Fertilizer Solution Research Articles

Fuzzy Neural Network PID Strategy Based on PSO Optimization for pH Control of Water and Fertilizer Integration

In the process of crop cultivation, the application of a fertilizer solution with appropriate pH value is more conducive to the absorption of nutrients by crops. If the pH of the irrigation water and fertilizer solution is too high, it will not only be detrimental to the absorption of nutrients by the crop, but will also damage the structure of the soil. Therefore, the precise regulation of pH in water and fertilizer solutions is very important for agricultural production and saving water and fertilizer. Firstly, the article investigates the hybrid control of fertilizer and water conditioning systems, then builds a fuzzy preprocessing controller and a neural network proportional–integral–differential controller, and optimizes the neural network parameters by means of an improved particle swarm algorithm. The effectiveness of the controller was verified by comparison with the common proportional–integral–differential control and fuzzy algorithm control for fertilizer control and fuzzy preprocessing neural network control. Simulation experiments for this study were designed through the MATLAB/Simulink simulation platform, and the simulation results show that the algorithm has good tracking and regulation capabilities in the system. Finally, the four control algorithms are experimentally validated under different pH regulations using designed field experiments. The results show that, compared with other control algorithms, the control algorithm in this paper has a smaller overshoot and good stability with a shorter rise time, which can achieve the purpose of better regulating the fertilizer application system.

THE FACTORS INFLUENCING AGROPRENEURS’ INTENTION USING TPB: A STUDY OF FERTIGATION PROGRAMME IN SELANGOR, MALAYSIA

Malaysia has been continuously practicing the fertigation system, which is applying fertiliser solutions with irrigation water, typically through a micro-sprinkler or a drip system. This system has helped numerous small and medium-scale agropreneurs (agriculture entrepreneur) develop constant business. At a larger scale, fertigation is a means to address food security issues. Many small and medium-scale agropreneurs apply fertigation techniques in their crop cultivation. What are the underlying factors that cause them to continue using these techniques in their cultivation practices? To what extent do their intentions in crop production using fertigation techniques measured? This study sought to investigate the factors that affect small and medium-scale agropreneurs’ intention to continue practicing fertigation techniques in their agricultural activities. Using the Theory of Planned Behavior (TPB), this study examined 319 small and medium-scale agropreneurs’ intentions and the moderating effect of personality traits under Farmer’s Organization Authority (FOA) agency. The results revealed that the interests of FOA participants were determined significantly by subjective norms and personality traits while attitude, perceived behavioral control did not affect their intentions. Household income, number of household, age and education similarly provides significant effect of the agropreneurs’ intention. The findings of this study lead to the success of the fertigation program conducted and can further maximise the application of this technique to the cultivation of diverse crops. Additionally, the framework used can be adapted in various agricultural subsectors such as crop production, animal production, fisheries and agribusiness .Keywords: Intention, personality traits, small and medium scale agropreneurs, agricultural entrepreneurship, attitude, Theory of Planned Behavior

Integration of algae treatment with hydroponic crop waste to reduce impact of nutrient waste streams

AbstractIntroductionControlled environment agriculture (CEA) is expanding globally, but little is known about nutrient losses within these systems, or how to reduce subsequent pollution. This experiment investigates the potential to treat wastewater from hydroponically produced lettuce via the application of algae.Materials and MethodsA total of 132 heads of lettuce were produced in the 4‐layer nutrient film technique (NFT) vertical farming rack. Waste from the hydroponic system was used to cultivate naturally occurring algae. Nitrogen (N), phosphorus (P) and other trace elements (Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Ni and Zn) were measured at each stage of production.ResultsOverall the nutrient use efficiency (NUE) of applied mineral nitrogen (N) and phosphorus (P) was 88.7% and 59.4%. After algae treatment of waste streams the full system NUE of N and P was 99.5% and 95.0% respectively, thus significantly reducing waste heading for sewage. It was found that the crops consumed large quantities of Ca, Cu, Fe and Zn from the rooting sponges used in this experiment, which may have become available due to mineralization and the presence of slightly acidic fertiliser solution. The overall waste produced by the rooting sponge is of concern regarding the full NUE of the system, accounting for approximately 53% and 6% of the total N and P input into the system.ConclusionsThis study highlights that treating wastewater streams from controlled environment agriculture (CEA) methods such as hydroponics with algae is successful and easy to achieve with little effort. Future efforts by researchers and the CEA industry to better manage nutrient streams is recommended to improve the environmental credentials of developing CEA systems.

Improving the efficiency of the Volga-SM multitower sprinkling machine with a polyethylene pipe-line

The research results of the multi-support sprinkler of cable-stayed construction «Volga-SM» with a polyethylene pipeline are presented. The parameters of a steel pipeline of small diameter 102-114 mm and a polyethylene pipeline with a diameter of 63-160 mm are substantiated, depending on the length of the machine and water consumption. A scheme for feeding fertilizer solutions only through a polyethylene pipeline and near-surface sprinkling devices is proposed in order to reduce corrosion of the pipeline and structural elements of the machine and increase the reliability and service life. The main advantages of the modernized machines of the cable-stayed design are presented.

Treatment of textile industry wastewater by using high-performance forward osmosis membrane tailored with alpha-manganese dioxide nanoparticles for fertigation.

Forward osmosis (FO) technology has been acknowledged as an energy-efficient cutting-edge water treatment innovation; however, the inefficient performance of polymer-based membranes remains a tailback in the practical utilization of FO. A significant issue in FO is membrane fouling, which negatively influences the flux efficiency, working expenses and membrane life expectancy. Membranes having high water flux and minimum reverse solute flux at low operating pressures are the ideal membranes for this process. This study reports a thin-film nanocomposite (TFNC) membrane for the treatment of textile industry wastewater utilizing fertilizer as draw solution fabricated via the phase inversion process. The chemical structure and morphology of the synthesized manganese oxide (MnO2) incorporated membrane were studied by various characterization techniques like X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, contact angle and gravimetry. The outcomes demonstrated that the nanoparticles were bonded to cellulose acetate polymer via covalent bonds and showed very hydrophilic membrane surface, along with an increased osmotic water flux of 52.5 L.m2.h-1 and reverse salt flux of 10.9g.m2.h-1, when deionized wastewater and potassium chloride were used as the feed solution and the draw solution, respectively. In this manner, incorporating manganese oxide into the FO membrane may introduce its extraordinary possible application for the production of diluted fertilizer solution with balanced nutrients.

THE APPLICATION OF ECO ENZYME BIOTECHNOLOGY AS WASTE MANAGEMENT ORGANIC FOR PREPARATION THE DEVELOPMENT OF TALANG LAKE TOURISM KABUPATEN SOLOK WEST SUMATERA

Talang Lake is located in the Nagari area of Kampung Batu Dalam Subdistrict The Twin Lakes of Solok Regency. A driving force for the development of tourist villages is called groups Tourism Awareness (POKDARWIS). A frequently reported problem for tourist areas is the increasing volume of waste originating from tourists. One solution to overcome the problem of organic waste, especially food waste is to turn the waste into an ecoenzyme. Ecoenzyme is an organic solution that produced from simple fermentation of fresh vegetables and fruit peel waste, brown sugar and water. Ecoenzyme could be used to hand sanitizer and disinfectant, that one of the most needed products during this COVID-19 pandemic. Ecoenzyme also has the potential to become organic fertilizer solutions for agriculture so as to reduce the use of chemical fertilizers, vegetable and fruit yields better and the environment is not polluted. Ecoenzymes can help the maintenance sanitation and control of lake water quality. So that ecoenzyme has the potential to save expenses and earn additional income public. Through the use of biotechnology ecoenzyme is expected to be a preventive effort for the development of tourist villages through good and useful waste management. Based on the feedback was given, in general, people feel very satisfied and know that organic waste can great benefit to life.

Thermodynamic limits of using fertilizer to produce clean fertigation solution from wastewater via forward osmosis

The potential for concentrated fertilizer to drive water recovery via forward osmosis has received increased attention in recent years. Questions remain however about the quantities of water that can be recovered from batch processes, and how significant recovery volumes are relative to the overall water balance of crops. In this study, we establish the thermodynamic and practical limits of recovering water from a fertilizer osmosis batch process, and thereby provide insights into the future prospects of this concept. It is shown that common fertilizers can recover between 112 and 138 l/kg via fertilizer osmosis from a municipal wastewater feed source while maintaining practical flux of at least 5 l m −2 h −1 . The effects of membrane type, feedwater concentration, and permeate to feed recovery ratio are analyzed with a combination of analytical, numerical, and experimental methods. Water recovery limits are compared against the irrigation requirements of hydroponic crops, and it is determined that between 32 and 99% of a plant's irrigation water can be supplied by fertilizer osmosis at competitive flux levels, provided that low concentration feed such as municipal or hydroponic wastewater is available. Such recovery volumes represent a significant portion of the plant water balance, and should justify future research in the area of fertilizer osmosis. • Limits of water recovery per unit fertilizer are established for fertilizer osmosis. • Over 1200 l/kg can be recovered before osmotic equilibrium with wastewater feed. • From 112 to 138 l/kg can be recovered while maintaining practical flux above 5 lmh. • Recovery volumes can practically supply 32–99% of a plant's irrigation water. • Membrane type, fertilizer solute, and wastewater feed concentration all affect limits.

The impact of time and environmental factors on the mitochondrial vesicle and subsequent motility of amphibian sperm

For amphibian species that display external fertilization in an aquatic environment, hypoosmotic shock to sperm cells can quickly result in damage to cellular structure and function. This study sought to determine how fertilization media osmolality, temperature, and time impact the stability of the mitochondrial vesicle's association with the sperm head and thus motility and quality of forward progression. The presence of the mitochondrial vesicle and its relationship with sperm motility and quality of forward progression were analyzed in sperm samples from the Fowler's toad (Anaxyrus fowleri) (n = 10) when held for six hours under two temperatures and four osmolalities. Results indicated that the presence of the mitochondrial vesicle is needed for sperm motility over time (p < 0.001), where higher osmolalities (p < 0.001) and lower temperatures (p < 0.001) correlated with maintaining the vesicle attachment to the spermatozoa. The higher osmolality of spermic urine was the most important factor for maintaining higher quality of forward progressive motility (p < 0.01) of spermatozoa. Sperm samples held at 4 °C and 40 mOsm/kg had the longest half-life for motility (540 min) and quality of forward progression (276 min), whereas sperm held at 22 °C and 2.5 mOsm/kg had the shortest half-life for motility (7 min) and quality of forward progression (18 min). Special attention should be given to the osmolality and temperature of fertilization solutions, or breeding tank water, when developing cold storage protocols for toad sperm or reproducing animals to ensure the retention of the mitochondrial vesicle for maximum fertilization capability.

Liquid Organic Fertilizer Effects on Growth and Biomass of Lettuce Grown in a Soilless Production System

Demand for locally produced, organically grown leafy greens is increasing throughout the United States. However, due to lack of efficient organic fertilizers (OFs) for soilless substrates, organic greenhouse production of leafy greens may be challenging. Therefore, a greenhouse study was conducted to analyze the effects of six liquid OFs on growth and development of lettuce in a soilless system. Two experiments were conducted using a randomized block design, and treatments included six fish- or plant-based OFs: OF1 (5N–1P–1K), OF2 (2N–5P–1K), OF3 (3N–1P–1K), OF4 (2N–2P–2K), OF5 (4N–1P–1K), and OF6 (3N–3P–2K); one inorganic fertilizer treatment (IF, 24N–8P–16K); and one unfertilized control treatment. Fertilizer solutions were prepared at 2 dS⋅m–1 and applied at 100 mL/plant. In Expt. 1, fresh biomass for IF-treated plants was 12% to 38% greater than OF treatments, whereas this difference ranged from 25% to 57% in Expt. 2. Similarly, leaf area values of IF-treated plants were 5% to 40% greater than OF treatments in Expt. 1, and the difference ranged from 28% to 90% in Expt. 2. A possible explanation could be greater availability of nutrients in the IF treatment compared with OF treatments. There was no significant difference among fertilized treatments for number of leaves and stem diameter. Based on the index-based ranking, fish-based (OF1) and fish- and plant-based (OF2 and OF6) performed well among different liquid OFs used in the study. Although the yield under OFs was less compared with that under IF, there is potential to reduce this yield gap by optimized fertility management of these fertilizers. Future research is needed to investigate the impact of optimized rate, timing, different placement, and additional nitrogen (N) sources of OFs on the soilless production of lettuce.

Making Nitrogen Fertilizer using Cassava Leaves and Papaya Leaves on Chili Plants

Nitrogen is one of the macro nutrients to increase plant growth and production. Yogurt is a processed product which is a fermented milk product that has long been known and has a specific sour taste. Yogurt contains streptococcus thermophilus and lactobacillus bulgaricus bacteria that live in symbiosis. Sweet potato leaves Its nutritional value can be increased through fermentation because fermentation can increase protein digestibility, reduce crude fiber content, improve the taste and aroma of feed ingredients and reduce heavy metal levels. Sweet potato leaves contain crude fiber of 25.71%, 69.50% moisture content. Nitrogen 13.41% .. This research was conducted for 3 weeks. 2 weeks in the fermentation process of nitrogen fertilizer solution and 1 week of giving it to plants. The results showed that the stem height, leaf color of the chilies changed after giving nitrogen fertilizer.

Research on Mixing Law of Liquid Fertilizer Injected into Irrigation Pipe

The time and position that fertilizer takes to uniformly mix with water in an irrigation system significantly affects the development of a fertilization strategy. A pipe irrigation system was used to study the fertilizer–water mixing law in irrigation pipes using numerical simulation and experiments. The effect of the diameter of the water pipe and fertilizer pipe, water and fertilizer flow rates, concentration and viscosity of fertilizer, frequency of fertilizer injection on the mixing speed, and uniform mixing length indicated that the frequency of fertilizer injection did not affect the mixing process. The increase in the water pipe diameter and fertilizer flow rate or the decrease in fertilizer pipe and water flow rate diameter result in the increase of the speed of fertilizer solution mixing with water along the radial direction of the mixing pipe. The uniform mixing length was directly proportional to the fertilizer pipe diameter, water pipe diameter, water flow rate, and fertilizer viscosity, while it was inversely proportional to the flow rate and concentration of fertilizer. The relationship between the uniform mixing length and six influencing factors was fitted, the fitting was highly accurate, and the fitting equation can be used to predict the uniform mixing length under other conditions.

Solar-pond assisted reverse osmosis-electrodialysis system for seawater desalination and hydroponic fertilizer solution production

ABSTRACT A thermodynamic analysis is performed on a solar-pond assisted reverse osmosis-electrodialysis system to produce freshwater and a hydroponic fertilizer solution for sustainable desalination and waste recovery. The reverse osmosis unit desalinates seawater to produce freshwater and a waste concentrated salt solution rich in many useful ions and minerals. The reverse osmosis unit’s waste stream is sent to an electrodialysis unit that utilizes monovalent membranes to reject magnesium, calcium and sulfate ions. These ions are beneficial for plant growth and the product can be used as a hydroponic fertilizer solution for agricultural purposes. A solar pond is integrated into the system to reduce the power requirements. The solar pond utilizes energy from the sun to store thermal energy in a large body of concentrated salt water with temperatures up to 90°C in the lower convecting zone. This thermal energy is utilized in an organic Rankine cycle with the working fluid R113 to create a self-sustaining desalination and waste treatment system running on solar energy. The system produces about 4.52 kg/s of freshwater and 4.75 kg/s of hydroponic solution. The overall energy and exergy efficiencies of the integrated system are found to be 20.36% and 2.55%, respectively.

Silver Nanoparticles (AgNPs) in Urea Solution in Laboratory Tests and Field Experiments with Crops and Vegetables.

Nanotechnology and nanomaterials, including silver nanoparticles (AgNPs), are increasingly important in modern science, economics, and agriculture. Their biological activity involves influencing plant health, physiological processes, growth, and yields, although they can also be toxic in the environment. A new fertiliser was made based on a urea solution with a relatively low content of AgNPs obtained by the reduction of silver nitrate V. Laboratory tests were used to assess the effect of a fertiliser solution containing 10 ppm AgNPs on the germination of agricultural plant seeds (barley, peas, oilseed rape) and vegetables (radish, cucumber, lettuce) and its foliar application on chlorophyll content, stomatal conductance, and seedling biomass. Field experiments were conducted to assess the effect that a foliar application of 15 ppm AgNPs in working liquid had on physiological plant parameters and yields of rape and cucumber. The AgNPs in the tested fertiliser reduced infestation of the germinating seeds by pathogens and positively affected the physiological processes, productivity, and yields of plants. Plant response depended on plant species and habitat conditions. Reduced pathogen infestation of seeds, higher germination energy, increased chlorophyll content and stomatal conductance, and higher seedling masses all occurred under the influence of AgNPs, mainly in oilseed rape and cucumber, and especially under thermal stress. The beneficial effect of AgNPs on the yield of these plants occurred in years of unfavourable weather conditions. The positive agricultural test results, especially under stress conditions, indicate that fertiliser produced with AgNPs as an ingredient may reduce the use of pesticides and highly concentrated mineral fertilisers. Such a fertiliser is fully in line with the idea of sustainable agriculture. However, research on the effects that AgNPs and fertiliser have on the environment and humans should continue.

Ultrasonic characterization on fertilizer solutions in view to sustainable agriculture

The volumetric and sound parameters are very helpful tools to predict the different kinds of intermolecular interactions and their strengths associated with them. It is revealed that the soil salinity problem incessantly spreads due to continuous changes in climate, excessive use of groundwater, and bulk use of low-quality water for irrigation. Excessive soil salinity reduces the many agricultural crop production, which is particularly sensitive throughout the development and growth of the plant. The effect of salinity could be controlled or counteracted by the application of suitable fertilizers into the saline soils. In this manuscript, numerous acoustic as well as thermodynamic parameters of ammonium sulphate (AS) fertilizer of different weight fractions at 293.15 K temperature have been studied. The results obtained, from calculated different acoustic and volumetric parameters expose the existence of strong interactions in the system taken for investigation, this depends on the ilk of molecules. The fertilizer: ammonium sulphate shows, maximum molecular interactions at higher concentrations in all the solvents (Water, Sodium Chloride, and Magnesium Chloride), and this can again castoff in view as a remedy for soil salinity using interactions among saline salts and fertilizers.

Assessment of agricultural techniques of grape cultivation in arid conditions of southern Russia based on analysis of variance

The aim of the research was to assess the effectiveness of agricultural techniques for growing table grapes in the arid conditions of southern Russia. The research is relevant, since the improvement of agricultural techniques for growing grapes improves its growth and development, marketability of products, and increases plant resistance to diseases. The experiments were carried out in a vineyard located on the light chestnut soils of the Astrakhan region. The number of grape bushes is 1250.0 pieces/hectare. Water-soluble fertilizers were tested separately and in combination on plantings of table grape varieties of early, middle and late ripening. The concentration of aqueous solutions of fertilizers was 0.3 % for Plantafol and 0.1 % for Boroplus. The high efficiency of foliar dressings is achieved when they are carried out in certain phases of the plant’s growing season. The background was a mineral fertilizer - Ca(H2PO4) 2 × H2O at the end of each growing season (60.0 kg a. s./he), as well as N16P16K16 (64.0 kg a. s./he) before bud break and before flowering. A strong dependence of the efficiency of growing grapes on the interaction of varietal samples and applied fertilizers has been established. At the same time, additional products were obtained according to the options for applying fertilizers for different varieties in the range of 2.5-6.1 t/hectare.

Effects of organic fertilizer with or without a microbial inoculant on the growth and quality of lettuce in an NFT hydroponic system

Organic food continues to increase in popularity worldwide. Similarly, hydroponic production of leafy greens is expanding globally and is an important component of the world's food supply. The purpose of this study was to evaluate the growth and quality of lettuce using six nutrient film technique (NFT) hydroponic systems. There were three treatments: organic fertilizer with or without a microbial inoculant and a conventional inorganic fertilizer as a control. The experiment was repeated over time. Results showed that the plants grown with organic fertilizer with additional microbial inoculant achieved similar shoot fresh and dry weight to those of the control, and dry weight was 17% higher than the organic fertilizer without inoculant. Nitrogen content in the shoot tissue of plants treated with organic fertilizer with inoculant was 10% and 24% greater than the control and the organic fertilizer without inoculant, respectively. However, when the organic fertilizer with inoculant was reused in a second experiment, shoot fresh and dry weight of plants in organic fertilizer with inoculant was lower than those in the control but were still higher compared to the organic fertilizer without inoculant. Additionally, electrical conductivity (EC) and pH of the organic fertilizer solutions fluctuated widely. Interestingly, relative chlorophyll content measured as SPAD and anthocyanin content in the leaf tissue increased in plants treated with organic fertilizer, regardless of inoculant, by 19% and 9%, respectively.

Ресурсосбережение - как основа совершенствования многоопорных дождевальных машин

The purpose of the study is to determine the directions of improvement of the «Volga-SM» multi-support sprinkler machines with a polyethylene pipeline and to assess their effi ciency. The article presents the research results of a new multi-support sprinkler with cable-stayed construction «Volga-SM». The peculiarity of this machine is that the water pipeline consists of a steel pipeline that provides suffi cient rigidity of the spans, and a polyethylene pipeline installed parallel to the steel pipeline. Depending on the length of the machine and water consumption, the parameters of a small-diameter steel pipeline 102…114 mm and a polyethylene pipeline with a diameter of 63…160 mm are substantiated. Resource saving of the «Volga-SM» DM has been substantiated by reducing the pressure at the inlet to the machine from 0.45…0.6 to 0.35…0.5 MPa (by 20…28%), reducing the mass of the water-conducting pipeline and the number of support bogies. The ability to supply fertilizer solutions only through a polyethylene pipeline and near-surface sprinklers reduces corrosion of the pipeline and structural elements of the machine, which increases the reliability of the machine and its service life. The main advantages of the modernized cable-stayed machine with a polyethylene pipeline are presented.

Design and Evaluation of a Control System for the Fertigation Device

Highlights A control system based on single-chip microcomputer and fuzzy control was designed for solid fertilizer applicators. The working parameters can be adjusted and detected accurately. The fertilization performance of the fertigation device improved after accessing the control system. Under the adjustment of the control system, the fertigation device can achieve variable fertilizer concentrations. Abstract. In view of low automation control and unstable output fertilizer solution concentrations of solid fertilizer applicators, a control system based on a single-chip microcomputer and fuzzy control was proposed and introduced into a fertigation device. The control system calculated and adjusted the fertilizer-feeding flow rate according to the input and feedback information, resulting in the automatic operation of the fertigation device. It can also detect the output fertilizer concentration in real time. Experiments were conducted to test the adjustment and detection accuracy of the control system and to investigate its performance. Adjustment and detection errors were below 5% when the inlet water flow rate, the fertilizer-feeding flow rate, and the fertilizer concentration were 0.2 to 1.5 m3/h, 1 to 50 kg/h, and 1 to 14 g/L, respectively. The time the output fertilizer reached the set concentration was around 5 minutes and was far shorter than the fertigation device without a control system. The fertilizer concentration deviation decreased by about 20% after accessing the control system for the fertigation device. Under the control system, the fertigation device can discharge fertilizer with a variable concentration, and the fertilization deviation was about 5%. Therefore, the control system not only made automatic operation and variable concentration fertilization of the fertigation device to be achieved but also improved the fertilization performance of the fertigation device. Keywords: Fertigation device, Fertilization concentration deviation, Fuzzy control, Single-chip microcomputer, Variable fertilizer concentration.

Use of Seaweed Liquid Extract and Cow Urine for Lettuce Growth in Hydroponic System

Lettuce cultivated by millennial farmers using a hydroponic system in urban areas. Seaweed extracts and cow urine contain nutrients and plant growth regulators. This study aims to determine the effect of a formulation containing inorganic nutrient solution, seaweed liquid extract, and mixed cow urine on lettuce growth, as well as the volume of commercial nutrient mixture that can be substituted by these additives in a hydroponic system. The treatment used contains a combination of inorganic fertilizer solution (CF), seaweed liquid extract (SLE), and cow urine (CU). Every repeated three times in a randomized block design. Results, the nutrient mixture had a significant effect on the height, leaves number as well as wet and dry weight of the plants. Lettuce planted on 50% CF+ 25% SLE+ 25% CU was the tallest when observed on days 7, 14, and 42 after planting. The highest fresh and dry weight was also obtained from this nutrient formulation. On day 35, the highest leaves number was recorded from plants on the 100% CF+ 0% SLE+0% CU medium. Concluded, a mixture of seaweed liquid extract and cow urine has the potential to reduce the inorganic fertilizers use as a nutrient solution in a hydroponic system.

Exploring the limitations of forward osmosis for direct hydroponic fertigation: Impact of ion transfer and fertilizer composition on effective dilution

There is a need for water reuse technologies and applications to minimize the imminent water crisis, caused by the world population growth, the reduction of freshwater resources and the increasing water pollution. Fertilizer-drawn forward osmosis (FDFO) is a promising process capable of simultaneously extracting fresh water from low-quality sources as feed water (e.g., wastewater or greywater), while diluting fertilizer solutions for direct fertigation, avoiding the demand for freshwater for irrigation. Achieving an adequate level of dilution for direct fertigation is a key element to be evaluated for the implementation of FDFO. This study assessed the performance of the forward osmosis process to dilute fertilizer solutions to be applied directly in hydroponic systems. Experiments were carried out under conditions close to osmotic equilibrium to evaluate the process performance up to the maximum dilution point. Tests were carried out with individual and blended fertilizers (i.e., (NH4)2HPO4 or DAP, and KNO3) used as draw solution (DS) and with deionized water or individual salts (NaCl, MgCl2, Na2SO4, MgSO4) in the feed solution (FS). Water fluxes and reverse salt fluxes indicated that both fertilizer DS composition and concentrations play a fundamental role in the process. Suitable nutrient concentrations to be directly applied without further dilution for N, P and K (119, 40, 264 mg.L−1 respectively) were obtained with deionized water as FS and blended DAP (0.025 M) and KNO3 (0.15 M) as DS. However, important fertilizer losses from DS to FS were observed, being the highest for NO3− (33–70% losses from DS to FS). The presence of salts in FS decreased the water fluxes and the DS dilution due to the osmotic equilibrium caused by a greater loss of nutrients from DS to FS (up to 100%), compared with tests using just deionized water as FS. This study points out the potential limitations of the FDFO process, due to the high solute fluxes and low water fluxes in conditions close to osmotic equilibrium.