Chemical Fertilizer Treatment Research Articles

Effect of Mild Organic Substitution on Soil Quality and Microbial Community

Mild organic substitution is advantageous for sustainable agricultural development. In order to determine the proper fertilization strategy, it is essential to investigate the impact of substituting chemical fertilizers with varying levels of organic manure on soil nutrients, microbial communities, and crop productivity. Four treatments were implemented: no fertilizer, sole chemical fertilizer, 20% organic manure substitution, and 40% organic manure substitution. Bacterial and fungal communities were characterized through high-throughput sequencing of the 16S rRNA gene V3–V4 region and the V4 region, respectively. The 20% and 40% organic manure substitutions increased soil organic matter (SOM) content, total nitrogen (TN) content, and reduced soil pH compared to the control (CK). The 20% organic manure substitution showed the most significant improvements in soil alkaline phosphatase, urease, and invertase activities. Soil nutrient enhancement increased bacterial alpha diversity, with a milder impact on fungal alpha diversity compared to bacteria. Different fertilization treatments elevated the relative abundance of bacterial Bacteroidetes (8.11%, 21.25%, and 1.88%), Actinomycetes (12.65%, 26.36%, and 15.33%), and fungal Ascomycota (16.19%, 10.44%, and 12.69%), known for degrading recalcitrant organic matter. The sole chemical fertilizer treatment increased the pathogenic Cheatotryiales. Shared species, primarily from bacterial Actinomycetes, Firmicutes, Proteobacteria, and fungal Ascomycota phyla, were found at 20% and 40% organic manure substitution levels. Specifically, the 20% organic manure substitution level promoted the relative abundance of beneficial plant growth-promoting taxa, Oxalobacteraceae and Massilia, and suppressed pathogens, with an increase in the relative abundance of the Purpureocillium genus and Mortierellomycota. These findings suggest that a 20% OF substitution can maintain crop yield, enhance soil nutrients and enzyme activities by fostering beneficial soil bacteria, inhibiting soil-borne pathogens, and refining microbial community structure.

Replacing chemical fertilizers with biogas slurry is an environment friendly strategy to reduce the risk of soil nitrogen leaching: evidence from the HYDRUS model simulation

Excessive chemical fertilizer use leads to soil nitrogen leaching. Biogas slurry, which is rich in nitrogen, has been proposed as an organic substitute for chemical fertilizer via drip irrigation. However, the dynamics of nitrogen migration and potential threats to biogas slurry return remain unclear. Using a two-year field experiment and HYDRUS software, this study modeled soil moisture and nitrogen migration under biogas slurry drip irrigation. The validated model accurately simulates water and nitrogen migration, predicting nitrogen leaching dynamics. Compared to chemical fertilizer treatment, differences in soil hydraulic parameters under biogas slurry drip irrigation impact moisture and nitrate nitrogen distribution. Increasing biogas slurry proportion enhances nitrate nitrogen content in the root layer, promoting plant nitrogen absorption while reducing leaching by 49.66%. Optimizing the irrigation system involves high concentration substitution in early growth and low concentration in late growth, mitigating nitrogen leaching, and enhancing plant root absorption.

Optimizing Soybean Crop Performance through the Integrated Application of Organic and Chemical Fertilizers: A Study on Alkaline Soil in Afghanistan

The excess application of chemical fertilizer contributes to environmental pollution. Therefore, this study aims to explore the integrated use of animal manure and chemical fertilizer to identify a more sustainable and environmentally friendly alternative to nitrogen fertilizer. Two experiments were conducted in 2018 and 2019 at Kabul University, Afghanistan, using an LD04-13265 soybean variety. The integration of animal manure and chemical fertilizer was categorized into six treatments: (1) control (no fertilizer), (2) animal manure low dose (AMLD), (3) animal manure high dose (AMHD), (4) chemical fertilizer (CF), (5) CF 50% + AMLD, and (6) CF 75% + AMLD. The results revealed that AMHD and its integration with 75% chemical fertilizer greatly influenced the vegetative growth of soybean plants in experiments I and II. The number of pods per plant and pod length significantly (p < 0.05) increased under the CF 75% + AMLD treatment. In experiment I, soybean yield increased the most with the CF treatment, followed by CF 75% + AMLD. In contrast, in experiment II, the highest yield per hectare was observed in the CF 75% + AMLD treatment, followed by CF. The CF 75% + AMLD treatment significantly increased the SPAD value in both experiments. Consequently, a strong relationship was observed between the SPAD value and yield (r = 0.74) in experiment I and between SPAD and pod length (r = 0.82) in experiment II. Incorporating animal manure with chemical fertilizer significantly impacted soybean growth and yield, offering a potential possibility for reducing reliance on nitrogen fertilizer application to mitigate environmental pollution.

Optimizing the manure substitution rate based on phosphorus fertilizer to enhance soil phosphorus turnover and root uptake in pepper (Capsicum).

In contemporary agriculture, the substitution of manure for chemical fertilizer based on phosphorus (P) input in vegetable production has led to a significant reduction in P fertilizer application rates, while, the effect of manure substitution rates on soil P transformation and uptake by root remain unclear. This research conducts a pot experiment with varying manure substitution rates (0%, 10%, 20%, 30%, 40%, 50%, 75% and 100%) based on P nutrient content to elucidate the mechanisms through which manure substitution affects P uptake in pepper. The result showed that shoot and root biomass of pepper gradually increased as manure substitution rate from 10% to 40%, and then gradually decreased with further increases in the substitution rate. Soil alkaline phosphatase activity and arbuscular mycorrhizal (AM) colonization gradually increased with manure substitution rates improvement. Specifically, when the substitution rate reached 30%-40%, the alkaline phosphatase activity increased by 24.5%-33.8% compared to the fertilizer treatment. In contrast, phytase activity and the relative expression of phosphate transporter protein genes in the root system was declined after peaking at 30% manure substitution. Additionally, soil available P remained moderate under 30%-40% substitution rate, which was reduced by 8.6%-10.2% compared to that in chemical fertilizer treatment, while microbial biomass P was comparable. In the current study, soil labile P similar to or even higher than that in chemical fertilizer treatment when the substitution rate was ≤40%. Correlation heatmaps demonstrated a significant and positive relationship between soil available P and factors related to labile P and moderately labile P. This finding suggested that substituting 30%-40% of chemical P with manure can effectively enhance root length, AM colonization, soil enzyme activity, soil labile P, and consequently improve P uptake in pepper. These findings provide valuable insights for future organic agricultural practices that prioritize P supply, aiming to standardize organic P management in farmland and achieve high crop yields and maintain soil health.

Concentrated biogas slurry and biogas residue can improve the yield and quality of pepper.

The organic fertilizer (biogas slurry and biogas residues) was produced by the self-developed integrated device of "Pressure swirl / inclined plate sedimentation separation pretreatment (P/I) combined with ultrafiltration / reverse osmosis two stages membrane separation (UF/RO)". The paper focuses on the effect of concentrated biogas slurry and biogas residue produced by this technology on the yield and quality (vitamin C, soluble sugar, protein and nitrate content) of pepper as organic fertilizer compared with chemical fertilizer. The concentrated biogas slurry and biogas residue separated by this technology contained active substances such as N, P, K, trace elements and humic acids with stable composition and potential for good fertilization efficiency. The experiment of seed soaking for pepper sprouting confirmed the best effect of seed soaking with a concentration of 80% biogas slurry. Compared with chemical fertilizer treatment, the application of concentrated biogas slurry and biogas residue can improve the yield and quality of pepper, which is related to the nutrient elements in concentrated digestate. Meanwhile, the results of pepper cultivation trials show that the base fertilizer treatment of biogas residue is best with 2000kg/667m2 and foliar spraying of 75% biogas slurry. The results strongly demonstrate the great potential of the concentrated biogas slurry and biogas residue produced by the self-developed digestate concentration technology for pepper cultivation.

SPRAYING NANO CHITOSAN LOADED WITH NPK, NETTEL AND GREEN TEA EXTRACTS AS A TOOL FOR IMPROVEMENT POTATO PRODUCTIVITY

This study was aimed to evaluate the effect of spraying nano chitosan loaded with NPK fertilizer and nettle leaf and green tea extracts on the growth and productivity of potato for the spring and fall seasons of 2021.It was conducted at private farm in Wasit Governorate, Iraq, as a factorial experiment (5 × 5) within randomized complete block design using three replicates. The first factor included spraying with four concentrations of chitosan nanoparticles loaded with NPK fertilizer 0, 10. 15 and 20% in addition to chemical fertilization treatment, the second factor was spraying nettle leaf extract 25 and 35 gL-1 and green tea extract with 2 and 4 g.L-1, in addition to the control treatment, spraying with distilled water only. The results showed a significant superiority of the interaction between spraying with Nano chitosan loaded with NPK at a concentration of 15% and spraying green tea extract at a concentration of 4 g L-1 significantly in producing the highest plant height 62.77 and 60.86 cm, number of main stems of the plant 4.45 and 4.36 stem for the both seasons respectively and mean of tuber weight (111.0 g tuber-1) for the spring season which increased the productivity of tuber yield (56.3 and 51.6 in ton ha-1 for both seasons, respectively).

Enhancing Soil Aggregation and Organic Carbon Retention in Greenhouse Vegetable Production through Reductive Soil Disinfestation with Straw and Fertiliser: A Comprehensive Study

In greenhouse vegetable production, reductive soil disinfestation (RSD) effectively mitigates soil-borne diseases, yet its impact on the dynamics of soil organic carbon (SOC) has not been adequately examined. This study investigated the distribution of soil aggregates and the organic carbon retention mechanism following intensive RSD treatment. Greenhouse experiments, including control (CK), wheat straw (RSD), and wheat straw with chemical fertilizer (RSD + NP) treatments, indicated augmentation in the formation of macro-aggregates (>2 mm and 0.25–2 mm) under RSD, particularly in the RSD + NP treatment. Silty clay particles transform into macro- and micro-aggregates. Fourier infrared spectroscopy highlighted the augmentation of carbon-containing functional groups in SOC, with aliphatic carbon accumulating in macro-aggregates and aromatic carbon in silt clay. Laboratory culture experiments employing different C/N ratios (RSD1 with wheat straw, RSD2 with kiwifruit branches) underscored the beneficial impact of low C/N ratio organic matter on coarse and fine macro-aggregate content, mean weight diameter, geometric mean diameter, and reduced silt clay. Low C/N ratios enhance SOC retention in large aggregates, while high ratios stabilise micro-aggregate carbon. This research underscores the severe degradation in continuous greenhouse cropping systems and emphasises RSD’s dual benefits—disease prevention and improved SOC retention. Implementing RSD requires careful consideration of organic material choices, specifically their C/N ratios, as a pivotal factor influencing SOC dynamics.

Using slow-release fertilizers ensures the maintenance of litchi (Litchi chinensis Sonn.) production by enhancing soil nutrient supply and optimizing microbial communities

High temperatures and rainy climate conditions result in a very low nutrient utilization rate during crop cultivation in tropical regions. To determine whether slow-release fertilizers could have a positive impact on the yield and quality of litchi, and the soil ecology of orchards while reducing chemical fertilizer application, a field plot experiment with two fertilizer types (chemical fertilizers and lignin-based slow-release fertilizers) combined with a 0 %, 15 % and 30 % reduction of fertilizer application rates was set up from 2018 to 2019. Subsequently, a demonstration trial with an optimum dose of slow-release fertilizers with chemical fertilizers was carried out from 2019 to 2020 in acidic soils. The results demonstrated that all treatments could maintain the yield of litchi between 11,825–13,056 kg/hm2 in 2018–2019. Furthermore, compared to conventional chemical fertilizer treatment, the treatment of lignin-based slow-release fertilizer application with a 15 % fertilizer reduction significantly reduced the concentration of alkaline nitrogen by 19.9 % and available phosphorus by 22.0 % at the 20–40 cm soil layer during the maturity period of litchi growth. The result of the demonstration trial in 2019–2020 further confirmed that a slow-release fertilizer, along with a 25 % reduction in fertilizer application, could maintain high levels of soil alkaline nitrogen and available potassium at the 0–20 cm soil layer without affecting soil bulk density, total soil porosity, and soil aeration. Moreover, the treatment of lignin-based slow-release fertilizer application with a 15 % fertilizer reduction significantly increased the relative abundance of Proteobacteria (1.21 times) and decreased the abundance of Firmicutes (0.81 times) compared to conventional fertilization treatment at the 0–20 cm soil layer. In contrast, it decreased the relative abundance of Firmicutes (0.67 times) and Proteobacteria (0.37 times) at the 20–40 cm soil layer. Meanwhile, the fertilizer application only affected the soil fungi richness but did not increase their diversity. Applying slow-release fertilizers can realize the goal of reducing chemical fertilizers and ensuring excellent litchi production in tropical acidic soils.

Nanochelating-based fertilizers: Innovations for yield enhancement in hydroponic cultivation

The increasing human population has resulted in a rise in the use of chemical fertilizers to enhance crop efficiency and quality. However, the utilization of these fertilizers has led to significant environmental pollution and raised concerns, including the potential risk of cancer. Consequently, there is a growing need for innovative fertilizer formulations that reduce dependency on chemical fertilizers. Nanochelating, an advanced technology, offers a promising solution by synthesizing chelated nutrients with diameters smaller than 100 nm. These nanochelates have shown considerable effects on crop productivity, even at lower concentrations compared with traditional chemical fertilizers. In this hydroponic study, we investigated the effects of various concentrations of nanochelated fertilizers (NCF) using the standard formulation outlined by "Resh" (0.25×Resh, 0.5×Resh, 0.75×Resh, 1×Resh and 1.25×Resh) in the cultivation of tomato and cucumber. Control plants were treated with chemical fertilizers (CF). The NCF-treated plants exhibited improvements in fruit attributes and plant development. Notably, the addition of 0.5×Resh-NCF significantly enhanced vegetative growth, fruit quality, total soluble solids, fruit length, and diameter, and plant pigments. Cucumber and tomato plants treated with 0.5×Resh NCF, at half the strength of the CF treatment, displayed the highest yield, with tomatoes yielding approximately 2.02 times more and cucumbers yielding 3 times more than the CF treatment. CF-fed tomato and cucumber plants exhibited lower cell membrane stability and water content. Proline content, an indicator of plant stress, decreased in the NCF-treated plants but increased at the highest concentration. Furthermore, catalase and peroxidase activity increased in tomato and cucumber plants following NCF application. These findings underscore the potential of nanochelating-based fertilizers to enhance growth, productivity, and associated components while minimizing fertilizer usage in hydroponic greenhouses.

DOM hydrophilic components of organic fertilizers increased the soil nitrogen retention capacity and succession of the microbial community.

Application of organic fertilizers affects soil properties and microbial communities, which in turn alters soil N transformation processes. Unfortunately, it is not clear how the difference in the character of the organic fertilizer DOM affects the soil nitrogen retention capacity and its microbial processes. According to the principle of equal nutrients, the treatments of chemical fertilizer alone (treatment CF), chemical fertilizer with organic fertilizer DOM hydrophilic components (treatment H), and chemical fertilizer with organic fertilizer DOM hydrophobic components (treatment P) were set up, where the characteristics of soil nitrogen transformation and changes in microbial community structure were studied with soil culture conditions for 24 days. It was discovered that the addition of organic fertilizer DOM components (H and P) slowed nitrification rate and increased protease activity resulting in a higher NH4+-N content compared to the CF treatment. The DOM addition (H and P) increased the microbial biomass nitrogen (MBN) levels in the soil and increased the soil nitrogen pool capacity. Moreover, the carbon use efficiency of the hydrophilic components is higher than that of the hydrophobic components, resulting in its further increase in nitrogen reservoir capacity and higher nitrogen retention capacity. Network analysis showed that the addition of organic fertilizer DOM hydrophilic components increased network complexity and synergy between microorganisms. In combination with random forest analysis, it was shown that Sphingomonas and Massilia were key species influencing soil nitrogen retention capacity and nitrogen availability characteristics.

Fatty Acids Profile of Olive Oil in Response to Nutrient-Based Organic Fertilizer of Olive Tree

This research was conducted in season 2022 in a private farm planted with olive tree var. “Nabali”, in Al-Muqailibah – Damascus countryside, in order to evaluate the impact of certified organic fertilizer named “Chap Liquid” in the oil composition of fatty acids. The orchard is divided in to six experimental plots, in the first four one’s trees received the certified organic fertilizer, at two concentrations 1/50 and 1/100, as a ground fertilizer and foliar application for each rate, as well as two treatments of cow manure and chemical fertilizer. Fatty acids composition in olive oil samples were estimated in the Food Technology Laboratory at Faculty of Agriculture, Damascus University.The results showed that the oil of studied olive variety was affected positively by using certified organic fertilizer, increasing concentration of fertilizer significantly improve the saturated fatty acids contents, however, this was accompanied by a decrease of Oleic acid proportion, so the concentration of 1/100 was the best as the oleic acid was significantly increased in this rate.No significant differences were observed between the method applications of liquid fertilizer on the fatty acids profile. It is very important to benefit from these results in finding alternatives to chemical fertilizers in olive groves, as well as providing the trees nutrients during conversion to produce organic olive oil, especially since it tops the desired products for consumption in foreign markets.

Mineralization mechanism of organic carbon in maize rhizosphere soil of soft rock and sand mixed soil under different fertilization modes.

This article endeavors to investigate the influence of various fertilization methods on the characteristics of rhizosphere soil and organic carbon mineralization in the mixed soil of Mu Us Sandy land under maize cultivation, with the objective of laying the groundwork for low-carbon agriculture and the development of high-quality farmland. The research focuses on soft rock and sand composite soil with a 1:2 ratio, and it comprises four treatments: no fertilization (CK), only chemical fertilization (CF), only cattle manure application (MF), and only oil residue application (DF). The findings revealed that the use of organic fertilizer substantially elevated nutrient content and enzyme activity in the maize rhizosphere soil. Furthermore, it had a notable influence on both soil aggregate diameter and stability. Specifically, the DF treatment led to a significant increase in both soil aggregate diameter and stability. The mineralization rate of organic carbon in the maize rhizosphere soil could be categorized into two distinct phases: a rapid initial decline followed by a slower release. By the end of the incubation period, the cumulative mineralization of organic carbon in the MF, DF, and CF treatments showed a significant increase of 119.87%, 57.57%, and 24.15%, respectively, in comparison to the CK treatment. Additionally, the mineralization rate constants of the DF and MF treatments experienced a substantial rise, with increments of 23.52% and 45.97%, respectively, when contrasted with the CK treatment. The bacterial phyla Actinobacteriota, Proteobacteria, Chloroflexi, Acidobacteriota, and Firmicutes were dominant in the rhizosphere soil bacterial community. Specific genera such as Nocardioides and Sphingomonas showed significant correlations with organic carbon mineralization. The application of different organic fertilizer can improve soil physical, chemical and biological properties, and promote the mineralization process of organic carbon in maize rhizosphere soil. Notably, the DF treatment exhibited the most favorable outcome, improving the overall quality of maize rhizosphere soil while incurring a minimal loss of unit organic carbon. These findings hold significant implications for optimizing field management practices and augmenting soil quality.

Synergistic effects of earthworms and cow manure under reduced chemical fertilization modified microbial community structure to mitigate continuous cropping effects on Chinese flowering cabbage.

The substitution of chemical fertilizers with organic fertilizers is a viable strategy to enhance crop yield and soil quality. In this study, the aim was to investigate the changes in soil microorganisms, soil chemical properties, and growth of Chinese flowering cabbage under different fertilization treatments involving earthworms and cow manure. Compared with the control (100% chemical fertilizer), CE (30% reduction in chemical fertilizer + earthworms) and CFE (30% reduction in chemical fertilizer + cow dung + earthworms) treatments at soil pH 8.14 and 8.07, respectively, and CFC (30% reduction in chemical fertilizer + cow manure) and CFE treatments increased soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), and available potassium (AK) contents. Earthworms and cow manure promoted the abundance of Bacillus and reduced that of the pathogens Plectosphaerella and Gibberella. The mantle test revealed that pH was not correlated with the microbial community. Random forest analysis verified that AN, SOM, and TN were important factors that jointly influenced bacterial and fungal diversity. Overall, the synergistic effect of earthworms and cow manure increased soil fertility and microbial diversity, thereby promoting the growth and development of Chinese flowering cabbage. This study enhanced the understanding of how bioregulation affects the growth and soil quality of Chinese flowering cabbage, and thus provided a guidance for the optimization of fertilization strategies to maximize the yield and quality of Chinese flowering cabbage while reducing environmental risks.

Vermicompost derived from mushroom residues improves soil C/P cycling, bacterial community, and fungal abundance

AbstractThe utilization of agricultural waste organic materials through composting technology has gained significant traction in agricultural production as an effective means of crop nutrient management. However, the differences in the impact of organic amendments prepared by traditional composting and vermicomposting on soil properties still deserve further research. Based on field experiments conducted in greenhouse, compared to chemical fertilizer treatments as control, we utilized traditional compost (OF) and vermicompost (VcF) derived from agricultural organic waste edible mushroom bran and cow manure (2:8). Variations in soil physiochemical properties, activities of soil enzymes related C and P cycling, abundances and diversities of bacterial 16S rRNA and fungal ITS gene at total DNA level were analyzed. Both compost treatments enhanced soil organic carbon, soil total phosphorus, and soil available P content significantly and also increased the activities of soil α‐glucosidase, β‐glucosidase, acid phosphomonoesterase, and alkaline phosphomonoesterase significantly. The above results suggested that soil C and P transformations were stimulated effectively by both organic amendments. OF and VcF increased the fungal ITS absolute abundances significantly while diversity indices of soil bacterial community increased significantly under both treatments. Correlation analysis indicated that bacterial community composition was strongly correlated with several soil property indexes while fungal community composition was only significantly correlated with soil total phosphorous content. In conclusion, similar to traditional compost, vermicompost significantly improved soil nutrient cycling (especially C and P aspects). In terms of soil microbes, bacteria and fungi showed different responding mechanism to vermicompost: bacteria adjust microbial structure, while fungi tend to proliferated. In consideration of the advantages of vermicompost in technology and economic cost, it could be applied in the subsequent agricultural production more frequently.

Responses of soil nutrients and rhizosphere microbial communities of a medicinal plant Pinelliaternata to vermicompost.

Vermicomposting is an important strategy for restoring soil function and fertility. However, information on the effects of vermicompost application in intensive Pinellia ternata planting systems has rarely been reported. Here, we focus on the effects of different vermicompost levels and chemical fertilizer (CF) strategies on soil chemical properties, soil enzymes, and soil rhizosphere microbial communities (bacteria and fungi) in a field experiment. Compared to no added fertilizers (CK), vermicompost was more effective than the CF treatment in increasing P. ternata yield. We found that the 5 t ha-1 vermicompost treatment (VC2) significantly increased the tuber yield by 44.43% and 6.55% compared to the CK and CF treatment, respectively, and water-soluble exudates by 6.56% and 9.63% (P < 0.05). The vermicompost and CF treatments significantly increased the total phosphorus (TP), urease (Ure), and soil catalase (Cat) contents (P < 0.05). Compared to the vermicompost and CK treatments, the CF treatment significantly decreased soil organic carbon (SOC), C/N ratio, and soil acid phosphatase (Pac) (P < 0.05). Redundancy analysis (RDA) showed that Ure and total potassium (TK) were the major drivers in the bacterial community, whereas TP, total nitrogen (TN), Pac, and TK were the major drivers in the fungal community. We also found a positive correlation between soil enzyme activities, including between Ure and bacterial genera (Clostridium, Pseudoclavibacter, Stella, Hyphomicrobium, Mesorhizobium, and Adlercreutzia). In summary, vermicompost application promotes P. ternata soil microecosystems and improves soil fertility, soil enzyme activities, and rhizosphere microbial structure and function. Vermicomposting is a novel and promising approach to sustainable ecological cultivation of Chinese herbs via the promotion of soil properties and beneficial organisms.

Long-term bioorganic and organic fertilization improved soil quality and multifunctionality under continuous cropping in watermelon

Continuous cropping has can majorly damage the soil ecosystem, leading to an increased prevalence of pathogenic microorganisms and severe yield losses for watermelons. Multiple prevention strategies have been adopted to overcome this obstacle, among which the application of bioorganic fertilizer can improve microbiome deterioration. However, the response of soil ecosystem multifunctionality and soil quality to fertilizer regimes under continuous cropping remains poorly understood. In this study, based on an 8-year field experiment, we evaluated soil health and ecosystem multifunctionality under different fertilization treatments. Long-term bio-organic fertilization preserved soil electrical conductivity and increased total Cu, Zn, Fe, Mn, Ca, and Mg, total and available nutrients, and enzyme activities compared with those in unfertilized control (CK) and chemical fertilizer treatments. Enzyme activities and yield rapidly changed, indicating their sensitivity to these management practices. Conversely, soil pH, biodiversity, medium/trace elements, and total NPK content were more resistant to change than enzyme activities, suggesting higher stability over time. The area of soil quality index under bio-organic fertilization was 1.2–2.9 times larger than that under CK treatment. Applying biological organic fertilizer and a mixture of chemical and organic fertilizers improved the multifunctionality decline caused by continuous cropping by 1.1–1.4 times, whereas the effect of the chemical fertilizer was weak. Soil health was positively correlated with ecosystem multifunctionality. These findings suggest that long-term bioorganic and organic fertilization is an effective strategy for improving soil quality and multifunctionality in continuous watermelon crops while also contributing toward a more sustainable agricultural system.

Effects of partial substitution of chemical fertilizer with organic manure on the activity of enzyme and soil bacterial communities in the mountain red soil.

The partial substitution of chemical fertilizer with organic manure takes on a critical significance to enhancing soil quality and boosting sustainable agricultural development. However, rare research has studied the effects of partial substitution of chemical fertilizer with organic manure on soil bacterial community diversity and enzyme activity in maize field in the mountain red soil region of Yunnan. In this study, four treatments were set up in which chemical fertilizer (the application rates of N, P2O5 and K2O were 240, 75 and 75 kg·ha-1, respectively) was substituted by 10% (M10), 20% (M20), 30% (M30) and 40% (M40) of organic manure with equal nitrogen, as well as two control treatments of single application of chemical fertilizer (M0) and no fertilization (CK). The maize (Zea mays L.) crop was sown as a test crop in May 2018. The effects of partial substitution of chemical fertilizer with organic manure on soil physicochemical properties, soil bacterial community diversity and enzyme activity were studied. The activities of Cellulase (CBH), Invertase (INV) and β-glucosidase (BG) increased with the increase of organic manure substitution ratio. The activities of β-1,4-N-acetylglucosaminidase (NAG), Urease (URE), and leucine aminopeptidase (LAP) also had the same trend, but the highest activities were 159.92 mg·g-1·h-1, 66.82 mg·g-1·h-1 and 143.90 mg·g-1·h-1 at 30% substitution ratio. Compared with CK and M0 treatments, Shannon index increased notably by 82.91%-116.74% and 92.42%-128.01%, respectively, at the organic manure substitution ratio ranging from 10% to 40%. Chao1 and ACE index increased significantly at the organic manure substitution ratio ranging from 10% to 30%. Proteobacteria was the dominant phylum in all treatments, the relative abundance of Proteobacteria decreased as the organic manure substitution ratio increased. Redundancy analysis showed that microbial biomass C was the main factor affecting the bacterial community composition under partial replacement of chemical fertilizer treatment, while Actinobacteria was the main factor affecting the enzyme activity. In addition, the maize yield of M30 and M40 treatments was significantly higher than that of CK and M0-M20 treatments, and the yield of M30 treatment was the highest, reaching 7652.89 kg·ha-1. Therefore, the partial substitution of chemical fertilizer with organic manure can improve soil biological characteristics, while increasing bacterial community diversity and soil enzyme activity. Therefore, a thirty percent organic manure substitution was determined as the optimal substitution ratio for maize farmland in the mountain red soil area of Yunnan, China.

Phosphorus availability and corn (Zea mays L.) response to application of P‐based commercial organic fertilizers to a calcareous soil

AbstractRecycling of organic wastes for agricultural production has been recommended as a sustainable way to close the phosphorus (P) cycle. This study seeks to characterize the P forms in organic fertilizers derived from agricultural and nonagricultural source materials to understand how these organic fertilizers will affect corn growth and soil available P. Organic fertilizers including turkey litter compost (TLC), biosolid pellets (BSP), and source separated organic compost (SSO) were applied to a sandy loam soil and compared to controls that received no nutrients or chemical fertilizer. Results from sequential chemical extractions and X‐ray absorption near edge structure spectroscopy revealed that most of the P species are inorganic, with SSO and TLC containing primarily Ca‐P and Mg‐P forms, while the P in the BSP treatments was mostly associated with aluminium (Al). The two chemical fertilizer treatments had the greatest impact on corn height at the initial growth stage; however, after 42 days, corn height was similar for the organic fertilizers and chemical treatment. This initial slow response from the organic fertilizer treatments reduced the grain yield compared to chemical treatment. The results of this study suggest that priority should be given to sufficient P availability at the initial growth stage. Overall, organic fertilizer is a promising P source for grain crop production, but calibration and correlation studies are needed to ensure optimum supply of P for the initial growth stage.

Effect of Co-application of Different Biochars and Inorganic Fertilizers on the Growth and Yield of Okra (Abelmoschus esculentus L.)

To manage necessary amount of food for the growing world population, it is very important to maintain fertility of usual arable land as well as to bring problem soils including sandy soil under coverage of regular crop cultivation. In this context, biochar is a very promising option as soil conditioner and therefore, a plant growth trial in pot was operated at the net house of the Department of Agroforestry and Environmental Science, Sylhet Agricultural University, Sylhet to evaluate the influence of tea waste and sugarcane bagasse biochar on the morphology, yield and yield contributing traits of okra (Abelmoschus esculentus) in sandy soil. The experimental set-up was arranged following randomized complete block design with three replications under eight treatments. The treatments were: T0 (CK, Control, no amendment), T1 (CF, Chemical fertilizers), T2 (2.5 % TWB (tea waste biochar) + CF), T3 (5% TWB + CF), T4 (10% TWB + CF), T5 (2.5% SBB (sugarcane Bagasse biochar) + CF), T6 (5% SBB + CF); and T7 (10% SBB + CF). The results revealed that the different morphological characteristics like plant height (PH), number of leaf plant-1 (NLP), leaf length (LL), plant fresh weight (PFW), and stem diameter (SD) showed no significant difference among the treatments. The highest PH (107.33 cm) and RL (70.67 cm) were found in T0 (CK) whereas the maximum LL (27.33 cm), SD (10.38 mm), and fresh root weight (FRW) (19.67g) were noted in T3. The maximum number of leaves plant-1 (NLP) (20) and PFW (110.67 gm) of okra were observed in T2 and T6, respectively. In case of total leaf chlorophyll content (TLCC), the maximum value was determined in T4 (47 µmol m-2), but the treatments were not significantly different from each other. The number of pod plant-1 (NPP) (23.7), pod length (PL) (18 cm), individual pod weight (IPW) (18 g), number of seed pod-1 (NSP) (45) and pod weight per plant-1 (PWP)(425 g) of okra were found to be highest in T7, followed by T4 and T6. The yield and yield contributing characters of okra showed significantly higher value for biochar treatments (T2 - T7) over to the control (T0) and sole chemical fertilizer treatment (T1). After the cultivation of okra, the highest pH value (7.2) was found in T7, followed by T6. The results of this study might contribute to enlarge the prospects of biochar application in the production of okra and other crops in both normal and less fertile soils.

Co-Incorporating Chinese Milk Vetch and Rice Straw Increases Rice Yield by Improving Nutrient Uptake during Rice Growth

In the past ten years, in paddy rice systems in southern China, the co-incorporation of Chinese milk vetch (MV) and rice straw (RS) has become a new and effective practice in which the advantages of the two species are combined to improve rice yields. However, more studies are needed to better understand the mechanisms by which rice productivity is improved through this practice. In this study, a pot experiment was performed to investigate the effects of different residue management treatments on rice productivity and soil properties. Five treatments were tested: (i) CK (no residue and no chemical fertilizer); (ii) CF (chemical fertilizer); (iii) FM (CF with MV returning); (iv) FR (CF with RS returning); and (v) FMR (CF with a mixture of MV and RS returning). The results showed that the application of MV and/or RS returning improved grain yields by between 13.7% and 31.5%, compared with CF treatment alone. In addition, the application of MV significantly improved rice yield relative to RS returning. However, co-incorporation of MV and RS resulted in the highest yield productivity of all. FMR treatment significantly increased shoot biomass and shoot N, P, and K uptake, compared with FR treatment, at all three growth stages, and compared with FM treatment at the jointing and maturity stages. Moreover, FMR treatment significantly improved grain N, P, and K uptake, relative to FM and FR treatments. These results clearly demonstrated that co-incorporation management promotes nitrogen and phosphorus nutrient uptake at jointing and maturity stages of the rice growth process, compared to application of single residues alone, resulting in higher rice yields. Because incorporation of MV and/or RS increases the available nutrients in the soil and enhances nutrient uptake by the crop, wide-scale adoption of the co-incorporation of residues would significantly increase rice yields and improve soil fertility.