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19 pages, 2351 KiB

Open AccessArticle

Co-Incorporation of Green Manure and Rice Straw Increases Rice Yield and Nutrient Utilization

by Cuilan Wei, Bingshuai Cao, Songjuan Gao and Hao Liang

Plants 2025, 14(11), 1678; https://doi.org/10.3390/plants14111678 (registering DOI) - 30 May 2025

The co-incorporation of green manure and rice straw is commonly used to increase rice yield and improve soil fertility in paddy fields. However, the effects on nutrient uptake and utilization of rice under the synergistic interaction mechanism in the Taihu Plain of the [...] Read more.

The co-incorporation of green manure and rice straw is commonly used to increase rice yield and improve soil fertility in paddy fields. However, the effects on nutrient uptake and utilization of rice under the synergistic interaction mechanism in the Taihu Plain of the Yangtze River Delta remain unclear. Based on field experiments, this study investigated the effects of green manure with rice straw return (GMS) under different nitrogen (N) fertilization rates on rice yield, nutrient use efficiency, and soil fertility. The results revealed that green manuring significantly increased rice yield while improving the uptakes and use efficiencies of N, phosphorus (P) and potassium (K). Green manure (GM) with 40% N fertilizer reduction (GM_N60) maintained the grain and straw yields and nutrient uptakes compared to winter fallow with 100% conventional N application (WF_N100). The N recovery efficiency in GM_N60 reached 45.52%, increasing by 41.26% compared to WF_N100. Rice yield and K uptake in the GMS with 40% N fertilizer reduction treatment (GMS_N60) was 10,058 and 15.41 kg/hm², increasing by 14.43% and 9.43% compared to winter fallow with rice straw return and 100% conventional N (WFS_N100). The N, P and K agronomic efficiencies in GMS_N60 increased by 77.04%, 50.22%, and 50.22% compared to WFS_N100, respectively. These findings indicate that rice straw return enhances the fertilizer-saving and yield-increasing effects of GM, promotes rice K uptake and improves P and K use efficiencies. The GM treatment increased the soil organic matter (SOM), total potassium (TK), ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃⁻-N) contents. Among the soil fertility indicators, TK and SOM were the most important factors influencing rice yield and N uptake. In conclusion, GMS can maintain or increase rice yield with 40% N fertilizer reduction, improve nutrient use efficiencies, and increase the reuse of rice straw, thereby supporting green and efficient rice production in the southern Jiangsu paddy area. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

22 pages, 1996 KiB

Open AccessArticle

Emergent Plants Improve Nitrogen Uptake Rates by Regulating the Activity of Nitrogen Assimilation Enzymes

by Yu Hong, Ruliang Liu, Wenhua Xiang, Pifeng Lei and Xi Fang

Plants 2025, 14(10), 1484; https://doi.org/10.3390/plants14101484 - 15 May 2025

Viewed by 286

Abstract

Effectively utilizing aquatic plants to absorb nitrogen from water bodies and convert it into organic nitrogen via nitrogen assimilation enzyme activity reduces water nitrogen concentrations. This serves as a critical strategy for mitigating agricultural non-point source pollution in the Yellow River Basin However, [...] Read more.

Effectively utilizing aquatic plants to absorb nitrogen from water bodies and convert it into organic nitrogen via nitrogen assimilation enzyme activity reduces water nitrogen concentrations. This serves as a critical strategy for mitigating agricultural non-point source pollution in the Yellow River Basin However, emergent plants’ rate and mechanism of uptake of different forms of nitrogen remain unclear. This study determined the nitrogen uptake rates, nitrogen assimilation activities, root properties, and photosynthetic parameters of four emergent plants, Phragmites australis, Typha orientalis, Scirpus validus, and Lythrum salicaria, under five NH₄⁺/NO₃⁻ ratios (9:1, 7:3, 5:5, 3:7, and 1:9) using ¹⁵N hydroponic simulations. The results demonstrated that both the form of nitrogen and the plant species significantly influenced the nitrogen uptake rates of emergent plants. In water bodies with varying NH₄⁺/NO₃⁻ ratios, P. australis and T. orientalis exhibited significantly higher inorganic nitrogen uptake rates than S. validus and L. salicaria, increasing by 11.83–114.69% and 14.07–130.46%, respectively. When the ratio of NH₄⁺/NO₃⁻ in the water body was 9:1, the uptake rate of inorganic nitrogen by P. australis reached its peak, which was 729.20 μg·N·g⁻¹·h⁻¹ DW (Dry Weight). When the ratio of NH₄⁺/NO₃⁻ was 5:5, the uptake rate of T. orientalis was the highest, reaching 763.71 μg·N·g⁻¹·h⁻¹ DW. The plants’ preferences for different forms of nitrogen exhibited significant environmental plasticity. At an NH₄⁺/NO₃⁻ ratio of 5:5, P. australis and T. orientalis preferred NO₃⁻-N, whereas S. validus and L. salicaria favored NH₄⁺-N. The uptake rate of NH₄⁺-N by the four plants was significantly positively correlated with glutamine synthetase and glutamate synthase activities, while the uptake rate of NO₃⁻-N was significantly positively correlated with NR activity. These findings indicate that the nitrogen uptake and assimilation processes of these four plant species involve synergistic mechanisms of environmental adaptation and physiological regulation, enabling more effective utilization of different nitrogen forms in water. Additionally, the uptake rate of NH₄⁺-N by P. australis and T. orientalis was significantly positively correlated with glutamate dehydrogenase (GDH), suggesting that they are better adapted to eutrophication via the GDH pathway. The specific root surface area plays a crucial role in regulating the nitrogen uptake rates of plants. The amount of nitrogen uptake exerted the greatest total impact on the nitrogen uptake rate, followed by root traits and nitrogen assimilation enzymes. Therefore, there were significant interspecific differences in the uptake rates of and physiological response mechanisms of emergent plants to various nitrogen forms. It is recommended to prioritize the use of highly adaptable emergent plants such as P. australis and T. orientalis in the Yellow River irrigation area. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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18 pages, 3576 KiB

Open AccessArticle

Effects of Nitrogen Application Strategies on Yield, Nitrogen Uptake and Leaching in Spring Maize Fields in Northwest China

by Ying Wang, Jingjing He, Zongyuan Gao, Ruliang Liu, Yu Hong, Fang Wang, Xinping Mao, Tianxiang Xu, Lina Zhou and Jun Yi

Plants 2025, 14(7), 1067; https://doi.org/10.3390/plants14071067 - 31 Mar 2025

Viewed by 525

Abstract

Nitrogen (N) is an essential nutrient for crop growth, as N fertilizer application regulates crop nitrogen uptake, affecting leaf photosynthetic rates, crop growth, and yield formation. However, both N deficiency and excess can reduce corn yields. Hence, optimizing the N fertilizer application strategy [...] Read more.

Nitrogen (N) is an essential nutrient for crop growth, as N fertilizer application regulates crop nitrogen uptake, affecting leaf photosynthetic rates, crop growth, and yield formation. However, both N deficiency and excess can reduce corn yields. Hence, optimizing the N fertilizer application strategy is crucial for crop production. In this study, a field plot trial with five N fertilization application strategies was conducted in the maize field from 2021 to 2022 in the Ningxia Yellow Irrigation District, Northwest China. These strategies contain zero N application rates (CK, 0 kg ha⁻¹), the farmer practical N fertilizer application strategy (FP, 420 kg ha⁻¹), the optimized N fertilizer application strategy (OPT, 360 kg ha⁻¹), organic fertilizer and chemical fertilizer combination application (ON, 300 kg ha⁻¹), and controlled-release N fertilizer and 33 urea application (CN, 270 kg ha⁻¹). The maize yield and N balance under each treatment were investigated to propose the optimized N application strategy. The results showed that the CN treatment’s grain yield (15,672 kg ha⁻¹) was the highest in both years, which was 109.97% and 8.92% higher than the CK and FP treatments, respectively. The apparent utilization rate and partial productivity of N fertilizer decreased with the increase in the N application rate. Also, the apparent utilization rate of N fertilizer in CN was 23.02%, 19.41%, and 13.02% higher than the FP, OPT, and ON, respectively. Applying controlled-release urea and organic fertilizers improved the physical and chemical properties of the soil, increased the organic matter content and soil fertility, and ultimately increased the spring maize yield. Meanwhile, the TN, NO₃⁻-N, and NH₄⁺-N concentrations in leaching water significantly correlated with the N application rate. With the extension of the maize growth period, the concentrations of TN, NO₃⁻-N, and NH₄⁺-N in leaching water gradually decreased. The N leaching amount in FP was the highest, while the CN was the lowest. The NO₃⁻-N is the primary N leaching form, accounting for 46.78~54.68% of the TN leaching amount. Compared with the CN, the ON significantly increased the inorganic N content in the 0–40 cm soil layer, and it reduced the residual inorganic N content below 40 cm soil depths compared with FP and OPT treatments. Considering the relatively high spring maize yield and N utilization efficiency, as well as the relatively low N leaching amount and soil inorganic N residues, the ON and CN treatments with 270–300 kg ha⁻¹ N application rate were the optimized N application strategies in the spring maize field in the study area. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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14 pages, 4575 KiB

Open AccessArticle

Irrigation Intensities Drive Soil N₂O Emission Reduction in Drip-Irrigated Cotton Fields

by Honghong Ma, Qi Wu, Xianglin Wu, Qianqian Zhu, Shenghai Pu and Xinwang Ma

Plants 2025, 14(7), 987; https://doi.org/10.3390/plants14070987 - 21 Mar 2025

Viewed by 390

Abstract

Drip irrigation with plastic mulch is widely used to save water and improve fertilizer efficiency in arid regions in Xinjiang. However, farmers freely use irrigation water in pursuit of a high cotton yield, and the impact of different irrigation amounts on nitrous oxide [...] Read more.

Drip irrigation with plastic mulch is widely used to save water and improve fertilizer efficiency in arid regions in Xinjiang. However, farmers freely use irrigation water in pursuit of a high cotton yield, and the impact of different irrigation amounts on nitrous oxide (N₂O) emissions is still unclear. A field experiment was conducted in 2023 in Xinjiang, China, with drip-irrigated cotton (Gossypium hirsutum L.) to determine N₂O emissions with different irrigation intensities. The different irrigation treatments were designed as follows: irrigation was performed to maintain soil moisture at (1) an 80% field capacity (Q80); (2) 90% field capacity (Q90); and (3) 100% field capacity (Q100). The results showed that the yield of cotton decreased with the increase in irrigation intensity. A 100% field capacity is beneficial for ammonium and nitrate transformation. The N₂O emissions remained at a relatively low level during the non-irrigated fertilization period. In every irrigation and fertilization cycle, the N₂O emissions were mainly concentrated during the process from wet to dry. The peak occurred during days 1–3 of irrigation. Throughout the growth period, the cumulative N₂O emissions were 1.15, 1.48, and 2.63 kg N ha⁻¹ under the Q80, Q90, and Q100 treatments, respectively. As the irrigation intensity increased, the dominant species of soil bacteria and fungi showed substitution, while the dominant species of soil actinomycetes were not replaced. Fungi, actinomycetes, the available potassium, and the carbon to nitrogen ratio were positively correlated with nitrous oxide emissions, and the soil temperature was negatively correlated with nitrous oxide emissions. These results demonstrate that increased irrigation could increase the risk of greenhouse gas emissions when using plastic mulch with drip irrigation. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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27 pages, 3101 KiB

Open AccessArticle

Effects of Increasing CO₂ Concentration on Crop Growth and Soil Ammonia-Oxidizing Microorganisms in a Fababean (Vicia faba L.) and Wheat (Triticum aestivum Yunmai) Intercropping System

by Xingshui Dong, Hui Lin, Feng Wang, Songmei Shi, Junwei Ma and Xinhua He

Plants 2025, 14(4), 516; https://doi.org/10.3390/plants14040516 - 8 Feb 2025

Viewed by 662

Abstract

Elevated carbon dioxide (eCO₂) levels can enhance crop yields but may simultaneously reduce quality, impacting both macronutrient and micronutrient concentrations, and potentially decreasing protein content in cereal grains. This study examined the effects of elevated CO₂ (eCO₂) and [...] Read more.

Elevated carbon dioxide (eCO₂) levels can enhance crop yields but may simultaneously reduce quality, impacting both macronutrient and micronutrient concentrations, and potentially decreasing protein content in cereal grains. This study examined the effects of elevated CO₂ (eCO₂) and nitrogen (N) fertilization on crop growth, yield, and soil nitrogen cycling through a glass greenhouse experiment using Eutric Regosol soil. The experimental design incorporated two CO₂ gradients: ambient CO₂ (aCO₂) at approximately 410 ppm during the day and 460 ppm at night, and eCO₂ at approximately 550 ppm during the day and 610 ppm at night. Additionally, two nitrogen fertilization treatments were applied: no fertilizer (N0) and 100 mg N kg⁻¹ dry weight (DW) soil (N100). Crops were cultivated under two cropping systems: the monoculturing of fababean (Vicia faba L.) or wheat (Triticum aestivum Yunmai) and the intercropping of both species. The results demonstrated that eCO₂ significantly enhanced the growth and yield of both fababean and wheat, particularly when nitrogen fertilization was applied. Nitrogen fertilizer application did not always enhance crop yield, considering the complexity of nitrogen management under elevated CO₂ conditions. Furthermore, the intercropping of fababean and wheat presented multiple advantages, including improved crop yields, enhanced soil health, and increased ecosystem services. These findings suggest that intercropping can serve as a sustainable strategy to boost productivity and ecosystem resilience in the face of climate change. The changes in nitrogen application and CO₂ concentration affect the gene copy number of ammonia-oxidizing bacteria and archaea, which may affect the nitrogen cycling process in soil. There are complex interactions between crop biomass, nitrogen accumulation, transpiration rate, photosynthetic rate and stomatal conductance with soil properties (e.g., pH, organic matter, nitrogen content) and microbial community structure. The interaction between CO₂ concentration, nitrogen application level and crop intercropping pattern had significant effects on crop growth, soil properties and microbial communities. Future research should prioritize investigating the long-term effects of intercropping on soil productivity and the development of management strategies that optimize the benefits of this cropping system. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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16 pages, 2718 KiB

Open AccessArticle

Controlled-Release Fertilizer Improving Paddy Yield and Nitrogen Use Efficiency by Reducing Soil Residual Nitrogen and Leaching Losses in the Yellow River Irrigation Area

by Jingjing He, Ying Wang, Hong Li, Junhua Ma, Xiang Yue, Xiangyu Liang, Yu Hong, Fang Wang, Chenxia Hu and Ruliang Liu

Plants 2025, 14(3), 408; https://doi.org/10.3390/plants14030408 - 30 Jan 2025

Viewed by 927

Abstract

The unreasonable application of nitrogen (N) fertilizer leads to high nutrient losses and severe potential of agricultural non-point source contamination, which threatens water quality in the upper Yellow River Basin. Therefore, the aim of this study is to explore the effects of N [...] Read more.

The unreasonable application of nitrogen (N) fertilizer leads to high nutrient losses and severe potential of agricultural non-point source contamination, which threatens water quality in the upper Yellow River Basin. Therefore, the aim of this study is to explore the effects of N application rates and various control measures on rice yield and N leaching in paddy fields in the Yellow River irrigation area. Four treatments were employed in this study, CK (no N fertilizer application, 0 kg N∙ha⁻¹), CRU (controlled-release urea application, 180 kg N∙ha⁻¹), OPT (optimal N fertilizer application, 210 kg N∙ha⁻¹), and FP (N fertilizer application based on farmer experience, 240 kg N∙ha⁻¹), to examine paddy yield, N use efficiency (NUE), N concentrations in leaching water at various soil depths, and N contents along the 0–100 cm depth of the soil profile. The results indicated that the amount of TN leached was 25.14–48.04 kg∙ha⁻¹ after different N applications, and the TN leaching coefficients of FP, OPT, and CRU were 10.88%, 11.27%, and 7.07%. Compared to FP and OPT, the CRU significantly reduced the concentrations of TN, ammonium N (NH₄⁺-N), and nitrate N (NO₃⁻-N) in the surface and soil water, with average TN leaching decreasing by 31.55% and 27.35% in the years 2022 and 2023, respectively. NO₃⁻-N was identified as the primary form of N leached from the paddy fields. Compared to FP and OPT treatments, the CRU treatment increased the average paddy yield by 19.99–20.66% and improved the average NUE by 19.04–16.38%. This study revealed that the application of high amounts of N positively affected soil N leaching, and controlled-release urea demonstrates superior efficacy compared to conventional fertilization. The application of controlled-release urea at a rate of 180 kg N∙ha⁻¹ not only ensures a good paddy yield but also reduce N losses, which should be recommended to local farmers. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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18 pages, 4080 KiB

Open AccessArticle

Interaction of Straw Mulching and Nitrogen Fertilization on Ammonia Volatilization from Oilseed Rape–Maize Rotation System in Sloping Farmland in Southwestern China

by Li Yao, Hong Wang, Haitao Liu, Xie Wang, Yueying Wu, Lin Wang, Honglin Chen and Chaowen Lin

Plants 2025, 14(1), 14; https://doi.org/10.3390/plants14010014 - 24 Dec 2024

Viewed by 661

Abstract

Ammonia (NH₃) volatilization caused by urea application has negative implications for human health, environmental quality, and the value of nitrogen fertilizers. It remains to be investigated how management strategies should be adopted to not only reduce NH₃ volatilization but also [...] Read more.

Ammonia (NH₃) volatilization caused by urea application has negative implications for human health, environmental quality, and the value of nitrogen fertilizers. It remains to be investigated how management strategies should be adopted to not only reduce NH₃ volatilization but also improve nitrogen use efficiency (NUE) in the agriculture industry at present. Hence, a two-year field trial, including subplots, was conducted to simultaneously evaluate the effects of mulching treatments (NM: non-mulching; SM: straw mulching) and different fertilizer treatments (U: urea; U + NBPT: urea plus 1% N-(n-butyl) thiophosphoric triamide; U + CRU: the mixture of urea and controlled-release urea at a 3:7 ratio; U + OF: urea plus commercial organic fertilizer at a 3:7 ratio) on NH₃ volatilization, crop production, and NUE in an oilseed rape–maize rotation system in the sloping farmland of purple soil in southwestern China between 2021 and 2023. Compared with NM + U, NH₃ volatilization losses under the NM + U + NBPT, NM + U + CRU, and NM + U + OF treatments decreased, on average, by 64.13%, 17.39%, and 15.09% during the oilseed rape growing season but by 64.01%, 11.67%, and 10.13% during the maize growing season, respectively. An average increase in NH₃ volatilization of 35.65% for the straw-mulching treatment was recorded during the oilseed rape season, while during the maize season, this parameter showed an increase of 10.69%, in comparison to NM + U. With the combination of urea with NBPT, CRU, and organic fertilizer, contrastingly, a reduction in NH₃ volatilization was achieved under the SM + U + NBPT, SM + U + CRU, and SM + U + OF treatments. When compared with NM + U, the difference in the NUE between the NM + U + NBPT, NM + U + CRU, and NM + U + OF treatments was not significant in the oilseed rape season. The NUE was around 4.27% higher under NM + U + NBPT during the maize season (p < 0.05). Compared with NM + U, under the NM + U + NBPT, NM + U + CRU, and NM + U + OF treatments, consistently lower values of yield-scaled NH₃ volatilization were noted: 13.15–65.66% in the oilseed rape season and 10.34–67.27% in the maize season. Furthermore, SM + U, SM + U + NBPT, SM + U + CRU, and SM + U + OF showed average annual emission factors (AEFs) of 14.01%, 5.81%, 12.14%, and 11.64%, respectively. Overall, straw mulching, along with the application of the mixture of NBPT and urea, was found to be the optimal strategy to effectively reduce the NH₃ emissions in the purple soil areas of southern China. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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18 pages, 4507 KiB

Open AccessArticle

Different Impacts of Long-Term Tillage and Manure on Yield and N Use Efficiency, Soil Fertility, and Fungal Community in Rainfed Wheat in Loess Plateau

by Mengni Chen, Hailiang Yang, Qingshan Yang, Yongshan Li, Hui Wang, Juanling Wang, Qiaolan Fan, Na Yang, Ke Wang, Jiancheng Zhang, Jiawei Yuan, Peng Dong and Lu Wang

Plants 2024, 13(24), 3477; https://doi.org/10.3390/plants13243477 - 12 Dec 2024

Viewed by 1111

Abstract

Conservation tillage and fertilization are widely adopted in agricultural systems to enhance soil fertility and influence fungal communities, thereby improving agroecosystems. However, the effects of no-tillage combined with manure on grain yield, nitrogen use efficiency (NUE), soil fertility, and rhizosphere fungal communities remain [...] Read more.

Conservation tillage and fertilization are widely adopted in agricultural systems to enhance soil fertility and influence fungal communities, thereby improving agroecosystems. However, the effects of no-tillage combined with manure on grain yield, nitrogen use efficiency (NUE), soil fertility, and rhizosphere fungal communities remain poorly understood, particularly in rainfed wheat fields on the Loess Plateau. A 15-year field experiment was conducted at the Niujiawa Experimental Farm of the Cotton Research Institute, Shanxi Agricultural University. Five treatments were assessed: conventional tillage without fertilizer (C), no-tillage with chemical fertilizer (NT), no-tillage with chemical fertilizer and manure (NTM), conventional tillage with chemical fertilizer (T), and conventional tillage with chemical fertilizer and manure (TM). The results demonstrated that the NTM treatment significantly increased grain yield by 124.95%, NT by 65.88%, TM by 68.97%, and T by 41.75%, compared to the C treatment (p < 0.05). NUE in the NTM treatment was improved by 58.73%–200.59%. Compared with the C treatment, NTM significantly enhanced soil nutrients, including organic matter (OM) by 70.68%, total nitrogen (TN) by 8.81%, total phosphorus (TP) by 211.53%, available nitrogen (AN) by 90.00%, available phosphorus (AP) by 769.12%, and available potassium (AK) by 89.01%. Additionally, the NTM treatment altered the rhizosphere fungal community of winter wheat, with Ascomycota (81.36%–90.24%) being the dominant phylum, followed by Mucoromycota (5.40%–12.83%) and Basidiomycota (1.50%–8.53%). At the genus level, NTM significantly increased the abundance of Mortierella and Dendrostilbella. An α-diversity analysis revealed that the richness and diversity of soil fungi were highest under NTM. The unweighted pair-group method with arithmetic mean (UPGMA) and principal coordinates analysis (PCoA) based on Bray-Curtis distances indicated that NTM formed a distinct fungal community with the highest phylogenetic diversity, which differed significantly from other treatments. Redundancy analysis (RDA) demonstrated that soil chemical properties variably influenced fungal community dynamics, with higher abundances of Ascomycota and Zoopagomycota positively correlated with OM, AN, AP, TP, and AK. Correlation analysis showed that wheat yield and NUE were positively correlated with Mortierella and Dendrostilbella, and negatively correlated with Fusarium, Chaetomium, and Alternaria. In conclusion, no-tillage with manure not only enhanced soil fertility but also enhanced soil fungal community structure, leading to greater wheat yield and NUE. These findings provide guidance for agricultural practices in rainfed wheat fields of the Loess Plateau. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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20 pages, 3128 KiB

Open AccessArticle

Straw Returning Methods Affects Macro-Aggregate Content and Organic Matter Content in Black Soils: Meta-Analysis and Comprehensive Validation

by Kangmeng Liu, Yu Hu, Yumei Li, Lei Wang, Liang Jin, Lianfeng Cai, Xiaoxiao Wu, Zhenguo Yang, Yan Li and Dan Wei

Plants 2024, 13(23), 3284; https://doi.org/10.3390/plants13233284 - 22 Nov 2024

Viewed by 1250

Abstract

Straw returning into the soil is a crucial method for boosting soil carbon levels. To research the influence of straw return practices on soil aggregates and organic matter content within the farmlands of the Northeast Black Soil Region, the objective was to clarify [...] Read more.

Straw returning into the soil is a crucial method for boosting soil carbon levels. To research the influence of straw return practices on soil aggregates and organic matter content within the farmlands of the Northeast Black Soil Region, the objective was to clarify the varying impacts of these practices on soil carbon enhancement. In this study, 89 pertinent papers were acquired through a rigorous literature compilation. Meta-analysis and the linear regression method were employed to analyze the influence of field return methods, their duration on soil water-stable aggregates, and their organic matter content. Furthermore, the study delved into the trends in the variation of aggregates and organic matter in relation to mean annual temperature and precipitation. Our results showed that the straw-returning method has been discovered to predominantly bolster soil organic matter by altering the proportions of macro-aggregate content. Specifically, straw incorporation has led to a notable enhancement in the content of macro-aggregates (57.14%) and micro-aggregates (20.29%), in addition to augmenting the content of macro-, small, and micro-aggregate organic matter by 13.22%, 16.43%, and 15.08%, respectively. The most significant increase in large agglomerates was witnessed in straw return over a period of more than 5 years (115.17%), as well as shallow mixing return (87.32%). Meanwhile, the highest increase in the organic matter content of large agglomerates was recorded in straw return over 5 years (12.60%) and deep mixing return (8.72%). In the field validation experiment, a period of seven years of straw return significantly boosted the macro-aggregate content across various soil layers, ranging from 11.78% to 116.21%. Furthermore, among the various climatic factors, the primary determinants of disparities in study outcomes were the average annual temperature and average annual precipitation. Specifically, lower precipitation and higher temperatures were conducive to the enhancement of macro-aggregate formation and organic matter content. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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16 pages, 1628 KiB

Open AccessArticle

Modeling the Effect of Milk Vetch–Rice Rotation on N Runoff Loss in the Middle and Lower Reaches of the Yangtze River

by Guodong Zhou, Cuilan Wei, Penghui Li and Hao Liang

Plants 2024, 13(22), 3160; https://doi.org/10.3390/plants13223160 - 10 Nov 2024

Viewed by 925

Abstract

The winter planting of green manure (GM) is widely used in South China to reduce chemical nitrogen (N) fertilizer use, improve soil fertility, and maintain rice yields, but its effect on N runoff loss in paddy fields remains unclear. This study combines multi-site [...] Read more.

The winter planting of green manure (GM) is widely used in South China to reduce chemical nitrogen (N) fertilizer use, improve soil fertility, and maintain rice yields, but its effect on N runoff loss in paddy fields remains unclear. This study combines multi-site field experiments with a process model (WHCNS-Rice) to assess how GM with reduced N fertilizer impacts N runoff loss and its forms in the Yangtze River’s middle and lower reaches, considering different rainfall years. The network field experiments included four treatments: conventional fertilization (FR), conventional fertilization plus straw return (FRS), GM with a 40% N reduction (MR), and GM-straw combined return with a 40% N reduction (MRS). Monitoring the results showed that compared to the winter fallow treatment, the GM treatments reduced the peak and average total N (TN) concentrations by 11.1–57.9% (average 26.9%) and 17.1–27.3% (average 22.3%), respectively. The TN runoff loss under the GM treatment decreased by 3.50–10.61 kg N ha⁻¹ (22.5–42.1%). GM primarily reduced the runoff loss of dissolved inorganic N (DIN), with reductions at different sites ranging from 0.22 to 9.66 kg N ha⁻¹ (8.4–43.4%), indicating GM effectively decreases N runoff by reducing DIN. Model simulations of ponding water depth, runoff, TN concentration in surface water, and TN loss in paddy fields produced the consistency indices and simulation efficiencies of 0.738–0.985, 0.737–0.986, 0.912–0.986, and 0.674–0.972, respectively, indicating that the model can be used to evaluate water consumption and N runoff loss in the GM-paddy system. The simulations showed that GM with a 40% N fertilizer significantly reduced N runoff loss under all rainfall conditions, with the greatest reductions in wet years. Under wet, normal, and dry conditions, the GM treatments significantly reduced average TN loss by 0.37–5.53 kg N ha⁻¹ (12.77–29.17%), 0.21–5.32 kg N ha⁻¹ (9.95–24.51%), and 0.02–3.2 kg N ha⁻¹ (1.78–23.19%), respectively, compared to the winter fallow treatment. These results indicate that the combination of GM and a 40% reduction in N fertilizer can significantly reduce N runoff loss from paddy fields, demonstrating good effectiveness under various rainfall conditions, making it a green production model worth promoting. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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22 pages, 7864 KiB

Open AccessArticle

A Plant Strategy: Irrigation, Nitrogen Fertilization, and Climatic Conditions Regulated the Carbon Allocation and Yield of Oilseed Flax in Semi-Arid Area

by Haidi Wang, Bangqing Zhao, Yuhong Gao, Bin Yan, Bing Wu, Zhengjun Cui, Yifan Wang, Ming Wen and Xingkang Ma

Plants 2024, 13(18), 2553; https://doi.org/10.3390/plants13182553 - 11 Sep 2024

Viewed by 1414

Abstract

The injudicious use of water and fertilizer to maximize crop yield not only leads to environmental pollution, but also causes enormous economic losses. For this reason, we investigated the effect of nitrogen (N) (N0 (0), N60 (60 kg ha⁻¹), and N120 [...] Read more.

The injudicious use of water and fertilizer to maximize crop yield not only leads to environmental pollution, but also causes enormous economic losses. For this reason, we investigated the effect of nitrogen (N) (N0 (0), N60 (60 kg ha⁻¹), and N120 (120 kg ha⁻¹)) at different irrigation levels (I0 (0), I1200 (budding 600 m³ ha⁻¹ + kernel 600 m³ ha⁻¹), and I1800 (budding 900 m³ ha⁻¹ + kernel 900 m³ ha⁻¹)) on oilseed flax in the Loess Plateau of China in 2019 and 2020. The objective was to establish appropriate irrigation and fertilizer management strategies that enhance the grain yield (GY) of oilseed flax and maximize water and N productivity. The results demonstrated that irrigation and N application and their coupling effects promoted dry matter accumulation (DMA) and non-structural carbohydrate (NSC) synthesis, and increased the GY of oilseed flax. The contents of NSC in various organs of flax were closely related to grain yield and yield components. Higher NSC in stems was conducive to increased sink capacity (effective capsule number per plant (EC) and thousand kernel weight (TKW)), and the coupling of irrigation and N affected GY by promoting NSC synthesis. Higher GY was obtained by the interaction of irrigation and N fertilizer, with the increase rate ranging from 15.84% to 35.40%. Additionally, in the increased yield of oilseed flax, 39.70–78.06%, 14.49–54.11%, and −10.6–24.93% were contributed by the application of irrigation and nitrogen and the interaction of irrigation and nitrogen (I × N), respectively. Irrigation was the main factor for increasing the GY of oilseed flax. In addition, different climatic conditions changed the contribution of irrigation and N and their interaction to yield increase in oilseed flax. Drought and low temperature induced soluble sugar (SS) and starch (ST) synthesis to resist an unfavorable environment, respectively. The structural equation model showed that the key factors to increasing the GY of oilseed flax by irrigation and nitrogen fertilization were the differential increases in DMA, EC, and TKW. The increases in EC and TKW were attributed to the promotion of DMA and NSC synthesis in oilseed flax organs by irrigation, nitrogen fertilization, and their coupling effects. The I1200N60 treatment obtained higher water use efficiency (WUE) and N partial factor productivity (NPFP) due to lower actual evapotranspiration (ETa) and lower N application rate. Therefore, the strategy of 1200 m³ ha⁻¹ irrigation and 60 kg ha⁻¹ N application is recommended for oilseed flax in semi-arid and similar areas to achieve high grain yield and efficient use of resources. Full article

(This article belongs to the Special Issue Water and Nitrogen Management in the Soil–Crop System (3rd Edition))

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