Liming By-products Research Articles

Citrus by-products: A dual assessment of antioxidant properties and food contaminants towards circular economy

Orange, lemon, and lime by-products emerge as promising sources of phenolic compounds. This study presents the first comprehensive assessment of the antioxidant capacity and food safety considerations of citrus pomace, aiming for their safe integration into the food industry. Results reveal that lemon and lime by-products are particularly rich in eriocitrin, hesperidin, trans-ferulic acid, and p-coumaric acid, significantly contributing to their antioxidant capacity. Regarding food safety, none of the nine regulated mycotoxins were detected. However, heavy metals were present below the maximum levels. Furthermore, pesticide residues were present, although at low levels in most cases. Contrarily, lime by-product presented high levels of the flutriafol. This study highlights the value of citrus by-products as source of natural antioxidants and emphasizes the necessity of monitoring and mitigating pesticide residues for their safe incorporation into functional food products. These findings support the sustainable utilization of citrus pomace within the circular economy framework, offering opportunities for innovation in the food industry.

Paper Mill Biosolids and Forest-Derived Liming Materials Applied on Cropland: Residual Effects on Soil Properties and Metal Availability

Combined paper mill biosolids (PB) and forest-derived liming by-products improve soil properties, but their residual effects following several years of application have hardly been investigated. A 13-year (2009–2021) field study was initiated at Yamachiche, QC, Canada, to assess the residual effects of PB and liming materials on the properties of a loamy soil. The PB was applied during nine consecutive years (2000–2008) at 0, 30, 60, and 90 Mg wet·ha−1, whereas the 30 Mg PB·ha−1 rate also received one of three liming materials (calcitic lime, lime mud, wood ash) at 3 Mg wet·ha−1. No amendment was applied during residual years. Past liming materials continued to increase soil pH but their effect decreased over time; meanwhile, past PB applications caused a low increase in residual soil NO3-N. Soil total C, which represented 40% of added organic C when PB applications ceased, stabilized to 15% after six years. Soil Mehlich-3-extractable contents declined over the thirteen residual years to be not significant for P, K, and Cu, while they reached half the values of the application years for Zn and Cd. Conversely, Mehlich-3 Ca was little affected by time. Therefore, land PB and liming material applications benefited soil properties several years after their cessation.

Characterizations of Lime Sludge from Indian Paper Industry: A Step towards Sustainable Growth for Indian Cement Industry

The kraft process of wood into wood pulp in the paper and pulp industry in the chemical recovery section generates lime sludge (LS) through the burning of the lime kiln. This by-product lime sludge from the paper industry has the major chemical composition of calcium carbonate in the form of calcite, moisture and minors are silica, magnesium, iron and aluminium. Here, we characterized the collected industrial lime sludge by-product from different parts of the country and evaluated its potential application in engineering construction material. The chemical composition of all samples contains CaO in around (52-55) %, SiO2 (1-4) %, Al2O3 and Fe2O3 make up less than 1% by weight. Minor alkalis of Na2O, K2O and SO3 content are less than 1 wt%. XRD profile and TG/DTA results showed that all lime sludge samples have major calcite (CaCO3) phase. The particle size distribution showed that grains are in the range of 11μm to 23μm which is compatible for cement manufacture and construction. Investigation by optical microscopy of microstructure and morphology revealed that calcite grains are presents as rounded shape agglomerated form. The characterization of all obtained results are encouraging for replacement of limestone in the cement and construction industry by using lime sludge which is technically suitable and economically viable for waste management in favour of circular economy.

Antioxidant Activity of Non-Volatile Lime (Citrus aurantifolia Swingle) Extract

The paper reports the antioxidant activity of a non-volatile fraction of lime processing byproducts from the lime syrup home industry. The activity was measured by spectrophotometry to obtain the 50% inhibition concentration (IC50) using the 2,2- diphenyl-1-picrylhydrazyl (DPPH) method. The sample was extracted by the maceration method with n-hexane, ethyl-acetate, and ethyl-ethanol. The IC50 values of 681 ppm, 458 ppm, and 2,775 ppm were n-hexane, ethyl-acetate, and ethyl-ethanol. The experiments concluded that the ethyl-acetate extract provides the best inhibition value to scavenge free-radicals DPPH. The HPLC and mass spectroscopy were measured to find out the content and group of active compounds. The significant compounds consisted of naringin, poncirin, or neoponcirin, which are known as antioxidant substances. The result shows the potential application of the lime by-products, its volatile fraction, and the nonvolatile fraction, which is the production residue of lime peel. This work can be applied as an alternative to zero-waste lime production, which may benefit the industry and the environment.

Residual effects of papermill biosolids and forest-derived alkaline materials on crop yield and plant metal accumulation

Combined papermill biosolids (PB) and forest-derived alkaline by-products are known for their direct benefits to agricultural crops, but their residual effects after several years of application have received little attention. A 10 yr field study was initiated on a loamy soil at Yamachiche, QC, to assess the residual effects of PB application after nine consecutive years, either alone or with several liming by-products, on nitrogen (N), phosphorus (P), and metal accumulation in plant and crop yield. The treatments consisted of PB at 0, 30, 60, and 90 Mg wet·ha−1, three liming by-products (calcitic lime, lime mud, and wood ash), each at 3 Mg wet·ha−1 with 30 Mg wet PB·ha−1, and a mineral N fertilizer (MIN). During the residual years, only the MIN treatment was carried out every year according to crop needs. Grain yield and total plant N and P accumulation were evaluated each year, whereas metal accumulation was determined on a 3 yr cycle. The residual effects of PB applications increased crop yields in some years, but the effects were generally lower than with MIN. Plant N recovery in the first three residual years was half of that recorded during years of application (15% vs. 30%), whereas P recovery was at 6%. Residual PB applications had little effect on metal accumulation in grain. Soil liming decreased zinc and cadmium concentrations in grain but increased molybdenum. This study showed that repeated applications of PB and alkaline materials continued to have a positive effect on field crops 3–5 yr after their cessation.

Loading lime by-product into derivative cellulose carrier for food enrichment.

The objective here is to enrich orange juice through encapsulated lime by‐product extract (LBE) through freeze‐drying, in order to increase lime by‐product consumption, in addition to increasing nutrition value of orange juice. The properties of both the LBE and microparticles are measured. The total polyphenolic compound (TPC) was measured to be 34.5 ± 0.5 (mg gallic acid/g LBE). The obtained value of encapsulation efficiency (EE) was within the 55%–70% range. The encapsulation method was satisfactory. The particle size is within 10–21 μm range, and differences between all treatments were statistically notable (p < 0.05). The lack of melting peaks in the thermal profiles by differential scanning calorimeter (DSC) of microparticles confirmed that hesperidin was well embedded in the polymeric cover. According to the sensory evaluations of orange juice which was enriched with LBE microparticles, the bitter taste was not perceived in some treatments.

The mould resistance of carbide lime by-products from deposits

The article deals with testing and evaluating the mould resistance of carbide lime by-product from deposits in comparison with the effect of reference conventional slaked lime. The mould resistance of limes was tested on a mixture of mould such as Gliocladium virens, Paecilomyces variotii, Penicillium funiculosum, Chaetomium globosum, and Aspergillus niger as well as evaluated according to the method stated in the technical standard STN 724310: 1993. The evaluating scale for mould resistance is from 0 up to 5 in the fungal growth degree (FGD). The FGD value 0 stands for no fungal growth comes about and construction materials and products have the microbiostatic effect against filamentous fungi. The experiments confirm the microbiostatic effect against mould of carbide lime by-product from deposits as well as reference conventional slaked lime; however, the microbicidal effect against mould has not been confirmed at all; the inhibiting area—zone—did not form on the agar growth media around the tested samples. Application of carbide lime by-product from deposits ensures increased mould resistance of construction materials with the microbiostatic effect against mould in accordance with technical standard STN 724310: 1993.

Microbial Response to Sodic Soil Amendments: Flue-Gas Gypsum, By-Product Lime, and Langbeinite

ABSTRACT Amendments are commonly applied to soil to ameliorate sodic conditions, but their effect on improving microbial activity depends on the severity of sodicity and the types and rates of amendments applied. Changes in metabolic activity in response to three chemical amendments (flue-gas gypsum (FG), spent lime, and langbeinite) applied at three rates to two sodic soils were measured using infrared gas analyzer during 76 days of incubation. Spent lime had the greatest influence on microbial activity at rates of 33.6 and 67.2 Mg ha−1, and at the highest rate of application (67.2 Mg ha−1) cumulative respiration was over two times greater than the control for both soils. High rates of langbeinite yielded the lowest respiration but were not significantly different than the control and the FG had no significant influence on respiration. The use of spent lime increased microbial activity which, in turn, may improve soil health through increased microbial activity.

Long term insight into biodiversity of a smelter wasteland reclaimed with biosolids and by-product lime

Smelter wastelands containing high amounts of zinc, lead, cadmium, and arsenic constitute a major problem worldwide. Serious hazards for human health and ecosystem functioning are related to a lack of vegetative cover, causing fugitive dust fluxes, runoff and leaching of metals, affecting post-industrial ecosystems, often in heavily populated areas. Previous studies demonstrated the short term effectiveness of assisted phytostabilisation of zinc and lead smelter slags, using biosolids and liming. However, a long term persistence of plant communities introduced for remediation and risk reduction has not been adequately evaluated.The work was aimed at characterising trace element solubility, plant and microbial communities of the top layer of the reclaimed zinc and lead smelter waste heaps in Piekary Slaskie, Poland, 20 years after the treatment and revegetation. The surface layer of the waste heaps treated with various rates of biosolids and the by-product lime was sampled for measuring chemical and biochemical parameters, which are indicative for metals bioavailability as well as for microorganisms activity. Microbial processes were characterised by enzyme activities, abundance of specific groups of microorganisms and identification of N fixing bacteria. Plant communities of the area were characterised by a percent coverage of the surface and by a composition of plant species and plant diversity. The study provides a strong evidence that the implemented remediation approach enables a sustainable functioning of the ecosystem established on the toxic waste heaps. Enzyme activities and the count of various groups of microorganisms were the highest in areas treated with both biosolids and lime, regardless their rates. A high plant species diversity and microbial activities are sustainable after almost two decades from the treatment, which is indicative of a strong resistance of the established ecosystem to a metal stress and a poor physical quality of the anthropogenic soil formed by the treatment.

Residual effects of paper mill biosolids and liming materials on soil microbial biomass and community structure

Repeated annual application of paper mill biosolids (PB) and liming materials may impact soil functioning, such as nutrient cycling, organic matter decomposition, and microbial activities. The objective of this study was to evaluate the residual effect of 9 yr annual applications of PB and different liming materials on soil microbial community structure and microbial biomass C, N, and P. Treatments consisted of PB at four rates (0, 30, 60, and 90 wet Mg ha−1), three liming by-products (calcitic lime, lime mud, and wood ash, each at 3 wet Mg ha−1 with 30 Mg PB ha−1), and a mineral N fertilizer surface-applied after annual crop seeding. Three years after treatment application ended, soils were sampled from 0–15 to 15–30 cm layers in each plot after corn harvest. Soil microbial community and microbial biomass C, N, and P were higher in the surface layer than deeper. Application of PB significantly increased soil microbial biomass C, N, and P and fungal biomass in both layers and induced changes in microbial community structure. In contrast, application of liming by-products did not affect microbial biomass and community. This study revealed that repeated PB application improved soil biological attributes, and those improvements can be sustained for years.

Visible near infrared reflectance spectroscopy prediction of soil heavy metal concentrations in paper mill biosolid- and liming by-product-amended agricultural soils

Continuous assessment of soil heavy metal concentrations in agricultural soils is critical for ensuring ecosystem health and minimizing potential adverse effects. However, conventional laboratory determinations are time-consuming, expensive and involve hazardous chemicals. We evaluated the potential of visible near infrared reflectance spectroscopy (VNIRS) to rapidly and simultaneously predict total, Mehlich-3 (M3), DTPA, and water-soluble (H2O) soil heavy metal concentrations. Soil samples were collected from a loam soil (n=64) and a loamy sand (n=32) after repeated annual applications (3–9years) of paper mill biosolids (PB) and liming by-products. Models were developed using modified partial least squares regression on 75% of the total sample set and also for each soil, after removal of the spectral outliers (n=3), with the remainder used for validation. The coefficient of determination in validation (R2V) and the ratio of performance to deviation (RPD) were used to assess model accuracy. Predictions for the total set were excellent for total Zn and Cd, M3-Cu and -Cd, and DTPA-Cd (R2V>0.90, RPD>3.0), good for total Cu, Ni and Mo, M3-Ni, DTPA-Cu and -Ni, and H2O-Cu and -Ni (R2V=0.70 to 0.90, RPD=1.70 to 3.0), but poor for M3-Zn, DTPA-Zn, and H2O-Zn, -Cd and -Mo (R2V<0.70, RPD<1.70). Except for one case, site-specific models were either more accurate or provided similar results with the model of the total set in predicting site-specific concentrations. The relationship with soil organic matter (SOM) was the major predictive mechanism for Cd in our dataset, while the prediction of other soil heavy metals was due to the combined influence of SOM and Fe oxides. We conclude that VNIRS has the potential to predict total, M3, DTPA and to a lesser extent water-soluble soil heavy metals, especially when developed using site-specific samples.

Evolution of forest soil properties after liming with a by-product derived from a sugar beet mill

Deciduous oak coppices (Quercus pyrenaica Willd.) of the “Sierra de Gata” mountains (central western Spain) are located on acid rocks and subjected to annual rainfall higher than 700 mm year−1. Accordingly, the soils are acidic (soil pH is often below 5.0) and feature the presence of Mn2+ and Al3+ in the exchangeable complex. The aim of the present study was to assess the response of these soils to the addition of a lime residue from a sugar beet mill to reach pH values close to 7.0 and 6.0 with in situ and in vitro experiments, respectively. Initially, the quality of the lime by-product was evaluated, which showed content close to 75 % CaCO3. Based on that analysis, calculations were accomplished to determine the dose of lime by-product necessary for achieving the targeted soil pH. We first performed an in vitro liming experiment, incubating 0.50 kg soil (0–20 cm layer) with 23.92 g CaCO3 kg−1 soil (20 °C and soil moisture equivalent to that of field capacity). Subsequently, another experiment was done adding an equivalent quantity of sub-product in lieu of the pure CaCO3; the factors monitored were: soil pH, exchange acidity, CEC, and exchangeable bases, every 24 h. The in situ experiment was performed in a forest plot located in Western Spain (Navasfrias), liming with 16.0 Mg DM by-product ha−1 (September 1999). Soil samples (two depths: 0–10 and 10–20 cm) were taken from both the control and the experimental forest plots for monitoring the liming effect. Sampling dates were September and December 1999; June 2000, January, June and September 2001; October 2002 and 2003, and March 2005). The dissolution of the lime by-product at the laboratory was almost immediate, but the effects in the field occurred approximately 2 years after initial liming, since lime dissolution depends on both the amount and distribution of rainfall and, also, on the application procedure.

Repeated Annual Paper Mill and Alkaline Residuals Application Affects Soil Metal Fractions

The application of industrial residuals in agriculture may raise concerns about soil and crop metal accumulation. A complete study using a fractionation scheme would reveal build-up in metal pools occurring after material addition and predict the transformation of metals in soil between the different forms and potential metal release into the environment. An experimental study was conducted from 2000 to 2008 on a loamy soil at Yamachiche, Quebec, Canada, to evaluate the effects of repeated annual addition of combined paper mill biosolids when applied alone or with several liming by-products on soil Cu, Zn, and Cd fractions. Wet paper mill biosolids at 0, 30, 60, or 90 Mg ha and calcitic lime, lime mud, or wood ash, each at 3 Mg ha with 30 Mg paper mill biosolids ha, were surface applied after seeding. The soils were sampled after 6 (soybean [ (L.) Merr.]) and 9 [corn ( L.)] crop years and analyzed using the Tessier fractionation procedure. Results indicated that biosolids addition increased exchangeable Zn and Cd, carbonate-bound Cd, Fe-Mn oxide-bound Zn and Cd, organically bound Cu and Zn, and total Zn and Cd fractions but decreased Fe-Mn oxide-bound Cu in the uppermost 30-cm layer. With liming by-products, there was a shift from exchangeable to carbonate-bound forms. Even with very small metals addition, paper mill and liming materials increased the mobility of soil Zn and Cd after 9 yr of application, and this metal redistribution resulted into higher crop grain concentrations.

Crop yield and soil fertility as affected by papermill biosolids and liming by-products

Ziadi, N., Gagnon, B. and Nyiraneza, J. 2013. Crop yield and soil fertility as affected by papermill biosolids and liming by-products. Can. J. Soil Sci. 93: 319–328. Papermill biosolids (PB) in combination with alkaline industrial residuals could benefit agricultural soils while diverting these biosolids from landfill. A greenhouse study was conducted to evaluate the effect of three types of PB at rates of 0, 30, and 60 wet Mg ha−1, as well as five liming by-products at 3 wet Mg ha−1 along with 30 Mg PB ha−1 on crop yield, nutrient accumulation, and soil properties. De-inking paper biosolids (DB, C/N of 65) were applied to soybean [Glycine max (L.) Merr.], and two combined PB (PB1, C/N of 31; and PB2, C/N of 14) were applied to dry bean (Phaseolus vulgaris L.) and barley (Hordeum vulgare L.), respectively. The liming by-products included lime mud (LM), wood ash (WA) from paper mills, commercial calcitic lime (CL), Mg dissolution by-product (MgD), and Mg smelting and electrolysis work (MgSE). Compared with the control, PB2 increased barley yield and total Mg and Na accumulation, and both PB increased plant N, P, and Ca accumulation in barley and dry bean. The impact of DB on soybean was limited. The addition of liming by-products to PB or DB did not affect crop attributes except the combination with MgSE, which severely reduced the growth of dry bean and, to a lesser extent, soybean. Soil NO3-N was immobilized following DB application, whereas there was a net release with both PB. Combining PB and liming by-products produced the greatest changes in soil properties at harvest. Generally, LM and CL raised pH and Mehlich-3 Ca, and MgSE caused a strong increase in Mehlich-3 Mg and Na and water-soluble Cl. When used with appropriate crops, biosolids from paper mills and alkaline residuals other than MgSE can efficiently enhance soil fertility by providing organic C and macronutrients for balanced crop fertilization.

Crop yield and soil fertility as affected by papermill biosolids and liming by-products

Ziadi, N., Gagnon, B. and Nyiraneza, J. 2013. Crop yield and soil fertility as affected by papermill biosolids and liming by-products. Can. J. Soil Sci. 93: 319-328. Papermill biosolids (PB) in combination with alkaline industrial residuals could benefit agricultural soils while diverting these biosolids from landfill. A greenhouse study was conducted to evaluate the effect of three types of PB at rates of 0, 30, and 60 wet Mg ha-1, as well as five liming by-products at 3 wet Mg ha-1 along with 30 Mg PB ha-1 on crop yield, nutrient accumulation, and soil properties. De-inking paper biosolids (DB, C/N of 65) were applied to soybean [Glycine max (L.) Merr.], and two combined PB (PB1, C/N of 31; and PB2, C/N of 14) were applied to dry bean (Phaseolus vulgaris L.) and barley (Hordeum vulgare L.), respectively. The liming by-products included lime mud (LM), wood ash (WA) from paper mills, commercial calcitic lime (CL), Mg dissolution by-product (MgD), and Mg smelting and electrolysis work (MgSE). Compared with...

Metal Availability following Paper Mill and Alkaline Residuals Application to Field Crops

Land application of residuals from the forest industry can help to restore soil fertility, but few studies have assessed the effects of metal accumulation in plants. An experimental study was initiated in 2000 on a loamy soil at Yamachiche, QC, Canada, to evaluate the effects of repeated annual applications of combined paper mill biosolids, when applied alone or with several liming by-products. This study assessed the accumulation of Cu, Zn, Mo, and Cd in plants and soil after 6 (soybean [ (L.) Merr.]) and 9 [corn ( L.)] crop yr. Wet paper mill biosolids at 0, 30, 60, or 90 Mg ha were surface applied after seeding. Calcitic lime, lime mud, and wood ash were applied wet each at 3 Mg ha with 30 Mg wet paper mill biosolids ha. Repeated applications of paper mill biosolids increased plant and soil metal concentrations after 6 and 9 yr in the order of Cd > Mo (soybean) > Zn > Cu. Liming increased soil pH and Mo availability and decreased Zn and Cd availability. Metals in crop stover responded more positively to applications than those in grains, but the concentrations in plant tissues were generally well below critical values. The Cu/Mo ratio of soybean plants at pH > 6.8 fell below 2:1, however, and may pose a risk for inducing Cu metabolism disorder in ruminants. Results of this study indicate that paper mill biosolids and alkaline residuals, when applied with respect to regulations and soil pH, have a limited effect on metal accumulation in plants and soil.

Papermill biosolids and alkaline residuals affect crop yield and soil properties over nine years of continuous application

Gagnon, B. and Ziadi, N. 2012. Papermill biosolids and alkaline residuals affect crop yield and soil properties over nine years of continuous application. Can. J. Soil Sci. 92: 917-930. Residues from paper and wood mills are a valuable source of nutrients for field crops, but little is known about the effectiveness of repeated applications over many years. A study was initiated at Yamachiche, QC, to assess the effect of continuous applications over 9 yr of combined papermill biosolids (PB), applied alone or with several liming by-products, on grain yield, plant nutrient accumulation, and soil fertility in a loamy soil cropped to grain corn, dry bean, and soybean. The PB treatments (0, 30, and 60 Mg wet ha-1) and liming by-products [calcitic lime (CL), lime mud (LM), wood ash (WA)], and two magnesium residuals, each at 3 Mg wet ha-1 along with 30 Mg PB ha-1) were surface applied annually at post-seeding. In the last 6 yr, the two treatments receiving magnesium residuals were replaced with 90 Mg wet PB ha-1...

Papermill biosolids and alkaline residuals affect crop yield and soil properties over nine years of continuous application

Gagnon, B. and Ziadi, N. 2012. Papermill biosolids and alkaline residuals affect crop yield and soil properties over nine years of continuous application. Can. J. Soil Sci. 92: 917-930. Residues from paper and wood mills are a valuable source of nutrients for field crops, but little is known about the effectiveness of repeated applications over many years. A study was initiated at Yamachiche, QC, to assess the effect of continuous applications over 9 yr of combined papermill biosolids (PB), applied alone or with several liming by-products, on grain yield, plant nutrient accumulation, and soil fertility in a loamy soil cropped to grain corn, dry bean, and soybean. The PB treatments (0, 30, and 60 Mg wet ha−1) and liming by-products [calcitic lime (CL), lime mud (LM), wood ash (WA)], and two magnesium residuals, each at 3 Mg wet ha−1 along with 30 Mg PB ha−1) were surface applied annually at post-seeding. In the last 6 yr, the two treatments receiving magnesium residuals were replaced with 90 Mg wet PB ha−1 and mineral N fertilizer (MIN), respectively. Repeated annual applications of LM followed by CL increased soil pH the most (up to 1.4 unit). Crop yields were not significantly affected by treatments in the first 3 yr but subsequent applications of PB at 90 Mg ha−1 increased yields in grain corn (+1.9 Mg ha−1) and dry bean (+0.77 Mg ha−1) relative to the control, while PB with WA increased yield in soybean (+0.85 Mg ha−1). The PB at 30 Mg wet ha−1 with supplemental N (average of 45 kg N ha−1), or at 60 Mg wet ha−1 applied alone, achieved yields comparable with MIN treatment under corn. The PB applications increased soil organic matter and all major soil nutrients except K and Mg. The results of this study indicate that PB and alkaline residuals can be effectively applied to agricultural soils over many years although PB exceeding 60 Mg wet ha−1 yr−1 induce significant nitrate leaching.

Soil phosphorus fractions following annual paper mill biosolids and liming materials application

Industrial by-products such as paper mill biosolids (PB) and different liming materials have been used as fertilizers and amendments in agricultural soils for many decades. However, little is known about the effects of their repeated application on soil nutrient availability, particularly phosphorus (P). A 6-yr field study (2000-2005) was conducted in the province of Quebec to investigate the effect of repeated annual applications of different PB and industrial by-products on selected soil chemical properties, especially soil P fractions. Different PB rates (0 to 90 Mg wet ha-1) and several liming products (lime mud, wood ash, calcitic lime, and Mg by-products) were annually applied to field crops after seeding. Soils were sampled before seeding in May 2003 and at harvest in October 2005. Results showed that HCl-P was the largest P pool, accounting for about 64% of the total P fraction, and that the repeated applications of liming products significantly increased this pool and decreased the organic P pools. The NaOH-Po and residual-P were significantly lower in 2005 than in 2003, indicating that PB application without supplemental P fertilizer inputs enhanced the mobility and/or mineralization of NaOH-Po and the transformation of recalcitrant P to more labile forms with time. Lime mud (LM) was found to be the best liming material owing to its high neutralization capacity and positive effect on soil P availability over time. Key words: Paper mill biosolids, alkaline residuals, lime, wood ash, soil P fractions

Integrating knowledge of nutrient forms and dynamics into improved nutrient management practices: Atribute to Régis Simard

Régis Simard and his colleagues developed a research program focussing on the agronomic and environmental impacts of nutrients in agricultural systems. The success of this program resulted from an integrated approach, linking assessment of nutrient availability to an understanding of nutrient dynamics in the soil, and applying this understanding to development of improved management practices for a variety of nutrient sources. Research into nutrient availability conducted by Régis and his co-workers led to improvements in quantification of nutrient supply, using traditional soil analysis with batch chemical extraction as well as ionic exchange membranes (IEMs) and electro-ultrafiltration (EUF). Ion exchange membranes are now used as a tool in routine soil fertility assessments and in agronomic and environmental research to study nutrient ion release rates. Additionally, intensive analytical techniques, such as sequential extraction and X-ray absorption near-edge structure (XANES) were developed and used to characterize the forms and relative availability of soil nutrients for plant uptake or environmental effects. Characterization of nutrient pools improved understanding of nutrient dynamics in the soil, allowing a more accurate assessment of the agronomic value and environmental risk of nutrients applied to agricultural systems. Building on this knowledge, Régis and his colleagues developed improved methods of utilizing manures, composts, paper mill sludge (PMS) and liming by-products, effectively diverting nutrients from the waste stream into a resource for crop production. This paper describes the contributions of Régis and his colleagues to the improvement of agronomically and environmentally sustainable nutrient management practices, based on an integrated research approach that provided a clear understanding nutrient availability and soil nutrient dynamics. Key words: Chemical extraction, integrated nutrient management, ion exchange membranes, paper mill sludge, soil phosphorus, soil potassium