Use Of Slow-release Fertilizers Research Articles

Effect of slow-release mineral fertilizer on the intensity of phosphorus and potassium mobilization in soil

The search for new technologies for effective regulation of yield and soil fertility is an urgent task. The use of slow-release fertilizers can simultaneously solve both problems – reducing fertilizer rates and increasing the mobilization of soil nutrients. In this paper, the mechanism of slow-release fertilizer effect on the mobilization rate of soil nutrients was investigated using mathematical modeling on the data of field trials with winter wheat. It is shown that in the plots with the slowest dissolving fertilizer (azofoska with 20% content of polyvinyl alcohol), the highest efficiency of azofoska was achieved (an increase in yield of 1.3 t/ha and an increase in mobile forms of phosphorus in the soil of 2.5 mg/100 g soil, potassium – 8.8 mg/100 g soil and nitrate nitrogen – 4.7 mg/100 g soil). The results of phosphorus modeling quantitatively confirmed the assumption that the low rate of dissolution of fertilizer enhances the mobilization of nutrients from soil due to the absence of an excess of plant available nutrients. We provide estimates of the polymer added efficiency for a series of polymer-modified fertilizer. It is shown that this form of fertilizer can be applied to effectively reduce the amount of fertilizer required for the planned harvest, simultaneously with the possibility of bringing the soil to a higher level of effective fertility in major nutrient elements.

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.

Optimization the growth and quality of ‘Picual’ olive plants according to the dose of slow-release fertilizer

Due to its importance for oil production in Brazil and worldwide, the ‘Picual’ olive trees deserves special attention of to its good climatic adaptation and high yield and stability in the oil produced. However, there is a need to generate more technical information to improve the propagation and production system for nursery plants. The use of slow-release fertilizer (SRF) affects the quality standard of the plants formed in the nursery. The purpose of this study was to evaluate the effect of doses (0, 1.5, 3.0, 6.0, and 12 g L−1) of the SRF, Osmocote® (NPK 14-14-14), on morphological, biochemical and nutritional parameters of ‘Picual’ olive plants. It was found that the average value of maximum technical efficiency dose (MTED) for several morphological variables (plant height, stem diameter, total plant dry weight and root volume) was 7.18 g L−1. Furthermore, an Osmocote® dose of 8.35 g L−1 resulted in optimal leaf number and area. For the carbohydrate concentration (sucrose, starch and Total Soluble Sugar) in leaves, the best average values were obtained at 4.51, 5.48 and 6.12 g L−1 of Osmocote®, respectively. Additionally, the best growth responses of plants may also be due to increased internal macronutrient concentration such as nitrogen (N), phosphorus (P) and potassium (K) after treatment with 7.87 g L−1 of Osmocote®. The use of SRF (Osmocote®) is a viable alternative in the production of ‘Picual’ plants, as it promotes good morphological characteristics, synthesis of photosynthetic products as well as satisfactory nutritional status and plant growth.

Dune soil nitrogen leaching for Chinese-yam cultivation: Impact of microbe-decomposable slow-release fertilizer

Chinese yam production is thriving in Aomori Prefecture, a cold and snowy region in Japan. Recently, there has been an increasing risk of nitrogen leaching in Chinese-yam fields, which consist of sandy soil, due to localized torrential rain. The relationships between the type of fertilizer used for Chinese-yam cultivation, the amount of nitrogen (N) leaching, and the timing of leaching remain unknown. Therefore, this study aimed to fill this knowledge gap by investigating the effects of different fertilizers (fast-acting and/or slow-release fertilizer) and irrigation practices (conventional and/or excessive irrigation) in order to mitigate the detrimental impact of nitrogen leaching on groundwater quality. An enhanced mathematical model and the spatiotemporal dynamics of inorganic nitrogen concentration in soil pore water were evaluated the negative impact of nitrogen leaching on the groundwater environment was evaluated. The results showed that the combined use of slow-release fertilizers could significantly reduce nitrate-nitrogen concentration in soil-water, especially during the harvest season. This study demonstrated that cultivating Chinese yam with a fertilizer application system that includes the use of slow-release fertilizer can diminish the negative impact of nitrogen leaching on the groundwater environment, contributing to our understanding of sustainable agricultural practices in regions facing similar environmental challenges. Therefore, our findings represent an important advancement providing new approaches to maintaining productivity while mitigating the adverse impacts on groundwater environments, as well as offering guidelines for agricultural practices in regions facing similar environmental challenges.

Superior glucose metabolism supports NH4+ assimilation in wheat to improve ammonium tolerance.

The use of slow-release fertilizers and seed-fertilizers cause localized high-ammonium (NH4 +) environments in agricultural fields, adversely affecting wheat growth and development and delaying its yield. Thus, it is important to investigate the physiological responses of wheat and its tolerance to NH4 + stress to improve the adaptation of wheat to high NH4 + environments. In this study, the physiological mechanisms of ammonium tolerance in wheat (Triticum aestivum) were investigated in depth by comparative analysis of two cultivars: NH4 +-tolerant Xumai25 and NH4 +-sensitive Yangmai20. Cultivation under hydroponic conditions with high NH4 + (5 mM NH4 +, AN) and nitrate (5 mM NO3 -, NN), as control, provided insights into the nuanced responses of both cultivars. Compared to Yangmai20, Xumai25 displayed a comparatively lesser sensitivity to NH4 + stress, as evident by a less pronounced reduction in dry plant biomass and a milder adverse impact on root morphology. Despite similarities in NH4 + efflux and the expression levels of TaAMT1.1 and TaAMT1.2 between the two cultivars, Xumai25 exhibited higher NH4 + influx, while maintaining a lower free NH4 + concentration in the roots. Furthermore, Xumai25 showed a more pronounced increase in the levels of free amino acids, including asparagine, glutamine, and aspartate, suggesting a superior NH4 + assimilation capacity under NH4 + stress compared to Yangmai20. Additionally, the enhanced transcriptional regulation of vacuolar glucose transporter and glucose metabolism under NH4 + stress in Xumai25 contributed to an enhanced carbon skeleton supply, particularly of 2-oxoglutarate and pyruvate. Taken together, our results demonstrate that the NH4 + tolerance of Xumai25 is intricately linked to enhanced glucose metabolism and optimized glucose transport, which contributes to the robust NH4 + assimilation capacity.

Technical and Economic Feasibility of Controlled Release Fertilizer in Production Coffee Crop

Objective: To evaluate the performance of a controlled release fertilizer on the vegetative and productive development of coffee trees in production. Theoretical framework: The use of slow, controlled release fertilizers or smart fertilizers can allow the reduction of fertilization operations, in addition to being characterized by the availability of nutrients to plants at the correct time, with the consequent reduction in maintenance expenses, labor of work and fuel. Method: A trial was conducted in Alto Paranaíba, Minas Gerais, during 4 harvests, to evaluate the performance of a slow-release fertilizer on the vegetative and productive development of coffee trees in production, as well as the impacts of this technology on the scaling of mechanized operations in property. Results and conclusion: With the use of slow-release fertilizers, it was concluded that: slow-release potassium nutrition reduces the competitive effect of potassium with Calcium and Magnesium; productivity gains are obtained when compared to the use of conventional fertilizers; there is an increase in coffee yield; at a rate of 80% of the dose, there are advantages in the nutrition of the coffee plant, especially in old crops; There is a reduction in the number of machine hours worked in the agricultural year with a consequent reduction in production costs, making it possible to redistribute mechanized operations, reducing labor and the volume of operations in the months that demand the most services. Implications of the research: With the results of the research, over two biennia, it was possible to identify the positive factors of using slow-release fertilizers for coffee trees, both in biometric and productive aspects and in the optimization of mechanized operations in a coffee farm cultivated in the cerrado miner. Originality/value: a better understanding of the effects of using slow-release fertilizer technology to increase productivity and better economic and environmental performance in coffee agribusiness.

Poly(vinyl alcohol)/sodium alginate polymer membranes as eco-friendly and biodegradable coatings for slow release fertilizers.

The use of slow release fertilizers (SRFs) is an effective approach for reducing agriculture cost, environmental and ecological issues simultaneously. The present study provides a series of poly(vinyl alcohol) (PVA)/sodium alginate (SA) polymer membranes as eco-friendly and biodegradable coatings for SRFs. Moreover, polymer-coated urea (PCU) granules were fabricated through coating the urea granules with the resulting membranes. Our first interest was to fabricate three membranes (PS1, PS2, PS3) of different PVA/SA weight ratios (9:1, 8:2, 7:3) using glutaraldehyde as a crosslinking agent, and crosslink the PS3 membrane with a CaCl2 solution further to obtain the PC3 membrane. The chemical properties and morphologies of the membranes were characterized. Second, the nitrogen release behavior of the PCU granules was measured and calculated, respectively. Crosslinking with glutaraldehyde made the PS1, PS2, PS3 membranes uniform and compact, whereas crosslinking with a CaCl2 solution formed an 'egg box' structure inside the PC3 membrane. PS3 membrane with the minimum PVA/SA weight ratio had the highest hydrophily (water uptake: 106.25%, water contact angle: 55.1o ), whereas PC3 membrane had the lowest hydrophily (water uptake: 21.57%, water contact angle: 67.3o ). The biodegradation ratios of the membranes were in the range 44-60% in 90 days, indicating that they had excellent biodegradability. The measured fractional release on the day 30 of the PCU granules ranged from 89.33% to 97.07%. The calculated nitrogen release behavior agreed well with the measured values. The resulting eco-friendly and biodegradable PVA/SA membranes are alternative coatings for SRFs. © 2022 Society of Chemical Industry.

Response of bacterial compositions to the use of slow-release fertilizers with long-acting agents and synergists

Slow-release fertilizer (SRF) is a new type of fertilizer, which is consistent with the physiological nutrient requirements of crops, but can also improve fertilizer utilization by reducing the total amount of fertilizers and the number of applications. However, its effects on soil fertility and bacteria in sugarcane fields are not clear. This study investigated the proper usage of SRF and the long-term application of SRF on soil fertility and health in sugarcane fields, seven fertilization treatments were set up as follows: SRF + 125 g/t long-acting agent (A), SRF +150 g/t long-acting agent (B), SRF + 235 g/t long-acting agent (C), SRF + 3 kg/t synergists (D), SRF + 8 kg/t synergists (E), SRF + 18 kg/t synergists (F) and traditional fertilization (CK). Traditional and Illumina HiSeq high-throughput sequencing technologies were used to compare and analyze soil enzyme activity, microbial biomass, and other biological traits and bacterial diversity. The results showed that sugarcane yields could be significantly increased by the application of SRFs. Meanwhile, soil fertility, which was represented by the content of total organic matter, nitrogen, phosphorus, and potassium, or the available nitrogen, phosphorus, and potassium, were all significantly improved or similar to those of CK. Moreover, the bioindicators of soil fertility, such as the activities of soil enzymes (β-Glucosidase, aminopeptidase, and phosphatase) and soil microbial biomass (carbon, nitrogen, and phosphorous), were also significantly increased or similar to those of CK in most of the SRFs treatments. In comparison with CK, soil microbial diversity, richness, and soil bacterial community structures were not significantly altered in sugarcane fields under different SRFs applications. In addition, although unclassified_f__Acetobacteraceae, Humibacter, and norank_f__Caulobacteraceae were the unique dominant bacterial genera in CK, some soil bacterial genera, such as unclassified__Subgroup_6, unclassified__Subgroup_2 and unclassified__IMCC26256 were also enriched as the special soil dominant bacterial genera in all or parts of the SRFs treatments. i.e., soil bacterial community structures also were not destroyed by SRFs application which compared to CK. In comparison to CK, cane yields increased significantly over three years, but soil fertility and health in sugarcane fields could also be improved or maintained by SRFs applications. All of the above results indicate that the traditional fertilization method for sugarcane production can be completely replaced by SRFs application. Furthermore, based on the cane yields and the prices of sugarcane and fertilizers in the local area, the treatment C can be concluded as the most cost-effective SRFs usage among the six SRFs treatments: A to F.

Fertilization methods affecting ‘Tahiti’ lime (Citrus latifolia) fruit yield and profitability

In Puerto Rico, the most commonly planted citrus crops are oranges, mandarins and limes. Farmers still have an interest in citrus production despite the detrimental effect of the Huanglongbing (HLB) disease on island orchards. Vector control and use of slow-release fertilizers (SRF) and soluble fertilizer (SF) applications to the soil are among the recommended management practices to increase citrus production. In 2009, the Department of Agriculture of Puerto Rico (DAPR) appointed the fruit tree specialist from the University of Puerto Rico and a DAPR staff member to evaluate the condition of citrus production in Puerto Rico. Based on that evaluation, DAPR developed an initiative to increase the number of marketable fruits of oranges, mandarins, and limes from trees between five and 12 years of age by promoting the use of SRF in combination with SF applications to the soil. An experiment was established during 2011 in a seven-year-old ‘Tahiti’ limeorchard in Ciales, Puerto Rico, to compare fertilization methods promoted by the DAPR with conventional methods, estimating the profitability of each method. The DAPR fertilizer recommendations were developed specifically for situations where HBL is present. In the orchards under study, HBL was not observed and therefore not tested. This does not mean that trees were not infected because symptoms may take months or years to become visible. The fertilization methods evaluated were: (1) granular fertilizers applied every four months (conventional fertilization), (2) manual application of SRF twice a year plus the application of SF to the soil with a backpack sprayer four times a year (SRF+SF/backpack), (3) manual application of SRF twice a year plus the application of SF to the soil with a motorized sprayer four times a year (SRF+SF/motorized), and (4) manual application of SRF twice a year. Total fruit number, total fruit weight, and average fruit weight were measured. Harvests were carried out monthly for 15 months. In the first seven harvests, the performance of trees submitted to the combination of SRF and SF was more efficient than was conventional fertilization or SRF alone, since the same production was maintained using a considerably lower amount of nutrients. At 14 months, the application twice a year of SRF alone almost doubled yield although the effect of this treatment was inconsistent during the year. We estimate that the combination of SRF and SF applications to the soil will result in the highest profitability with an income of $27 per tree per year and a profitability of $8.05 per dollar spent.

Management Strategies to Mitigate N2O Emissions in Agriculture.

The concentration of greenhouse gases (GHGs) in the atmosphere has been increasing since the beginning of the industrial revolution. Nitrous oxide (N2O) is one of the mightiest GHGs, and agriculture is one of the main sources of N2O emissions. In this paper, we reviewed the mechanisms triggering N2O emissions and the role of agricultural practices in their mitigation. The amount of N2O produced from the soil through the combined processes of nitrification and denitrification is profoundly influenced by temperature, moisture, carbon, nitrogen and oxygen contents. These factors can be manipulated to a significant extent through field management practices, influencing N2O emission. The relationships between N2O occurrence and factors regulating it are an important premise for devising mitigation strategies. Here, we evaluated various options in the literature and found that N2O emissions can be effectively reduced by intervening on time and through the method of N supply (30–40%, with peaks up to 80%), tillage and irrigation practices (both in non-univocal way), use of amendments, such as biochar and lime (up to 80%), use of slow-release fertilizers and/or nitrification inhibitors (up to 50%), plant treatment with arbuscular mycorrhizal fungi (up to 75%), appropriate crop rotations and schemes (up to 50%), and integrated nutrient management (in a non-univocal way). In conclusion, acting on N supply (fertilizer type, dose, time, method, etc.) is the most straightforward way to achieve significant N2O reductions without compromising crop yields. However, tuning the rest of crop management (tillage, irrigation, rotation, etc.) to principles of good agricultural practices is also advisable, as it can fetch significant N2O abatement vs. the risk of unexpected rise, which can be incurred by unwary management.

The carbon footprint of beef cattle systems in the Southeast United States

Grasslands in the Southeast United States (SE US) cover 15.8 million ha and most of this area is dedicated to beef production systems. This region holds 6.3 million beef cows and 12.1 million cattle, including calves. Beef cattle systems in the SE US are mostly cow-calf based, and most of the greenhouse gas emission from cattle occurs during this phase (cow-calf) because of their forage-based diet. This review assessed the carbon footprint (C footprint) of beef cattle systems in the SE US and indicates possible ways to reduce it. Major emissions in beef cattle systems come from livestock enteric fermentation and greenhouse gases from excreta. Cow-calf systems in the SE US are typically low input, although they use some industrial fertilizers, machinery, and fossil fuel, which adds to the C footprint of the sector. There are opportunities to reduce the beef C footprint in the SE US by adopting climate-smart practices, including preservation of natural ecosystems that have potentially high carbon sequestration, afforestation, integration of forage legumes (and reduction of nitrogen fertilizer), use of slow-release fertilizers, and dietary interventions. In fact, depending on the level of adoption of some of these practices, it is possible to establish climate-neutral beef at the farm gate in the SE US. Beef is a key food for humans and has large economic effects. Development of climate-smart beef could create opportunities for a niche market that recognizes the environmental footprint of agricultural production and could incentivize producers to pursue those systems.

Crystallization of struvite-K from pumpkin wastes.

Use of slow-release fertilizers derived from biological sources is important in sustainable agricultural development. Struvite-K (KMgPO4 ·6H2 O) is magnesium potassium phosphate mineral that has high potential for use as fertilizer in agriculture. Struvite-K is particularly suitable for slow-release fertilizer systems since struvite-K crystals are sparingly soluble in water. Seeds of pumpkin Cucurbita pepo L. are recovered and consumed as food, but the remaining pulp has no economic value. The present study evaluated the feasibility of struvite-K crystals recovery from pyrolysis products of pumpkin wastes. In the study C. pepo pulp was decomposed at high temperatures and potassium was extracted from the residue and then crystalized from the solution by addition of NaH2 PO4 ·2H2 O and MgCl2 ·6H2 O salts. Struvite-K was characterized by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy-energy-dispersive X-ray (SEM-EDX) spectroscopy and X-ray diffraction (XRD) analysis. The study revealed pumpkin wastes can be evaluated as source of potassium and 80% of potassium could be recovered as struvite-K crystals, which have a potential use as a slow-release mineral fertilizer for sustainable agriculture operations. © 2021 Society of Chemical Industry.

Studi Adsorpsi-Desorpsi Anion Fosfat Pada Bentonit Termodifikasi CTAB

Adsorption-desorption studies of phosphate on CTAB modified bentonite have been investigated. The results were characterized by FT-IR spectrometer to determine the functional groups in bentonite and X-ray diffractometer to determine the type of minerals in the bentonite. Adsorption was conducted by shaking 10 mg adsorbent in 5 mL adsorbate solution at the optimum condition of pH, contact time, and concentration. Furthermore, desorption studies were conducted on 5 mL medium of both water and citric acid 0.33 M and using 6.5 mg of adsorbent which has adsorbed phosphate. The results showed that the bentonite has been successfully modified with CTAB. The adsorption capacity of phosphate is 0.028 mmol g-1. Desorption studies showed that the solubility percentage of phosphate anion in citric acid was 0.33 M (73.33%) greater than in water (57.81%) which is a requirement for the use of slow-release fertilizers (SRF).

The Impact of a Controlled-Release Fertilizer on Greenhouse Gas Emissions and the Efficiency of the Production of Chinese Cabbage

Optimization of plant fertilization is an important element of all quality systems in primary production, such as Integrated Production, GLOBAL G.A.P. (Good Agriculture Practice) or SAI (Sustainable Agriculture Initiative). Fertilization is the most important element of agricultural treatments, affecting the quantity and quality of crops. The aim of the study was to assess greenhouse gas (GHG) emissions in the cultivation of Chinese cabbage, depending on the technological variant. The factor modifying the production technology was the use of fertilizers with a slow release of nutrients. One tonne of marketable Chinese cabbage crop was selected as the functional unit. To achieve the research goal, a strict field experiment was carried out. Calculation of the total amount of GHG emitted from the crop was made in accordance with ISO 14040 and ISO 14044. The system boundaries included the production and use of fertilizers and pesticides, energy consumption for agricultural practices and the emission of gases from soil resources and harvesting residue. The use of slow-release fertilizers resulted in a greater marketable yield of cabbage compared to conventional fertilizers. The results of the research indicate a significant potential for the use of slow-release fertilizers in reducing agricultural emissions. From the environmental and production point of view, the most favourable variant is the one with 108 kg N·ha−1 slow-release fertilizers. At a higher dose of this element, no increase in crop yield was observed. At this nitrogen dose, a 30% reduction in total GHG emissions and a 50% reduction in fertilizer emissions from the use of per product functional unit were observed. The reference object was fertilization in accordance with production practice in the test area.

Assessment of the Efficiency of Nitrogen Slow-Release Fertilizers in Integrated Production of Carrot Depending on Fertilization Strategy

Optimization of plant nutrition is a very important part of primary production quality systems. Crop fertilization is the most important agrotechnical measure because it determines the amount and quality of the yield. Moreover, excess fertilization intensifies the eutrophication processes and the greenhouse effect. The study aimed to assess the suitability of slow-release fertilizers in cultivation of carrot subspecies Daucus carota L. ssp. sativus in the integrated production system. The objective was realized on the basis of a strict field experiment set up on a clay loam soil with low nutrient content. The dose of fertilizer was the experimental factor. The fertilizers were applied during the formation of the ridges. Traditional fertilizers (ammonium phosphate, potassium salt, ammonium nitrate, and a multi-component fertilizer Polifoska 6), as well as a multi-component fertilizer with slow release of nutrients, NPK Mg (18-12-24-4), were used. In individual variants of the experiment, different fertilization strategies were applied: integrated production fertilization, traditional fertilization, and fertilization based on the use of slow-release fertilizers. The control treatment comprised of unfertilized plants. The efficiency of nitrogen fertilization was evaluated based on agronomic efficiency, partial factor productivity, physiological efficiency, and removal efficiency. Fertilization strategy significantly impacted the quantity of obtained yield. In the control sample, prior to mineral fertilization, the crop yield was 33.53 Mg·ha−1. The largest yield was 82.30 Mg·ha−1.The largest yields were obtained from plants fertilized with a combination of slow-release fertilizers, with nitrogen introduced in the form of ammonium phosphate, and through conventional fertilization. The highest productivity and environmental efficiency were obtained in treatments with fertilization according to the principles of integrated production and with slow-release fertilizers. In terms of environmental efficiency, the best results were obtained through nitrogen fertilization using 400 kg of slow-release fertilizers. The use of slow-release fertilizers in carrot cultivation can significantly improve the efficiency of fertilization, both in terms of production and environmental protection.

The utilization of activated carbon as micronutrients carrier in slow release fertilizer formulation

In many plantations, fertilizers were often added in high dosage and applied several times to get maximum productivity. But processes in soil caused not all nutrients in fertilizer could be uptaken by plants. Besides, the high dosage can be toxic to plants. The use of slow release fertilizer can overcome this case. This research was aimed to obtain the data of adsorptive capacity of activated charcoal to the nutrients mixed and gathering the information about nutrients release rate of fertilizer produced. The study was conducted by converting materials into activated charcoal. SRF was formulated by soaking fine activated charcoal CuSO4, FeSO4 or ZnSO4 solution for 24 hours. Analysis conducted were the observation of surface topography, qualitative analysis using EDX, and determination of total Cu, Fe and Zn in SRF. The optimal treatment was chosen to determine its release rate by extracting fertilizer with distilled water and 2% citric acid. The results showed the activated charcoal could be used to adsorb nutrients mixed as shown by SEM and EDX results. Nutrients in the charcoal could be released slowly and could not be easily leached out.

Nutrient release properties of a urea–magnesium–natural rubber composite coated with chitosan

Abstract The use of slow release fertilizer to prevent pollution is studied but the development of a new formula as well as studies on nutrient dissolution are subjects that still need to be explored further. This study we investigated the nutrient-release characteristics of urea–magnesium tablets prepared from rice husk ash, urea, magnesium sulfate and natural rubber. The ammonia-dissolution, urea leaching, and the nitrate-formation rate were found to be proportional to the incubation time. The presence of magnesium in tablet and the chitosan coating affected nutrient-dissolution rate in water. The chitosan coating retarded the release of urea, ammonia and nitrate only if the composite contained high proportion of the magnesium sulfate, but the chitosan coating also accelerated magnesium-ion dissolution.

The Use of Slow-Release Fertilizers as a Part of Optimization of Celeriac Production Technology

Abstract The aim of this study was to assess the possibility of using slow-release fertilizers under intensive vegetable cultivation. To achieve the set research objective, a field experiment was set up in 2017, where slow-release fertilizer (NPK (%) 20-10-10+4MgO) was applied. The experiment comprised three levels of fertilization with the use of slow-release fertilizers, the control without fertilization, and the control fertilized with conventional fertilizers. The slow-release fertilizer was applied directly under each plant and in rows – approximately 8 cm below the root level. The designed systems were evaluated based on the size of commercial yield, productivity index, agronomic efficiency index, removal efficiency index, and physiological efficiency index. The results obtained in the field experiment indicate that the highest plant yield (54.22 Mg of commercial yield∙ha−1) was obtained at the highest dose of slow-release fertilizers (600 kg∙ha−1 applied in rows approximately 8 cm below the root level). In the case of direct fertilization, in the treatment with the highest dose of slow-release fertilizer, a reduction in yield was observed. The best results, in terms of equalizing the mass of individual roots, were obtained under conventional fertilization. The most favorable value of the productivity index was obtained in the variant where 400 kg∙ha−1 slow-release fertilizer was applied directly, while in the case of row application the best results were obtained at the dose of 600 kg∙ha−1. Celeriac fertilization with slow-release fertilizers under root may result in producing a yield of bigger differences in root mass, compared to conventional fertilization system.

RESISTÊNCIA À GEADA E CRESCIMENTO INICIAL DE <i>Toona ciliata</i> EM CULTIVOS CONSORCIADOS COM <i>Eucalyptus grandis</i> EM DIFERENTES ADUBAÇÕES

A restrição nutricional e a ocorrência de geadas no sul do Brasil frequentemente afetam o crescimento de cultivos florestais. Com o objetivo de quantificar o crescimento inicial e a resistência à geada das plantas de Toona ciliata em cultivos consorciados com Eucalyptus grandis, com diferentes adubações, foi conduzido um experimento na UFSM, campus de Frederico Westphalen. O delineamento experimental foi de blocos ao acaso com três repetições, no arranjo fatorial 2 x 2 x 3: duas espécies florestais (Eucalyptus grandis Hill ex Maiden e Toona ciliata M. Roem var. australis), dois tipos de cultivos (solteiro e consorciado) e três tipos de adubação (NPK, NPK + Si e NP de liberação lenta + K + bioestimulante). O crescimento em altura das plantas foi mensurado em datas diferenciadas até 346 dias após o plantio. No final deste período foi quantificado o diâmetro a altura do peito e a massa seca da parte aérea. A avaliação do nível de danos às plantas e o grau de resistência à geada foi feito com atribuição de notas com base nas plantas inteiras e nas copas das plantas. Os dados foram submetidos à análise de variância e, quando significativa (p ≤ 0,05), procedeu-se a comparação das médias dos tratamentos pelo teste de Tukey (p ≤ 0,05). As duas espécies florestais foram tolerantes à geada, mas com maior dano na área foliar nas plantas de Toona ciliata em relação a Eucalyptus grandis. O cultivo de Toona ciliata sob proteção de Eucalyptus grandis não diminuiu os danos da geada no primeiro ano de implantação no campo. O uso de fertilizante de liberação lenta, de Si e de bioestimulante não contribuíram para aumentar o crescimento e a resistência à geada das plantas das duas espécies florestais.

Estimating nitrogen and phosphorus losses from lowland paddy rice fields during cropping seasons and its application for life cycle assessment

Estimating nitrogen and phosphorus losses into water bodies is crucial for evaluating the environmental impacts of rice cultivation. In this study, published data (N = 80) were used to estimate the total nitrogen (TN) and total phosphorus (TP) that could be lost through leaching and runoff during cropping seasons, taking into account factors that influence these losses. According to second-order Akaike's Information Criterion (AICc, one of the model selection methods), a model with soil temperature, TN input, inflow water, the incorporation of rice straw residue, puddling, and the use of slow-release fertilizer (P < 0.05) was chosen to estimate TN losses. A model with soil temperature, no application of phosphate fertilizer, medium- and coarse-textured soils (P < 0.05) and inflow water was chosen to estimate TP losses. The root mean square error was reduced by 34.5% for TN and by 21.8% for TP when these models were used compared to when the average proportions of outflowing nutrients were used (e.g., 17.0% for TN and 7.3% for TP in this study). The multiple regression model, taking into account site-specific conditions, was proven to be a readily available method to obtain knowledge of nutrient loading. Once process-based models are readily available, they will improve the estimates of eutrophication potential in life cycle assessments. Further improvement of the method is required, especially for the winter fallow period.