidic Soil

by Junhui Yin, Xin Bai, Owen Fenton, Bingbing Tang, Shuo Chen, Yan Ma, Shuai Zhang, Wenchao Cao, Shuai Ding, Rui Liu and Qing Chen

Agronomy 2022, 12(12), 3015; https://doi.org/10.3390/agronomy12123015 - 29 Nov 2022

Cited by 3 | Viewed by 1444

Abstract

Nitrogen (N) availability is generally a limiting factor in highly acidic soil, which could be improved by amending these soils with alkaline materials. Soil extracellular enzyme activity (EEA) plays an important role in N transformation; a current knowledge gap is how this occurs in acidic soils amended with alkaline material. The present 45-day incubation experiment was designed to examine the effects of different amounts of alkaline materials (urea and/or calcium–silicon–magnesium–potassium fertilizer (CSMP)) on N transformation. The results show that soil pH significantly increased after the CSMP amendment (1.2 units) and increased soil net N mineralization (R_min), net nitrification (R_nit) rates, and net ammonification (R_amo) rates. CSMP amendment changed the different soil EEA but with differing or opposing effects, e.g., R_nit was positively correlated with the activities of L-leucine aminopeptidase, β-xylosidase, α-glucosidase, and N-acetyl-β-glucosaminidase but negatively correlated with β-1, 4-glucosidase and β-cellobiosidase. A machine learning analysis indicated that the best predictor for R_min and R_amo was soil pH, and for R_nit, it was nitrate. The results of the present study improve our understanding of N availability in acidic soils amended with materials to control soil pH. Such knowledge could lead to more bespoke nutrient management planning at the field scale, leading to better agronomic and environmental outcomes. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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11 pages, 1465 KiB

Open AccessArticle

Fe(II)-OM Complexes Formed by Straw Returning Combined with Optimized Nitrogen Fertilizer Could Be Beneficial to Nitrogen Storage in Saline-Alkaline Paddy Soils

by Yinghui Jiang, Shirong Zhang, Bing Gao, Ruxue Wei and Xiaodong Ding

Agronomy 2022, 12(10), 2295; https://doi.org/10.3390/agronomy12102295 - 24 Sep 2022

Viewed by 1636

Abstract

Soil organic carbon (SOC) plays a crucial role in controlling the nitrate-dependent Fe(II) oxidation (NDFO) process, especially for saline-alkaline soils. The effects of straw returning combined with Nitrogen (N) fertilizer application on soil NO₃⁻-N content, Fe(II) form and nirK genes in saline-alkaline soil were studied in a five-year field experiment to explore the regulatory mechanism of SOC on NDFO process. Six treatments were designed with two factors (1) three straw returning rates (C0, C1 and C2, which was 0, 4500 and 9000 kg C ha⁻¹, respectively) and (2) two N fertilization rates (N1 and N2, which was 255 and 400 kg N ha⁻¹, respectively). Under both N levels, compared with C0 and C2 rates, NO₃⁻-N content was increased by 65% and 50% in C1 rate, respectively. NirK genes were decreased with straw returning, in which they were 42.9–58.8% lower in C1 and C2 treatments than that in C0 treatment, respectively. In the N1C1 treatment, the increase of SOC reduced the denitrification by converting aqueous Fe(II) (Fe(II)_aq) into Fe(II)-OM complexes and reducing the abundance of nirK genes. Overall, appropriate straw returning (C1) under optimal N fertilization rate (N1) could reduce N loss by decreasing the NDFO process in saline-alkaline paddy soils. Full article

(This article belongs to the Special Issue Environmental Impacts and Carbon-Nitrogen Transformations in Agriculture Activities)

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