Fertilizer Granules Research Articles

Phosphorus fertilization promotes carbon cycling and negatively affects microbial carbon use efficiency in agricultural soils: Laboratory incubation experiments

Soil organic carbon (SOC) loss from intensive agriculture represents a major global concern. Consequently, strategies to improve soil management to mitigate or abate SOC losses and enhance carbon (C) sequestration are urgently needed. Nutrient availability, especially nitrogen (N) and phosphorus (P), regulates soil C cycling and storage. While N effects are well studied, less is known about how soil P status and different fertilizer types affects SOC dynamics. This laboratory incubation assessed how two common P fertilizers, diammonium phosphate (DAP) and single superphosphate (SSP), affected microbial activity and C immobilization in the zone of soil directly around the fertilizer granule (prillosphere) across three contrasting agricultural soils (Inceptisol, Vertisol, Alfisol). Soils were amended with DAP or SSP granules and C turnover assessed with 14C-labeled glycine, malic acid or glucose, alongside unfertilized controls. After three weeks, soil pH, electrical conductivity (EC), Olsen-P and microbial C use efficiency (CUE) were measured. DAP increased pH in the Inceptisol (acidic soil), while SSP decreased pH in all soils. Both fertilizers increased EC and Olsen-P, but SSP enhanced Olsen-P more than DAP. Cumulative 14CO2 emissions were 19–20 % higher with P fertilizers compared to the control, with DAP stimulating faster initial C mineralization rates than SSP, except in the Alfisol. P addition reduced microbial CUE by 23–34 % across all soils and substrates versus the unfertilized control. We ascribe this reduction in CUE to an alleviation of nutrient limitation or a fertilizer-induced osmotic stress. The co-addition of N either in DAP or glycine did not alter the P-induced CUE response suggesting that P was more important than N in regulating microbial CUE in these soils. We conclude that P fertilization increased short-term C turnover and may lead to reduced C storage in soil, however, further long-term (>1 year) research is needed to identify optimum P management strategies to minimize C losses in agricultural soils.

Operational excellence in total productive maintenance: statistical reliability as support for planned maintenance pillar

PurposeTotal productive maintenance consists of strategies and procedures that aim to guarantee the entire functioning of machines in a production process so that production is not interrupted and no loss of quality in the final product occurs. Planned maintenance is one of the eight pillars of total productive maintenance, a set of tools considered essential to ensure equipment reliability and availability, reduce unplanned stoppage and increase productivity. This study aims to analyze the influence of statistical reliability on the performance of such a pillar.Design/methodology/approachIn this study, we utilized a multi-method approach to rigorously examine the impact of statistical reliability on the planned maintenance pillar within total productive maintenance. Our methodology combined a detailed statistical analysis of maintenance data with advanced reliability modeling, specifically employing Weibull distribution to analyze failure patterns. Additionally, we integrated qualitative insights gathered through semi-structured interviews with the maintenance team, enhancing the depth of our analysis. The case study, conducted in a fertilizer granulation plant, focused on a critical failure in the granulator pillow block bearing, providing a comprehensive perspective on the practical application of statistical reliability within total productive maintenance; and not presupposing statistical reliability is the solution over more effective methods for the case.FindingsOur findings reveal that the integration of statistical reliability within the planned maintenance pillar significantly enhances predictive maintenance capabilities, leading to more accurate forecasts of equipment failure modes. The Weibull analysis of the granulator pillow block bearing indicated a mean time between failures of 191.3 days, providing support for optimizing maintenance schedules. Moreover, the qualitative insights from the maintenance team highlighted the operational benefits of our approach, such as improved resource allocation and the need for specialized training. These results demonstrate the practical impact of statistical reliability in preventing unplanned downtimes and informing strategic decisions in maintenance planning, thereby emphasizing the importance of your work in the field.Originality/valueIn terms of the originality and practicality of this study, we emphasize the significant findings that underscore the positive influence of using statistical reliability in conjunction with the planned maintenance pillar. This approach can be instrumental in designing and enhancing component preventive maintenance plans. Furthermore, it can effectively manage equipment failure modes and monitor their useful life, providing valuable insights for professionals in total productive maintenance.

Theoretical studies of the movement of mineral fertilizer granules in the mixing chamber of a centrifugal mixing plant

Relevance. The use of mineral fertilizers helps to improve soil fertility, stimulates the growth and development of plants, which is achieved due to the availability of necessary nutrients. In turn, it is important to observe the correct application of fertilizers, which allows you to control the level of nutrients in the soil, preventing both their excess and deficiency. Currently, the main application of fertilizers falls on complex mineral fertilizers, while one of their disadvantages is that they may contain nutrients that will not be in demand by the plant, which can lead to a violation of the ecological balance. One of the solutions to this problem is the use of flour mixtures. When using mixtures, the determining factor is the uniformity of mixing, which is largely determined by the equipment used. In this regard, the urgent task is to develop a mixing equipment that meets the necessary indicators.Methods. During the research, the processes occurring in the mixing chamber of the developed mixing plant were studied using methods of mathematical analysis, graphical and mathematical modeling.Results. As a result of the research, it was found that during the operation of the mixing plant, the mixing quality is determined by the rotation frequency of the conical rotor. At the same time, the granules of mineral fertilizers after leaving the conical rotor, pouring into the collecting funnel, continue their movement along a spiral trajectory. During the movement of the granules along the surface of the rotating cone, as well as when moving through the funnel, their trajectories will intersect with each other, which will lead to their active mixing.

Humic Acid-Functionalized Lignin-Based Coatings Regulate Nutrient Release and Promote Wheat Productivity and Grain Quality.

The rational application of fertilizers is crucial for achieving high crop yields and ensuring global food security. The use of biopolymers for slow-release fertilizers (SRFs) development has emerged as a game-changer and environmentally sustainable pathway to enhance crop yields by optimizing plant growth phases. Herein, with a renewed focus on circular bioeconomy, a novel functionalized lignin-based coating material (FLGe) was developed for the sustained release of nutrients. This innovative approach involved the extraction and sustainable functionalization of lignin through a solvent-free esterification reaction with humic acid─an organic compound widely recognized for its biostimulant properties in agriculture. The primary objective was to fortify the hydration barrier of lignin by reducing the number of its free hydroxyl groups, thereby enhancing release control, while simultaneously harnessing the agronomic benefits offered by humic acid. After confirming the synthesis of functionalized lignin (FLGe) through 13C NMR analysis, it was integrated at varying proportions into either a cellulosic or starch matrix. This resulted in the creation of five distinct formulations, which were then utilized as coatings for diammonium phosphate (DAP) fertilizer. Experimental findings revealed an improved morphology and hardness (almost 3-fold) of DAP fertilizer granules after coating along with a positive impact on the soil's water retention capacity (7%). Nutrient leaching in soil was monitored for 100 days and a substantial reduction of nutrients leaching up to 80% was successfully achieved using coated DAP fertilizer. Furthermore, to get a fuller picture of their efficiency, a pot trial was performed using two different soil textures and demonstrated that the application of FLGe-based SRFs significantly enhanced the physiological and agronomic parameters of wheat, including leaf evolution and root architecture, resulting in an almost 50% increase in grain yield and improved quality. The results proved the potential of lignin functionalization to advance agricultural sustainability and foster a robust bioeconomy aligning with the premise "from the soil to the soil".

Enhancing Film Cross-Linking through VTES Copolymerization in Polymer Latex for Increasing Controlled-Release Performance of Film-Coated Fertilizer Granules

Enhancing Film Cross-Linking through VTES Copolymerization in Polymer Latex for Increasing Controlled-Release Performance of Film-Coated Fertilizer Granules

Optimizing Nutrient Management: Slow-Release NPK Granule Fertilizer Enhanced with Zeolite and Humic Acid for Sustainable Plantation Crops

A study focused on addressing the efficiency issues associated with NPK fertilizer, which is crucial for plant growth but prone to nutrient loss through various mechanisms such as leaching, volatilization, and denitrification. This research investigates the potential of zeolite and humic acid in controlling the release of nitrogen (N) and potassium (K) from NPK Granule Plus fertilizer. NPK Granules Plus are made by mixing NPK fertilizer with zeolite and humic acid as a coating for controlled-release fertilizer (CRF). Incubation experiment was carried out at the Department of Soil Science and Land Resources, Faculty of Agriculture, IPB University to determine the release pattern of NPK Granule Plus in the soil. At the same time, field experiments were carried out in rubber plantations and kopyor coconut (Cocos nucifera L.) plants planted at Karangnunggal District, Tasikmalaya, West Java to determine the effect on rubber production and growth of kopyor coconut. The results of the study demonstrate that the application of NPK Granule Pus effectively mitigates the slower release of N and K. Application of NPK Granule Plus 300 kg/ha to rubber plants increased the rubber latex production by 28% over control. Meanwhile, application of NPK Granule Plus fertilizer to kopyor coconut plants increased the plant height, plant diameter, and number of leaves compared to those of NPK Granule Conventional Fertilizer. These findings suggest that the use of zeolite and humic acid in NPK Granule Plus holds promise for optimizing nutrient retention in plantation crops, ultimately enhancing the efficiency and increasing production of plants.

Biodegradable maleic–itaconic polymer‐coated phosphatic fertilizer improved phosphorous recovery in calcareous soil

AbstractBackgroundThe poor nutrient recovery of phosphatic (P) fertilizers in calcareous soils is a serious worldwide problem resulting in sub‐optimal P use efficiency. This is mainly attributed to P fixation with calcium (Ca) and magnesium (Mg) ions in the soil solution. As a result, most of the applied P (in the form of fertilizer) becomes insoluble or immobilized in soil due to complex edaphic processes, making it unavailable to plants. Polymer‐coated fertilizers are relatively new approaches to minimizing P‐fixation. However, concerns have been recently raised on the environmental effects of synthetic polymers and microplastic loads in agroecosystems.AimHere we developed and investigated the effectiveness of biodegradable polymer‐coating on commercial diammonium phosphate (DAP) fertilizer to improve P availability in the soil, hence making P more accessible for plant uptake.MethodsThe polymers were coated on DAP fertilizer granules, and two products based on increasing polymer concentration (namely, C‐1 and C‐2, respectively) were achieved. The coated and uncoated DAP granules were characterized for surface properties to confirm the appropriate coating of polymers using scanning electron microscopy (SEM) and crushing strength by a universal telson machine. The biodegradable polymer‐coated C‐1 and C‐2 fertilizers were tested for P availability compared to commercial DAP using spinach as a test plant.ResultsThe SEM micrographs indicated a uniform coating of biodegradable polymers on DAP granules. Application of C‐1 increased the plant's fresh and dry biomass (+10.71% and +18.09%) over commercial DAP, respectively. The C‐1 application increased the N, P, and K uptake by +24.9%, +66.7%, and +11% over commercial DAP. In contrast, C‐2 produced less biomass than C‐1 due to relatively less nutrient uptake and different concentrations of ingredients in C‐2.ConclusionTogether, our results showed that the novel biodegradable polymer approach has demonstrated the potential to improve P recovery and agronomic yield in alkaline soils.

Humic acid enhances phosphorus transport in soil and uptake by maize

AbstractBackgroundMost of the phosphorus (P) applied to low fertility, acidic tropical soils with high iron and aluminum oxide contents end up adsorbed to soil colloids and not available to crops. Diffusion of P from fertilizers was found to be facilitated by coating with humic substances and by soil moisture.AimHowever, there is still controversy on the effect of humic substances on soil P forms and diffusion, and there is a gap in the knowledge of how coating the fertilizer interacts with soil water.MethodsWe studied P diffusion and availability from a conventional single superphosphate and a humic acid‐coated superphosphate in Petry dishes as affected by soil moisture and the effect of the distance of the fertilizer to the roots using a root‐matt methodology.ResultsCoating single superphosphate with humic substances from leonardite (0.5%) and increasing water moisture resulted in improved P diffusion in the soil and plant P uptake. Maize dry matter increased by humic acid‐coated phosphate from 3% to 26%, depending on the distance from the fertilizer to the roots. Therefore, there is evidence of a lower P adsorption to soil colloids. The coated fertilizer increased labile P by 76% around the fertilizer granule, while higher levels of less labile P were observed with the use of conventional single superphosphate.ConclusionAll this resulted in facilitated P transport from the soil to the roots, which is important mainly in double‐cropped systems where the second crop is usually exposed to temporary drought.

Granulated fertilizers are more efficient in reducing potassium leaching losses than combining biosolids with inorganic sources

ABSTRACT Widespread use of soluble mineral fertilizers derived from non-renewable sources has raised concerns about environmental impacts, energy expenditures, and sustainability. Combining biosolid and mineral sources of phosphorus and potassium to produce organomineral fertilizers (OMF) can be used as an alternative nutrient source while reducing the environmental impact of sewage residues. As this approach simultaneously provides nutrients and incorporates organic matter, we hypothesized the presence of an organic source (biosolid) granulated with mineral sources of potassium (K) and phosphorus (P) would reduce leaching due to the benefits of the organic source and the slower release caused by granulation. Our goal was to evaluate the effect of different OMFs on the leaching losses of nutrients. Two forms of isolated N, P, and K sources (granulated and non-granulated), five OMFs with different NPK proportions (1-2-0, 1-4-0, 1-0-2, 1-2-2, 1-2-4), and a control (unfertilized) were evaluated over ten weeks in a leaching column experiment. Non-granulated potassium sulfate exhibited the highest K leaching and did not differ from OMFs with K in their formulation (granulated PS, 1-0-2, 1-2-2, and 1-4-2). Planned contrasts showed that granulation was particularly effective at reducing K leaching, resulting in a 70 % reduction compared to non-granulated PS. While formulation and granulation showed a trend of potential benefits in reducing N-(NO 3 - + NO 2 - ) leaching, the effect was not statistically significant. Interaction between fertilizer treatments and leaching events was marginally significant for NH 4 + leaching, indicating temporal variations of OMFs in nutrient dynamics may be influenced by mineralization. As granulation modulated how OMFs affected nutrient leaching dynamics, this highlights the importance of the physical characteristics of fertilizers for effective nutrient management.

Multilayer Silk Sericin-Based Coating for Controlled Release of Water and Nutrients in Soil: Development, Characterization, and Performance Evaluation in Agricultural Production Model

The use of fertilizers coated with insoluble organic compounds is a promising approach for enhancing fertilizer efficiency and crop yield. Silk sericin (SS) is a protein with a high potential for the development of materials oriented toward fertilizer coating and soil amendment because of its biodegradability and the fact that it represents an important source of nitrogen for plants. Thus, this study proposes the design and evaluation of a novel SS-based multilayer coating for fertilizer granules. A pan-coating process was applied to form two distinct layers on the granules: an inner layer made of silk sericin/polyvinyl alcohol, SS/PVA (50/50 w/w), which has low solubility and porosity, and an outer hydrogel layer of SS/PVA with carboxymethyl cellulose CMC (SS/CMC/PVA 45/25/30 w/w/w). Scanning electron microscopy (SEM) was employed for the morphological characterization of the coated fertilizer (CF), examining both the cross-section and surface, while SEM with energy-dispersive X-ray spectroscopy (SEM/EDS) was used to analyze the chemical composition of the surface. The ability of the coating to reduce the nutrient-release rate was studied using water- and soil-release tests. Furthermore, its performance was evaluated in in vivo assays using jalapeño bell pepper (Capsicum annum) plants. The results revealed that the structure and composition of the multilayer coating significantly influenced its ability to delay nutrient release in both water and soil. Moreover, the inclusion of SS in the coating potentially contributed to the increased nitrogen content in the soil, thereby improving plant growth rates.

Investigating Fertilizer Spreader Blades for Improved Flow Behaviours and Material Resilience in Palm Plantation Settings

Fertilizer spreaders play a crucial role in evenly distributing granule fertilizer across palm plantations. However, in specific areas where growth conditions are unsuitable, fertilizer application becomes unnecessary. Therefore, this study aims to improve granule fertilizer distribution efficiency through enhanced fertilizer blade design. Using Finite Element (FE) simulation, the stress deformation and deflection of the existing spreader blade were evaluated. Meanwhile, Computational Fluid Dynamics (CFD) simulation was used to investigate the influence of spreader design on fertilizer projection speed and direction in the case of open and closed side discharge. The study revealed that the applied forces increased both the critical stress deformation and deflection. To ensure the fertilizer spreads properly over the desired area, the initial velocity had to be increased proportionally with an increase in the angle of direction. These findings contributed to a deeper understanding of the relationship between fertilizer projection velocity, spreader blade strength, and flow behaviour, enabling the reduction of waste in granule fertilizer, while enhancing the operational efficiency and reliability of fertilizer spreader.

Integration of mycorrhiza hyphae into organic fertilizer granules on the growth of sugarcane crops

Arbuscular mycorrhizae fungi (AMF) are important for tropical soils where soil phosphorus (P) availability is low so that plants can use P with higher efficiency. AMF can increase the P concentration in the plant root area, by releasing the bonds of fixed P into available P. One of the obstacles in utilizing AMF fertilizer is the limited availability of AMF inoculant in the form of AMF spores. In addition, AMF spore production takes a long time. AMF in the form of hyphae is an alternative as an inoculant because it has a faster infection capacity than AMF spores and does not break apart like AMF spores when made in the form of granular organic biofertilizer. The aim of this research was to analyze the effectiveness of various doses of AMF hyphae granule organic fertilizer on sugarcane plants. This research was conducted using a randomized block design. The treatment doses used were control (without AMF), 750 kg/ha, 1000 kg/ha, 1500 kg/ha, and 2000 kg/ha AMF hyphae granule organic fertilizer which was repeated five times. The results of the research showed that the application of AMF hyphae granule organic fertilizer at a dose of 1500 kg/ha could increase plant height, stem diameter, number of tillers and root infections of sugarcane plants. The P status of sugarcane plants increased from medium to high with a plant P content of 0.442% P2O5. This effect was seen more clearly in sugarcane plants grown in the field than grown in the greenhouse.

Theoretical study of the working body of a centrifugal type mixing plant

Relevance. The use of fertilizers in the agro-industrial complex is an important means to ensure sustainable development, food and environmental security. The scientific application of various types of fertilizers can reduce the negative impact on natural ecosystems, as well as optimize the use of resources and take into account the individual needs of each plant. Due to the balanced composition and biological modification by chelate complexes, fertilizer mixture has increased biological efficiency and stimulate plant growth. At the same time, there is an urgent task of obtaining mixtures that have a high degree of uniformity. In this connection, the requirements for the mixing equipment are very high, since the structural and kinematic parameters are the most important factors affecting the stability of the mixing process and the uniformity of the final mixture.Methods. Based on the analysis of existing mixing plants, the authors proposed the concept of a centrifugal type mixing plant with a working body in the form of a conical surface. In the course of the research, the processes occurring during the operation of the working body, the proposed centrifugal mixer, were studied using methods of mathematical analysis, graphical and mathematical modelling.Results. As a result of the research, it was found that the greatest influence on the change in the absolute velocity of the granules is exerted by the circumferential velocity of the granules, which is largely determined by the rotation frequency and parameters of the conical surface. In turn, it was found that over time, the angle between the direction of the absolute velocity of the fertilizer granules and the forming conical surface tends to the direction of the circumferential velocity, while with increasing rotation frequency, this indicator changes more rapidly.

Bioindustry Development of Environment Friendly Organic Granular Fertilizer at Farming Groups in West Kalimantan Indonesia

Management of organic fertilizers from cattle waste can increase economic growth in rural areas that are environmentally friendly and sustainable (a green economy). This study aims to obtain granular organic fertilizer products on the Farmer Group scale (home industry), which can increase added value and income of farmers to be environmentally friendly and sustainable. The management of this granular organic fertilizer utilizes site-specific (in-situ) technological innovations and the use of local resources that can restore sustainability. The analytical methods used are comparative analysis, namely comparing bulk fertilizer and granule fertilizer on efficiency and effectiveness, analysis of organic fertilizer from cattle waste using experimental design and institutional engineering. To achieve this goal, the research uses a rural agro-industry approach based on local agricultural resources and applies appropriate technological innovations. The results showed that the management of granular organic fertilizer from cattle waste can improve product quality and efficiency in the use of organic fertilizers. The management of this granular organic fertilizer is carried out using social engineering and strengthening of farmer group agribusiness institutions in rural areas that are environmentally friendly so that they can be sustainable. The utility of granular organic fertilizer is more efficient because it does not dissolve easily and is not carried away by water flows when done in irrigated agriculture or wetlands.

The role of an Ascophyllum nodosum extract in lowering the environmental impact and improving nitrogen use efficiency in pasture systems under a reduced nitrogen regime

Nitrogen is a macronutrient that is applied in substantial amounts as a chemical fertiliser to conventional agricultural systems. However, loss of nitrogen from agricultural systems to the environment, in the form of gases (N2O) and leachate (NO3), is detrimental to the environment. As such, improving the nitrogen use efficiency (NUE) of crops is an essential component of sustainable agriculture. Biostimulants are a category of products that improve NUE when applied to crops and/or soil. Here, we examined the effects of PSI-362, an Ascophyllum nodosum biostimulant mixed with and applied on calcium ammonium nitrate (CAN) granules, on grass yield, quality traits, and environmental impacts in lysimeter trials under natural weather conditions. By using PSI-362, it was possible to reduce nitrogen application by 25% without a significant loss in yield compared to a conventional 100% N system. We also observed an increase in NUE under a 75% N with PSI-362 co-application fertilisation regime, and a significant increase in crude protein content compared to the 100% N fertilisation controls. Furthermore, this reduced nitrogen application also resulted in reduced nitrogen loss through leachate (NO3) and N2O to the atmosphere. The total NUE for PSI-362 + fertiliser granules ranged from 58.7% to 78.6% depending on the biostimulant dose, which was significantly better than the fertiliser alone. Our results showed that this biostimulant, which can easily be incorporated into conventional agronomic practices, allows for a more sustainable approach to pasture-based systems.

THE INFLUENCE OF FERTILIZER TYPE AND Trichoderma harzianum INOCULATION ON THE GROWTH AND PHYSIOLOGY OF YOUNG PLANTS OF Cordia americana

In this study, we sought to determine the influence of combined treatments with different types of fertilizer and inoculation of the fungus Trichoderma harzianum on the growth and physiological characteristics of young plants of Cordia americana. To this end, we adopted a completely randomized experimental design, comprising six replications in a 5 × 2 factorial scheme, to assess the effects of five different types of fertilizer applied with or without T. harzianum inoculation. At 180 days post-planting, we performed measurements of plant height, stem diameter, leaf dry mass, root dry mass, stem dry mass, total dry mass, leaf area, Falker’s chlorophyll index, and chlorophyll fluorescence. It was found that the combined application of T. harzianum and a controlled-release fertilizer or manure-based organominerals was effective in enhancing the growth of C. americana plants under conditions similar to those in the field. The use of controlled-release fertilizer as a base fertilization was found to have a positive influence on all evaluated variables and was effective in maximizing the initial development of C. americana plants. Granulated fertilizers derived from swine manure were established to promote plant growth and photosynthetic efficiency, thereby confirming their efficacy as a fertilizer for the cultivation of C. americana.

Granulation of nanocomposites based on glauconite and urea: binding materials and characterization of activated mineral fertilisers

Relevance. Development of controlled release fertilisers and their granulation is at the forefront of agriculture and environment. With growing world population and increasing food demand, agriculture faces the challenge of efficient resource management and increased crop yields. In this environmentally friendly and easy to obtain and use fertilisers become a key element for sustainable development of agribusinesses. Aim. To study the complete cycle of creation of granular fertilisers based on new materials, including aggregation of mineral particles with different binding solutions and mechanochemical activation of initial mixtures of glauconite and urea. Potassium-containing clay mineral – glauconite of Karinskiy deposit (Russia) was used as a "container" material. Urea containing up to 46 wt % of nitrogen was used as an additive (nutrient) component for fertilisers. The following parameters were stable during mechanochemical preparation: mineral/urea ratio and abrasion type. Solutions with different nitrogen concentrations were used as binders during granulation. The methodology for investigating the characteristics of the resulting nanocomposites included particle size analysis, X-ray diffraction analysis, scanning electron microscopy, and FTIR spectrometer. Results. The advantages of different granulation options for mechanochemically activated composites were investigated. The authors have produced f full cycle of controlled-release granular fertiliser. The average nitrogen content in glauconite particles reaches 5.5 wt %. The granule size depends on the content of urea gel concentrate in the binder. The maximum strength and proportionality of granules are achieved, when using a binder consisting of 100% urea gel concentrate. Determination of the optimal content of gel concentrate in the binder used in granulation plays a key role in obtaining strong fertiliser granules.

Compression Strength and Critical Impact Speed of Typical Fertilizer Grains

The application of fertilizer is necessary for the growth and yield of crops, especially for paddy rice. Precision application is important for the fertilizer utilization rate and sustainable development of agriculture. However, the crushing of fertilizer grains will reduce the quality of fertilization, for the decrease in the size and mass of the fertilizer particles and the degree of crushing mainly depend on the physical and mechanical properties of the fertilizer grains. In this study, the compression strength and critical impact speed of four typical commonly used fertilizer grains, a compound fertilizer of nitrogen, phosphorus, and potassium (NPK compound fertilizer), organic fertilizer, large granular urea, and small granular urea, were measured and analyzed. The static compression test was carried out using a TMS-Pro texture analyzer and the results show that the four kinds of fertilizer grains are brittle materials, and their elastic moduli are 208 MPa, 233 MPa, 140 MPa, and 107 MPa, respectively; the theoretical impact model of fertilizer granules is established based on the compression test result and Hertz elastic contact theory, the theoretical formula for the critical impact speed of fertilizer grains is derived, and the theoretical critical impact strength and speed are worked out. An image capture system for the impact process of fertilizer grains was developed, and the impact test was conducted. The results show that the critical impact speed of the four kinds of fertilizer grains decreases with the increase in granule size, while the variance analysis shows that the effect is not significant. The comparison of the experimental results with the theoretical values shows that the theoretical formula could be used to predict the trends of the critical impact speed of fertilizer grains. The model was optimized with the MATLAB 2018 function fitting tool based on the test and analysis. The goodness of fit of the formula is 0.824, which is 13.43% greater than that of the original theoretical formula, indicating that the modified formula based on the compression test data might estimate the critical impact speed of the granular fertilizer with brittle material properties more accurately. The results may provide a reference for the parameter design of a precision fertilization machine.

Visualizing small-scale subsurface NH3 and pH dynamics surrounding nitrogen fertilizer granules and impacts on nitrification activity

In agricultural soils, nitrogen (N) fertilizer is typically applied as ammonium salts or urea, and undergoes microbially mediated oxidation. However, insights regarding substrate concentrations nitrifiers are exposed to in the zones immediately surrounding N fertilizer granules remain unexamined, as well as how this affects the activity or inhibition of nitrifier groups adapted to different ranges of ammonia (NH3) concentrations. To examine millimeter scale changes in soil chemistry after sub-surface fertilizer granule application with high spatiotemporal resolution, we applied a newly developed NH3 and pH planar optical sensor (optode) system. With this system, we visualized in situ subsurface NH3 production, diffusion, and associated pH shifts in an agricultural soil following the application (from 5 min up to 65.5 h) of ammonium chloride (NH4Cl) or urea granules in a laboratory study. Ammonia from both NH4Cl and urea granules diffused up to 1.5 and 2 cm and reached maximum concentrations of >49 and >130 ppmv, respectively. Spatially informed destructive subsampling (0.5–2 cm from granules) revealed that nitrate accumulation was greatest closest (0.5–1 cm) to the ammonium chloride granules, while nitrite was not detected. In contrast, urea application resulted in both nitrite and nitrate accumulation, with the highest concentrations detected furthest (1.5–2 cm) from urea granules. Urea hydrolysis also caused a significant localized pH increase, while ammonium chloride caused a circular elevated pH zone migrating outwards leaving a decreased pH at the center. Transcription of the ammonia-oxidizing bacterial amoA gene was highest in areas furthest (1.5–2 cm) from the urea granules, while there were no significant differences in amoA transcription with increasing distance from the NH4Cl granules. Ammonia-oxidizing archaea and comammox amoA transcripts were not detected. This study is the first to directly visualize small-scale subsurface changes in NH3 concentration and pH after fertilizer granule application and relate these to nitrification activity.

Use of shrimp farming waste in the production of biomaterials for sustainable agriculture and mitigation of environmental damage

AbstractBackgroundDue to the environmental degradation caused by shrimp farming in Brazilian mangrove ecosystems, it is of great importance to develop techniques capable of inserting waste into the production chain, strengthening the premise of sustainable shrimp farming development due to its economic and social impact. In this work, solid residues from shrimp farming were used as a slow‐release fertilizer (SRF) in formulations that also contain chitosan, montmorillonite, and urea.ResultsFertilizer granules produced without (FERT A) and with additional layers (FERT B) were characterized by elemental analysis (Carbon, Hydrogen, Nitrogen), obtaining values of 14.4%–18.4% for carbon, 5.6%–6.9% for hydrogen, and 12.3%–19.3% for nitrogen. The fertilizers had low C/N ratios of around 1.0–1.50, compared to a value of 0.87 for urea, the nitrogen fertilizer most widely used in Brazilian agriculture. Release tests in water showed the same release pattern in the first 5 min for FERT A and FERT B, with <10% urea release. After 30 min, the release from the fertilizers progressively increased, reaching >60% after 1 day and a maximum of 95%–97% after 15 days. In the first 3 days of incubation in the soil, the releases of nitrogen from FERT A, FERT B, and conventional urea presented different patterns, with values of 32%, 10%, and 90%, respectively. After incubation for 25 days, FERT A and FERT B presented nitrogen releases lower than 78%, confirming the slow release of the nutrient from these fertilizers. Degradation experiments showed that the fertilizers were biodegradable in the soil, with degradation exceeding 60% after 30 days, indicating that they could be applied to the soil without leaving residues.ConclusionsThe fertilizer granules produced are SRFs that have the potential to increase the efficiency of nitrogen fertilization, reducing the frequency of applications and minimizing nitrogen losses in the soil. In addition, they enable the reuse of shrimp farming waste, producing a new material of agricultural interest.