Slow-release Fertilizer Research Articles

Facile synthesis, release mechanism, and life cycle assessment of amine-modified lignin for bifunctional slow-release fertilizer

Biomass-based slow-release fertilizers (SRFs) are a sustainable solution for addressing food scarcity, improving fertilizer efficiency, and reducing pollution, whereas they still face complex preparation, high costs, and low release characteristics. This study introduces a simple and innovative approach to producing bifunctional green SRFs with controlled release and conditioning properties for saline soils and harsh environments. The method involves a one-pot preparation of microsphere-structured amine-modified lignin slow-release fertilizer (L-UX) using biomass lignin as the starting material. The L-UX demonstrates an exceptional fertilizer loading rate (66.2 %) and extended slow-release performance (288 h), effectively enhancing the fertilizer's release ability. Compared to traditional fertilizers, the bifunctional L-UX significantly improves soil water retention capacity (824.3 %), plant growth, and germination percentage in challenging soil conditions (133 %). These findings highlight the potential of L-UX as a large-scale controlled-release fertilizer in harsh environments. A life cycle assessment (LCA) was also conducted to evaluate the environmental impact of L-UX from its production to disposal. This revealed that L-UX has a minimal environmental footprint compared to conventional inorganic fertilizers. This study further supports the widespread application of L-UX as an environmentally friendly alternative.

Impact of fertilization depth on sunflower yield and nitrogen utilization: a perspective on soil nutrient and root system compatibility.

The depth of fertilizer application significantly influences soil nitrate concentration (SNC), sunflower root length density (RLD), sunflower nitrogen uptake (SNU), and yield. However, current studies cannot precisely capture subtle nutrient variations between soil layers and their complex relationships with root growth. They also struggle to assess the impact of different fertilizer application depths on sunflower root development and distribution as well as their response to the spatial and temporal distribution of nutrients. The Agricultural Production Systems sIMulator (APSIM) model was employed to explore the spatial and temporal patterns of nitrogen distribution in the soil at three controlled-release fertilizer (CRF) placement depths: 5, 15, and 25 cm. This study investigated the characteristics of the root system regarding nitrogen absorption and utilization and analyzed their correlation with sunflower yield formation. Furthermore, this study introduced the modified Jaccard index (considering the compatibility between soil nitrate and root length density) to analyze soil-root interactions, providing a deeper insight into how changes in CRF placement depth affect crop growth and nitrogen uptake efficiency. The results indicated that a fertilization depth of 15 cm improved the modified Jaccard index by 6.60% and 7.34% compared to 5 cm and 25 cm depths, respectively, maximizing sunflower yield (an increase of 9.44%) and nitrogen absorption rate (an increase of 5.40%). This depth promoted a greater Root Length Density (RLD), with an increases of 11.95% and 16.42% compared those at 5 cm and 25 cm, respectively, enhancing deeper root growth and improving nitrogen uptake. In contrast, shallow fertilization led to higher nitrate concentrations in the topsoil, whereas deeper fertilization increased the nitrate concentrations in the deeper soil layers. These results provide valuable insights for precision agriculture and sustainable soil management, highlighting the importance of optimizing root nitrogen absorption through tailored fertilization strategies to enhance crop production efficiency and minimize environmental impact.

Climate Change and Nitrogen Dynamics: Challenges and Strategies for a Sustainable Future

Global warming driven by climate change has profound impacts on nitrogen dynamics in terrestrial and aquatic ecosystems. The increased emissions of greenhouse gases alter the distribution and availability of nitrogen, which is a critical nutrient for all living organisms. This review examines the connections between climate change and nitrogen cycling, highlighting the adverse effects on ecosystem health and productivity. The proliferation of nitrogen pollution due to agricultural runoff, industrial effluents, and urban wastewater aggravates eutrophication, leading to significant environmental and economic consequences. The imbalance in nitrogen availability not only affects plant growth and soil fertility but also disrupts aquatic ecosystems, resulting in harmful algal blooms and hypoxic conditions. Effective mitigation and adaptation strategies are essential to addressing these challenges. Sustainable agricultural practices, such as precision farming and the use of slow-release fertilizers, along with robust policies and innovative technologies, like biochar application and nitrification inhibitors, are essential in managing nitrogen levels. This review underscores the importance of interdisciplinary approaches that involve integrating insights from ecology, agronomy, and the social sciences to develop comprehensive solutions. Future research should focus on long-term studies to assess the cumulative impacts of climatic changes on nitrogen availability and ecosystem health to guide policies and management practices for sustainable development.

Boronic ester bonds hydrogel with temperature and pH responsiveness for controlled release fertilizer

The growth of plants can be severely restricted by insufficient water and fertilizers in pure soil. There exists a significant demand for developing a hydrogel to enhance water retention and enable control release fertilizer. In this study, we synthesized the boronic ester bonds hydrogel with temperature and pH responsiveness using sodium alginate, borax pentahydrate and carboxymethyl chitosan (CMCS) via a one-pot method. Urea was loaded in the hydrogel as a model fertilizer. The dual responsive hydrogel exhibited a rapid release behavior of fertilizer due to the dissociation of boronic ester bonds at 40 °C and pH 5.5. The incorporation of CMCS improved the non-covalent interaction within the hydrogel, accompanied by a reduction in the pore size and swelling ratio to 74 μm and 11.3 g/g, respectively. The hydrogel exhibited desirable water retention capacity in soil with a weight loss of only 41.9 % at day 15, while the degradation rate of hydrogel was 49.0 %. Additionally, the hydrogel displayed good antibacterial activity against both Rhizobium and Bacillus cereus strains while being non-toxic to plants. The dual responsive hydrogel holds promising applications in agriculture, forestry, and horticulture.

Promising superabsorbent hydrogel based on carboxymethyl cellulose and polyacrylic acid: synthesis, characterization, and applications in fertilizer engineering

The combination of hydrogel and fertilizer as slow release fertilizer hydrogel (SRFH) has become one of the most promising materials to overcome the shortcomings of conventional fertilizer by decreasing fertilizer loss rate, supplying nutrients sustainably, and lowering the frequency of irrigation. The hydrogel based on carboxymethyl cellulose (CMC) and polyacrylic acid (PAA) (CMC/PAA) was synthesized. All materials, Vinasse, hydrogel (CMC/PAA) and (Vinasse/CMC-PAA) were characterized by FTIR, XRD, and SEM. The formed hydrogel was applied to control the salinity of Vinasse to use it as a cheap and economical fertilizer. The results showed that using the prepared hydrogel with Vinasse (V/CMC-PAA) as a slow-release organic fertilizer decreased the EC value through the first six hours from 1.77 to 0.35 mmohs/cm. Also, using V/CMC-PAA can control and keep the potassium as fertilizer for 50 days. The productivity per feddan from the sugar cane crop increased by about 15%, and the number of irrigations decreased from 5 to 4 times.

Impact of microplastic residues from polyurethane films on crop growth: Unraveling insights through transcriptomics and metabolomics analysis

The utilisation of coated controlled-release fertilizers (CRFs) leads to the persistence of residual plastic films in agricultural soils, posing a potential threat to crop health. This study investigates the impacts of four residual films (0.39 %, w/w) derived from CRFs in soil, including petrochemical polyether, bio-based polyether, castor oil polyester, and wheat straw polyester polyurethane on wheat growth. This study found that PecPEUR significantly reduced wheat plant height, stem diameter, leaf area, and aboveground fresh weight by 24.8 %, 20.2 %, and 25.7 %. Through an in-depth exploration of transcriptomics and metabolomics, it has been discovered that all residual films disrupted glycolysis-related metabolic pathways in wheat roots, affecting seedling growth. Among them, PecPEUR significantly reduced the fresh weight of aboveground parts by 20.5 %. In contrast, polyester polyurethane residue had no discernible impact on aboveground wheat growth. This was attributed to the enrichment of wheat root genes in jasmonic acid and γ-aminobutyric acid metabolic pathways, thus mitigating oxidative stress, enhancing stress resistance, and ensuring normal plant growth. This study, for the first time, provides comprehensive insights into the effects of polyurethane film residue on wheat seedling growth, underscoring its potential as a promising alternative to conventional plastics in soil.

Soil fertilization with microalgae biomass from municipal wastewater treatment causes no additional leaching of dissolved macronutrients and trace elements in a column experiment.

Microalgae are a promising bio-fertilizer that can be cultivated in municipal wastewater, where the organisms perform water purification by incorporation of nutrients and contaminants. Before bio-fertilization with wastewater-grown microalgae can be put into practice, its impact on the leaching of macronutrients and trace elements needs to be evaluated. Here, we studied the leaching behavior of a microalgae-fertilized soil against a control in column percolation setup. Microalgae were grown in real municipal wastewater supplemented with bromide for the analysis of within-cell Br- accumulation by time-of-flight secondary ion mass spectrometry. Dry biomass (45.0g N kg-1 and 28.9g P kg-1) was added to the topmost layer of the fertilized column at a level of 3g biomass kg-1 on a whole soil basis. Column irrigation was equivalent to 3 years of precipitation in central Germany. The leaching of macronutrients and trace elements from the fertilized and control columns was largely identical. Except for P, depth profiles confirmed very low vertical translocation within the soil. This is held for total element contents as well as for operationally defined pools, suggesting that microalgae cultivated in municipal wastewater provide a slow-release fertilizer largely resistant to leaching. Mass spectrometric imaging gave clear evidence for bromide uptake by the microalgae, and pure cultures of the genus Scenedesmus showed that it was preferentially located in the cell membrane. Therefore, bromide could potentially be employed as a mineralization tracer in future studies on the use of microalgae as a bio-fertilizer.

Effect of different rates of slow-release potassium fertilizers on growth and fruiting of banana var. Grand Nain plants

Effect of different rates of slow-release potassium fertilizers on growth and fruiting of banana var. Grand Nain plants

Urea Cocrystals as a Potential Fertilizer for Turfgrass: Responses of ‘Tifway’ Hybrid Bermudagrass and Nitrogen Release Behavior

Urea cocrystal materials are a potential fertilizer source that has shown to decrease environmental nitrogen losses. Novel nitrogen (N)-containing urea cocrystal fertilizers, CaSO4·4urea (UC1) and Ca(H2PO4)2·4urea (UC2), were synthesized using the mechanochemical method to form stable urea cocrystals to be tested as a fertilizer source for turfgrass. The objectives of this study were to 1) evaluate the response of ‘Tifway’ hybrid bermudagrass (Cynodon dactylon × C. traansvalensis Burt Davy) to N fertilization by urea cocrystals and traditional coated urea products (MU·PCU, methylene urea, urea, polymer-coated urea; PCU, polymer-coated urea, urea) supplied at two rates at the beginning of two, 10-week study periods conducted under a greenhouse setting and 2) investigate N release behavior of urea and two cocrystal products using a rapid water release test. In the turfgrass response study conducted in the greenhouse, improved turfgrass quality above the minimum quality threshold was observed when averaging across all products. For normalized difference vegetation index (NDVI), cocrystal outperformed all other products in the summer study and both cocrystal products outperformed the traditional product (MU·PCU) in the winter study. Further, both cocrystal products showed favorable growth responses compared with the commercial products provided by positive clipping production and vertical extension rates. In the nitrogen release experiment, a rapid water release test revealed the N release peak of urea was significantly higher than both UC1 and UC2. Furthermore, significantly higher N was leached from urea (15% loss) compared with both UC1 and UC2 (≈8% loss). Results from both studies provide evidence supporting suitability of urea cocrystal application on bermudagrass and potential as a slow-release fertilizer source through sustained turfgrass vigor, growth, decreased N release peak, and decreased leaching losses.

Optimizing modified natural rubber in starch-based hydrogels: A cost-effective approach for high-performance sustainable slow-release fertilizer coatings

Effective compatibility between natural rubber (NR) and cassava starch (CSt) is crucial for enhancing the water swelling and retention properties of CSt/NR-based hydrogels. In this study, NR was modified by grafting glycidyl methacrylate (NR-g-GMA, NRG) at 3, 6, and 9 parts per hundred rubber (phr) for blending with CSt. Subsequently, CSt was grafted with acrylamide (AM), crosslinked with N,N′ − methylene-bis-acrylamide (MBA), and interpenetrated with NRG to produce CSt-g-PAM/NRG hydrogels. The resulting CSt-g-PAM/NRGx (x = phr of GMA) hydrogels were characterized using FTIR, XRD, TGA, tensile testing, and water swelling measurements. Results revealed that CSt-g-PAM/NRG3 exhibited the highest equilibrium water swelling at 3300 %, surpassing CSt-g-PAM/NR (1430 %) and demonstrated the highest mechanical strength (0.92 MPa), desirable biodegradability (69 % at 30 days), and good water retention. These properties are attributed to the superior compatibility and stronger interactions between NRG and the CSt-g-PAM networks. Additionally, the WUHNRG3 (urea coated with CSt-g-PAM/NRG3 and wax layers) fertilizer demonstrated good biosafety, an acceptable slow-release rate (50.26 % at 30 days), and effectively promoted the growth of chili plants at a reasonable cost. This study demonstrates that modifying NR with optimal GMA content provides an effective CSt-g-PAM/NRG coating membrane, suitable for sustainable slow-release fertilizers and green agricultural practices.

Wood Distillate Interactions with Urea in Soil: A First Step to Developing a Slow-Release Next-Generation Fertilizer.

We tested the ability of wood distillate (WD) to interact with urea in agricultural soil. WD is a sustainable material that has been addressed as a promising alternative to synthetic soil corroborants. However, there is little information about the effect of WD on the nitrogen cycle. In this study, soils with different amounts of WD and with/without urea were tested for ammonium, urease, nitrate/nitrite, and potential nitrification activity at different points in a 30 day time frame. High concentrations of WD (1-2%) inhibited the hydrolysis of urea and the oxidation of ammonium to nitrate. Thermal desorption coupled to GC-MS and high-performance liquid chromatography-tandem mass spectrometry characterization allowed us to reveal that WD-urea interactions mainly involve lignin-derived compounds in the distillate, such as catechol, resorcinol, and syringol. This study provides the first evidence of a strong interaction between WD and urea in soil that could be used to develop slow-release fertilizers.

Acetylated lignin sulfonate as a biodegradable coating for controlled-release urea fertilizer: A novel acetylation method and diffusion coefficient analysis

Plants require essential nutrients to grow, which soil alone cannot provide. Chemical fertilizers like urea supply the necessary nutrients, including nitrogen. They quickly dissolve in water and can contaminate it with nitrate and nitrite, which can cause diseases. Slow-release fertilizers are a better option to reduce environmental risks. Researchers are exploring cheap and biodegradable alternatives, such as lignin. A critical discussion in the coated urea fertilizer is modeling the nitrogen diffusion process in the coating, which predicts the system's behavior. This article uses lignin sulfonate to coat urea fertilizer, which should first be acetylated with decanoyl chloride. One of the critical parameters is the diffusion coefficient (D). D is determined using the mass transfer flux and the completion time of the effective substance, and with its help, the graph of the total mass transferred from the membrane in a specific time (Mt) is determined. D equals 6.298813 × 10−8 cm2/s using the time lag method. Also, with the fixed-point convergence method, 5.8849 × 10−8 cm2/s was obtained, which has about 0.80 % error with the D obtained by the time lag method. The Mt obtained from the analytical method and the experimental data coincides with a minimal error, which indicates high accuracy.

Electrochemical Recovery of N and P from Municipal Wastewater

Phosphorus, P, is a vital element of paramount importance for both humans and for the Environment. Wastewater contains often relatively high concentrations of P which can be recovered as crystalline struvite (MgNH4PO4·6H2O, MAP). This option is quite attractive in assisting sustainable development because struvite can be used as a slow-release fertilizer. Domestic wastewater is usually high in P and nitrogen, N, but relatively poor in magnesium, Mg. It is necessary to develop low-cost solutions for the enrichment of wastewater with Mg. In the present work, sacrificial magnesium anodes were used, which dissolve upon anodic polarization, releasing sufficient magnesium for the selective precipitation of MAP. The application of constant current between two electrodes of which the anode is a low-cost magnesium cylindrical rod (4 cm2 exposed surface area) and the other a platinum cathode electrode, both immersed in ammonium phosphate solutions, without adjustment of the solution pH, was investigated. Constant current density over the range 10–100 A·m−2, between the Mg- Pt electrodes immersed in solutions of ammonium hydrogen phosphate of exactly known initial concentration, was applied using a potentiostat. In the presence of sodium chloride solutions, on the magnesium anode and in the bulk solution, Mg(OH)2 (brucite) formed because of the passivation of the Mg electrode. In dilute ammonium hydrogen phosphate solutions, the magnesium anode dissolution resulted in struvite precipitation, even at a low applied current (10 mA). Struvite crystals with an average size of 20 μm were precipitated. The behavior of the cell for the electrolyte solutions used was Faradaic as long as the surface coverage of the anode was relatively low. The anodic dissolution of Mg resulted in high pH values (pH 11) eliminating the need for alkali addition.

Benefits of controlled-release fertilizers for potato sustainable nitrogen management

The evaluation of potato response to controlled-release fertilizers (CRFs), as a sole source of nitrogen (N) or as a blend with a soluble N source, is essential to 1) develop the best management recommendations for using CRFs in potato production and 2) provide guidelines to CRF manufacturers for developing an optimal product. This study aimed to evaluate the potato yield and quality responses to N CRFs (polymer-coated urea [PCU]) vs soluble N sources. The experiments were conducted in major potato-growing regions in the United States and China. The current industry-recommended practice of 112 kg N/ha pre-plant soil broadcast of urea plus five in-season fertigations of 224 kg N/ha as urea ammonium nitrate (UAN-32) was compared to a single pre-plant application of 224 kg N/ha as a CRF as the sole source of N or as multiple blends of CRFs and soluble N sources (i.e., urea) at various ratios. The results demonstrated that petiole nitrate_N (NO3_N) levels and tuber yield with single pre-plant broadcast applications of 224 kg N/ha as CRF/urea blends (ratio of 25/75 or 50/50) were similar to those obtained with industry-standard N management practice. N uptake and yield were significantly greater with 220 kg/ha N as the CRF than those with the same N rate as urea. Unlike the current potato industry N practice, using CRFs as either a sole source of N or blended with urea reduces the total N rate and application frequency.

Synthesis and characterization of chitosan-modified membrane for urea slow-release fertilizers

BackgroundUrea is a fertilizer widely used by farmers, especially vegetable farmers, due to its high nitrogen content, around 46 %. However, plants only use a small amount of nitrogen, a maximum of 35 %, while the remaining nitrogen is wasted and released into the environment. Undeniably, it causes increases production costs and environmental problems. A slow-release urea fertilizer (SRF) has been formulated to resolve these issues. MethodsIn this study, the membrane was made of chitosan with several crosslinking agents such as Tripolyphosphate (TPP). In addition, calcium ion bonds are expected to increase the interaction with urea fertilizer through the encapsulation process. The resultsOur data showed that urea slow-release fertilizer (SRF) with the chitosan/TPP/Ca membrane, was successfully synthesized. This membrane has the characteristics of a thin white layer that is transparent. The physical and chemical characterization of SRF membranes with various coating membrane variations showed that the chitosan/TPP/Ca-urea membrane has Young's modulus of 7.75–22.05 N/mm2, swelling of 109.52–132.62 % and porosity of 0.756–1.06 %. Functional group analysis shows that several spectral changes indicate the presence of crosslinking process between the chitosan functional groups and TPP. The urea release results show that the membrane is released through a diffusion mechanism. Furthermore, SEM results show that these membranes have pores with various shapes and sizes. ConclusionBased on the result, it can be concluded that chitosan membrane modification with the addition of TPP and calcium oxide provides improved membrane characteristic cs including degree of development, hydrophobicity, membrane stress, and nitrogen release on the membrane. This membrane shows is indicating suitability as a slow-release fertilizer.

Combined effect of thermal hydrolysis process and low-temperature pyrolysis on the classification and bioavailability of phosphorus in sewage sludge

Existing phosphorus (P) resources are becoming increasingly scarce, so it is necessary to recover P from potential sources. This paper is based on thermal hydrolysis process (THP) at 140–180 °C, coupled with low-temperature pyrolysis at 300 °C, to study its effect on the recovery and conversion of P from sewage sludge. Most significant change was observed in apatite P, which increased from 3.43 ± 0.48 mg/g in raw sludge to 30.17 ± 1.17 mg/g in biochar (BTHP-180-4-300) during optimal process (THP condition: 180 °C, 4 h; pyrolysis condition: 300 °C). Reactions between phosphates and metal ions became more complete during this combined process. Unstable forms of P were converted into more stable forms, with transformations from Al-P and Fe-P toward Ca-P compounds like Ca3(PO4)2, Ca3Mg3(PO4)4, Ca2P2O7, and Ca(H2PO4)2, making P less degradable and more suitable as slow-release fertilizers. Additionally, P characteristics of actual THP in a sewage treatment plant were similar to those of laboratory THP.

Synergistic recovery of aluminum phosphorus from incinerated sewage sludge ash via acid and alkaline treatment

The “phosphorus (P) crisis” has increased interest in improving P recovery methods and their efficiency. Incineration of sewage sludge ash is a recognized method for efficient P recovery, but challenges persist because of low recovery efficiency using thermochemical or biological methods and the issue of heavy-metal contaminants. Traditional wet-chemical processes, which yield calcium phosphate as the main product, are complex and costly. In contrast, aluminum (Al) phosphate (AlP) not only serves as a slow-release phosphate fertilizer but also has diverse high-value industrial applications, such as its use in battery coatings. To address these challenges, we developed a novel recovery route based on AlP extraction from Al-rich incinerated sewage sludge ash via acid leaching and alkaline precipitation. Our findings indicate that nitric acid (HNO3) achieves the highest Al leaching efficiency. The leaching kinetics of PO43− and metals follow second-order kinetics. Furthermore, pH adjustment with NaOH showed that the P precipitation efficiency from oxalic acid leachate was lower than that from hydrochloric acid, sulfuric acid (H2SO4), and HNO3 (88.0%–99.8%) because of buffering effects. These results underscore the potential of Al-rich ash for effective P recovery and considerably broaden the range of applications for P products.

Higher rice productivity and lower paddy nitrogen loss with optimized irrigation and fertilization practices in a rice-upland system

Intermittent irrigation and controlled-release fertilizers are considered effective practices for rice growth; however, their combined effects on nitrogen (N) loss from intensified agricultural lands remain unclear. Here, a two-year field experiment was conducted using two irrigation regimens (flooded irrigation, FI; controlled irrigation, CI) and two fertilizer types (conventional urea, CU, split applied; controlled-release blend fertilizer, CRBF, one-time basal applied) to investigate their effects on N turnover in rice upland systems. The results demonstrated that CI not only saved 56.7 % of irrigation water compared to FI but also increased rice yield (5.3 %) and N use efficiency (7.8 %). The significant reduction in water input and soil water content for the CI led to lower N leaching (47.5 %) and N runoff (20.2 %) than for the FI. In contrast, N2O emissions increased by 27.8 % under CI compared with FI. CRBF reduced NH3 volatilization by 18.8 % and improved N use efficiency by 14.0 %, due to decreased N diffusion from the soil to surface water compared to CU. However, the N runoff of the CRBF was 23.8 % greater than that of the CU. The CI-CRBF improved the rice yield by 6.3 % and decreased N loss (22.3 %) by reducing NH3 volatilization (21.4 %) and N leaching (46.9 %). The findings suggest CI-CRBF to be an eco-friendly and lightly simplified pattern in rice upland systems, with higher rice productivity and lower paddy N loss.

Exploring sustainable agriculture: Investigating the impact of controlled release fertilizer damage through bonded particle modeling

Controlled release technology of chemical fertilizers is an important cornerstone for the efficient development of sustainable agriculture. Damage to the coating layer and fragmentation of particles during the application of controlled release fertilizers can lead to the loss of their controlled release properties, making the development of effective damage reduction operations a key focus in the study of such agricultural materials. Therefore, this paper employs the bonded particle model (BPM) method within the discrete element method (DEM) framework to investigate the mechanism of coating damage in controlled-release fertilizers. It establishes a classification of damage types based on the level of damaged particles as an effective analytical approach. Furthermore, a comparative analysis is conducted between the discrete element particle model (DEPM) method and the bonded particle model method in terms of their performance in discharge mechanics and flow characteristics. The results indicate that the breakage rate of fertilizer discharge is influenced by both the formation of a steady state and the depletion of the fertilizer load within the container, with an average breakage rate of 1.511% over the total period. Differences in the average maximum compression force and mass flow rate between the discrete element particle model group and the bonded particle model group were 60.355 N and 1.998 g/s, respectively, reflecting limitations imposed by the fertilizer models on expected damage deformation behaviors. This study elucidates the process and potential impacts of fertilizer particle damage and deformation, revealing the strengths and limitations of two simulation model approaches under different application conditions, providing insights for sustainable agricultural production and technological innovation in fertilization equipment.

The effect of different peat-free growing media and fertilization levels on the plant nutrition of Leucanthemum vulgare (lam.) and Dianthus barbatus (L.)

Research on peat-free substrates is increasing due to the environmental concerns associated with peat extraction and with the aim of promoting sustainable horticultural practices. Previous research has shown that green compost mixed with coconut coir dust and stabilized wood fiber can be a valuable peat-free alternative for growing media. This study extends this knowledge by exploring the possibility of reducing fertilization levels by exploiting the nutrient content of green compost. In this paper we tested two ornamental herbaceous perennial plants, Leucanthemum vulgare Lam. and Dianthus barbatus L. For each species, we carried out five different substrate mixtures: 1) peat:pumice 70:30 v v−1; 2) coconut coir dust:pumice 70:30 v v−1; 3) coconut coir dust:green compost 55:45 v v−1; 4) green compost:stabilized wood fiber 60:40 v v−1; and 5) coconut coir dust:green compost:stabilized wood fiber 40:30:30 v v−1. For each mixture, we explored three different levels of fertilization: i) no fertilizer application; ii) low dosage of a controlled-release fertilizer at 2 g L−1; and iii) high dosage of the same controlled-release fertilizer at 4 g L−1. Plant biomass, biometric parameters, eco-physiological parameters, and plant mineral content were measured as performance indicators. The results showed that the nutrient surplus provided by the peat-free substrate, particularly when it contains green compost, can enhance the growth potential of the plants. Adding green compost to non-peat substrates can be an opportunity to optimize plant nutrition while reducing the presence of peat in plant nurseries and the use of chemical fertilizers.