Root-knot nematodes (RKN) cause extensive damage to grapevine cultivars. RKN-resistant grapevine rootstocks remain vulnerable to biotic and abiotic stresses. This study aimed to determine the influence of composted animal manures (CAMs) [chicken manure (CM), cow manure (CowM), and sheep manure (SM)] with or without plant growth-promoting rhizobacteria (PGPR) on the population of Meloidogyne incognita, free-living nematodes (FLNs) and predaceous nematodes (PNs) residing in the soils of vineyard cultivars (Flame, Superior and Prime). The nematodes were isolated from grapevine roots and rhizosphere soils, then the absolute frequency of occurrence (FO), relative FO, prominence value (PV), and population density (PD) were assessed. The impact of CAMs and PGPR on the growth parameters, fruit output, and quality of three grapevine varieties was subsequently evaluated. Eight treatments included a control without CAMs or PGPR amendments, the CAMs alone, or CAM treatments combined with PGPR. The results showed that FLNs and PNs were more abundant in Prime than Flame or Superior cultivars when poor sandy loam soils were supplied with CAMs. Among all tested manures, CM was the best treatment as a nematicide. This was evident from the decreased numbers of M. incognita and increased numbers of FLNs and PNs in grapevine fields. Compared to the soil-applied oxamyl (a systemic nematicide), which was efficiently suppressive on M. incognita for two months, CM significantly (P < 0.05) decreased PD of the phytonematodes for five months, improved soil structure and enhanced the soil biological activities. There were significant (P < 0.05) increases in the number of leaves/vines by 79.9, 78.8, and 73.1%; and total fruit weight/vine by 76.9, 75.0, and 73.0% in Flame, Superior, and Prime varieties, respectively, compared to untreated vines. Regardless of the cultivar, soils amended with CM + PGPR achieved the lowest number of M. incognita among all other treatments, followed by SM + PGPR and CowM + PGPR. It was concluded that CAMs amendment, mainly CM, along with PGPR in poor sandy soils of temperate areas, is considered a sustainable approach for reducing parasitic nematodes and improving agricultural management.
Excessive boron (B) levels in soil can lead to toxicity in plants, impacting their growth and productivity. Effective strategies to reduce B uptake are important for improving crop performance in contaminated soils. This experiment aimed to investigate the effects of chicken manure incineration ash (CMA) and triple superphosphate (TSP) on B uptake in barley plants grown in B-contaminated soil. Before the experiment, the chemical composition and molecular structure of CMA were analyzed using XRF, XRD and SEM. The soil was contaminated with 15 mg kg-1 of B, and both TSP and CMA were applied at rates of 40, 80, and 160 mg kg-1 of phosphorus (P). Neither P source had a significant impact on plant dry weight. However, increasing doses of applied TSP and CMA increased plant P concentration while significantly decreasing B concentration. Particularly with CMA applied at 160 mg kg-1 P dose, plant B concentration decreased to the lowest level of 194 mg kg-1. Increasing P doses led to a slight decrease in plant silicon (Si) concentration. The pH of soil samples taken after the experiment slightly increased with CMA treatments compared to TSP. The available P concentration in soils increased with increasing P doses. The available B concentration decreased with increasing P doses, especially reducing to the lowest level of 2.52 mg kg-1 in soils with a 40 mg kg-1 P, CMA. In conclusion, in addition to the effect of P, the molecular structure of P is also important in reducing B uptake in barley.
Straw return is widely acknowledged as a crucial strategy for enhancing soil fertility and increasing crop yields. However, the continuous addition of straw, its slow decomposition, and retention can hinder crop growth. Therefore, it is essential to elucidate the characteristics of the crop straw decomposition. This study aims to explore the alterations in straw decomposition rates, as well as the content and structure of organic components, under the combined application of swine manure and corn straw in the broken skin yellow soil of black soil over time. The findings revealed that the straw decomposition rates in all treatments increased rapidly in the early stage, gradually slowed down and stabilized in the later stage. The decomposition rates of cellulose and hemicellulose were generally consistent with those of straw, while lignin decomposed more rapidly in the middle and later stages. Notably, the decomposition rate of straw and its components was significantly higher under the combined application of swine manure and biochar compared to other treatments, with decomposition rates of straw, cellulose, hemicellulose, and lignin recorded at: 66.16%, 63.38%, 61.16% and 47.96%, respectively, after 360 days. This treatment exhibited the most substantial damage to the apparent structure of corn straw over time, and it resulted in lower C/N ratios and the most pronounced decrease in the intensity of absorption peaks. Among all the treatments, the alkyl carbon/alkoxy carbon ratio was highest in the SCZ treatment, indicating that the addition of swine manure and biochar can significantly enhance straw decomposition. Correlation analysis revealed that the decomposition rates of straw, cellulose, hemicellulose, and lignin were significantly and positively correlated with the rates of alkyl carbon, aromatic carbon, and phenolic carbon in the organic functional groups of straw residues, and significantly negatively correlated with alkoxy carbon. The study suggested that the combined application of straw, swine manure and biochar in the field can effectively promote the decomposition of corn straw. Our findings provided insights into the efficient utilization of various exogenous conditioners, serving as a scientific basis for accelerating straw decomposition and enhancing nutrient utilization.
Microbially Induced Calcite Precipitation (MICP) is an eco-friendly method for improving sandy soils, relying on micro-organisms that require nitrogen and essential nutrients to induce carbonate mineral precipitation. Given the substantial annual generation of chicken manure (CM) and the associated challenges in its disposal resulting in environmental pollution, the nutrient-rich composted form of this waste material is proposed in this study as a supplementary additive (along with more costly industrial reagents, e.g., urea) to provide the necessary carbon and nitrogen for the MICP process. To this end, different CM contents (5 %, 10 %, and 15 %) along with various concentrations of cementation solution (1 M, 1.5 M, and 2 M) are employed in multiple improvement cycles to augment the efficiency of the MICP technique. Unconfined Compressive Strength (UCS), Ultrasonic Pulse Velocity (UPV), and Water Absorption (WA) tests are performed to assess the mechanical properties of the samples before and after exposure to freeze-thaw (F-T) cycles, while SEM, XRD, and FTIR analyses are carried out to delineate the formation of calcite within the porous structure of MICP-CM-treated sands. The findings suggest that an optimum percentage of CM (10 %) in the MICP process not only contributes to environmental conservation but also significantly enhances all the mechanical properties of bio-cemented sandy soils due to markedly improved bonding within their porous fabric. The results also show that although prolonged exposure to consecutive F-T cycles causes a reduction in strength and stiffness of enhanced MICP-treated soils, the mechanical properties of such geo-composites still remain within an acceptable range for optimal CM-enhanced biocemented mixtures, significantly superior to those of MICP-treated sands.
Historically, cow dung has been widely used as a biostabilizer in earth building, although the scientific research on this subject is still limited. The available research provides evidence of the positive effects of this bioaddition on earthen blocks and plasters, as it improves their physical and mechanical properties and durability in water contact. The present research does not aim to characterize biostabilized earthen mortars or to explain the interaction mechanisms between the earth and cow dung components, because this topic has already been investigated. Instead, it aims to investigate strategies to optimize the collection and processing of cow dung so as to optimize their effects when used in earth-plastering mortars, as well as considering the effects of using them fresh whole, dry whole, and dry ground (as a powder); the effects of two different volumetric proportions of cow dung addition, 20% and 40% (of the earth + added sand); the effects of 72 h (fermentation-humid curing) before molding the biostabilized mortar; the influence of the cow diet; and the potential of reusing cow dung stabilized mortars. The results show that as the freshness of the cow dung increases, the mortar's durability increases under water immersion, as well as the mechanical and adhesive strength. Collecting cow dung fresh and drying (composting) it in a plastic container is more efficient than collecting cow dung that is already dry on the pasture. The cow diet and the use of dry (composted) cow dung, whole or ground into a powder, does not result in a significant difference. A 72 h period of humid curing fermentation increases the adhesive strength and durability under water. The proportion of 40% promotes better durability under water, but 20% offers greater mechanical and adhesive strength. Finally, cow dung addition does not reduce the reusability of the earth mortar. The new mortar obtained by remixing the mortar with water presents increased properties in comparison to the original reference mortar with no cow dung addition. Therefore, the contributions of this research are innovative and important, offering technical support in the area of biostabilized earth-plastering mortars. Furthermore, it is emphasized that cow dung addition can be optimized as an efficient traditional solution to increase the mechanical resistance, but especially to increase the durability of earth mortars when in contact with water. This effect is particularly important for communities lacking financial resources, but also reveals the possibility of using eco-efficient waste instead of binders obtained at high firing temperatures.
In order to solve the problems of traditional orchard-specific green manure crushing and returning machines, such as the single operation effect, root system damage, unsustainable green manure growth, and low utilization rate, an offset crushing-furrowing-burying-straw-returning machine was designed for green manures in orchards. Based on quadratic regression combination experiments, the Discrete Element Method (EDEM) was used to construct a discrete element model simulating the deep furrowing and burying processes of the furrowing and soil-covering device, where the advance speed, plow-shaped furrowing blade rotation speed, and furrowing depth were considered as experimental factors and the coverage rate was taken as an evaluation index, and then simulation analyses were carried out to obtain experimental data; Design-Expert was used to perform ANOVA and RSM analyses, thus finding that its optimal working parameter portfolio consists of the advance speed of 42 m/min, the furrowing blade rotation speed of 300 r/min, and the furrowing depth of 190 mm, and that the coverage rate is 95.82% when this parameter portfolio is applied. Field experiments were conducted to validate the optimal parameter portfolio. The experimental results show that with an average coverage rate of 90.87% (4.95% away from the optimal value based on the simulation experiments on average), an average crushing length qualification rate of 91.24%, and an average root system damage rate of 5.6%, this device is applicable for its operation conditions. The development of this machine and the construction of its parameter model can provide a certain reference value for developing and optimizing related machines including green manure-returning machines.
Biochar amendment and substituting chemical fertilizers with organic manure (organic substitution) have been widely reported to improve intensive vegetable production. However, considering its high potential for reducing carbon and reactive nitrogen (Nr) footprints, very few comprehensive evaluations have been performed on the environmental and economic aspects of biochar amendment or organic substitution. In this study, the comprehensive environmental damage costs from carbon and Nr footprints, measured using the life cycle assessment (LCA) methodology, followed a cradle-to-gate approach, and the carbon storage benefits were incorporated into the newly constructed net ecosystem economic benefit (NEEB) assessment frame in addition to the conventional product income-input cost-benefit methods. One kilogram of harvested vegetables for carbon/Nr footprints and one hectare of cultivated land per crop for cost and benefit were adopted as functional units considering the multi-cropping characteristics for intensive vegetable production. Five fertilization treatments were included: no fertilizer (CK); synthetic fertilizer application (SN); biochar amendment (NB); organic substitution (NM); and a combination of biochar and organic substitution (NMB). These were investigated for five consecutive years of vegetable crop rotations in a typically intensified vegetable production region in China. Adopting the revised NEEB methodology, NB significantly reduced carbon footprint by 73.0% compared to no biochar addition treatment. Meanwhile, NB significantly increased the total benefits by 9.7% and reduced the environmental damages by 52.7% compared to NM, generating the highest NEEB, making it the most effective fertilization strategy among all treatments. It was 4.3% higher compared to NM, which was not significant, but significantly higher than SN and NMB, by 23.0% and 13.6%, respectively. This finding highlights the importance of considering carbon storage benefit for properly assessing NEEB, which is important for developing effective agricultural management strategies and promoting intensive vegetable production with a more sustainable approach.
The effect of pesticide pollution on environmental microorganisms in soil has become the focus of widespread concern in society today. The response of earthworm gut and surrounding soil microbial functional diversity and enzyme activity to carbendazim (CBD) was studied in a soil-earthworm ecosystem amended with manure. In the experiment, CBD was added to the manured soil (MS). Meanwhile, the pesticide treatment without manure and the control treatment without pesticides were also set up. The activities of catalase (CAT) and acetylcholinesterase (AChE) were measured to evaluate the toxicity of CBD. The Biolog method was used to assess the functional diversity of the microbial community. In the 2 mg/kg CBD treatment, earthworm AChE activity decreased significantly in the MS after 14 d, which occurred earlier than in the un-manured soil (NS). The changes of earthworm CAT activity in the pesticide treatments showed a trend of initially increasing and then maintaining at a high activity level. However, the CAT activities at 28 d in the manured soils were clearly lower than that at 7 d for both the CBD treatments, while they remained stable in the control treatments. The carbon source utilization, Simpson index, Shannon index, and McIntosh index of soil microorganisms in the MS treatments were significantly higher than those in the NS treatments. The overall activity of earthworm gut microorganisms in the MS treated with 2 mg/kg CBD was higher than that in the control. Also, CBD treatment (2 mg/kg) increased significantly the Simpson index and McIntosh index of earthworm gut microorganisms. The results indicated that the enzyme activities in the manured soils increased before 7 d for the pesticide treatments. Furthermore, exposure to CBD at a high concentration in the MS not only led to the earlier inhibition of earthworm enzyme activity but also significantly improved the overall activity of earthworm gut microorganisms and microbial functional diversity. This study revealed the ecotoxicological effects of earthworms in response to pesticide stress following the use of organic fertilizers under facility environmental conditions, which can provide a theoretical basis for the remediation of pesticide pollution in soil in the future.
Biochar (B) has low nutrient content and is recalcitrant to biodegradation. Supplementing B with a fast-releasing nutrient source may improve soil fertility and physical conditions and increase crop productivity. A three-season field study was conducted on sandy loam and sandy clay loam textured soils to investigate the effect of B mixed with livestock manure (LM) on soil properties (pH, organic carbon (OC), cation exchange capacity (CEC), total Nitrogen (TN), available Phosphorus (Avail P)), and French bean yield (Phaseolus vulgaris L.) in Rwanda. The study used a factorial randomized block design with four replications. Treatments comprised three levels of B (0, 1, and 3 t/ha) and three levels of LM (0, 1, and 3 t/ha). Biochar was used from S. sesban, G. sepium, A. angustissima, Eucalyptus, and Grevillea sp., prepared using a drum kiln, while LM was prepared using the pit method. The Analysis of Variance (ANOVA), Tukey (HSD) function at p < 0.05, and linear mixed-effects model were performed in R software version 4.3.3 (R Core Team, 2024). The analysis showed that the treated plots significantly increased French bean yield compared to the control plots, with the highest value found in plots treated with 3 t/ha. The combined plots showed an increased yield compared to sole Biochar or manure. The seasonal increase has been observed, with percentage increases recorded as follows: 16%, 33.56%, 173.06% in sole B plots; 40.28%, 14.43%, and 11.76% in sole LM plots and 125%, 156%, and 209.8% in B + LM plots for season 1, 2, and 3, respectively. Furthermore, the results indicated that the application of B alone or combined with LM significantly enhanced soil pH, OC, TN, avail P, and CEC with the pH ranging from 6.77 to 5.43 for B alone, 6.7-5.35 for LM alone, 8.53-6.06 for B-LM plots, and 4.34-3.78 for control plots. Applying Biochar, either alone or in combination with LM, at a low rate demonstrated positive effects on French bean yield and soil nutrients in smallholder farmers. This study encourages using natural materials such as B and LM to improve soil fertility and increase vegetable production while reducing chemical fertilizers that can cause pollution and damage the environment.
The study investigated the prolonged impact of swine manure application on soil inorganic phosphorus (P) fractions over an 8-year continuous, randomized field trial involving rotating wheat (wet conditions) and rice (flooded conditions) crops. The trial comprised six treatments: triplicate control plots receiving only chemical fertilizers, and triplicate plots receiving chemical fertilizers and/or swine manure ranging from 150 to 1200 kg P2O5 ha- 1. The continuous application of swine manure increased soil P content and availability. Initially, P primarily accumulated in the soil as Fe-P during the first four years of manure application, transitioning to Ca8-P over the following four years. The main driver of these changes in P fractions was soil total organic carbon (TOC) was identified as the main driver of these changes in P fractions, contributing 31.5% to the observed variations. TOC increased steadily throughout the trial, with a faster rising in years 1-4 compared to years 4-8. Laboratoryscale soil incubation experiments were conducted, involving the addition of glucose or cellulose as exogenous carbon sources to test their effects on soil P dynamics and mitigate environmental damage from P leaching. The addition of cellulose to soil that had received high quantities of swine manure for eight years resulted in increased the moderately labile and moderately resistant organic P fractions while decreasing the Ca8-P and Olsen-P fractions. This promoted adsorption of high-activity inorganic P to organic matter, consequently limiting the accumulation of Ca8-P. The long-term application of swine manure altered soil P fractions and enhances P lability, enhancing P lability and availability. This study identified an optimized the risk of leaching of labile P from soil under a fertilization regime applying 10,300 kg ha- 1 yr- 1 swine manure. To further mitigate the risk of P leaching, the inclusion of additional cellulose-based organic matter (e.g., straw) in swine manure fertilization regimes is recommended.