Promote Crop Growth Research Articles

Phosphorus-, potassium-, and silicon-solubilizing bacteria from forest soils can mobilize soil minerals to promote the growth of rice (Oryza sativa L.)

BackgroundForest soils are usually highly weathered and abundant in mineral-weathering bacteria, which have not been used to mobilize soil minerals for crop production. Here, we used an acidic forest soil with low available phosphorus (P), potassium (K), and silicon (Si) to isolate bacteria capable of co-solubilizing P, K, and Si (PKSi-solubilizing) and the model rice plant to test their potential to mobilize soil P, K, and Si for crop nutrition.ResultsSix PKSi-solubilizing strains representative of common mineral-weathering proteobacteria taxa (genera Burkholderia, Paraburkholderia, Collimonas, Pseudomonas, and Agrobacterium) were screened out. They showed diverse P-, K-, or Si-solubilizing activities and produced diverse organic acids. Their mineral-solubilizing activities were positively correlated with the levels of medium pH reduction and gluconic acid production. They promoted the growth of rice seedlings grown in the forest soil by increasing soil available P and Si, plant P, K, and Si cumulative contents and dry weight, and the corresponding root-to-shoot ratios. The growth of rice seedlings alone and with the inoculated PKSi-solubilizing stains in the acidic forest soil did not reduce the soil pH.ConclusionsThe forest soil with low available P, K, and Si is a valuable resource for high-performance PKSi-solubilizing bacteria improving soil fertility and crop nutrition. The PKSi-solubilizing bacteria screened out can promote rice seedling growth by mobilizing P, K, and Si from soil to plant in the acidic soil with low available P, K, and Si. They show potentials to mitigate soil P, K, and Si deficiency and promote crop growth, and to recover soluble P, K, and Si from chemical fertilizers and improve the use efficiency of chemical fertilizers, thus reducing the input of chemical fertilizers. They may retard soil acidification by Si-solubilization and improve soil quality.Graphical

Iskanje in določanje bakterij, ki so sposobne razgraditi celulozo s pomočjo IAA kot potencialnih pospeševalcev rasti rastlin

Strains with both straw degradation and plant growth promotion ability were selected from the cultivated soil in Bac Kan, Vietnam to solve the problems of poor soil microbial diversity status, weak corrosion promotion effect, and poor crop growth caused by fungal rot diseases. Among seventeen bacteria isolated, strain NR1 presented the highest value for cellulase enzyme activity (Hydrolysis index = 24.8 mm), and IAA production (20.15 mg l-1), and was identified as Bacillus amyloliquefaciens Priest et al., 1987. Inoculation with NR1 significantly increased the rot promotion rate of straw under liquid fermentation by 54.71 % compared with the control and increased the root length and average diameter, and SPAD value of maize under soil culture by 18.3 %, 22.0 %, and 5.24 % respectively (p < 0.05). In addition, fertilizing 8 or 9 tons of NR1-degraded compost fertilizer per hectare had the best effect on the growth, development, and productivity of the L14 peanut variety. These results suggest strain NR1 could be used to produce multi-functional humus, accelerate the decomposition of straw in the cultivated soil, and promote crop growth.

Earthworms promote crop growth by enhancing the connections among soil microbial communities

Abstract Earthworms benefit plant growth and play a vital role in shaping soil microbial communities. However, how earthworms modify the soil microorganisms and thus affect plant growth is still unclear. Although fertilizers alter the assembly of microbial communities, further investigations are required to test the effect of fertilizer type on the relationship between earthworms, soil microbial communities and plants. We evaluated the role of earthworms in soil microorganisms and maize plant growth characteristics under organic or chemical fertilizers in field and greenhouse experiments. We explored the relationships between earthworms, soil microbial community and plant growth under different fertilizer types. We found that the presence of earthworms promoted plant growth, increased the amount of plant root exudates, and enhanced the connections between rhizosphere bacterial, fungal and protist communities. Both earthworms and fertilizer application significantly changed the structure of soil bacterial, fungal and protist communities. The complexity of the soil microbial community network increased under organic, compared to chemical fertilizer application. The greenhouse experiment showed that the effect of earthworms on plant growth was weakened when maize plants were grown in sterilized soil under organic or chemical fertilizers. Synthesis and applications: Our study provides solid evidence that earthworms largely depend on soil microorganisms for their effects on plants under the application of different fertilizer conditions. This may provide new insights into reducing the amounts of fertilizer used by enhancing the role of earthworms and soil microorganisms.

Zno nanoparticles: improving photosynthesis, shoot development, and phyllosphere microbiome composition in tea plants

BackgroundNanotechnology holds revolutionary potential in the field of agriculture, with zinc oxide nanoparticles (ZnO NPs) demonstrating advantages in promoting crop growth. Enhanced photosynthetic efficiency is closely linked to improved vigor and superior quality in tea plants, complemented by the beneficial role of phyllosphere microorganisms in maintaining plant health. However, the effects of ZnO NPs on the photosynthesis of tea plants, the sprouting of new shoots, and the community of phyllosphere microorganisms have not been fully investigated.ResultsThis study investigated the photosynthetic physiological parameters of tea plants under the influence of ZnO NPs, the content of key photosynthetic enzymes such as RubisCO, chlorophyll content, chlorophyll fluorescence parameters, transcriptomic and extensive targeted metabolomic profiles of leaves and new shoots, mineral element composition in these tissues, and the epiphytic and endophytic microbial communities within the phyllosphere. The results indicated that ZnO NPs could enhance the photosynthesis of tea plants, upregulate the expression of some genes related to photosynthesis, increase the accumulation of photosynthetic products, promote the development of new shoots, and alter the content of various mineral elements in the leaves and new shoots of tea plants. Furthermore, the application of ZnO NPs was observed to favorably influence the microbial community structure within the phyllosphere of tea plants. This shift in microbial community dynamics suggests a potential for ZnO NPs to contribute to plant health and productivity by modulating the phyllosphere microbiome.ConclusionThis study demonstrates that ZnO NPs have a positive impact on the photosynthesis of tea plants, the sprouting of new shoots, and the community of phyllosphere microorganisms, which can improve the growth condition of tea plants. These findings provide new scientific evidence for the application of ZnO NPs in sustainable agricultural development and contribute to advancing research in nanobiotechnology aimed at enhancing crop yield and quality.Graphical

Effects of composite soil conditioner on soil properties and corn yield in a saline–alkali soil

AbstractBiochar is widely used in agricultural production because of its ability to improve the physical and chemical properties of soil and promote crop growth. In this study, a combination of different biochar and lake sediments were used to improve saline soils. The four raw materials, including corn stalk and chicken manure liquefaction product (SMLP), rice husk charcoal (RHC) and two types of sediment (S‐1 and S‐2), which was used to improve the saline–alkali soil, respectively. The most significantly effective applied on the soil was when the composite soil conditioner (CSC) prepared by mixing SMLP, RHC, S‐1 and S‐2 at 5:20:6000:500 t·100 ha−1. The results of soil experiments using the above blending levels showed that the spike weight, plant height and root length of corn increased by 12.49%, 47.17% and 22.10%, respectively, and the pH and electrical conductivity (EC) of soil decreased by 4.83% and 24.02%, respectively. The contents of soil nutrients, soil organic matter (SOM), water content (WC) and soluble cations (K+, Ca2+ and Mg2+) all presented an increasing trend, and the contents of Na+ and soluble anions (Cl−, CO32−, HCO3− and SO42−) of soil showed a downward trend. Accordingly, the composite soil conditioner with biochar and dredged sediment achieves a synergistic improvement in soil physical structure and an increase in nutrient content, which is beneficial for promoting the growth characteristics and yield of corn.

Comparison of characteristics of biochar modified by earthworm and potassium permanganate

Biochar has is widely used for environmental remediation, carbon sequestration and crop growth promotion. However, its limited effects are becoming increasingly apparent, therefore, it is necessary to modify biochar to enhance its effects. Earthworms are important biological components of soil, and their daily activities impact the soil environment. However, the effects of earthworm modification of biochar are not clearly understood. Earthworms were placed in straw charcoal (CSBC) and fruit charcoal (FCBC) and cultured for 30 days to prepare earthworm-modified biochar (EW-CSBC and EW-FCBC). Potassium permanganate was also used to modify biochar (MnOx-CSBC and MnOx-FCBC). The effects of biochar modification were analyzed by comparing the properties of unmodified and modified biochars. The results of Fourier transform infrared spectrometer and X-ray diffraction showed that the number of functional groups (-OH, -NH, C-H, CC, and CO) and elemental composition (SiO2 and CaCO3) of biochar modified by EW and MnOx significantly increased. Field emission scanning electron microscopy results showed tube wall rupture, collapse, and increased pore size in biochars modified by MnOx and EW. Meanwhile, the specific surface areas of CSBC and FCBC significantly decreased. Functional Annotation of Prokaryotic Taxa function prediction showed an increase in the relative abundance of chemoheterotrophy and aerobic_chemoheterotrophy functions of EW biochar, which can participate in the carbon cycle of biochar. In summary, the excellent effects of earthworm-modified biochar can play a key role in future ecological environments.

Effect of Aminating Lignin Loading with Arbuscular Mycorrhizal Fungi on Soil Aggregate Structure Improvement.

Lignin is an important component of plant fiber raw materials, and is a three-dimensional network structure aromatic polymer with abundant resources and a complex structure in nature. Lignin is generally used as industrial waste, and its potential value has not been fully utilized. Modern agriculture extensively uses chemical fertilizers, leading to the gradual degradation of soil fertility and structure, which seriously affects crop growth, nutrient transport, and root respiration function. Based on soil bulk density, porosity, aggregates, and their stability indicators, this study analyzed the effects of aminated industrial lignin and its loading with arbuscular mycorrhizal fungi on soil structure improvement and plant growth. It was hoped that resource-rich lignin could play a beneficial role in improving soil structure and promoting crop growth. The phenolic hydroxyl group of lignin was epoxidized and further aminated to load with arbuscular mycorrhizal fungi. The results indicated that amine-modified lignin could effectively load with arbuscular mycorrhizal fungi. The application of arbuscular mycorrhizal fungi-supported aminated lignin to soil aggregate structure improvement greatly reduced the bulk density of soil, and increased the porosity of soil and the content of large granular soil. Compared with unmodified soil, soil bulk density decreased by 73.08%, the porosity of soil increased by 70.43%, and the content of large granular soil increased by 56.38%. Using the improved soil for corn cultivation efficiently increased the biomass of corn. The plant height was increased by 72.16%, the root-shoot ratio was increased by 156.25%, and other indexes were also improved to varying degrees. The experimental method provides an important basis for the effective utilization of lignin materials in agriculture in the future.

Eco-friendly pH-responsive iron-doped insect larval frass extract as a hexaconazole nano-delivery system for controlling fungal disease and promoting crop growth

Developing environmentally friendly pesticides and improving pesticide utilization efficiency are urgent needs for modern agriculture. Herein, a pH-responsive biodegradable dual pesticide-fertilizer was fabricated using extracts from naturally occurring Protaetia brevitarsis larval frass (PBLF) material. Iron ions (Fe3+) were integrated as metal nodes into PBLF, and hexaconazole (Hex), a triazole fungicide, was encapsulated in Fe-PBLF with a loading rate of 22.93 %. Hex@Fe-PBLF nanoparticles (NPs) presented a sphere-like construction with a hydrated size of 715.3 ± 5.0 nm and exhibited acid-responsive controlled release behavior, gradually self-degrading in acidic environments within 120 h. The NPs showed good foliar adhesion and were effectively absorbed and translocated by pathogenic fungal mycelium and the rice seedling. Compared with Hex Technical control (TC), the control effects of Hex@Fe-PBLF against Rhizoctonia solani (R. solani) and Botrytis cinerea (B. cinerea) increased by 9.9 % and 12.73 %, respectively, after 7 days. This naturally sourced nanocarrier not only promoted the growth of rice seedlings as a fertilizer but also enhanced their stress resistance. The low mobility of Hex@Fe-PBLF NPs in soil effectively reduced environmental risks. The excellent biosafety of the Fe-PBLF nanocarrier was further evaluated. Overall, this environmental-friendly multifunctional nano pesticide-fertilizer has promising application potential in agriculture.

Straw Returning Proves Advantageous for Regulating Water and Salt Levels, Facilitating Nutrient Accumulation, and Promoting Crop Growth in Coastal Saline Soils

Saline soils limit plant growth due to high salinity. Straw returning has proven effective in enhancing soil adaptability and agricultural stability on saline lands. This study evaluates the effects of different straw-returning methods—straw mulching (SM), straw incorporation (SI), and straw biochar (BC)—on soil nutrients, water dynamics, and salinity in a barley–cotton rotation system using field box experiments. SM improved soil water retention during barley’s jointing and heading stages, while SI was more effective in its filling and maturation stages. BC showed lesser water storage capacity. During cotton’s growth, SI enhanced early-stage water retention, and SM benefited the flowering and boll opening stages. Grey relational analysis pinpointed significant water relationships at 10 cm and 20 cm soil depths, with SM regulating water across layers. SM and BC notably reduced soil conductivity, primarily within the top 20 cm, and their effectiveness decreased with depth. SI significantly lowered soil conductivity at barley’s jointing stage. SM effectively reduced salinity at 10 cm and 20 cm soil depths, whereas BC decreased soil conductivity throughout barley’s jointing, filling, and heading stages. For cotton, SI lowered soil conductivity at the seedling and boll opening stages. SM consistently reduced salinity across all stages, and BC decreased conductivity in the top 30 cm of soil during all growth stages. Both SM and BC significantly enhanced the total nutrient availability for barley and cotton, especially improving soil organic carbon and available potassium, with BC showing notable improvements. At barley’s heading stage, SI maximized dry matter accumulation, while SM boosted accumulation in leaves, stems, and spikes during the filling and maturation stages. Straw returning increased barley yield, particularly with SM and BC, and improved water use efficiency by 11.60% and 5.74%, respectively. For cotton, straw returning significantly boosted yield and water use efficiency, especially with SI and SM treatments, enhancing the total bolls and yield. In conclusion, straw returning effectively improves saline soils, enhances fertility, boosts crop yields, and supports sustainable agriculture. These results provide a robust scientific foundation for adopting efficient soil improvement strategies on saline lands, with significant theoretical and practical implications for increasing agricultural productivity and crop resilience to salt stress.

Quantification and valorization of compost derived from urban households’ waste in Bukavu City, Eastern D.R. Congo

This study focused on quantifying and valorizing domestic waste in Bukavu, a rapidly growing city in eastern Democratic Republic of Congo (DRC). With increasing anthropogenic pressure, waste management has become a pressing issue, yet documentation in this area is still limited. This study aimed to fill this gap by providing comprehensive data on domestic waste generation, composition, and disposal practices in Bukavu city. Through field surveys and analysis, waste quantities and types were documented, revealing significant challenges in waste management infrastructure and practices. Additionally, the study explores opportunities for waste valorization, particularly through composting, given the region's agricultural potential and growing urban food demand. The findings revealed that ~ 5% of the domestic waste is biodegradable, with the majority consisting of metals and plastics. These wastes are predominantly used as livestock feed (10%), incinerated (66%), or buried (17%), with ~ 5% undergoing composting. Waste management is primarily handled by children (82%), with very few non-governmental organizations (NGOs) involved in such activities. Among the three composting methods evaluated, outputs from vermicomposting demonstrated superior qualities in terms of promoting crop growth, increasing yield, and achieving a high germination index. Overall, the application of composts improved plant growth and yield parameters of the two major legumes (common bean and soybean). Future interventions should explore the implementation of large-scale composting units at the household or citywide level, while also considering additional strategies to enhance the quality of the compost products. Such efforts are crucial in mitigating the environmental and health impacts of urban household waste and promoting sustainable practices in urban agriculture.

Calcium alginate−biochar composite promotes nutrient retention, enzyme activity, and plant growth in lime soil

Soil nutrients loss in karst area is an urgent eco-environmental problem. To control soil erosion and improve soil quality, calcium alginate−rice straw biochar composite (CA−MRB300) was prepared by embedding method. The retention mechanisms of soil nutrients onto CA−MRB300 were explored through batch adsorption experiments of soil nutrients, soil column leaching experiments combined with the analysis of physicochemical properties and soil enzyme activity. The effects of CA−MRB300 and its co-application with fertilizer on plant growth were investigated by a pot experiment. The results suggested that CA−MRB300 effectively retained PO43− and NO3− in lime soil mainly through surface precipitation and physical adsorption. The addition of CA−MRB300 increased the activities of alkaline phosphatase, urease, and sucrase in lime soil. Increased activity of urease accelerated the hydrolysis of urea to NH4+ in lime soil. Compared to a low proportion, a high proportion of CA−MRB30 was more likely to lead to the loss of K+. Moreover, the application of CA−MRB300 alone was more beneficial to the growth of soybean than the co−application of CA−MRB300 with fertilizer. This study indicates that CA−MRB300 has a great potential for application in retaining nutrients and promoting crop growth in lime soil.

Synergistic Effects of Humic Acid, Biochar-Based Microbial Agent, and Vermicompost on the Dry Sowing and Wet Emergence Technology of Cotton in Saline–Alkali Soils, Xinjiang, China

Soil amendments such as humic acid (HA), a biochar-based microbial agent (M), and vermicompost (V) can improve soil quality and promote crop growth. However, it remains unclear whether the co-application of the three soil amendments (HMV) has a synergistic effect on alleviating soil quality deterioration obstacles caused by dry sowing and wet emergence technology in Xinjiang cotton fields. A three-year field experiment was conducted in saline–alkali soils using plastic-film-mulched drip irrigation in Xinjiang, China. Through the orthogonal experiment method, the application amounts of HA, M and V were 75 kg ha−1, 75 kg ha−1 and 225 kg ha−1 respectively in 2021. In 2022, three application amount gradients were used for HA, M and V: 60 kg ha−1, 90 kg ha−1 and 120 kg ha−1 respectively. In 2023, the application amounts of HA, M, and V were 60 kg ha−1, 120 kg ha−1, and 120 kg ha−1. It should be pointed out that V contains HA in the range of 20–35%. This study aimed to explore the improvement effect of a single or combined application of HA, M, and V on soil quality and cotton emergence rate using dry sowing and wet emergence technology in Xinjiang cotton fields. The results showed that the single and combined applications of HA, M, and V improved the soil quality and water–heat–salt environment of the cultivated layer. In the combined application, the cotton seedling emergence rate and yield increased by 1.9–22.8% and 7.0–54.1%. Therefore, it is recommended to jointly apply HA, M, and V to promote cotton seedling emergence and increase yield using dry sowing and wet emergence technology in Xinjiang cotton fields.

Unravelling the biostimulant activity of a protein hydrolysate in lettuce plants under optimal and low N availability: a multi-omics approach.

The application of protein hydrolysates (PH) biostimulants is considered a promising approach to promote crop growth and resilience against abiotic stresses. Nevertheless, PHs bioactivity depends on both the raw material used for their preparation and the molecular fraction applied. The present research aimed at investigating the molecular mechanisms triggered by applying a PH and its fractions on plants subjected to nitrogen limitations. To this objective, an integrated transcriptomic-metabolomic approach was used to assess lettuce plants grown under different nitrogen levels and treated with either the commercial PH Vegamin® or its molecular fractions PH1(>10 kDa), PH2 (1-10 kDa) and PH3 (<1 kDa). Regardless of nitrogen provision, biostimulant application enhanced lettuce biomass, likely through a hormone-like activity. This was confirmed by the modulation of genes involved in auxin and cytokinin synthesis, mirrored by an increase in the metabolic levels of these hormones. Consistently, PH and PH3 upregulated genes involved in cell wall growth and plasticity. Furthermore, the accumulation of specific metabolites suggested the activation of a multifaceted antioxidant machinery. Notwithstanding, the modulation of stress-response transcription factors and genes involved in detoxification processes was observed. The coordinated action of these molecular entities might underpin the increased resilience of lettuce plants against nitrogen-limiting conditions. In conclusion, integrating omics techniques allowed the elucidation of mechanistic aspects underlying PH bioactivity in crops. Most importantly, the comparison of PH with its fraction PH3 showed that, except for a few peculiarities, the effects induced were equivalent, suggesting that the highest bioactivity was ascribable to the lightest molecular fraction.

Evolution of hotspots and research trends in agricultural mulch film research: a bibliometric review

Agricultural mulch film (AMF) can increase the soil temperature, reduce the evaporation of water and soil erosion, control the number of weeds and pests, and improve the yield and quality of crops. However, the environmental pollution caused by AMF residues is becoming serious and has attracted increasing amounts of research. Research on AMF is a complex subject with diverse content and rich perspectives. Currently, there have been few systematic reviews of the use of AMF. To comprehensively and deeply understand the current status, hotspots, and trends of research on AMF, this paper conducted a bibliometric analysis of AMF literature from 1960 to 2022. Results are as follows: the overall publication volume in the field of AMF has increased 1960 to 2022. The top three countries contributing to publication volume include China, United States (US) and India, which are also the main collaborating nations. Notably, cooperation between China and US is the most frequent, and a cluster constituted by European nations serve as a primary collaborator for other countries. Owing to the introduction and development of the concept of degradable plastics, the field entered a period of rapid growth after 1970 and has primarily focused on continuous development in the areas of horticulture and environmental science. Current research on AMF primarily aims to: 1) develop applications that are aimed at enhancing the yield and quality of crops, and 2) improve the materials used to produce AMF to reduce its environmental impact. The persistent hotspots of research in AMF revolve around modifying the soil microclimate, promoting crop growth and development, and increasing crop yields. Frontier AMF research includes: exploring crop quality enhancement mechanisms, developing low-cost biodegradable film technologies and their natural degradation effects, and investigating AMF’s impact on soil nitrous oxide emissions and associated mechanisms.

Efficient preparation of alginate oligosaccharides by using alginate lyases and evaluation of the development promoting effects on Brassica napus L. in saline-alkali environment

Enzymatic degradation of alginate for the preparation of alginate oligosaccharides (AOS) is currently receiving significant attention in the field. AOS has been shown to promote crop growth and improve plant resistance to abiotic stresses. In this study, two PL6 family alginate lyases, AlyRmA and AlyRmB, were expressed and characterized. These enzymes demonstrate exceptional activity and stable thermophilicity compared to other known alginate lyases. AlyRmA (8855.34 U/mg) and AlyRmB (7879.44 U/mg) exhibited excellent degradation activity towards sodium alginate even at high temperatures (70 °C). The AlyRmA and AlyRmB were characterized and utilized to efficiently produce AOS. The study investigated the promotional effect of AOS on the growth of Brassica napus L. seedlings in a saline-alkaline environment. The results of this study demonstrate the high activity and thermal stability of AlyRmA and AlyRmB, highlighting their potential in the preparation of AOS. Moreover, the application of AOS prepared by AlyRmB could enhance the resistance of Brassica napus L. to saline-alkali environments, thereby broadening the potential applications of AOS.

Multifunctional N, Fe dual active site hydrothermal biochar for efficiently degrading paclobutrazol and promoting crop growth

The development of a low-cost, highly catalytic, and soil fertility-improving biochar material is of significant importance for the sustained remediation of organic pollutants in the environment. In this study, multifunctional N, Fe dual active site biochar (NF-BC) was successfully synthesized by hydrothermal method using cotton straw, urea, and FeCl3 as raw materials. Compared to the original biochar, NF-BC exhibits high graphitic-N content and abundant Fe2+, enabling efficient activation of Peroxymonosulfate (PMS) for the removal of Paclobutrazol (PBZ) in water and soil. EPR and quenching experiments confirm that the free radical pathway (•OH) and the non-free radical pathway (1O2) act together in PBZ degradation. The DFT results illustrate the benzene and pyridine rings of PBZ are electron-rich regions, which can be attacked by reactive oxygen species. Then three possible degradation pathways are provided by combining them with the LC/MS test. After remediation by the NF-BC/PMS system, the soil fertility index and plant growth are significantly improved. Compared to CK, the pH value and SOM content of the soil remained unchanged after remediation with the NF-BC/PMS system, while the content of available K and hydrolyzed N increased by 27.18 and 2.27 times, respectively. The pot experiments showed that the NF-BC/PMS system not only alleviates the stress of PBZ on mung bean seedlings, but also promotes an increase in leaf area, accumulation of dry biomass, and root growth. This work provides a new idea for the preparation of low-cost and multifunctional biochar for the efficient removal of pesticides in soil and water environments.

Effect of coal gasification coarse slag on soil water and nutrition at an arid opencast coal mine site in Northwest China

AbstractThough amendment using coal gasification coarse slag (CGCS) has garnered attention, the intrinsic mechanism of how CGCS, a glassy material, works to amend physicochemical properties in the soil is not yet clear. This study aimed to analyze the effects of different CGCS particle sizes on soil water infiltration and nutrient retention, and to identify the relationship between the physicochemical properties of the amended soil and the water nutrient amendment. The continuous infiltration pattern of soil water and plant growth after the amendment was measured using an indoor continuous dynamic soil column simulation experiment and a field pot experiment of CGCS with different particle sizes (0.25, 1, and 2 mm). The CGCS amendment loosened the soil, improved the pore channels, and amended the water infiltration. However, this process was negatively correlated with CGCS particle size. The Kostiakov performed better in simulating soil water infiltration of heterogeneous dump soil. The CGCS amendment had no heavy metal risk and promoted plant growth. Though amendment enhanced nutrients, in terms of soil organic matter (SOM), the presence of C must be verified by a long team of nutrient cycling if it can be transformed into accessible SOM. Therefore, CGCS amended water nutrition by amending the soil's physical structure. Soil pore adsorption improved water nutrient availability and had a positive effect on chemical properties, which promoted crop growth. The amendment effect was greatest at 0.25 mm particle size.

Nitrogen Addition Decreased Respiration and Heterotrophic Respiration but Increased Autotrophic Respiration in a Cabbage (Brassica pekinensis Rupr) Experiment in the Northeast Plains

Farmland soil respiration (Rs) significantly impacts the global carbon (C) cycle. Although nitrogen (N) can promote crop growth and increase yields, its relationship with Rs and its constituents, including autotrophic respiration (Ra) and heterotrophic respiration (Rh), remains unclear. Therefore, a field study was carried out in a cabbage (Brassica pekinensis Rupr) system to probe the impact of N addition on Rs, Ra, and Rh. Five levels of N addition, including 0 kg N hm−2·yr−1 (N0), 50 kg N hm−2·yr−1 (N50), 100 kg N hm−2·yr−1 (N100), 150 kg N hm−2·yr−1 (N150), and 200 kg N hm−2·yr−1 (N200), started in March 2022. The Rs (Ra and Rh) and soil samples were measured and collected twice a month. The findings revealed the following: (1) N fertilizer enhanced Ra while reducing Rs and Rh; (2) soil temperature (ST), belowground net primary productivity (BNPP), soil inorganic N (SIN), and soil total C/total N (C/N) were the significant elements influencing Ra, and microbial biomass carbon (MBC), SIN, and microbial diversity (MD) were the primary factors influencing Rh; (3) partial least squares-path models (PLS-PM) showed that ST and SIN directly impacted Rh, while ST and BNPP tangentially influenced Ra; (4) 150 kg N hm−2·yr−1 was the ideal N addition rate for the cabbage in the region. In summary, the reactions of Ra and Rh to N fertilizer in the Northeast Plains are distinct. To comprehend the underlying processes of Rs, Ra, and Rh, further long-term trials involving various amounts of N addition are required, particularly concerning worsening N deposition.

Impact of treated wastewater on plant growth: leaf fluorescence, reflectance, and biomass-based assessment.

The study evaluated the impact of treated wastewater on plant growth through the use of hyperspectral and fluorescence-based techniques coupled with classical biomass analyses, and assessed the potential of reusing treated wastewater for irrigation without fertilizer application. Cherry tomato (Solanum lycopersicum) and cabbage (Brassica oleracea L.) were irrigated with tap water (Tap), secondary effluent (SE), and membrane effluent (ME). Maximum quantum yield of photosystem II (Fv/Fm) of tomato and cabbage was between 0.78 to 0.80 and 0.81 to 0.82, respectively, for all treatments. The performance index (PI) of Tap/SE/ME was 2.73, 2.85, and 2.48 for tomatoes and 4.25, 3.79, and 3.70 for cabbage, respectively. Both Fv/Fm and PI indicated that the treated wastewater did not have a significant adverse effect on the photosynthetic efficiency and plant vitality of the crops. Hyperspectral analysis showed higher chlorophyll and nitrogen content in leaves of recycled water-irrigated crops than tap water-irrigated crops. SE had 10.5% dry matter composition (tomato) and Tap had 10.7% (cabbage). Total leaf count of Tap/SE/ME was 86, 111, and 102 for tomato and 37, 40, and 42 for cabbage, respectively. In this study, the use of treated wastewater did not induce any photosynthetic-related or abiotic stress on the crops; instead, it promoted crop growth.

Silicon Improves Soil Environment and Promotes Crop Growth under Compound Irrigation via Brackish Water and Reclaimed Water

Not only is solving freshwater resource shortages effective but also an important measure for realizing the sustainable development of agriculture through the development and use of unconventional water resources. This pot experiment investigated the role of exogenous silicon in the risk of secondary soil salinization and the growth physiology of Lvxiu pakchoi cabbage under irrigation by using brackish water alone (BW), reclaimed water alone (RW), and compound irrigation with brackish water and reclaimed water at a ratio of 1:1, as well as the distribution of silicon in a soil–crop system. The results showed that with the extension of the spraying period of silicon fertilizer, the electrical conductivity (EC) decreased under 1:1 compound irrigation. The pH values in all treatments ranged from 7.95 to 8.10 without a potential risk of alkalization. Spraying silicon fertilizer had a positive effect on increasing the ratio of exchangeable potassium to sodium in soil. Spraying silicon fertilizer significantly reduced the percentage of exchangeable sodium (ESP) and the sodium adsorption ratio (SAR) in soils irrigated using BW, and increased the soil ESP and SAR under compound irrigation and RW irrigation, but these factors did not exceed the threshold of soil salinization. The proper application of silicon fertilizer had no significant effect on the total silicon content in the soil but increased the total silicon content in the plants to some extent. In addition, the yield was improved through proper silicon fertilizer application. In summary, exogenous silicon has positive effects on soil physical and chemical properties and crop growth, and relieves secondary salinization risk under compound irrigation via brackish water and reclaimed water.