Consecutive Experiment Research Articles

Biochar application does not improve crop growth and yield in a semi-humid region in the HuangHuaiHai Plain of China: A 7-year consecutive field experiment

Biochar (BC) has gained worldwide attention as a soil amendment to improve soil fertility and crop yield. However, long-term field data are still lacking to evaluate the effectiveness of BC application in increasing crop yield under various specific site conditions. A 7-year field experiment of BC application with consecutive corn-wheat rotations was carried out in a semi-humid region in the HuangHuaiHai Plain in north China. Straw-derived BC was mixed with the sandy loam soil in 9 m2 (3 m × 3 m) plots to a depth of 20 cm with the application rates (w/w) of 0 t ha−1, 12 t ha−1, 24 t ha−1, 36 t ha−1, 48 t ha −1, and 60 t ha −1, respectively. Physiological indexes, e.g. plant height, spike number, number of ears, spike length, straw dry matter and root dry matter, and the crop yield, i.e. 1000-grain weight, and grain yield, were measured for each growing season under different BC treatments. Disturbed and undisturbed soil samples were collected 4 years after BC application. Laboratory measurements were conducted to determine soil properties, such as bulk density, saturated hydraulic conductivity (Ks), aggregate size distribution, soil water retention characteristics, pore size distribution, and soil nutrient contents under different BC treatments. The results showed that plant physiological indexes and grain yield of both corn and wheat were not significantly affected by BC application, being independent of the application rate, climate variation and time. Besides, the BC application significantly improved soil physio-chemical properties, indicated by increases in soil macro-aggregate, aggregate stability, Ks, plant available water capacity and soil available nutrients. The long-term field results demonstrate that the soil fertility improved by BC application may not always lead to significant increase in crop yield. Apart from soil properties, genetic merits of the specific crop cultivar and field managements of irrigation and fertilization could be the dominating factors affecting crop growth and yield under particular soil type and climate conditions. Thus, applying BC as a soil amendment to improve crop yield should be approached with comprehensive consideration of the local environmental conditions, crop cultivars and field managements.

Dynamic alterations and ecological implications of rice rhizosphere bacterial communities induced by an insect-transmitted reovirus across space and time

BackgroundCereal diseases caused by insect-transmitted viruses are challenging to forecast and control because of their intermittent outbreak patterns, which are usually attributed to increased population densities of vector insects due to cereal crop rotations and indiscriminate use of pesticides, and lack of resistance in commercial varieties. Root microbiomes are known to significantly affect plant health, but there are significant knowledge gaps concerning epidemics of cereal virus diseases at the microbiome-wide scale under a variety of environmental and biological factors.ResultsHere, we characterize the diversity and composition of rice (Oryza sativa) root-associated bacterial communities after infection by an insect-transmitted reovirus, rice black-streaked dwarf virus (RBSDV, genus Fijivirus, family Spinareoviridae), by sequencing the bacterial 16S rRNA gene amplified fragments from 1240 samples collected at a consecutive 3-year field experiment. The disease incidences gradually decreased from 2017 to 2019 in both Langfang (LF) and Kaifeng (KF). BRSDV infection significantly impacted the bacterial community in the rice rhizosphere, but this effect was highly susceptible to both the rice-intrinsic and external conditions. A greater correlation between the bacterial community in the rice rhizosphere and those in the root endosphere was found after virus infection, implying a potential relationship between the rice-intrinsic conditions and the rhizosphere bacterial community. The discrepant metabolites in rhizosphere soil were strongly and significantly correlated with the variation of rhizosphere bacterial communities. Glycerophosphates, amino acids, steroid esters, and triterpenoids were the metabolites most closely associated with the bacterial communities, and they mainly linked to the taxa of Proteobacteria, especially Rhodocyclaceae, Burkholderiaceae, and Xanthomonadales. In addition, the greenhouse pot experiments demonstrated that bulk soil microbiota significantly influenced the rhizosphere and endosphere communities and also regulated the RBSDV-mediated variation of rhizosphere bacterial communities.ConclusionsOverall, this study reveals unprecedented spatiotemporal dynamics in rhizosphere bacterial communities triggered by RBSDV infection with potential implications for disease intermittent outbreaks. The finding has promising implications for future studies exploring virus-mediated plant-microbiome interactions.2AL1xEb7k2nunVBmbuNCsVVideo

Maximizing food equivalent unit yield for forage maize production without notably compromising dry matter yield and feed quality in a semi-arid region

Food equivalent unit (FEU) is a vector used to measure the value of food based on its calorie and protein content and their digestibility. However, the optimal planting density and N application rate for maximizing the FEU yield (FEUY) of forage maize (Zea mays L.) is still poorly understood in the fast-growing animal husbandry regions of the Chinese Loess Plateau. Here, a 2-year consecutive field experiment was conducted to explore the impacts of planting density, N application rate, and their interactions on growth, dry matter yield (DMY), forage quality, and FEUY of a dominant forage maize cultivar. Planting density significantly affected the stem diameter, LAI, DMY, and dry matter allocation (DMA) of the leaf. Initially, increasing the N rate increased the stem diameter, LAI, FEUY, and DMY of forage maize and then decreased. The stem diameter, LAI, FEUY and above-ground DMY peaked under 180 kg∙ha−1 N in both years. Moreover, N application significantly increased the crude protein content of the whole plant and decreased the acid detergent fiber content. The surface fittings of the 2-year study indicated that 110,000 plants∙ha−1 (plant density) and 171.2 kg∙ha−1 (N rate) obtained the greatest DMY (19.0 t∙ha−1). The grade index (a comprehensive evaluation index for forage quality) peaked at 15.4 MJ∙d−1 under 94,000 plants ha−1 and 270 kg∙ha−1. The 110,000 plants∙ha−1 plant density and 181.5 kg∙ha−1 N rate jointly maximized the FEUY (11,125.4 FEU∙ha−1), maintaining 99.9 % of the maximum DMY and 97.5 % of the maximum grade index. Thus, 110,000 plants∙ha−1 plant density and 181.5 kg∙ha−1 N rate are recommended for high-productivity forage maize production, without notably compromising dry matter yield and feed quality. This research is conducive to advancing the coordinated development of forage crop cultivation and herbivorous livestock farming in semi-arid rainfed areas.

Growth performance and selection signatures revealed by whole-genome resequencing in genetically selected grass carp (Ctenopharyngodon idella)

Grass carp (Ctenopharyngodon idella) is a highly productive freshwater fish species that is widely cultivated worldwide, contributing substantial economic value to the aquaculture industry annually. Recently, a breeding program for grass carp has progressed to the fourth generation (F4) after four consecutive generations of family selection. To further assess the growth performance of the genetically selected grass carp F4, a 90-day consecutive growth comparison experiment was conducted between the selected population and a wild base population. The results showed that the selected grass carp F4 had better growth performance. Whole-genome resequencing of both wild and selected populations of grass carp yielded a total of 4,354,416 high-quality single nucleotide polymorphisms (SNPs). Parameters of genetic diversity including observed heterozygosity (Ho), expected heterozygosity (He), nucleotide diversity (π), and polymorphic information content (PIC) were slightly decreased in the selected population compared to the wild population. The fixation index (Fst) indicated a low level of genetic differentiation (Fst = 0.021). Selection signatures analysis identified a total of 173 candidate selected regions with a cumulative size of 23.75 Mb, and 912 candidate genes including igf-1r, igfbp-2, igfbp-5 and itga6. This study provides valuable insights into the growth performance and the genetic basis of selection signatures in the process of grass carp selective breeding, and offers guidance for future breeding programs.

Long-term effects of compound passivator coupled with silicon fertilizer on the reduction of cadmium and arsenic accumulation in rice and health risk evaluation

Cadmium (Cd) and arsenic (As) are precedence-controlled contaminants in paddy soils, that can easily accumulate in rice grains. Limestone and sepiolite (LS) compound passivator can obviously reduce Cd uptake in rice, whereas Si fertilizer can effectively decrease rice As uptake. Here, the synergistic effects of the LS compound passivator coupled with Si fertilizer (LSCS) on the soil pH and availability of Si, Cd, and As, as well as rice grain Cd and As accumulation and its health risk were studied based on a 3-year consecutive field experiment. The results showed that the LSCS performed the best in terms of synchronously decreasing soil Cd and As availability and rice Cd and As uptake. In the LSCS treatments, soil pH gradually decreased with the rice-planting season, while soil available Cd and As contents gradually increased, suggesting that the influence of LSCS on Cd and As availability gradually weakened with rice cultivation. Nonetheless, the contents of Cd and inorganic As (i-As) in rice grains treated with LSCS were slightly affected by cultivation but were significantly lower than the single treatments of LS compound passivator or Si fertilizer. According to the Cd and As limit standards in food (GB2762-2022), the Cd and i-As content in rice grains can be lowered below the standard by using the 4500 kg/hm2 LS compound passivator coupled with 90 kg/hm2 Si fertilizer in soil and spraying 0.4 g/L Si fertilizer on rice leaves for at least three years. Furthermore, health risk evaluation revealed that LSCS treatments significantly reduced the estimated daily intake, annual excess lifetime cancer risk, and hazard quotient of Cd and i-As in rice grains. These findings suggest that LSCS could be a viable approach for reducing Cd and As accumulation in rice grains and lowering the potential health risks associated with rice.

Reducing greenhouse gas intensity using a mixture of controlled-release urea and common urea combining suitable maize varieties in a summer maize system

The one-time application of common urea blended with controlled-release urea (CRU) is considered effective for improving nitrogen use efficiency and grain yield and reducing the greenhouse gas emissions of summer maize in intensive agricultural systems. However, the trade-off between the economic and environmental performances of different blended fertilizer treatments for different maize varieties remains unclear. Therefore, a consecutive two-year field experiment was conducted in the North China Plain to study the effects of different ratios of CRU and common urea on the yield, nitrous oxide (N2O) emissions, yield-scaled total N2O emissions, greenhouse gas intensity (GHGI), and net ecosystem economic benefit (NEEB) in 2021 and 2022. Four N fertilizer treatments with equal rate at 180 kg N ha−1 were applied as N180U (all Urea), N180C1(1/3CRU), N180C2(2/3CRU), and N180C (all CRU), and two maize varieties (JNK728-yellow ripe variety and ZD958-green ripe variety) were used. The N180C1 and N180C2 treatments produced the highest grain yield in varieties JNK728 and ZD958 (9.4–11.5 t ha−1 and 9.0–11.0 t ha−1), respectively. Compared to the N180U treatment (conventional method), the N180C1 treatment reduced the GHGI (24.8 %–25.9 %) and increased the NEEB (33.1 %–33.4 %) in the JNK728 variety, whereas the N180C2 treatment reduced the GHGI (16.9 %–28.8 %) and increased the NEEB (27.2 %–48.1 %) in the ZD958 variety. The study concludes that a one-time application of blended nitrogen fertilizer in suitable varieties can minimize the GHGI and maximize the NEEB, which is an effective strategy for balancing yield and nitrogen efficiency in the summer maize system in the North China Plain.

Influence of climatic variables on maize grain yield and its components by adjusting the sowing date.

Yield and its components are greatly affected by climate change. Adjusting the sowing date is an effective way to alleviate adverse effects and adapt to climate change. Aiming to determine the optimal sowing date of summer maize and clarify the contribution of climatic variables to grain yield and its components, a consecutive 4-year field experiment was conducted from 2016 to 2019 with four sowing dates at 10-day intervals from 5 June to 5 July. Analysis of historical meteorological data showed that more solar radiation (SR) was distributed from early June to mid-August, and the maximum temperature (Tmax) > 32°C appeared from early July to late August, which advanced and lasted longer in 1991-2020 relative to 1981-1990. Additionally, the precipitation was mainly distributed from early June to late July. The climate change in the growing season of summer maize resulted in optimal sowing dates ranging from 5 June to 15 June, with higher yields and yield stability, mainly because of the higher kernel number per ear and 1,000-grain weight. The average contribution of kernel number per ear to grain yield was 58.7%, higher than that of 1,000-grain weight (41.3%). Variance partitioning analysis showed that SR in 15 days pre-silking to 15 days post-silking (SS) and silking to harvest (SH) stages significantly contributed to grain yield by 63.1% and 86.4%. The extreme growing degree days (EDD) > 32°C, SR, precipitation, and diurnal temperature range (DTR) contributed 20.6%, 22.9%, 14.5%, and 42.0% to kernel number per ear in the SS stage, respectively. Therefore, we concluded that the early sowing dates could gain high yield and yield stability due to the higher SR in the growing season. Meanwhile, due to the decreasing trend in SR and increasing Tmax trend in this region, in the future, new maize varieties with high-temperature resistance, high light efficiency, shade tolerance, and medium-season traits need to be bred to adapt to climate change and increased grain yield.

How does straw returning combined with nitrogen fertilizer drive N2O emission in wheat–maize rotation system

AbstractStraw returning not only improves carbon (C) and nitrogen (N) pools but also increases soil nitrous oxide (N2O) emissions, which poses a threat to the sustainable development of agriculture. To investigate the effect of straw return combined with nitrogen fertilizer on labile C and N pools in the soil and short‐term response to soil N2O emissions in wheat–maize rotation system. The consecutive field experiment was conducted from 2019 to 2021. Single factor randomized block design was used in the experiment design, with no straw returning and no fertilizer (CK), no straw returning and nitrogen fertilizer (S0N) and straw returning combined with nitrogen fertilizer (SN). The results indicated that the SN and S0N treatments significantly (p < .05) increased N2O emissions by 170.45% (2.43 kg N ha−1 year−1) and 119.5% (1.70 kg N ha−1 year−1), soil organic carbon (SOC) by 17.23% and 14.50% and soil total nitrogen (STN) by 58.50% and 31.50% respectively. In the 2020–2021 growing season, The soil microbial biomass carbon (SMBC) content of the SN and S0N treatments were higher than those of CK in the winter wheat seedling, winter wheat jointing, winter wheat booting, summer maize seedling and summer maize bell‐mouth stages. The structural equation model (SEM) indicated that C:N and NO3−‐N were the major drivers that increased soil N2O emissions, but SMBN was the main driver that decreased soil N2O emissions. The SN and S0N treatments significantly increased soil N2O emissions by increasing the NO3−‐N content. However, compared with the CK and S0N treatments, the SN treatment mitigated soil N2O emissions by increasing the SMBN content. More importantly, compared with CK treatment, SN treatment increased annual yield by 48.41% and 34.52%, the SN treatment could effectively improve the soil C and N pools. Therefore, straw return combined with nitrogen fertilizer (SN) may be the best choice of the treatments tested for reducing greenhouse gas emissions and achieving green and sustainable development.

Accelerated iron valence cycling in Fenton system using activated hydrogen enhanced by MIL-100(Fe) modified by nano-Pd0 Particle.

In this paper, a novel Fenton reaction system which was called MHACF-MIL-100(Fe) was constructed. In this system, based on active hydrogen-accelerated FeIII reduction, the hydroxyl radical was continuously produced with a trace amount of total iron. The MIL-100(Fe) modified with the nano-Pd0 particle could be used to activate the H2. Under normal temperature and pressure, the target organic pollutants, such as sulfamethazine and 4-chloro phenol, could be degraded fast. In the condition of initial aqueous solution pH 3, 2 g L-1 dosage of MIL-100(Fe) catalyst loaded with nano-Pd0, Pd/MIL-100(Fe), 20 mM 30 wt% hydrogen peroxide, 25 μM ferrous chloride and 60 mL H2 min-1, 97.8% of sulfamethazine and 100% 4-chloro phenol could be degraded within only 5 min, respectively. Although the surface of the catalyst exhibited more obvious defects and roughness after 5 consecutive destructive experiment cycles, its basic structure could be maintained. The removal efficiency could be maintained at least more than 79% (sulfamethazine) and 94% (4-chloro phenol). That may be mainly attributed to the degradation of hydroxyl radical.

Straw Residual Retention on Wheat Photosynthetic Characteristics, Utilization of Water and Nitrogen, and Reactive Nitrogen Losses

Straw residual retention is an emerging and promoted practice in rain-fed northwest China, but its effect on wheat photosynthetic characteristics, the utilization of water and nitrogen, and reactive nitrogen losses is poorly understood. A two-year consecutive field experiment was conducted to investigate the impacts of residual incorporation into soil and nitrogen application on wheat nitrogen and water utilization, yield and nitrogen losses during 2018–2020. The split-plot design of two tillage systems [conventional tillage (CT), and straw residue incorporated into soil (SR)] and three nitrogen rates [0 kg ha−1 (N0), 144 kg ha−1 (N144), 180 kg ha−1 (N180)] was implemented. Our results demonstrated that compared to CT, SR significantly influenced several key metrics. Compared with CT, SR increased the wheat photosynthetic rate (Pn), transpiration rate (Tr), leaf area index (LAI), leaf total chlorophyll (Chl-total), glutamine synthetase (GS) and nitrate reductase (NR) by an average of 5.38%, 12.75%, 8.21%, 5.79%, 16.21% and 20.08%, respectively (p < 0.05). In addition, SR increased the wheat grain yield and nitrogen uptake accumulation (NUA), evapotranspiration (ET), precipitation storage efficiency (PSE), and mineral nitrogen residual after harvest (except for SR-N180 in 2019–2020), but decreased the apparent nitrogen recovery when compared with CT. However, there was an insignificant difference in the ammonia (NH3) volatilization and nitrous oxide (N2O) emissions of SR and CT. With an increase in the N-fertilization rate, the Pn and Tr, NH3 volatilization, N2O emission, mineral nitrogen residual (except for SR-N180 in 2019–2020), LAI, Chl-total (except for SR-N180 and CT-N180 in 2018–2019), GS, NR, grain yield, WUE, and NUA increased significantly; however, the ET, PSE, apparent nitrogen recovery (ANR), and nitrogen harvest index (NHI) decreased significantly. Furthermore, the differences between N144 and N180 in terms of the photosynthetic characteristics of wheat, the utilization of water and nitrogen, and yield were not significant. Overall, straw retention with N144 could be recommended as a resource-saving and environment-friendly management practice in a rain-fed winter wheat–fallow cropping system in northwest China.

English

Global warming stimulates soil salinization and calcification, resulting in phosphorus (P) deficiency in arid and semiarid regions worldwide. Phosphate-solubilizing bacteria (PSB) can enhance phosphorus availability, but their role has been less explored under arid and semiarid climatic conditions. A two-year consecutive field experiment was conducted to assess the effectiveness of PSB loading onto seeds, organic, and mineral fertilizers. The trial followed a randomized complete block design (RCBD) with three replications for each treatment. There were five treatments: T1 was the uninoculated control with no fertilizer (Control), T2 was uninoculated with recommended NPK (NPK), T3 was PSB-inoculated wheat seeds (PSB-Seed), T4 was PSB-inoculated organic fertilizer (PSB-OF), and T5 was PSB-inoculated mineral fertilizer (PSB-MF). Results revealed that inoculation with PSB onto seeds, organic, or mineral fertilizer had a more pronounced impact not only on the vegetative development and yield of wheat but also on P contents in grains. It was observed that the PSB-inoculated mineral fertilizer treatment responded well, showing noticeable wheat biomass accumulation, grain yield, and improved P uptake in grain and straw. Interestingly, the highest uptake of nitrogen (N) in wheat grain was observed with both PSB-inoculated organic fertilizer treatment and PSB-inoculated mineral fertilizer treatment, highlighting the efficacy of slow-release nitrogen from organic fertilizer in addition to the impact of PSB. In conclusion, PSB inoculation on organic or mineral fertilizer has substantial potential in enhancing crop productivity and combating P deficiency in arid and semi-arid regions.

Design and application of zirconium-based coordination polymers for selective capture of copper

The heavy metal copper in the wastewater is extremely harmful to human and ecological environment. The new metal coordination polymer (Zr-TPTA) adsorbent is prepared to capture copper ion from aqueous medium. The effects of reaction time, initial concentration of Cu(II) ion, pH value and temperature on adsorption efficiency of Cu(II) ion by Zr-TPTA are studied. The maximum adsorption capacity of Zr-TPTA is 148.32 mg/g at pH 3.0. The thermoisopleth and kinetic data conform to Langmuir and pseudo-second-order models, indicating that the adsorption mode is monolayer chemisorption. The capture of Cu(II) ion on Zr-TPTA surface is a spontaneous exothermic process according to thermodynamic parameter calculation results. The strength of interaction force between adsorbent and Cu(II) ion (15,649 mL/g) shows that the Zr-TPTA adsorbent has selective adsorption for Cu(II) ion. The consecutive adsorption-desorption experiment demonstrates the excellent reusability of Zr-TPTA. The X-ray photoelectron spectroscopy (XPS), zeta potential and density functional theory (DFT) prove that the adsorption mechanism is the complexation reaction of Cu(II) ion with CS and CN groups. This work illustrates the value of self-designed novel metal coordination polymer in adsorbent materials with selective capture of copper ion.

Innovative no-till seeding technology improves yield and nitrogen use efficiency while reducing environmental pressure in wheat after rice harvesting

Optimizing tillage and seeding strategies is important for increasing crop productivity and nitrogen use efficiency (NUE) while reducing environmental impact. A newly developed innovative no-till seeding (INtS) technology was shown to effectively enhance seeding quality and increase wheat yield in wet clay soil after puddled rice harvest in the Yangtze River Basin (YRB) of China. However, comprehensive assessments of the yield, NUE, and eco-environmental benefits of INtS technology have not been performed. The present study conducted a consecutive three-year field experiment combining field plots and microplots with the 15N tracer method using two wheat seeding technologies (INtS and typical rotary-till seeding (TRtS) technology) and three nitrogen (N) application rates (0, 90, and 180 kg ha−1). The study evaluated the yield, NUE, fate of fertilizer/straw N, N budgets, and environmental footprints of wheat production after rice harvesting. The results showed that compared with TRtS, the average yield, N uptake and NUE of wheat under INtS technology increased by 27.2%, 28.9%, and 31.9%, respectively. By tracing the multi-seasonal fate of 15N-labeled fertilizer/straw N in soil-crop systems, it was found that 43.8% and 6.0% of fertilizer N and rice straw N applied in the first wheat growing season were recovered by wheat plants in the same season under INtS technology, which significantly decreased to 29.0% and 4.1% for TRtS technology. Over the five growing seasons, the cumulative recoveries of fertilizer and straw N for INtS technology were 26.2% and 15.6% higher, while the total fertilizer and straw N losses were 20.6% and 20.0% lower than those for TRtS technology, respectively. Over 50% of straw N remained in the soil after the fifth growing season, while only 14.5–23.6% of fertilizer N remained. In addition, INtS technology significantly reduced the fertilizer/straw N losses when applied in the subsequent rice growing season. Unlike TRtS technology, INtS could maintain a low-level soil N balance (2.1 kg N ha−1 for N180) and generate less soil surface N surplus in the wheat growing season. On average, INtS significantly reduced the carbon footprint and N footprint in the wheat growing season by 26.8% and 19.1%, respectively. In conclusion, INtS technology can significantly improve crop production and agricultural sustainability while minimizing negative environmental impacts for wheat production after rice cultivation in the YRB of China and other areas of the world with similar field conditions.

Effects of N fertilizer reduction combined with straw biochar application on the yield, Si, and N nutrition of double-cropping rice.

Nitrogen (N) and silicon (Si) are important nutritional elements for rice. However, excessive N fertili-zer application and the ignorance of Si fertilizer are common in practice. Straw biochar is rich in Si, which can be used as a potential Si fertilizer. In this study, we conducted a consecutive 3-year field experiment to explore the effects of N fertilizer reduction combined with straw biochar application on rice yield, Si and N nutrition. There were five treatments: conventional N application (180 kg·hm-2, N100), 20% N reduction (N80), 20% N reduction with 15 t·hm-2 biochar (N80+BC), 40% N reduction (N60), and 40% N reduction with 15 t·hm-2 biochar (N60+BC). The results showed that compared with N100, 20% N reduction did not affect the accumulation of Si and N in rice; 40% N reduction reduced foliar N absorption, but significantly increased foliar Si concentration by 14.0%-18.8%; while combined application of biochar significantly increased foliar Si accumulation, with an increase of Si concentration by 38.0%-63.3% and Si absorption by 32.3%-49.9%, but further reduced foliar N concentration. There was a significant negative correlation between Si and N concentration in mature rice leaves, but no correlation between Si and N absorption. Compared with N100, N reduction or combined application of biochar did not affect soil ammonium N and nitrate N, but increased soil pH. Nitrogen reduction combined application of biochar significantly increased soil organic matter by 28.8%-41.9% and available Si content by 21.1%-26.9%, with a significant positive correlation between them. Compared with N100, 40% N reduction reduced rice yield and grain setting rate, while 20% N reduction and combined application of biochar did not influence rice yield and yield components. In summary, appropriate N reduction and combined with straw biochar can not only reduce N fertilizer input, but also improve soil fertility and Si supply, which is a promising fertilization method in double-cropping rice fields.

Experimental and numerical investigation on a radiative cooling driving thermoelectric generator system

Thermoelectric (TE) technology and radiative sky cooling (RSC) technology have proven to be a promising and green way to harvest energy from the environment. Combining RSC technology with Thermoelectric generator (TEG) device for passive power generation at night is meaningful and remains a challenge. Here, a radiative sky cooling driving thermoelectric generator (RSC-TE) system integrated by a doped modified TiO2/PMMA radiative cooling film, a commercial TEG, and an aluminum heat sink is developed, with a simple structure, low cost and high efficiency. The thermal-electrical performance of the RSC-TE system was evaluated through a consecutive nighttime experiment. Experimental results show that the temperature of the cold side of the TEG in contact with the radiative cooler is 2.7–4.2 °C lower than the ambient temperature, and the temperature difference between the hot and cold sides of TEG is 2.3–3.2 °C. The temperature difference at 00:00 can reach 2.5 °C, which corresponds to an open circuit voltage of 87 mV. Furthermore, a 3D model has been established by COMSOL software to investigate the effects of different environmental parameters and component-related parameters on system performance, which has guiding significance for the improvement and optimization of the experimental setup. This study can provide a new thinking and some practical guidelines for the design and application of the RSC-TE system.

Additive fungal interactions drive biocontrol of Fusarium wilt disease.

Host-associated fungi can help protect plants from pathogens, and empirical evidence suggests that such microorganisms can be manipulated by introducing probiotic to increase disease suppression. However, we still generally lack the mechanistic knowledge of what determines the success of probiotic application, hampering the development of reliable disease suppression strategies. We conducted a three-season consecutive microcosm experiment in which we amended banana Fusarium wilt disease-conducive soil with Trichoderma-amended biofertilizer or lacking this inoculum. High-throughput sequencing was complemented with cultivation-based methods to follow changes in fungal microbiome and explore potential links with plant health. Trichoderma application increased banana biomass by decreasing disease incidence by up to 72%, and this effect was attributed to changes in fungal microbiome, including the reduction in Fusarium oxysporum density and enrichment of pathogen-suppressing fungi (Humicola). These changes were accompanied by an expansion in microbial carbon resource utilization potential, features that contribute to disease suppression. We further demonstrated the disease suppression actions of Trichoderma-Humicola consortia, and results suggest niche overlap with pathogen and induction of plant systemic resistance may be mechanisms driving the observed biocontrol effects. Together, we demonstrate that fungal inoculants can modify the composition and functioning of the resident soil fungal microbiome to suppress soilborne disease.

Effects of different shallow and saline groundwater depths on soil salinity, evapotranspiration, grain yield and spike traits of winter wheat

AbstractThe contribution of groundwater to evapotranspiration in crop irrigation scheduling is gaining importance worldwide. A two consecutive year wheat experiment was conducted in drainable lysimeters to evaluate the response of grain yield and quality, spike traits, water use efficiency, evapotranspiration and thousand kernel weight of wheat plants under twelve different shallow and saline groundwater conditions. The treatments included three groundwater depths (GWD) (D1: 30 cm, D2: 55 cm and D3: 80 cm) and four groundwater salinities (GWS) (S1: 0.38, S2: 2, S3: 4 and S4: 8 dSm−1). The results show that the average decrease in grain yield for D2and D1compared to D3was 20.9% and 30.7%, respectively, while the decrease for S2, S3and S4compared to S1was 11.8%, 18.0% and 25.1%. The highest evapotranspiration was found in the D3S1treatment (630.1 and 550.1 mm in 2017–2018 and 2018–2019, respectively), which increased by 48.0% and 30.2% in the first and second seasons, respectively, compared to the D1S4treatment. Thus, a GWD at 80 cm with 0.38 dSm−1GWS was able to meet 72% of the total water requirement of wheat under loam soil conditions. Water use efficiency values ranged from 1.49 to 1.65 kg m−3in the first season and from 1.18 to 1.73 kg m−3in the second season, with the highest water use efficiency values found at 80 cm GWD. Regression analysis showed that GWS had a greater effect on water use efficiency than GWD. On average, thousand kernel and hectolitre weights were highest under D3S1, reaching 49.6 g and 77.8 kg hl−1, respectively. Soil salinity increased steadily with increasing GWS at all GWD conditions, and higher soil salinity values were observed at 30 cm GWD. In addition, controlling a groundwater depth at 80 cm with 8.0 dSm−1GWS did not significantly increase soil salinity, which did not result in high grain yield losses. Finally, it is recommended to control groundwater at a constant depth of 80 cm with 0.38 dSm−1GWS after the tillering period of winter wheat to save more irrigation water, control soil salinity and improve yield and grain quality in the region with shallow‐saline groundwater.

Self-heating potential of geopolymer metashale mortars with graphite powder

Geopolymers are eco-friendly materials with favorable material properties and, therefore, suitable candidates for optimization in terms of electrical properties which broadens their potential in self-heating, self-sensing, or energy harvesting applications. The effectivity of self-heating function crucially depends on the presence of a sufficient number of conductive paths in a non-conductive material matrix corelating with the effective electrical conductivity of the material. The optimization of self-heating function, therefore, consists in appropriate dosing and homogenization of supplementing electrically conductive admixtures, as well as correct embedment of electrodes ensuring good contact with the material. The paper is focused on the design of multifunctional geopolymer mortar based on metashale precursor that was activated by a mix of potassium hydroxide and silicate. Electrical properties of the composite were optimized by graphite powder in the amount of 3 wt% and electrical experiments were performed using embedded copper grid electrodes. The material was characterized in terms of basic physical, mechanical, thermal, and electrical properties. The consecutive self-heating experiment was performed under the AC voltage of 130 V RMS with the initial power at the beginning of the measurement of 10 W. It was observed power increase of approximately 3 W and 25 °C rise of temperature during the 2 h lasting experiment.

Water-stable aggregates and aggregate-associated organic carbon after two years of biochar application

ABSTRACT Solving the soil organic carbon (SOC) sequestration problem is crucial for agricultural sustainability. The main objective of our study was to assess the effects of biochar derived from different organic wastes on SOC, SOC storage, and soil aggregate fractions in a corn-Chinese cabbage rotation system. A consecutive two-year field experiment was conducted with six fertilization treatments, including nonfertilization (CK), mineral N, P, and K fertilizer (NPK), distiller-derived biochar (NPK + D), tobacco-derived biochar (NPK + T), tobacco-derived modified biochar (NPK + TM), and corn straw-derived biochar (NPK + CS). Compared to the NPK treatment, the NPK + D, NPK + T, and NPK + TM treatments significantly increased SOC by 56.3%, 58.6%, and 31.7%, respectively. Among all treatments, the NPK + T treatment had the highest SOC storage at 32.1 t ha−1. Compared with CK, the NPK + T treatment increased large macroaggregates and small macroaggregates by 38.3% and 10.7%, respectively. Compared to the NPK treatment, the biochar treatments improved the geometric mean diameter (GMD) by 15.5%–25.2%. Biochar has considerable potential for enhancing crop productivity in degraded yellow soils by improving the physical environment.

Soil Microbial Co-Occurrence Patterns under Controlled-Release Urea and Fulvic Acid Applications.

The increasing amount of agricultural applications of controlled-release urea (CRU) and fulvic acids (FA) demands a better understanding of FA’s effects on microbially mediated nitrogen (N) nutrient cycling. Herein, a 0–60 day laboratory experiment and a consecutive pot experiment (2016–2018) were carried out to reveal the effects of using CRU on soil microbial N-cycling processes and soil fertility, with and without the application of FA. Compared to the CRU treatment, the CRU+FA treatment boosted wheat yield by 22.1%. To reveal the mechanism of CRU+FA affecting the soil fertility, soil nutrient supply and microbial community were assessed and contrasted in this research. From 0–60 days, compared with the CRU treatment, leaching NO3−-N content of CRU+FA was dramatically decreased by 12.7–84.2% in the 20 cm depth of soil column. Different fertilizers and the day of fertilization both have an impact on the soil microbiota. The most dominant bacterial phyla Actinobacteria and Proteobacteria were increased with CRU+FA treatment during 0–60 days. Network analysis revealed that microbial co-occurrence grew more intensive during the CRU+FA treatment, and the environmental change enhanced the microbial community. The CRU+FA treatment, in particular, significantly decreased the relative abundance of Sphingomonas, Lysobacter and Nitrospira associated with nitrification reactions, Nocardioides and Gaiella related to denitrification reactions. Meanwhile, the CRU+FA treatment grew the relative abundance of Ensifer, Blastococcus, and Pseudolabrys that function in N fixation, and then could reduce NH4+-N and NO3−-N leaching and improve the soil nutrient supply. In conclusion, the synergistic effects of slow nutrition release of CRU and growth promoting of FA could improve the soil microbial community of N cycle, reduce the loss of nutrients, and increase the wheat yield.