Slow Release Of Nutrients Research Articles

Comparison of different slow-release nutrient composites produced to stimulate microorganisms

Concern for environmental quality has increased in society because industrial and technological development has released high levels of contaminants into the environment, such as hydrocarbons. A technique widely used for bioremediation is biostimulation, which may be enhanced by microencapsulation. This research formulated slow-release nitrogen and phosphorus compounds using different polymer (Alginate/Capsul®, carboxymethyl cellulose) matrices and compared them with the agricultural product Osmocote® and mineral medium Bushnell-Haas as hydrocarbonoclastics biostimulation agents in the environment for pollutant bioremediation. N (nitrogen) and P (phosphorus) were immobilized using lyophilization and ionic gelation techniques. Experiments were conducted using encapsulated material and evaluated for biomass production, glucose consumption as organic carbon source and N and P supply. The immobilized carboxymethyl cellulose compound showed the best results of glycosidic degradation (66.7%) and microbial biostimulation (350 mg L-1 protein) compared to systems containing free nutrients (11.3% and 150 mg L-1 degradation glycosidic and microbial biostimulation, respectively). Thus, this compound is a potential slow release product for bioremediation processes.

Evaluation of vermicompost and chemical fertilizers on performance of Pak choi (Brassica rapa cv. Hong Tae) and soil biological process

A field experiment was conducted to evaluate the effect of vermicompost and chemical fertilizers on the performance of Pak choi (Brassica rapa CV. Hong Tae) in Chitwan Nepal during November 2012 to January 2013. Four levels of vermicompost (0, 5, 10 and 15 t/ha) and four levels of NPK equivalent in the form of inorganic fertilizer (100, 50, 25 and 0% of recommended doses of 100:60:60 Kg/ha) in 16 combinations were assessed for yield, yield contributing parameters of Pak choi and microbial activities of soil. All levels of chemical fertilizers increased plant height, leaf number and chlorophyll content of leaves but they had no effect in increasing root length. Chemical fertilizers at 100:60:60 kg NPK/ha increased biological and economic yield of Pak choi. However, all levels of chemical fertilizers were found strongly suppressing in soil microbial activities. Vermicompost on the other hand increased root length, leaf number, biological and economic yield and more significantly increased soil microbial activities resulting in increased level of soil respiration. Chemical fertilizers were effective in increasing plant growth but suppressed microbial activities of soil. Vermicompost on the other hand was effective in long run through slow release of plant nutrients and improving soil health by increased soil microbial activities.Journal of the Institute of Agriculture and Animal Science. Vol. 33-34, 2015, page: 243-250

Preliminary Study on Potential of EAF Slag as Nutrients Source for Mangrove Seedling

Electric Arc Furnace (EAF) slag generated from steel making process mainly consist of calcium oxide (CaO), iron oxide (FeO), silicon oxide (SiO2), manganese oxide (MnO), aluminium oxide (Al2O3 ) and magnesium oxide (MgO) in different phases. Since the elements are matching some of the nutrients or micro-nutrients that are needed in plant growth, this study was carried out with the purpose of finding the potential of EAF Slag as nutrients source for mangrove seedling in nursery centre. EAF slag taken from steel making plant during normal production process was crushed and analysed with XRF to obtain chemical composition result and XRD for phase analysis. ICP-OES elemental test was done on leachate from kinetic leaching experiment to assess the leaching trend for each elements form EAF slag in distilled water. Result obtained shows Ca and Si are the major elements that leached from EAF slag with uptrend line, and achieved about 25 mg/l for Ca and 7.5 mg/l for Si after 10 days in distilled water with L/S ratio as main affecting factor. Fe and Mn leaching will be enhanced by stirring at highest speed of 700 rpm. Both elements show uptrend with highest leaching at 0.27 mg/l for Fe and 0.14 mg/l for Mn at day 10, and this shows good potential of EAF slag as slow release element. Mg as an important element in chlorophyll shows uptrend leaching to about 1.5 mg/l at day 10, with L/S ratio as main influential factor. Potassium (K) and sodium (Na) leaching fluctuated below 0.50 mg/l for K and below 0.08 mg/l for Na. Al is the only element that achieved highest level in between day 3 to 7, and then drop gradually to day 10, at about 1.0 mg/l for sample with 700 rpm stirring speed. The results showed good potential for EAF slag to be used as slow release nutrients source for mangrove seedling. Further studies are currently underway to evaluate the effect of EAF slag in altering pH of the soil, as well as efficiency of EAF slag as fertilizer for mangrove plant by observing the growth rate of seedling planted in mangrove nursery site.

Cassava starch‐graft‐poly(acrylonitrile)‐coated urea fertilizer with sustained release and water retention properties

AbstractCassava starch‐graft‐poly(acrylonitrile) samples were synthesized by a free radical‐initiated polymerization reaction, and urea fertilizer was coated with these grafted starches to obtain the dual benefit of sustained release and water retention properties. A response surface design was used to optimize the synthetic conditions of starch‐graft‐copolymers to maximize the slow nutrient release and water absorbency. The FT‐IR analysis confirmed the grafting reaction, and scanning electron micrographs revealed the ultrastructure of polymer coating. The release of nitrogen in soil from coated urea was more sustained than that from uncoated urea and it varied with grafting level of the polymer. The uncoated urea showed almost complete release of nitrogen by 1 month, whereas %N release was in the range of 69.8%–78.3% from the grafted starch‐coated urea even after 108 days of incubation. The water retention capacity of the coated urea ranged from 74.2% to 426.6% and it decreased with increase in % grafting of the coating material.

Establishing Vadose Zone Slow‐Release Carbon Sources for Enhanced Bioremediation Using Silica Suspension

Core Ideas Nutrient‐laden silica suspension increases viscosity over time and gels at the end. Aqueous colloidal silica suspension can be readily injected into the subsurface. Silica gelation enables setting up slow‐release nutrient sources in the vadose zone. Gelled silica suspensions act as long‐term nutrients for enhanced bioremediation. Delivery of C sources (nutrients) to the vadose zone and establishing a slow‐release C source in this unsaturated zone are essential for promoting long‐term, enhanced contaminant bioremediation at sites with deep vadose zones, such as the Hanford Site in the southeast of the state of Washington. Conventional solution‐based injection and infiltration approaches face challenges in achieving delivery goals. Aqueous colloidal silica suspension has characteristics that can potentially be used for nutrient delivery and slow‐release source setup. This research was conducted to (i) demonstrate delayed gelation of colloidal silica suspensions with the presence of nutrients; (ii) prove that gelation takes place in sediment and the gel slowly releases nutrients; and (iii) show that silica suspensions are injectable for vadose zone emplacement. Results demonstrated that nutrient‐laden colloidal silica suspensions have low initial viscosity and then increase in viscosity with time until reaching gelation, allowing for a slow release of nutrients into the environment. Higher salt and silica concentrations increased the rate of viscosity climbing and the rate of gelation, whereas higher silica concentrations resulted in stronger gels. Nutrients were slowly released from gels in both batch and column experimental settings. The rheological and injection behavior of the silica suspensions revealed the injectability of these fluids. This study demonstrated that colloidal silica suspension could be used as a carrier to distribute nutrients to the vadose zone and to establish slow‐release nutrient sources.

Organic coating on biochar explains its nutrient retention and stimulation of soil fertility

Amending soil with biochar (pyrolized biomass) is suggested as a globally applicable approach to address climate change and soil degradation by carbon sequestration, reducing soil-borne greenhouse-gas emissions and increasing soil nutrient retention. Biochar was shown to promote plant growth, especially when combined with nutrient-rich organic matter, e.g., co-composted biochar. Plant growth promotion was explained by slow release of nutrients, although a mechanistic understanding of nutrient storage in biochar is missing. Here we identify a complex, nutrient-rich organic coating on co-composted biochar that covers the outer and inner (pore) surfaces of biochar particles using high-resolution spectro(micro)scopy and mass spectrometry. Fast field cycling nuclear magnetic resonance, electrochemical analysis and gas adsorption demonstrated that this coating adds hydrophilicity, redox-active moieties, and additional mesoporosity, which strengthens biochar-water interactions and thus enhances nutrient retention. This implies that the functioning of biochar in soil is determined by the formation of an organic coating, rather than biochar surface oxidation, as previously suggested.

Biochar‐Based Fertilization with Liquid Nutrient Enrichment: 21 Field Trials Covering 13 Crop Species in Nepal

AbstractBiochar produced in cost‐efficient flame curtain kilns (Kon‐Tiki) was nutrient enriched either with cow urine or with dissolved mineral (NPK) fertilizer to produce biochar‐based fertilizers containing between 60–100 kg N, 5–60 kg P2O5 and 60–100 kg K2O, respectively, per ton of biochar. In 21 field trials, nutrient‐enriched biochars were applied at rates of 0·5–2 t ha−1 into the root zone of 13 different crops. Treatments combining biochar, compost and organic or chemical fertilizer were evaluated; control treatments contained same amounts of nutrients but without biochar. All nutrient‐enriched biochar substrates improved yields compared with their respective no‐biochar controls. Biochar enriched with dissolved NPK produced on average 20% ± 5·1% (N = 4 trials) higher yields than standard NPK fertilization without biochar. Cow urine‐enriched biochar blended with compost resulted on average in 123% ± 76·7% (N = 13 trials) higher yields compared with the organic farmer practice with cow urine‐blended compost and outcompeted NPK‐enriched biochar (same nutrient dose) by 103% ± 12·4% (N = 4 trials) respectively. Thus, the results of 21 field trials robustly revealed that low‐dosage root zone application of organic biochar‐based fertilizers caused substantial yield increases in rather fertile silt loam soils compared with traditional organic fertilization and to mineral NPK or NPK‐biochar fertilization. This can be explained by the nutrient carrier effect of biochar, causing a slow nutrient release behaviour, more balanced nutrient fluxes and reduced nutrient losses, especially when liquid organic nutrients are used for the biochar enrichment. The results open up new pathways for optimizing organic farming and improving on‐farm nutrient cycling. Copyright © 2017 John Wiley & Sons, Ltd.

Decomposition rates and nutrient dynamics of Picea abies needles, twigs and fine roots after stem-only harvesting in eastern and western Norway

Decomposition of the finest harvest residues is important for the carbon and nutrient cycle in forest ecosystems both before and after tree felling. We assumed that decomposition is dependent on harvest residue fraction and chemistry, soil temperature and moisture, and aimed at determining decomposition rates and nutrient dynamics of needles, twigs and fine roots from newly felled Picea abies trees in two sites with different climate and topography. Decomposition of needles, twigs and fine roots in mesh bags was followed for up to six years and four years in harvesting sites in eastern and western Norway, respectively. The western site had a more humid climate and a steeper terrain than the eastern site. The mass loss after two years was significantly higher for needles (49–59%) than for twigs and fine roots (29–38%). Between sites, there was no significant difference between mass loss for neither needles nor twigs. Nitrogen accumulated in needles during the first year, but 35% of initial needle N had been released after three years. The initial needle and twig decomposition rate was dependent on soil moisture and topographic aspect. During the first three years, needle lignin concentrations retarded whereas P concentrations stimulated needle mass loss. For twigs, P concentrations stimulated mass loss, whereas higher soil temperatures reduced it. Lignin and P concentrations of plant parts and soil temperature were the most important factors for the first three-year mass loss. The slow release of nutrients shows the importance of remaining needles, twigs and fine roots as a long-time nutrient source in the ecosystems under study.

Effect of nanofertilizers on growth and yield of selected cereals - A review

Nanoscience coupled with nanotechnology has emerged as possible cost-cutting measure to prodigal farming and environmental clean-up operations. Nanoscale science, engineering, and technology, which is more widely known using the novel term ‘nanotechnology’, is an emerging multidisciplinary field that can have enormous potential impact on our society. Nanofertilizers facilitate slow and steady release of nutrients and thereby reduce the loss of nutrients and enhance the nutrient use efficiency. The full recommended rate of conventional and nanofertilizer (FRR-CF+FRR-NF) enhanced the plant height, chlorophyll content, number of reproductive tillers, panicles, and spikelets in rice. The magnitudes of increase over the FRR-CF were 3.6%, 2.72%, 9.10%, 9.10%, and 15.42%, respectively. In rice, an exposure to Zn NP (at 0, 25, 50, 75, 100 and 150 mg L-1) caused significant changes in root and shoot length and mass (fresh and dry mass). The ZnO nanoparticles increased the shoot dry matter and leaf area indexes by 63.8% and 69.7% respectively in mineral poor soils. The effect of TiO2 Nano particles was significant on number of corn in plant, maize dry weight and corn yield in P£0.05 in . Mean comparison showed that the highest number of corn in plant (10.10), maize dry weight (2396.35 kg ha-1) and corn yield (1744.13 kg ha-1) were achieved by flowering stage. Silver nanoparticles in 25 ppm concentration have showed significant improvement in maximum leaf area and highest grain yield while 75 ppm concentration resulted in decrease in grain yield in wheat. Maximum number of grains per spike was recorded with 25 ppm followed by 50 ppm whereas maximum 100-grain weight was obtained for 25 and 125 ppm soil applied silver nanoparticles in wheat.

Organo-mineral fertilization effects on biomass and essential oil of lavender (Lavandula dentata L.)

Large-scale production of aromatic plants is subject to phytotechnical challenges, such as management, irrigation, nutrition, and soil fertility, as well as exogenous issues that may affect the chemical composition of secondary metabolites. The aim of this study was to evaluate the effect of organo-mineral fertilizer on the biomass and essential oil of lavender (Lavandula dentata L.). A randomized block experimental design was used in a split-plot arrangement, consisting of five rates of organo-mineral fertilizer, and an additional treatment with only mineral fertilizer. The organo-mineral fertilizer was used at the same recommended rate as the mineral fertilizer. The organo-mineral fertilizer was formulated with 10% total nitrogen, 10% P2O5, 10% total potassium, and 8% organic carbon, and was applied at the following rates: 100%, 80%, 60%, 40%, and 20%. Flowers, leaves, and stems were harvested three times. Plant biomass, and the concentration, yield, and chemical composition of the essential oils were evaluated. Results showed that the highest flower yield was obtained at 145days after planting through use of the 100% rate of the organo-mineral fertilizer. The 60% rate of the organo-mineral fertilizer produced more than 320g plant−1 of fresh biomass. The major compounds were 1,8-cineole, camphor, and fenchone, and these compounds together represented more than 80% of the chemical composition. The organo-mineral fertilizer can ensure greater yield through slow release of nutrients around the root system, especially at the flowering stage. We conclude that associating organo-mineral fertilization with the appropriate harvest season has a noticeable impact on the chemical composition of lavender essential oil.

Biodegradable blends of urea plasticized thermoplastic starch (UTPS) and poly(ε-caprolactone) (PCL): Morphological, rheological, thermal and mechanical properties

Biodegradable blends of urea plasticized thermoplastic starch (UTPS) and poly(ε-caprolactone) (PCL) were prepared in a co-rotating twin screw extruder. The UTPS and PCL content varied in a range of 25wt%. The materials were characterized by capillary rheometry, scanning electron microscopy (SEM), termogravimetry (TGA), differential scanning calorimetry (DSC) and tensile tests. Capillary rheometry showed better interaction between UTPS and PCL at 110°C than at 130°C. SEM showed immiscibility of all blends and good dispersion of UTPS in PCL matrix up to 50wt%. However, a co-continuous morphology was found for UTPS/PCL 75/25. Thermal analysis showed that introducing PCL in UTPS, increased Tonset due to higher thermal stability of PCL, and blends presented an intermediate behavior of neat polymers. The presence of PCL in blends improved significantly the mechanical properties of neat UTPS. Because they are totally biodegradable, these blends can be vehicles for controlled or slow release of nutrients to the soil while degraded.

Biochar compound fertilizer increases nitrogen productivity and economic benefits but decreases carbon emission of maize production

While biochar use for soil amendment has been widely tested in world agriculture, little is known on crop production, greenhouse gases (GHG) emissions and economic performance of biochar used as compound fertilizer (BCF) combined with chemical nutrients. Using a field experiment in a low fertility Inceptisol from North China Plain, changes under different combinations with BCF in maize (Zea mays L.) growth, in grain yield and in GHGs emission were examined, as well as economical net farm income impact was analyzed. The treatments included: No fertilizer (Blank), inorganic compound fertilizer in 100% N dose (ICF-N) as control, combination of BCF and ICF in 100% N dose (BCFj-N, 40% of N derived from BCF) and in 80% N dose (BCFj-Nr, 50% of N derived from BCF) as well as BCF in 100% N dose (BCF-N, all N derived from BFC). Soil properties, agronomic traits and grain yield were measured at harvest while soil GHG emissions monitored across the whole growing season as well as cost-benefit analysis performed using the sale prices of all fertilizer inputs and grain outputs, for a single maize production cycle. Results showed that BCF significantly increased grain yield by 10.7% and carbon efficiency by 46.2%% of maize production, compared to the ICF. Meanwhile, BCF with full N provided exerted a 43.1% increase in nitrogen agronomic use efficiency, a 12% increase in net income and in cost efficiency, over the ICF. However, the fertilization partly combined with BCF did not exert positive effects. These benefits of BCF fertilization could be attributed partly to soil improvement especially of moisture regime and phosphorus supply for maize growth, apart from its potential to slow nutrient release for prolonged supply to plant nutrition. Our findings suggest that biochar compound fertilizers can substitute chemical fertilizers for maize production in North China and allow farmers to receive higher net income via increased yields.

Sulfur and Zinc Availability from Co-granulated Zn-Enriched Elemental Sulfur Fertilizers.

Acidification by oxidation of elemental sulfur (ES) can solubilize ZnO, providing slow release of both sulfur (S) and zinc (Zn) in soil. For this study, a new granular fertilizer with ES and ZnO was produced and evaluated. The effect of incorporating microorganisms or a carbon source in the granule was also evaluated. Four granulated ES-Zn fertilizers with and without S-oxidizing microorganisms, a commercial ES pastille, ZnSO4, and ZnO were applied to the center of Petri dishes containing two contrasting pH soils. Soil pH, CaCl2-extractable S and Zn, and remaining ES were evaluated at 30 and 60 days in two soil sections (0-5 and 5-9 mm from the fertilizer application site). A visualization test was performed to evaluate Zn diffusion over time. A significant pH decrease was observed in the acidic soil for all ES-Zn fertilizer treatments and in the alkaline soil for the Acidithiobacillus thiooxidans-inoculated treatment only. In agreement with Zn visualization tests, extractable-Zn concentrations were higher from the point of application in the acidic (62.9 mg dm-3) compared to the alkaline soil (5.5 mg dm-3). Elemental S oxidation was greater in the acidic soil (20.9%) than slightly alkaline soil (12%). The ES-Zn granular fertilizers increased S and Zn concentrations in soil and can provide a strategically slow release of nutrients to the soil.

Can Phosphate Salts Recovered from Manure Replace Conventional Phosphate Fertilizer?

Pig farming produces more manure than can reasonably be spread onto surrounding fields, particularly in regions with high livestock densities and limited land availability. Nutrient recycling offers an attractive solution for dealing with manure excesses and is one main objective of the European commission-funded project “BioEcoSIM”. Phosphate salts (“P-Salt”) were recovered from the separated liquid manure fraction. The solid fraction was dried and carbonized to biochar. This study compared the fertilizing performance of P-Salt and conventional phosphate fertilizer and determined whether additional biochar application further increased biomass yields. The fertilizers and biochar were tested in pot experiments with spring barley and faba beans using two nutrient-poor soils. The crops were fertilized with P-Salt at three levels and biochar in two concentrations. Biomass yield was determined after six weeks. Plant and soil samples were analysed for nitrogen, phosphorus and potassium contents. The P-Salt had similar or even better effects than mineral fertilizer on growth in both crops and soils. Slow release of nutrients can prevent leaching, rendering P-Salt a particularly suitable fertilizer for light sandy soils. Biochar can enhance its fertilizing effect, but the underlying mechanisms need further investigation. These novel products are concluded to be promising candidates for efficient fertilization strategies.

The Possibility of Organo-Mineral Fertilizer Production from Sewage Sludge

A lot of attention has been paid in current literature to sewage sludge due to its increasing amount and problem with its disposal. In the age of expensive energy sources and depletion of natural feedstocks it is necessary to find ways of reusing and recycling waste. Sewage sludge has a high valuable fertilizing potential. It is known as a rich source of nutrients. In addition, it includes a large amount of organic matter, which could facilitate the bioavailability of macro- and micronutrients and improves the soil structure. However, a direct application of sewage sludge to the soil is restricted by heavy metals content. Sewage sludge commonly includes pathogenic microorganisms and toxic compounds. The aim of the study was to determine the state of the art and availability of technology for fertilizers production based on waste, especially on sewage sludge. As sewage sludge from different wastewater treatment plants varies in its chemical composition and physical properties, it is important to find a local solution to the problem of sewage sludge disposal. It has been found that organo-mineral fertilizers (OMFs) derived from sewage sludge and modified by the addition of mineral fertilizers seem to be suitable for application to the soil. Adding acids or alkali agents provide sterilization and binding of the components. Novel OMFs gave a comparable crop yield response as conventional fertilizers. They show a slow release of nutrients, which is the main advantage in relation to mineral fertilizers.

Organic technology of tea production at Black sea coast of Krasnodar region

This paper presents preliminary results of the first try to introduce organic technology of tea leaves production at the resort area on the Black Sea coasts in Krasnodar district. The named technology is introduced on the tea gardens of the firm Matsetinskyi tea in 2007. Tea gardens situated on hill slopes which have elevation 350 above the sea level. Experimental plots (three on each of two gardens) were situated 170 m apart down along the slope of a range of Caucasus mountains. Soil and leaf samples were taken at leaf harvesting time in June 2015. Chemical analysis of soil and leaves were carried out in accordance with recommendations adopted by Georgia Institute of subtropical crops. Tea leaves for analysis and yield on experimental plots were collected five times during the season. Chemical analysis of nutrient content in the leaves, and quality of tea have been done in the analytical laboratory of the Agrotechnological Institute Of PFUR. Preliminary results of experiment revealed rather notable decrease of total yields of leaves in both gardens in comparison with previous yields when mineral fertilizers were applied annually in the rate N300P150K150. Decrease of the yield may be explained by the decrease of nutrient supply due to slow nutrient release by mineralization from trimming materials. Dead leaves, cut weeds and tea bush trimmings, which are the only source of nutrients might be added to the soil. Lower yields at the top of the hills also correlate with lower supply of organic material to the soil on the top of the hills. Thorough analysis has to be done to determine for and contra to organic tea production taking into account loses of yield and gains in cost of production decrease and possible higher price for organic tea. Positive affect of organic technology of tea production on ecology should be also accounted for.

DESIGN AND EVALUATION OF MOBILE DRIP IRRIGATION SYSTEM

Mobile drip irrigation system ''MDIS'' consists of on/in-line drip hoses at different spaced between lines being dragged through various crops by a center pivot or lateral move irrigation system. Technology of MDIS combines the efficiency of surface drip irrigation (95%) with the flexibility and economics of center pivot and lateral move irrigation systems. While conventional center pivot and lateral move irrigation water application packages are efficient and provide many different options for distributing water. MDIS technology increased system application efficiency through precision drip irrigation with the slow methodical release of water and nutrients directly to the soil area for optimal plant growth. A mobile drip irrigation system ''MDIS'' was designed using the classic dripping irrigation materials and determine the best system speed which gives best witting front advance in horizontal, vertical and diagonal directions in the loamy sand soil. The MDIS was evaluated at four system speeds of 5, 10, 15, and 20 and three types of drip tubes of . The results showed that the classification of all used drip tubes were fully pressure compensating and the application efficiency of MDIS was higher than 82%. Also, results obtained the mathematical relationships which describe wetting front advance in horizontal ''H'', vertical ''V'', and diagonal ''D'' directions in loamy sand soil.

Stability of pyrochar and hydrochar in agricultural soil - a new field incubation method

The application of chars on soil offers an option to sequester carbon (C) and to improve soil fertility. Different types of chars are available as soil amendments, produced with mainly two different processes: pyrochar produced with pyrolysis and hydrochar produced with hydrothermal carbonization. However, there are few studies to assess the stability of these two char types in soils in situ at field sites. A 19-month in-situ field incubation was conducted in northern Germany. With a mini-plot method we were able to assess the decomposition dynamic of chars with few operational costs. Zinc was used as inert tracer mixed with the char in order to account mixing so that char losses could be accurately quantified. We used chars from Miscanthus (C4-plant) as feedstock with a higher δ13C value than the C3 plant derived soil C. Changes in δ13C value allowed the calculations of char-derived C in the soil at three sampling dates. While C derived from pyrochar did not change significantly over time, 23–30% of initial added hydrochar-C was mineralized after 19months in-situ field incubation. There was no difference in the decomposition dynamics of the chars among the three field sites with different soil types. Moreover, we did not observe a decline in decomposition rates with time. For hydrochar the data were well fitted with a linear one-pool decay model. The average model derived mean residence times were 4 (95% confidence interval: 3–14) years for hydrochar and 60 (95% confidence interval: 16–224) years for pyrochar. Thus, while pyrochar has a higher potential for C-sequestration, faster mineralization of hydrochar compared to pyrochar showed their potential to act as a mid-term fertilizer through slow nutrient release to soils. Advantages of the Zinc method were the low price for application and analysis as well as the ability for farmers to manage their field in the course of their normal activities. However, variability in results gained from the Zinc method is not insignificant which mostly affect the calculated MRTs.

Synthesis, characterization and application of ion exchange resin as a slow-release fertilizer for wheat cultivation in space

In addition to the bio-regenerative air revitalization, water recycling and waste management systems and their associated challenges, enhancing the crop yield with less fertilizer input for sustainable food production in space is also a challenge that needs to be overcome. The purpose of this study is to investigate the feasibility of applying ion exchange resin as a slow-release fertilizer for wheat cultivation in space. Strong-acid cationic exchange resins and weak-base anion exchange resins soaked in 1X, 5X, 10X and 15X Hoagland nutrient solutions, respectively, were used as fertilizers in clinoptilolite to cultivate wheat plants, and the morphological and physiological characteristics of the wheat plants were studied and compared with that of the wheat planted in vermiculite and nutrient solutions. The results showed that more ions were attached on the surface of the ion exchange resins as the solution concentration increased. After 14 days, the fresh weight of wheat planted in the ion exchange resin-clinoptilolite (IER-clinoptilolite) treated with 10X and 15X solutions were 190% and 192% higher than that of wheat planted in nutrient solution with the same concentration. Chlorophyll content of wheat plants cultivated in the two kinds of solid medium is significantly higher than that of liquid cultivation. The lowest peroxidase (POD) activity and malondialdehyde (MDA) contents of wheat plants cultivated in the IER-clinoptilolite appeared on the 14th day. According to all the experimental data, it's promising to produce slow-release nutrient fertilizer by using strong-acid cationic exchange resins and weak-base anion exchange resins for wheat cultivation in space.

Environmental impact of fertilizer use and slow release of mineral nutrients as a response to this challenge

Abstract This paper presents the most important issues relating to the influence of mineral fertilizers on both the natural environment and human and animal health. The physiological, environmental and economic impact of fertilizer production and application, resulted from a low assimilation of mineral components by crops, has been described. The research on the development and production of a large and diverse group of materials with slow-release properties that can increase the effectiveness of nutrient uptake, alleviate the negative influence of fertilizers on the environment and reduce labor and energy consumption associated with the use of conventional fertilizers, has been reviewed.