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Acidification and metal mobility may present challenges in soil receiving paper mill biosolids (PB). Co-applying biochar and PB could help prevent these issues, but its effect must be assessed. The objective of this 224 d incubation study was to evaluate the effect of amending two acidic soils, a clay and sandy loam, with two PB types varying in pH (PB1, pH = 7.80; and PB2, pH = 4.51) co-applied with three rates (0%, 2.5%, and 5% w/w) of pine (Pinus strobus L.) biochar on soil pH and macro- (P, K, Ca, and Mg) and micronutrients (Cu, Zn, Fe, and Mn). In both soils, co-applying biochar and PB significantly increased soil pH and extractable K concentration compared with PB-only application, whereas amending with PB significantly increased soil extractable P concentration compared with the unamended soil. In comparison with PB only, co-applying 5% biochar and PB decreased extractable Cu concentration in both soils and extractable Fe concentration in the sandy loam soil. This study showed that co-applying biochar and PB can be more beneficial to agricultural soils than application of PB alone by supplying nutrients and helping prevent metal toxicity by raising pH, especially in acidic sandy soils.

High levels of trace metals such as copper (Cu) can affect water quality and induce toxic effects on living organisms in aquatic ecosystems. This research assesses the potential capacity for Cu phytofiltration by three emergent macrophytes from Cu-contaminated sediments and water containing five concentrations of Cu (0, 50, 100, 150, and 200 µM). We conducted a greenhouse study using semi-hydroponic and hydroponic experimental conditions to simulate a natural wetland system. We selected three plant types that were collected in Quebec (Canada): nativeStudies in wetland phytoremediation have focus on either contaminated soil or water. This research highlights the comparison of three emergent macrophytes in removing copper from both soil (a simulated riparian wetland) and water (floating treatment wetland). This study compares the phytoextraction and rhizofiltration capacity of

Residual soil NO3-N (RSN) is susceptible to loss during the non-growing season. This 5 yr study investigated the effects of three N fertilizer sources [ammonium nitrate (AN), ammonium sulfate (AS), and polymer-coated urea (PCU)] applied at four rates (60, 120, 200, and 280 kg N ha−1) plus an unfertilized control on RSN following potato production and on overwinter NO3-N changes in an irrigated sandy soil in Quebec, Canada. Composite soil samples were collected at the 0–15, 15–30, 30–60, and 60–90 cm depths immediately after potato harvest in fall and again in the following spring from 2008 to 2012. Residual soil NO3-N content within the 0–30 cm depth (RSN0–30) was highly correlated with the RSN content in the 0–90 cm depth (RSN0–90), indicating that RSN0–30 can be used as an indicator of soil profile NO3-N accumulation. Overall, RSN0–90 increased with fertilizer N application rate, particularly for above the minimum fertilizer N rate required to maximize yield (Nmax), and was generally higher for years with greater pre-plant soil NO3-N. The split application of AN and AS resulted in lower RSN0–90 than the single application of PCU at above Nmax. Overwinter losses of soil NO3-N were generally increased with increasing RSN0–90 in fall. The results suggest that reducing the fertilizer N rate is more important than the choice of N source in managing RSN.

Adding biochar to paper mill biosolids (PB) amendments may affect PB mineralization rate and nitrogen (N) availability. The objective of this 224-day incubation study was to evaluate the effect of amending two PB types varying in carbon (C)/N ratio (PB1, C/N = 24; and PB2, C/N = 13) with three rates (0%, 2%, and 5%) of pine (Pinus strobus L.) biochar produced at 700 °C on the dynamics of total C, total N, mineral N, N mineralization rate, and microbial biomass C (MBC) and N (MBN) in two agricultural soils (Kamouraska clay and St-Antoine sandy-loam). Two reference treatments were also included, namely, mineral fertilization and unamended soil. Total soil C concentration remained stable over the incubation period, whereas a decrease in total soil N was observed in both soils. In comparison with the unamended soil, the application of PB significantly increased total N, NH4-N, NO3-N, net mineralized N, applied N mineralization rate, and MBC in both soils. In comparison with the application of PB alone, biochar addition increased total C and MBC but decreased NH4-N, NO3-N, net N mineralization, and applied N mineralization rate in both soils. The co-application of biochar and PB1 resulted in the sequestration of mineral N released, which was more pronounced in the Kamouraska clay soil. The co-application of biochar and PB2 resulted in moderate release of mineral N. This study showed that the co-application of biochar and PB can benefit agricultural soils by improving NO3-N retention in agroecosystems while increasing organic matter and promoting microbial biomass.

Nitrate leaching is of great environmental concern, particularly with potatoes grown on sandy soils. This 3-year study evaluated the effect of three N rates (100, 150, and 200 kg ha−1) of single applications of polymer-coated urea (PCU) and a 75% PCU + 25% urea mixture, plus a conventional split application of 200 kg N ha−1 of a 50% ammonium sulfate + 50% calcium ammonium nitrate mixture (CONV) on NO3−-N leaching, potato yield, and N uptake under irrigated and non-irrigated conditions on a sandy soil in Quebec (Canada). Fertilizer N application increased growing season NO3−-N leaching only under irrigation. On average, irrigation increased seasonal NO3−-N leaching by 52%. Under irrigated conditions, PCU reduced NO3−-N leaching compared to PCU + urea. However, both PCU and PCU + urea significantly increased NO3−-N leaching compared to the CONV at the equivalent N rate of 200 kg N ha−1. This was attributed to the timing of soil N availability and deep-water percolation. Total (TY) and marketable (MY) yields in the CONV were similar to those in the PCU applied at the equivalent N rate of 200 kg N ha−1. Despite lower plant N uptake, PCU resulted in greater TY and MY compared to PCU + urea. Residual soil inorganic N was greater for PCU and PCU + urea compared to the CONV, providing evidence that PCU products have the potential to increase NO3−-N leaching after the growing season. In this study, PCU was an agronomically and environmentally better choice than PCU + urea. The results also showed that the efficiency of PCU to reduce seasonal NO3−-N leaching may vary according to the timing of precipitation and irrigation.

Co-applying biochar and paper mill biosolids (PB) improves the potential of these by-products as soil amendments. Assessing the response of soil microbial communities to the co-application of biochar and PB is of great importance to further understanding their effectiveness. This hypothesis was tested in a 112-day incubation study performed separately on two acidic soils (Kamouraska clay and St-Antoine sandy loam) using two PB types (PB1 with C/N = 24 and PB2 with C/N = 13), co-applied with one of three rates (0%, 2.5%, and 5% w/w) of pine (Pinus strobus L.) biochar. An unamended control and a mineral-fertilized treatment were used as a reference. In the Kamouraska clay soil, co-applying 5% biochar and any PB increased microbial activity compared to PB-only application, as indicated by the fluorescein diacetate (FDA) hydrolysis assay. In both soils, co-applying biochar and PB did not affect microbial diversity and community structure compared with PB only. The application of any PB, however, increased microbial activity in both soils, while only PB2 shifted microbial community structure. Within each amendment and in both soils, microbial activity was lower at day 112 than at days 28 and 56, while major temporal shifts were observed only for bacterial community structure. Indeed, the difference in bacterial community structure between amendments was more pronounced at day 112. This study suggests that co-applying biochar and PB can improve soil properties than application of PB alone by increasing soil microbial activity without side effects on microbial diversity and community structure, especially in acidic clay soils.

Phosphorus (P) is an essential nutrient for grassland production systems. However, continuous applications of P fertilizers result in soil P accumulations, increasing the risk of P losses in runoff and erosion. This study aims to investigate the field-scale variability of soil-test P (STP) in two contrasting grassland fields using descriptive statistics and geostatistics for accurate recommendations on soil sampling strategy and sustainable approaches to P management. A young grassland (YG, 2 years) and an old grassland (OG, 10 years under permanent pasture) were classified as humo-ferric podzol and received organic fertilizers. Soil samples were collected in 16-m by 16‑m triangular grids at two depths (0&ndash, 5 and 5&ndash, 20 cm). They were analyzed for available P and other soil elements extracted using the Mehlich-3 method (M3). The agri-environmental P saturation index (P/Al)M3 was calculated. Phosphorus accumulation was observed in OG (0&ndash, 5 cm) as a result of long-term manure applications. Repeated applications of organic fertilizers can impact the long-term buildup of soil P, thus decreasing soil P va-riability and spatial dependence in permanent grasslands. A soil sampling strategy focusing on the 0&ndash, 5 cm layer should be retained in permanent grasslands for sustainable P recommendations in Eastern Canada.

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 (H 2 O) soil heavy metal concentrations. Soil samples were collected from a loam soil ( n = 64) and a loamy sand ( n = 32) after repeated annual applications (3–9 years) 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 (R 2 V ) 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 (R 2 V > 0.90, RPD > 3.0), good for total Cu, Ni and Mo, M3-Ni, DTPA-Cu and -Ni, and H 2 O-Cu and -Ni (R 2 V = 0.70 to 0.90, RPD = 1.70 to 3.0), but poor for M3-Zn, DTPA-Zn, and H 2 O-Zn, -Cd and -Mo (R 2 V

Acid mine drainage (AMD) production by sulfide mine tailing (SMT) is a major environmental preoccupation because it can degrade water surface quality on account of its strong acidity and advanced content of sulfide, iron (Fe) and other metals and metalloids. Acid neutralization and the precipitation of metals present in AMD were carried out by electro-activation with ion-exchange membranes, which is based on the self-generation of necessary conditions for acid neutralization and metal precipitation. The treatment of SMT was carried out by using an electro-activation cell generated alkaline solution in the cathode compartment. After 60 min of electro-activation, a pHcatholyte of 7.9–9.6, depending on the experimental conditions, was obtained. The absence of Fe and other trace metal ions in the catholyte provide evidence that the electro-activation of SMT promotes the precipitation of insoluble trace metals in the cathode compartment. This approach can be applied to real conditions in combination with a pretreatment of SMT neutralization, in which biological calcareous amendments are available. Finally, the electro-activation technology of acid mine drainage may be a feasible, cost-effective approach for SMT neutralization because it focuses on sustainable development.

The study goal is to document the prevalence of salvia use among patients admitted for detoxification of other illicit drug use and to determine its effect. This cross-sectional study included 47 heavy drug users who were admitted for detoxification of other illicit drug abuse at a psychiatric hospital in Lebanon. The prevalence of salvia use was 66%. The salvia effect started and dissipated rapidly (15 min). No significant difference was found between salvia and non-salvia users in terms of affect, cognition and somaesthesia subscales of the Hallucinogen Rating Scale. Ratings of intensity and volition subscales were higher in non-salvia users than salvia users, while perception score was higher in users. Salvia use was correlated with perceptual alteration and hallucinogenic effects.

Acid mine drainage (AMD) generated from pyrite oxidation in sulfide mine tailings is a major geoenvironmental problem. This AMD is characterized by pH

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.

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.

In this paper, we present a new method for multi-view 3D reconstruction based on the use of a binocular stereo vision system constituted of two unattached cameras to initialize the reconstruction process. Afterwards , the second camera of stereo vision system (characterized by varying parameters) moves to capture more images at different times which are used to obtain an almost complete 3D reconstruction. The first two projection matrices are estimated by using a 3D pattern with known properties. After that, 3D scene points are recovered by triangulation of the matched interest points between these two images. The proposed approach is incremental. At each insertion of a new image, the camera projection matrix is estimated using the 3D information already calculated and new 3D points are recovered by triangulation from the result of the matching of interest points between the inserted image and the previous image. For the refinement of the new projection matrix and the new 3D points, a local bundle adjustment is performed. At first, all projection matrices are estimated, the matches between consecutive images are detected and Euclidean sparse 3D reconstruction is obtained. So, to increase the number of matches and have a more dense reconstruction, the Match propagation algorithm, more suitable for interesting movement of the camera, was applied on the pairs of consecutive images. The experimental results show the power and robustness of the proposed approach.

In the process of phytoremediation of mine tailing land, the bioavailability of heavy metals is an important factor. Greenhouse experiment was conducted to assess the availability and uptake of copper (Cu) by maize (Zea mays L.) grown on a slightly alkaline Cu-mine tailing amended with commercial compost and chelators. A second objective was to evaluate the distribution of Cu in cultivated Cu-mine tailings. The experimental design consisted of 12 treatments resulting from the combination of four rates (0, 5, 10 and 20%, by humid weight) of peat moss-shrimp wastes compost and three rates (0, 1.2 and 2.4 dm3) of organic complexing agents applied as a 0.0025 M EDTA + 0.001 M citric acid solution before plant harvest. The results showed that compost and chelators had a positive effect on top biomass production of maize. Compared with the control, the application of compost decreased CuCAR and increased CuORG whereas the addition of chelating solution increased CuSOL and CuEXC and decreased CuCAR and CuORG. Th...

With rising environmental concerns for current practices of fertilizer N management in the humid and cool areas, we simulated soil N dynamics and plant N use in the potato (Solanum tuberosum L.) cropping system using the software Stella. The objectives were to predict in-season N requirements by the potato crop, tuber yield, N uptake, N partitioning within root, leaf, stem and tuber, and N loss in the plant–soil system, and to examine the accuracy of using model predictions for N management in potato. The first-order linear and S-shaped growth processes were used in the simulation. The model was unidimensional and used a daily time step. Sensitivity analysis indicated that N inflow in the system was the key trait affecting potato N uptake and tuber yield. The model was validated by comparisons of the predictions with field study datasets at four sites conducted across Quebec, Canada. The simulated daily N uptake by the potato followed a S-growth pattern from the early vegetative stage to full bloom, and a plateau of N uptake appeared at late tuberization. The predicted maximum daily N uptake rate (4.46 kg ha−1 day−1) occurred at early bloom whereas the predicted maximum N transfer from stems and leaves to tubers (4.31 kg ha−1 day−1) occurred 3 weeks after the peak of N uptake. Simultaneously, high daily N uptake occurred when N concentrations in the root zone ranged between 90 and 120 kg ha−1. The predicted N uptake and potato tuber yield values were correlated to N inflows in the model (R2 = 0.91). The model estimated loss of N was 34% of the field measurements. Using model balancing the amounts of N needed by crops would lead to optimize plant growth and N use efficiency and to minimize N lost to the environment.

Low soil organic matter content and limited soil water holding are the major natural constraint of dryland cropping on sandy soils in the Quebec boreal regions. We conducted a 3-yr (1994–1996) study in a boreal sandy soil, Ferro-Humic Podzol (Spodosols), to determine the potential of Sphagnum peat for improving soil organic matter (SOM), water holding capacity, bulk density (BD), plant leaf nutrient status, and potato and barley yields. The cropping was a rotation of 2-yr potato (Solanum tuberosum L. ‘Superior’) and 1-yr barley (Hordeum vulgare L. ‘Chapais’). The treatments consisted of Sphagnum peat at rates of 0, 29, 48, and 68 Mg ha−1 3-yr−1 on a dry weight basis, and granular N-P-K fertilizers (12-7.5-7) at rates of 1.4, 1.6, and 1.8 Mg ha−1 yr−1, respectively, arranged in a split-block design. The peat-amended soils were higher in water content (SWC), SOM and total porosity but lower in BD and N than neighboring non-peat soils (P < 0.05). Effects of peat and fertilizer treatments and their interaction were significant on potato leaf N, Ca, Mg, and P, tuber yield, dry weight, harvested N and tuber specific gravity (P < 0.05), depending on year. Potato tuber yield and N increased simultaneously up to 30% (compared to the control), and were significantly correlated with SWC, SOM, BD, and NO3-N (−0.52 ≤r ≤ 0.80). In the 3rd year, the linear effect of peat treatments was significant on barley grain yield. In 1995 there was a decline of 4.5−7.3% of SOM of the previous year level. It is suggested that Sphagnum peat at a rate of 48 Mg ha−1 had the potential for improving sandy soil productivity. A longer-term investigation of soil water, N, SOM pool and crop yield changes is necessary to better understand the physical, chemical and biological processes of peat in cropping systems and to maximize the benefits of peat applications.

Liming can modulate phosphorus (P) availability to plants growing in acid-forming media. The objectives of this study were to determine the effects of lime and phosphorus rates on corn (Zea mays L.) grown under greenhouse conditions on an acid-producing mine tailing, and to evaluate P desorption from the mine tailing after harvest. The acid-sulfide tailing (pH 2.65) collected from the Solbec-Cupra mine in Quebec was limed using CaCO3 to theoretical pH values of 5 (11 g/kg), 6 (17 g/kg) and 7 (30 g/kg) prior to corn production. Phosphorus was thoroughly mixed with the tailing at rates of 0, 22.4, 44.8 and 89.6 mg P/kg. Commercial peat-shrimp waste compost; a commercial bone flour fertilizer and reagent-grade KH2PO4 were used as P sources. Corn (Zea Mays L. cv. 'Pride 1122') was grown for 50 days after emergence. After harvest, the mean tailing pH values varied from 4.20 to 7.20. Dry matter yield of plant tops was significantly affected by lime and phosphorus treatments. Corn yields were significantly correlated with pH, salinity index (electrical conductivity of aqueous extracts) and ammonium acetate-extractable Ca and Mg. In all P treatments, the highest yield was obtained with plot receiving 44.8 mg P/kg and lime rate to achieve pH 6 (17 g of CaCO3/kg). In general, mineral composition of the tops did not show toxic accumulation of trace metals. The P extracted by Na2EDTA from some tailing samples was a time-dependent process. Results from another P desorption study indicated that the amounts of DTPA-TEA-CaCl2 (pH 7.3) extractable substrate P increased with temperature. The DTPA-extracted P data from the 30 tailing samples over a period of 1 to 48 hours were best described by an empirical first-order-rate equation using t0.5 instead of t as the time variable. Liming and P fertilization were determinant factors for the growth of corn in acid sulfide tailings.

It was hypothesized that soil N variability, and fertilization and cropping management affect potato (Solanum tuberosum L.) growth and fertilizer N efficiency. Following a 20-year sod breakup on a loamy soil in eastern Quebec, Canada (46 ◦ 37 � N, 71 ◦ 47 � W), we conducted a 3-year (1993–1995) study to investigate the effects of soil pool N and fertilizer N management on non-irrigated potato (cv. Superior) tuber yield, fertilizer N recovery (NRE), and residual N distribution in soils under humid, cool and acid pedoclimatic conditions. The fertilizer N treatments consisted of a control, side-dress at rates of 70, 105 and 140 kg ha −1 , and split applications (at seeding and bloom) at rates of 70+70, 105+70 and 140+70 kg ha −1 , respectively. Soil acidity was corrected with limestone following the plow down of the sod. Years of cropping, main effect of N treatment, and year and fertilizer N interaction were significant on total and marketable tuber yields and N uptake, which were significantly related to soil N, and root growth. Apparent NRE ranged between 29 and 70%, depending on years and N rates. Total tuber yield, N uptake, soil N use and NRE were significantly higher in the first (sod–potato) year, but decreased by 41.8, 22.7, 21.4 and 14.7%, respectively, in the third (sod–potato–potato–potato) year. Initial soil N pool was declined by 75% following the 3-year cropping. In 2–3 years, the side-dress N (140 kg ha −1 ) increased significantly tuber yields (11.4–19.8%) compared to the split N (70+70 kg ha −1 ). Higher split N had no effect on tuber yield and N uptake but increased residual N at harvest. Unused fertilizer N was strongly linked (R 2 = 0.98) to fertilizer N rates. Time factor and N treatment had significant effects ( P< 0.0001) on loss of N to below the root zone. Smaller scale rate and timing of split N need to be further determined. Increasing fertilizer N use efficiency could be expected with sod breakup and 75% of regional recommendation rate under humid, cool and acid pedoclimatic conditions. Abbreviations: Nf – fertilizer N; Ns – soil N; Nsf – N in soil at bloom; NRs – N uptake in control; NRs – N uptake in fertilizer plot; NRt – total N uptake; NRE – fertilizer N recovery; SMP – Schoemaker, McLean, and Pratt soil buffer pH test; SP – sod–potato; SPP – sod–potato–potato; SPPP – sod–potato–potato–potato; UNf – use of fertilizer N

The accumulation of P originating from animal wastes in the soil profile is of agronomic and environmental concern. Sequential extraction procedure provides relevant information to mobility, bioavailability and distribution of P in animal manure-amended soils. Such information is needed to assess the potential for biological P leaching, under organic amendments, in some Quebec agriculture ecosystems. This study was conducted using soil samples from the long-term experimental plots of the Soil Research Station of the Quebec Ministry of Agriculture, Fisheries and Food at St-Lambert de Levis, Quebec, Canada. The objective of this work was to examine the distribution of P fractions in the profile of a Le Bras silt loam soil (Gleysol) growing corn (Zea mays L.) which had received liquid pig manure (LPM) for 14 years. The surface soil was fertilized annually with various rates of LPM (0, 30, 60, 90 and 120 cm3 ha−1) in a randomized complete block design with four replicates since 1979. In the fall of 1992, soil samples were collected after the corn harvest from 20 soil plots at 20-cm intervals to a depth of 100 cm. Soil samples were air-dried, crushed, sieved through a 2-mm sieve, and analyzed for soil P fractions using a sequential extraction technique. All treatments resulted in an increase in the labile P pool contents of surface or profile soil compared with the control. Without exception, the amounts of P pools decreased with soil depth and were highly correlated with the LPM rates. The proportion of total P as labile (resin-Pi + NaHCO3-P + NaOH-P) in the soil profile increased from 61 (control) to 79% (highest LPM rate). The amounts of P generally increased in the following order: moderately labile NaOH-Pi and -Po (254 mg kg−1) > labile P extracted by resin and NaHCO3 (209 mg kg−1) > stable P (172 mg kg−1). On average, the amount of labile Pi forms (304 mg kg−1) was larger than the amount of labile Po forms (159 mg kg−1) and represented an important fraction of the total labile P pools. Compared to the control treatment, the mean concentration of geochemical P (resin-Pi + NaHCO3-Pi + NaOH-Pi + HCl-Pi + residual P) increased in the soil profile by 16, 26, 33 and 50% for 30, 60, 90 and 120 m3 ha−1 LPM, respectively. On a profile basis, the soil receiving the highest rate of LPM contained 1.8-fold the biological P (NaHCO3-Po + NaOH-Po) of the unamended soil. Amounts of labile Po pools in the soil profile were highly correlated with the organic carbon content. Results from this study suggest that heavy application of LPM over the 14-year period promotes P movement to lower portions of the soil profile. The leaching or translocation of P compounds would be responsible for the distribution of P in the various soil layers. Management of LPM rates is necessary after a long-term fertilization of corn.

Sphagnum peat is an abundant resource in the Quebec boreal zone and can be used to improve water retention in sandy soils of low productivity. Our objective was to select a peat application rate suitable for growing potato (Solanum tuberosum L. 'Superior') and barley (Hordeum vulgare L. 'Chapais') on a ferro-humic podzol. The experiment was conducted in Mistassini, Quebec, from 1994 to 1997. Organic matter content (OMC) of a Parent loamy sand was 2.7–2.9% initially. Peat was applied to small plots in a 2-yr potato and 2-yr barley rotation at rates of 0 (control), 29, 48 and 68 t ha−1 on a dry weight basis. A cupric fertilizer trial (0 vs. 2.2 kg Cu ha−1) was combined with the peat treatments. A yearly potato–barley rotation was also established in a nearby field receiving 25 t peat ha−1. The arable layer of peat-amended soils was stratified into a 5.3- to 14.8-cm thick upper layer (A1) down to the limit of peat incorporation, and an underlying layer (A2), averaging 15 cm in thickness, keeping the original soil properties. The highest tuber yield, but reduced tuber specific gravity, were obtained with the 48 t ha−1 treatment compared with the control and the 29 t ha−1 treatments. Peat rates excceeding 29 t ha−1 reduced yield and quality of the barley crop. The Cu concentration in barley and potato diagnostic tissues decreased as peat rate increased. Copper was needed to counteract the detrimental effects of peat amendments on maturation, yield and quality of barley. At field scale, peat increased the lower limit of soil water content for starting irrigation from 0.12 m3m−3 in the control to 0.15 m3m−3 in the peat-amended soil. Irrigation rate should be augmented at each passage, and frequency of waterings diminished, in peat-amended soils compared with the control, due to increased water storage capacity. Peat improved the productivity of the sandy soil up to 4–5% OMC, but could induce Cu shortage in barley. Key words: Soil water, potato, Solanum tuberosum L., barley, Hordeum vulgare L.

Revegetation of red mud can be difficult without chemical or organic ameliorant for red mud. A greenhouse experiment was conducted to examine the short-term effect of a commercial peat moss-shrimp wastes compost on the growth of pucinellia (Pucinellia distorts L.) in a bauxite residue (red mud) from the Alcan's Vaudreuil alumina refinery at Jonquiere (Quebec), Canada. Characterization of the red mud revealed that the residue was strongly alkaline (pHse=11.4) and contained soluble salts (ECse=10.3 dS m−1), soluble Na (2743 mg L−1), soluble Al (275 mg L−1) and low levels of plant-available nutrients. Red mud components included approximately 40.4% Fe, 18.3% Al, 13.4Percnt; Si, 7.5% Ti, 6.7% Na and 3.5% Ca expressed in oxide. Hematite (∝Fe2O3) was the main mineral in the red mud. The results of the revegetation study have shown that compost amendment treatments affected pH values, salinity, organic carbon and DTPA-exlractable Al contents compared to the control. The highest rate (45%) of compost red...

Nitrogen release from peat-ammonia-mineral fertilizers (PAMF) could be partly controlled by granule size and soil application of nitrification inhibitors. The objective of this study was to evaluate the effects of various combinations of nitrapyrin, a nitrification inhibitor, and granule sizes of PAMF on onion (Allium cepa L. ’Norstar 210B’) yield and N recovery. The study was conducted in a growth chamber, with two soils, two nitrapyrin rates (0 and 8 mg kg−1), three PAMF rates (0, 133 and 266 mg N kg−1) and three granule sizes (2-, 4- and 10-mm diameters). Nitrogen-use efficiency was assessed using the 15N technique. Nitrapyrin considerably depressed onion yield and failed to improve PAMF efficiency because of apparent ammonia toxicity. The 10-mm granules produced higher dry matter yield (3–8%) and root length (1–9%) than 2-mm and 4-mm granules. Maximum N recovery from PAMF 10-mm granules reached 47% in the Tilly soil and 76% in the Chaloupe soil. In contrast to nitrapyrin, granule size may improve N availability to onions from PAMF. Key words: Ammonia, fertilizers, 15N isotope, nitrapyrin, N recovery, onions, peat

The objective of this study was to evaluate the effects of intermediate to high rates of granulated mineral or organo-mineral fertilizers on onion N uptake, nutrient balance, root growth and water influx. Ammonium sources were ammoniated peat (AP), ammonium sulfate (AS) and peat treated with ammonium sulfate (PAS). Onion was grown for 84 d in four soils at five N levels under growth-chamber conditions. Root length, N uptake, and root growth rate were influenced significantly by soil type, N source and N rate and were highest with 133 and 266 mg N kg−1 on loamy soils. On a sandy soil, maximum N uptake was obtained with 133 mg N kg−1. Water influx was influenced significantly by soil type and N application rate and reached its maximum value with 133 mg N kg−1. AP produced the greatest N uptake, root length and root growth rate. Except in the sandy soil, the highest water uptake was also obtained with AP. Compositional nutrient diagnosis (CND) indicated that plants fertilized with AP achieved a more adequate nutrient balance (or the lowest d value) over a larger range of N rates (133–266 mg N kg−1) than AS and PAS. AP, thus, attenuated ammonium toxicity to the crop more than AS and PAS. At AP rates exceeding 266 mg N kg−1, CND indicated a nutrient imbalance involving P or K deficiency. Key words:Allium cepa L., ammoniated peat, compositional nutrient diagnosis, root growth, water influx

The modelling of ion uptake by plants requires the measurement of kinetic and growth parameters under specific conditions. The objective of this study was to evaluate the effect of nine NH inf4 sup+ :NO inf3 sup− ratios on onions (Allium cepa L.). Twenty-eight to 84 day-old onion plants were treated with NH inf4 sup+ :NOf3/sup− ratios ranging from 0 to 100% of each ionic species in one mM solutions in a growth chamber. Maximum N influx (Imax) was assessed using the N depletion method. Except at an early stage, ionic species did not influence significantly Imax, the Michaelis constant (Km) and the minimum concentration for net uptake (Cmin). Imax for ammonium decreased from 101 to 59 pmole cm-2 s-1 while Imax for nitrate increased from 26 to 54 pmole cm-2 s-1 as the plant matured. On average, Km and Cmin values were 14.29 μM, and 5.06 μM for ammonium, and 11.90 μM and 4.54 μM for nitrate, respectively. In general, the effect of NH4 +:NO3 - ratios on root weight, shoot weight and total weight depended on plant age. At an early stage, maximum plant growth and N uptake were obtained with ammonium as the sole source of N. At later stages, maximum plant growth and N uptake were obtained as the proportion of nitrate increased in the nutrient solution. The was no apparent nutrient deficiency whatever NH4 +:NO3 - ratio was applied, although ammonium reduced the uptake of cations and increased the uptake of phosphorus.

Within the last decade, inventories of the soil’s productive capacity indicate severe degradation and loss of arable lands as a result of soil erosion, cultivation, salinization, over-grazing, land clearing, desertification, soil pollution, and atmospheric pollution. Large areas of land have been, and continue to be, contaminated by trace metals, and petroleum hydrocarbons. Many technologies using physical and chemical treatment methods have been developed to remediate contaminated soils. Recently, phytoremediation has been thought to provide an environmentally friendly alternative for the treatment of polluted soils. In phytoremediation of metal-contaminated soils, bioavailability and metal uptake are important factors. Among soil-plant factors controlling metal uptake, the rhizosphere flora is known to play a special role in the phyto-availability of trace elements. In this regard, arbuscular mycorrhizal fungi (AMF), which are among the most common components of soil rhizosphere flora, is of great interest to soil and environmental scientists, from a phyto-remediation and an environmental standpoint. AMF play important roles in the restoration of contaminated ecosystems and are increasingly used in many countries to improve plant nutrition and fertility of degraded land. As AMF are becoming commercially available, their use will also provide further avenues for reducing pollution from agriculture. This chapter reviews the role, the importance, and the application of AMF in ecologically remediating contaminated soils (mycorrhizoremediation). Emphasis is given to the effects of AMF on growth and yield, and on the uptake of trace metals by plants (rhizo-availability) from agricultural and metal-contaminated soils. The chapter also addresses the AMF’s potential for improving or sustaining soil fertility.

Ammonia sorption is an important peat property for making composts and peat-mineral fertilizers. In this study, we investigated the influence of moisture content of fibric, hemic and sapric peat materials on ammonia sorption capacity, and we determined the N forms and the amount of solubilized humic substances following peat ammoniation. Ammonia sorption capacity increased curvilinearly with degree of decomposition from the fibric to the sapric peats, and increased with peat moisture content up to 600 g H2O [kg wet peat]−1 in the range of 400 to 700 g H2O [kg wet peat]−1. The amount of chemically sorbed ammonia was highest in the sapric peat containing [600 g H2O] [kg wet peat]−1. On a dry weight basis, maximum sorption capacity was 24 g NH3-N kg−1 for the fibric peat, 29 g NH3-N kg−1 for the hemic peat and 49 g NH3-N kg−1 for the sapric peat. Ammonia loss of physically retained ammonia was greatest at the highest moisture content and for the least decomposed peat. At ammoniation rates exceeding 30 g NH3 [kg dry peat]−1, exchangeable ammonium and acid-hydrolyzable N were the dominant N fractions in ammoniated peats. Peat ammoniation increased significantly (p < 0.001) the amounts of water-soluble carbon in all peat materials, of fulvic acid in the fibric peat and of both humic and fulvic acids in the hemic and the sapric peats. At maximum ammonia sorption capacity, the total amount of water-soluble and alkali-extractable organic matter reached 338 g kg−1 in fibric peat, 683 g kg−1 in the hemic peat and 848 g kg−1 in the sapric peat. The hemic and sapric peats appeared more appropriate than the fibric peat for making peat-base fertilizers.

A study was conducted under laboratory conditions to determine the quantity of N mineralized from four composted manures incorporated into 2.7 kg of St-Jude sand or Tilly silty loam at rates of 0.05%, 0.10% and 0.20% of total N. With one exception (a hog slurry-sawdust based compost), net cumulative mineralization of N (Nm) during successive incubation periods increased with incubation time and with the rate of addition. After four months of incubation, Nm values varied from 0 to 14% of total added N. A significant third order interaction on Nm values was obtained with compost type, application rate and soil type. Net immobilization of N was apparent at all incorporation rates of hog slurry compost in the two soils. To evaluate C mineralization, composts were applied at the highest N rate and CO2 production measured periodically. One to 8.2% of total added C from manure composts was mineralized after 28 days of incubation. For each compost type, C mineralization was higher with the sandy than wit...

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