Optimizing potassium and nitrogen fertilizer strategies to mitigate greenhouse gas emissions in global agroecosystems.

The efficient management of fertilizer application in agriculture is vital for both food security and mitigating greenhouse gas (GHG) emissions. However, as potassium fertilizer (KF) is an essential soil nutrient, its impact on soil GHG emissions has received little attention. To address this knowledge gap and identify key determinants of GHG emissions, we conducted a comprehensive meta-analysis of 205 independent experiments conducted worldwide. Our results revealed that, in comparison to sole nitrogen fertilizer (NF) application, the concurrent use of KF elevated nitrous oxide (N2O) and methane (CH4) emissions by 39.5 % and 21.1 %, respectively, while concurrently reducing carbon dioxide (CO2) emissions by 8.1 %. The ratio of nitrogen and potassium fertilizer input (NF/KF) is identified as the primary factor explaining the variation in N2O emissions, whereas the type of KF plays a crucial role in determining CH4 and CO2 emissions. We observed a significant negative correlation between the NF/KF ratio and response ratios of N2O and CH4 emissions and a positive correlation with CO2 emissions response ratios. Furthermore, our findings indicate that when the NF/KF ratio surpasses 1.97, 4.61, and 3.78, respectively, the impact of KF on reducing N2O, CH4, and CO2 emissions stabilizes. Overall, our results underscore that the global integration of KF into agricultural practices significantly influences N2O and CH4 emissions, while simultaneously reducing CO2 emissions at a large scale. These findings provide a foundational framework and practical guidance for optimizing fertilizer application in the development of GHG emission reduction models.

Impact of long-term fertilization on phosphorus fractions and manganese oxide with their interactions in paddy soil aggregates.

One under-studied microelement, manganese (Mn), due to its potential to considerably interact, and limit labile, and moderately-labile soil phosphorus (P) pools, was studied in Nanchang (NC), and Qiyang (QY) under paddy conditions. The Hedley's P sequential fractionation procedure was utilized to extract, and quantify various P fractions at both surface (0-20 cm) and subsurface (20-40 cm) layers. Unfertilized control (CK), nitrogen, phosphorus, and potassium (NPK), and NPK amended with animal manure (NPKM) were used as treatments. From both sites, the manure amended fertilizer (NPKM) compared to chemical NPK formed higher proportions of macro-aggregates (>2 and 2-0.25 mm) in both layers. Total P (TP) values of 842.1 (>2 mm), and 744.4 mg kg-1 (2-0.25 mm) from NC, and QY, respectively were accumulated by NPKM compared to NPK, and CK. Total P values of 806.4, and 350.4 mg kg-1 in the >2 mm aggregate size, respectively for NC, and QY were observed in the subsurface layer. Inorganic moderately labile P (NaOH-Pi) was the dominant fraction under all fertilizer treatments. Concentrations of 232.3 (<0.053 mm), and 202.1 mg kg-1 (0.25-0.053 mm) of NaOH-Pi were accumulated by NPKM, respectively for NC, and QY in the surface layer. In the subsurface layer, concentrations of NaOH-Pi (217.5 mg kg-1; <0.053 mm) from NC, and residual-P (57.3 mg kg-1; >2 mm) from QY were accumulated by NPKM. Similarly, NPKM in contrast to NPK contributed higher Mehlich-3 manganese (M3-Mn) oxide in all aggregate sizes from both sites. Generally, macro-aggregates contributed higher TP, fractions of P, and M3-Mn oxide than micro-aggregates. There was a positive relationship between P pools and M3-Mn oxide at both sites. Additions of animal manure were associated with increased P fractions, and Mn oxides in the paddy soil aggregates, which raises environmental concern.

Addition of walnut shells biochar to alkaline arable soil caused contradictory effects on CO2 and N2O emissions, nutrients availability, and enzymes activity.

Mitigation of greenhouse gas (GHGs) emissions and improving soil health using biochar (BC) shall help achieving the UN-Sustainable Development Goals. The impacts of walnut shells biochar (WSB) pyrolyzed at different temperatures on CO2 and N2O emission and soil health have not been yet sufficiently explored. We investigated the effects of addition of WSB pyrolyzed at either 300 °C (WSB-300), 450 °C (WSB-450), or at 600 °C (WSB-600) to alkaline soil on CO2 and N2O emissions, nutrients availability, and soil enzymes activities in a 120-day incubation experiment. Cumulative N2O emissions were reduced significantly as compared to the control, by 64.9%, 50.6%, and 36.4% after WSB-600, WSB-450 and WSB-300, respectively. However, the cumulative CO2 emissions increased, over the control, as follows: WSB-600 (50.7%), WSB-450 (68.6%), and WSB-300 (73.4%). Biochar addition, particularly WSB-600 significantly increased soil pH (from 8.1 to 8.34), soil organic C (SOC; from 8.6 to 22.3 g kg-1), available P (from 21.0 to 60.5 mg kg-1), and K (181.0-480.5 mg kg-1), and activities of urease, alkaline phosphatase, and invertase. However, an opposite pattern was observed with NH4+, NO3-, total N and ß-glucosidase activity after WSB application. The WBS produced from high temperature pyrolysis can be used for N2O emissions mitigation and improvement of soil pH, SOC, available P and K, and activities of urease, alkaline, phosphatase. However, WBS produced from low temperature pyrolysis can be used to promote N availability and ß-glucosidase; however, these findings should be verified under different field and climatic conditions.

The impact of pristine and modified rice straw biochar on the emission of greenhouse gases from a red acidic soil.

With the growing awareness of environmental impacts of land degradation, pressure is mounting to improve the health and productivity of degrading soils, which could be achieved through the use of raw and modified biochar materials. The primary objective of the current study was to investigate the efficiency of pristine and Mg-modified rice-straw biochar (RBC and MRBC) for the reduction of greenhouse gases (GHG) emissions and improvement of soil properties. A 90 days' incubation experiment was conducted using treatments which included control (CK), two RBC dosages (1% and 2.5%), and two MRBC doses (1% and 2.5%). Soil physico-chemical and biological properties were monitored to assess the effects due to the treatments. Results showed that both biochars improved soil physicochemical properties as the rate of biochar increased. The higher rates of biochar (RBC2.5 and MRBC2.5) particularly increased enzymatic activities (Catalase, Invertase and Urease) in comparison to the control. Data obtained for phospholipid fatty acid (PLFA) concentration indicated an increase in the Gram-negative bacteria (G-), actinomycetes and total PLFA with the increased biochar rate, while Gram-positive bacteria (G+) showed no changes to either level of biochar. As regards fungi concentration, it decreased with the biochar addition, whereas arbuscular mycorrhizal fungi (AMF) showed non-significant changes. The release of CO2, CH4 and N2O showed a decreasing trend over the time. CO2 cumulative emission decreased for MRBC1 (5%) and MRBC2.5 (9%) over the pristine biochar treatments. The cumulative N2O emission decreased by 15-32% for RBC1 and RBC2.5 and by 22-33% for MRBC1 and MRBC2.5 as compared to the control, whereas CH4 emission showed non-significant changes. Overall, the present study provides for the first-time data that could facilitate the correct use of Mg-modified rice biochar as a soil additive for the mitigation of greenhouse gas emission and improvement of soil properties.

Mitigation of greenhouse gas emissions from a red acidic soil by using magnesium-modified wheat straw biochar.

To mitigate greenhouse gas (GHG) emissions, different strategies have been proposed, including application of dolomite, crop straw and biochar, thus contributing to cope with the increasing global warming affecting the planet. In the current study, pristine wheat straw biochar (WBC) and magnesium (MgCl2.6H2O) modified wheat straw biochar (MWBC) were used. Treatments included control (CK), two WBC dosages (1% and 2.5%), and two MWBC doses (1% and 2.5%). After 90 days of incubation, WBC and MWBC improved the soil physiochemical properties, being more pronounced with increasing rates of biochar. MWBC2.5 significantly decreased microbial biomass carbon (MBC), while microbial biomass nitrogen (MBN) increased when both biochar materials (WBC1 and MWBC1) were applied at low rate. Compared to control soil, Urease and Alkaline phosphatase activities increased with the increasing rate of WBC and MWBC. The activities of dehydrogenase and ß-glucosidase decreased with the WBC and MWBC application, compared to CK. The fluxes of all the three GHGs evaluated (CO2, CH4 and N2O) decreased with time for both biochar amendments, while cumulative emission of CO2 increased by 58% and 45% for WBC, and by 54% and 41% for MWBC, as compared to CK. The N2O cumulative emissions decreased by 18 and 34% for WBC, and by 25 and 41% for MWBC, compared to CK, whereas cumulative methane emission showed non-significant differences among all treatments. These findings indicate that Mg-modified wheat straw biochar would be an appropriate management strategy aiding to reduce GHG emissions and improving the physiochemical properties of affected soils, and specifically of the red dry land soil investigated in the current work.

Long-term vegetation restoration increases deep soil carbon storage in the Northern Loess Plateau.

Afforestation plays an important role in soil carbon storage and water balance. However, there is a lack of information on deep soil carbon and water storage. The study investigates the effect of returning farmland to the forest on soil carbon accumulation and soil water consumption in 20-m deep soil profile in the hilly and gully region of the Chinese Loess Plateau. Four sampling sites were selected: Platycladus orientalis (Linn.) Franco forest (PO: oriental arborvitae), Pinus tabulaeformis Carr. Forest (PT: southern Chinese pine), apple orchard (AO) and farmland (FL, as a control). Soil organic carbon (SOC) and soil inorganic carbon (SIC) content were measured in 50-cm sampling intervals of 20-m soil profiles, as well as the associated factors (e.g. soil water content). The mean SOC content of PT was the highest in the 1-5 m layer and that of FL was the lowest (p < 0.05). Compared with FL, the SOC storages of PO, PT and AO increased by 2.20, 6.33 and 0.90 kg m-2 (p > 0.05), respectively, in the whole profile. The SIC content was relatively uniform throughout the profile at all land-use types and SIC storage was 9-10 times higher than SOC storage. The soil water storage of PO, PT and AO was significantly different from that of FL with a decrease of 1169.32, 1161.60 and 1139.63 mm, respectively. After the 36-yrs implementation of the "Grain for Green" Project, SOC in 20 m soil profiles increased as a water depletion cost compared with FL. Further investigation is still needed to understand the deep soil water and carbon interactions regarding ecological restoration sustainability in the Northern Loess Plateau.

Exploring the role of fossil fuels, hydroelectricity consumption, and financial sector in ensuring sustainable economic development in the emerging economy.

This study is conducted to address the research question of whether hydroelectricity and fossil fuels contribute to sustainable economic development in an emerging economy in this era of globalization? Further, this study applies the novel approach of Harvey unit root test which is a linearity test to predict the possible existence of non-linearity. The results confirmed that the majority of the series in this study are linear. Furthermore, the two break test is applied to investigate the integration sequence of the series. The bounds test approach confirms the existence of a long-run association among the variables. Additionally, the long-run relationship is analysed within the framework of the ARDL approach. Financial development, fossil fuel, and capital positively contribute to economic development, while the effect of hydroelectricity is insignificant. Moreover, globalization effects GDP negatively. The symmetric causality suggests a uni-directional causal movement from hydroelectricity consumption and globalization towards GDP. The outcome of the study emphasizes the importance of renewable sources such as hydropower energy for ensuring sustainable development in the presence of globalization.

Some Physiological and Biochemical Mechanisms during Seed-to-Seedling Transition in Tomato as Influenced by Garlic Allelochemicals.

The effects of aqueous garlic extracts (AGEs), diallyl disulfide (DADS), and allicin (AAS) were investigated during seed-to-seedling transition of tomato. Independent bioassays were performed including seed priming with AGE (0, 100, and 200 µg∙mL-1), germination under the allelochemical influence of AGE, DADS, and AAS, and germination under volatile application of AGE. Noticeable differences in germination indices and seedling growth (particularly root growth and fresh weights) were observed in a dose-dependent manner. When germinated under 50 mM NaCl, seeds primed with AGE exhibited induced defense via antioxidant enzyme activities (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)), lipid peroxidation (malondialdehyde content (MDA)), and H2O2 scavenging. Enzyme-linked immunosorbent analysis (ELISA) of the endogenous phytohormones auxin (IAA), abscisic acid (ABA), cytokinin (ZR), and gibberellic acid (GA3) in the roots and shoots of the obtained seedlings and the relative expression levels of auxin-responsive protein (IAA2), like-auxin (LAX5), mitogen-activated protein kinase (MAPK7 and MPK2), respiratory burst oxidase homolog (RBOH1), CHI3 and SODCC1 suggested allelopathic functions in stimulating growth responses. Our findings suggest that garlic allelochemicals act as plant biostimulants to enhance auxin biosynthesis and transportation, resulting in root growth promotion. Additionally, the relative expressions of defense-related genes, antioxidant enzymes activities and phytohormonal regulations indicate activation of the defense responses in tomato seedlings resulting in better growth and development. These results, thus, provide a basis to understand the biological functions of garlic allelochemicals from the induced resistance perspective in plants.

Evaluation of orange peel waste and its biochar on greenhouse gas emissions and soil biochemical properties within a loess soil.

The environmentally safe disposal of the large quantity of orange peels waste produced each day causes economic and environmental problems, which after conversion into biochar via pyrolysis technique might be used as an effective soil amendment. In this study, a 90-day incubation experiment was conducted to investigate the effects of orange peel waste and waste-derived biochar amendments on greenhouse gas emissions (GHG), soil biochemical properties, and soil enzyme activities. There were five treatments with different amendment levels: control without an amendment (Control), orange waste 1% (W1), orange waste 2% (W2), orange waste biochar 1% (B1), and orange waste biochar 2% (B2). The results showed that, compared with control, the amendments decreased cumulative N2O emissions by 59.2% (B2), 45.2% (B1), 20.6% (W2) and 10.2% (W1), respectively; and increased cumulative CH4 emissions by 81.7% (W1), 84.4% (W2), 75.8% (B1) and 74.9% (B2), respectively. Cumulative CO2 emissions decreased for the B1 (29.3%) and B2 (43.5%) over the waste treatments. While soil pH, SOC, nitrate nitrogen (NO3--N) and enzyme activities (urease and catalase) were significantly increased with the passage of time from the biochar amendments, ammonium nitrogen (NH4+-N) and invertase activities did not show this trend with time. Our study suggests that orange peel waste conversion to biochar should be a viable alternate method of disposal since land application resulted in reduced GHG and improvements in soil fertility.

Changes in phosphorus fractions associated with soil chemical properties under long-term organic and inorganic fertilization in paddy soils of southern China.

The identification of phosphorus (P) fractions is essential for understanding the transformation and availability of P in paddy soils. To investigate the soil P fractions associated with soil properties under long-term fertilization, we selected three fertilization treatments, including no fertilization (CK), chemical fertilizers (NPK) and chemical fertilizers combined with manure (NPKM), from three long-term experiments located in Nanchang (NC), Jinxian (JX) and Ningxiang (NX). The results showed that chemical fertilizers combined with manure (NPKM) significantly (P ≤ 0.05) increased the soil total phosphorus, Olsen P and soil organic matter (SOM) by 2, 3 and 1 times, respectively, compared with the NPK treatment, and by 4, 17 and 2 times, respectively, compared with the CK treatment. NPKM significantly increased the grain yield compared with CK and NPK at all sites. The apparent P balance with NPK was higher in NC and NX but lower in JX compared with NPKM. Hedley fractionation revealed the predominance of most of the organic and inorganic phosphorus (Po and Pi) fractions with long-term fertilization, especially with the NPKM treatment, at all sites. The nonlabile P pool decreased by 14% and 18% whereas the moderately labile P pool proportions increased by 3 and 6 times with the NPK and NPKM treatments, respectively, compared to the CK treatment. The labile P pool showed a significant positive relationship with the SOM, total P and Olsen P contents. The moderately labile P was positively correlated with the total P and Olsen P. A significant positive correlation was observed between soil pH and the nonlabile P pool. Redundancy analysis revealed that the moderately labile P fraction (HCl dil. Pi fraction) was remarkably increased by the NPKM treatment and significantly correlated with the soil pH and total P concentration. The labile P fraction (NaHCO3-Pi) showed a strong relationship with the Olsen P and total P. However, the residual P fraction was negatively correlated with the HCl. dil. Pi fraction. We concluded that NPKM application improved P availability by many folds compared to NPK, which could lead to environmental pollution; therefore, the rate of combined application of manure and chemical fertilizer should be reduced compared to chemical fertilizer inputs to minimize the wastage of resources and environmental P losses.

Co-Application of Milk Tea Waste and NPK Fertilizers to Improve Sandy Soil Biochemical Properties and Wheat Growth.

Desert soil is one of the most severe conditions which negatively affect the environment and crop growth production in arid land. The application of organic amendments with inorganic fertilizers is an economically viable and environmentally comprehensive method to develop sustainable agriculture. The aim of this study was to assess whether milk tea waste (TW) amendment combined with chemical fertilizer (F) application can be used to improve the biochemical properties of sandy soil and wheat growth. The treatments included control without amendment (T1), chemical fertilizers (T2), TW 2.5% + F (T3), TW 5% + F (T4) and TW 10% + F (T5). The results showed that the highest chlorophyll (a and b) and carotenoids, shoot and root dry biomass, and leaf area index (LAI) were significantly (p < 0.05) improved with all amendment treatments. However, the highest root total length, root surface area, root volume and diameter were recorded for T4 among all treatments. The greater uptake of N, P, and K contents for T4 increased for the shoot by 68.9, 58.3, and 57.1%, and for the root by 65.7, 34.3, and 47.4% compared to the control, respectively. Compared with the control, T5 treatment decreased the soil pH significantly (p < 0.05) and increased soil enzyme activities such as urease (95.2%), ß-glucosidase (81.6%) and dehydrogenase (97.2%), followed by T4, T3, and T2. Our findings suggested that the integrated use of milk tea waste and chemical fertilizers is a suitable amendment method for improving the growth and soil fertility status of sandy soils.