Journal Articles
Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915
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Item A low-cost simple lysimeter soil retriever design for retrieving soil from small lysimeters(IOP Publishing, 2024-06-06) Gunaratnam A; McCurdy M; Grafton M; Jeyakumar P; Davies CE; Bishop PItem The Potential Impact of Long-Term Copper Fungicide Sprays on Soil Health in Avocado Orchards(MDPI AG, 2024-05-25) Matse D; Geretharan T; van Gorp E; Anderson S; Jeyakumar P; Anderson CItem Enhanced denitrification driven by a novel iron-carbon coupled primary cell: chemical and mixotrophic denitrification(Springer, 2024-01-10) Wu R; Jeyakumar P; Nanthi B; Zhai X; Wang H; Pan M; Lian J; Cheng L; Li J; Hou M; Cui Y; Yang X; Dai KIron-carbon micro-electrolysis system is a promising method for promoting electron transfer in nitrate removal. However, many traditional approaches involving simple physical mixing inevitably suffered from the confined iron-carbon contact area and short validity period, leading to the overuse of iron. Here, a ceramsite-loaded microscale zero-valent iron (mZVI) and acidified carbon (AC) coupled-galvanic cell (CMC) was designed to support chemical, autotrophic and heterotrophic denitrification. Long-term experiments were conducted to monitor the nitrogen removal performance of denitrification reactors filled with CMC and thus optimized the denitrification performance by improving fabrication parameters and various operating conditions. The denitrification contributions test showed that the chemical denitrification pathway contributed most to nitrate removal (57.3%), followed by autotrophic (24.6%) and heterotrophic denitrification pathways (18.1%). The microbial analysis confirmed the significant aggregation of related denitrifying bacteria in the reactors, while AC promoted the expression of relevant nitrogen metabolism genes because of accelerated uptake and utilization of iron complexes. Meanwhile, the electrochemical analysis revealed a significantly improved electron transfer capacity of AC compared to pristine carbon. Overall, our study demonstrated the application of a novel mZVI-AC coupled material for effective nitrate removal and revealed the potential impact of CMC in the multipathway denitrification process. Graphical Abstract: [Figure not available: see fulltext.]Item Exploring Phosphorus Dynamics in Submerged Soils and Its Implications on the Inconsistent Rice Yield Response to Added Inorganic Phosphorus Fertilisers in Paddy Soils in Sri Lanka(2024-03-01) Palihakkara J; Burkitt L; Jeyakumar P; Attanayake CPRice is the primary energy source of more than half of the global population. Challenges persist in managing phosphorus (P) in paddy soils of tropical rice-growing countries. In Sri Lanka, one specific challenge is the inconsistent yield response observed when inorganic P fertilisers are applied to paddy soils. Previous research conducted in Sri Lanka has shown that the rice yield response to added P fertilisers cannot be adequately explained by factors such as soil available P, irrigation schemes, soil texture, pH, electrical conductivity, total carbon content and available Fe and Mg concentrations. Due to the submerged conditions in which rice is grown for a significant portion of its lifespan, a unique environment controlled by redox-driven processes is developed in paddy soils. Therefore, releasing P from submerged soils is an outcome influenced by complex hydrological and biogeochemical processes, strongly influenced by inherent soil characteristics. The present review paper aimed to critically examine existing literature on soil P behaviour in submerged paddy soils of Sri Lanka, to clarify the behaviour of P under submergence, identify the factors affecting such behaviour and highlight the research gaps that need to be addressed, in order to effectively manage P in the paddy soils of Sri Lanka.Item Simulating gibberellic acid effect on pasture yield on naturally deposited and fixed area urine(MDPI, 2/07/2023) Matse D; Avendano F; Bishop P; Jeyakumar P; Bates GNitrate (NO3−-N) leaching from urine patches is a serious environmental concern in dairy pastoral systems. In our previous research, we established that application of a plant growth hormone, gibberellic acid (GA), can potentially reduce NO3−-N leaching in urine patches; however, this was investigated in two locations in New Zealand. The performance of GA in influencing pasture nitrogen (N) uptake and NO3−-N leaching needs to be undertaken in multi-locations to draw conclusions. However, multi-location studies are a challenge due to a lack of funding and time constraints, so models such as the agricultural production systems simulator (APSIM) have been used. Therefore, field studies were conducted to determine whether APSIM can be used to quantify and simulate the effect of GA on NO3−-N leaching and pasture yield in three experimental sites known as Ashburton, Stratford, and Rotorua in New Zealand. Treatments examined were control (no urine applied), urine at 600 kg N ha−1, urine + GA at 8 g ha−1. The observed data was used to calibrate and validate the model. APSIM simulated that application of GA reduced NO3−-N leaching (relative to urine treatment) by 4.6, 5.1, and 8.8 kg NO3−-N ha−1 in Ashburton, Stratford, and Rotorua, respectively. APSIM reliably simulated pasture dry matter yield, and this was confirmed by the coefficient of determination ranging from R2 = 0.8562 to 0.995 in all treatments and experimental sites. This study demonstrated that APSIM can effectively be used to simulate the effect of GA application on NO3−-N leaching and pasture yield. Therefore, APSIM can be applied in other areas to simulate NO3−-N leaching and pasture yield.Item Remediation Technologies for Neonicotinoids in Contaminated Environments: Current State and Future Prospects(Elsevier, 16/06/2023) Wei J; Wang X; Tu C; Long T; Bu Y; Wang H; Jeyakumar P; Jiang J; Deng SNeonicotinoids (NEOs) are synthetic insecticides with broad-spectrum insecticidal activity and outstanding efficacy. However, their extensive use and persistence in the environment have resulted in the accumulation and biomagnification of NEOs, posing significant risks to non-target organisms and humans. This review provides a summary of research history, advancements, and highlighted topics in NEOs remediation technologies and mechanisms. Various remediation approaches have been developed, including physiochemical, microbial, and phytoremediation, with microbial and physicochemical remediation being the most extensively studied. Recent advances in physiochemical remediation have led to the development of innovative adsorbents, photocatalysts, and optimized treatment processes. High-efficiency degrading strains with well-characterized metabolic pathways have been successfully isolated and cultured for microbial remediation, while many plant species have shown great potential for phytoremediation. However, significant challenges and gaps remain in this field. Future research should prioritize isolating, domesticating or engineering high efficiency, broad-spectrum microbial strains for NEO degradation, as well as developing synergistic remediation techniques to enhance removal efficiency on multiple NEOs with varying concentrations in different environmental media. Furthermore, a shift from pipe-end treatment to pollution prevention strategies is needed, including the development of green and economically efficient alternatives such as biological insecticides. Integrated remediation technologies and case-specific strategies that can be applied to practical remediation projects need to be developed, along with clarifying NEO degradation mechanisms to improve remediation efficiency. The successful implementation of these strategies will help reduce the negative impact of NEOs on the environment and human health.Item Effects of biochar in combination with varied N inputs on grain yield, N uptake, NH3 volatilization, and N2O emission in paddy soil(Frontiers Media, 12/05/2023) Yi Z; Jeyakumar P; Yin C; Sun HBiochar application can improve crop yield, reduce ammonia (NH3) volatilization and nitrous oxide (N2O) emission from farmland. We here conducted a pot experiment to compare the effects of biochar application on rice yield, nitrogen (N) uptake, NH3 and N2O losses in paddy soil with low, medium, and high N inputs at 160 kg/ha, 200 kg/ha and 240 kg/ha, respectively. The results showed that: (1) Biochar significantly increased the rice grain yield at medium (200 kg/ha) and high (240 kg/ha) N inputs by 56.4 and 70.5%, respectively. The way to increase yield was to increase the rice N uptake, rice panicle number per pot and 1,000 grain weight by 78.5–96.5%, 6–16% and 4.4–6.1%, respectively; (2) Under low (160 kg/ha) N input, adding biochar effectively reduced the NH3 volatilization by 31.6% in rice season. The decreases of pH value and NH4+-N content in surface water, and the increases of the abundance of NH4+-N oxidizing archaea and bacteria (AOA and AOB) communities contributed to the reduction of NH3 volatilization following the biochar application; (3) Under same N input levels, the total N2O emission in rice season decreased by 43.3–73.9% after biochar addition. The decreases of nirK and nirS gene abundances but the increases of nosZ gene abundance are the main mechanisms for biochar application to reduce N2O emissions. Based on the results of the current study, adding biochar at medium (200 kg/ha) N level (N200 + BC) is the best treatment to synchronically reduce NH3 and N2O losses, improve grain yield, and reduce fertilizer application in rice production system.Item Supplying silicon alters microbial community and reduces soil cadmium bioavailability to promote health wheat growth and yield(Elsevier, 30/06/2021) Song A; Li Z; Wang E; Xu D; Wang S; Bi J; Wang H; Jeyakumar P; Li Z; Fan FSoil amendments of black bone (BB), biochar (BC), silicon fertilizer (SI), and leaf fertilizer (LF) play vital roles in decreasing cadmium (Cd) availability, thereby supporting healthy plant growth and food security in agroecosystems. However, the effect of their additions on soil microbial community and the resulting soil Cd bioavailability, plant Cd uptake and health growth are still unknown. Therefore, in this study, BB, BC, SI, and LF were selected to evaluate Cd amelioration in wheat grown in Cd-contaminated soils. The results showed that relative to the control, all amendments significantly decreased both soil Cd bioavailability and its uptake in plant tissues, promoting healthy wheat growth and yield. This induced-decrease effect in seeds was the most obvious, wherein the effect was the highest in SI (52.54%), followed by LF (43.31%), and lowest in BC (35.24%) and BB (31.98%). Moreover, the induced decrease in soil Cd bioavailability was the highest in SI (29.56%), followed by BC (28.85%), lowest in LF (17.55%), and BB (15.30%). The significant effect in SI likely resulted from a significant increase in both the soil bioavailable Si and microbial community (Acidobacteria and Thaumarchaeota), which significantly decreased soil Cd bioavailability towards plant roots. In particular, a co-occurrence network analysis indicated that soil microbes played a substantial role in rice yield under Si amendment. Therefore, supplying Si alters the soil microbial community, positively and significantly interacting with soil bioavailable Si and decreasing Cd bioavailability in soils, thereby sustaining healthy crop development and food quality.Item Influence of Soil Moisture Status on Soil Cadmium Phytoavailability and Accumulation in Plantain (Plantar lanceolata)(MDPI (Basel, Switzerland), 2018-03) Stafford A; Jeyakumar P; Hedley M; Anderson CThe effect of fluctuating soil moisture cycles on soil cadmium (Cd) phytoavailability was investigated in a pot trial with two contrasting soils (Kereone (Allophanic), total Cd 0.79 mg kg−1; and Topehaehae (Gley), total Cd 0.61 mg kg−1) that were either sown with plantain (Plantago lanceolata) or left unseeded. Varying soil moisture contents were established using contrasting irrigation regimes: “flooded” (3 days flooded and then 11 days drained); or “non-flooded” (irrigation to 70% of potted field capacity every 7 days). Overall, there was no significant difference in mean 0.05 M CaCl2 soil extractable Cd concentrations or plant tissue Cd concentrations between flooded and non-flooded irrigation. However, there was a consistent trend for an increase in soil extractable Cd concentrations following irrigation, regardless of the irrigation regime. Mean soil extractable Cd and plant tissue Cd concentrations were significantly greater (approximately 325% and 183%, respectively) for the Topehaehae soil than the Kereone soil, despite the lower soil total Cd concentration of the Topehaehae soil. These results indicate that Cd solubility is sensitive to increases in soil moisture following periods of soil drainage, but insensitive to short-term periods of soil saturation. Plant tissue Cd concentrations in Cd-sensitive forage crops such as plantain are likely to be greater following large rainfall events over summer and autumn. This has the potential to increase animal dietary Cd exposure and rate of liver/kidney Cd accumulation.Item Responses of rice (Oryza sativa L.) plant growth, grain yield and quality, and soil properties to the microplastic occurrence in paddy soil(Springer, 18/05/2022) Chen S; Feng Y; Han L; Li D; Feng Y; Jeyakumar P; Sun H; Shi W; Wang HPurpose: Agricultural soil has been recognized as a major sink of microplastic, an emerging pollutant to environmental biodiversity and ecosystem. However, the impacts of microplastic on soil–plant systems (e.g., crop growth, grain yield and amino acid content, nitrogen uptake capacity, and soil properties) remain largely unknown. Methods: Four typical microplastics, i.e., polythene (PE, 200 μm), polyacrylonitrile (PAN, 200 μm), and polyethylene terephthalate (PET) in diameter of 200 μm and 10 μm (PET200 and PET10), were tested to assess the consequent aforementioned responses under rice (Oryza sativa L.) paddy soil in a mesocosm experiment. Results: Microplastics multiply influenced the soil pH, NH4+-N and NO3−-N contents, which effects were depended on the rice growth stage and plastic type. Overall, microplastics significantly decreased the soil urease activity by 5.0–12.2% (P < 0.05). When exposed to PAN and PET (in both diameter of 200 μm and 10 μm), there were significantly 22.2–30.8% more grain yield produced, compared to the control (P < 0.05), which was attributing to the higher nitrogen uptake capacity of rice grain. Meanwhile, microplastics exhibited nominal influences on rice plant height, tillering number, leaf SPAD, and NDVI. The amino acids were affected by microplastic, depending on the types of plastics and amino acids. Conclusion: This study provides evidence that microplastic can affect the development and final grain yield, amino acid content, nitrogen uptake capacity of rice, and some major soil properties, while these effects vary as a function of plastic type. Our findings highlight the positive impacts that could occur when the presence of microplastics in paddy soil.
