bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphorus adsorption characteristics of a constructed wetland soil receiving dairy farm wastewater
Authors: Jamieson T. S. , Stratton G. W. , Gordon R. , Madani A.
Published: April 2011

Adsorption to soil has been identified as a key wastewater P removal mechanism in treatment wetlands. Batch incubation experiments were performed to measure the capacity of a constructed dairy farm wetland in Pictou County, Nova Scotia, to remove P from solution. The constructed wetland had been receiving wastewater since 1996. Non-linear regression analysis was performed using the Langmuir adsorption model to describe the P adsorption characteristics for the wetland soil under study. The Langmuir model was adequate in describing the P adsorption characteristics of the system studied. The P adsorption maxima found were approximately 925, 924, and 1600 mg P kg-1 soil, for the deep zone soil, shallow zone soil, and a background soil (not receiving wastewater), respectively. The P adsorption maxima for the deep zone and shallow zone soils were not significantly different (P > 0.05) from one another, but were significantly lower (P < 0.05) than the background soil. These data, together with information on wastewater inflow and P loading, were used to predict a lifespan of 8 yr for this wetland, relative to P removal. Key Words: Phosphorus, wetlands, constructed, adsorption, Langmuir, saturation
Longevity of deep ripping effects on Solonetzic and associated soils
Authors: Mathison M N , Chanasyk D S , Naeth M A
Published: April 2011

The longevity of deep ripping effects on Solonetzic soils was investigated at 11 field sites in east-central Alberta after a period of 15 to 20 yr. Select soil properties and crop yield of deep-ripped and non-ripped control plots were analyzed. Dryland yield data of wheat, barley, oats and canola were assessed for 10 of the 11 sites over a 16-yr time period. Select soil properties were analyzed once in 1998 with penetration resistance (PR) evaluated again in 1999. A significant difference in penetration resistance was found between the deep ripped versus control treatments (P ≤ 0.05). There were no significant treatment differences for soil texture, bulk density (Db), pH, electrical conductivity (EC) or sodium adsorption ratio (SAR). A significant yield difference between the deep ripping and control treatments (for all crop species) was found for 6 of 10 sites (P ≤ 0.10), with all sites having an increase in mean yield for the majority of years evaluated. Generally, sites in the drier ecoregions had smaller yield increases than those in the wetter ones. Hence some beneficial effects from deep ripping remain for a long time period. Key words: Subsoiling, soil chemical properties, soil physical properties, crop yield, electrical conductivity, sodium adsorption ratio, bulk density
Determination of soil organic carbon and nitrogen at the field level using near-infrared spectroscopy
Authors: Martin P D , Malley D F , Manning G. , Fuller L.
Published: April 2011

This study explored the use of near-infrared spectroscopy (NIRS) for the rapid analysis of organic C (Corg) and organic N (Norg) in the A horizon of soil within a single field. Soil was sampled throughout a field in Manitoba, Canada to capture soil variability associated with topography. The soil samples were oven-dried and treated with acid to remove carbonates, after which C and N were determined by dry combustion. In this study, portions of the dried soil samples not treated with acid were scanned with a near-infrared scanning spectrophotometer between 1100 and 2500 nm. Correlating the spectral and the chemical analytical data using multiple linear regression or principal component analysis/partial least squares regression gave useful correlations for Corg. Over the range of 0–40 mg g-1 Corg, NIR-predicted values explained 75–78% of the variance in the chemical results. Results were improved to 80% for calibrations developed for the 0–20 mg g-1 organic C range. Useful results were not obtained for Norg although the literature shows that total N in soil is predictable using NIRS. It is likely that the acid treatment altered the composition of the samples in an inconsistent manner such that the chemically analyzed samples and those scanned by NIRS were different from each other in Norg concentration or composition. Extrapolation of these Corg results to the landscape scale implies that NIRS has potential to be a suitable method for mapping C for the purposes of monitoring C sequestration. Key words: Near-infrared spectroscopy, soil, carbon, nitrogen, topography, soil monitoring
A pedological investigation of soil erosion severity on undulating land in Lithuania
Authors: Jankauskas B. , Fullen M A
Published: April 2011

It is essential that we can rapidly characterize soil erosion severity. This paper describes a field methodology to classify soil erosion severity on Dystric Albeluvisols in Lithuania. The goal was to assess cumulative soil loss due to the combined action of accelerated and natural soil erosion. Evaluation of soil erosion severity helps us understand which segments of the landscape are susceptible to erosion and therefore require soil conservation. Factors considered in evaluating soil erosion severity included the existing genetic soil horizons remaining after soil erosion processes, the estimated thickness of lost soil, and slope inclination. The estimated depth of soil loss due to the combined action of natural (geological) and accelerated soil erosion was 0.1–0.8 m on the undulating hilly topography of the Zemaiciai Uplands of Western Lithuania. Erosion rates increased with slope steepness. Soil erosion changed soil physical and chemical properties. Therefore, natural soil fertility, as indicated by spring barley yields, decreased 22, 40 and 62% on slopes of 2–5° (3.5–8.3%), 5-10° (8.3–17.7%) and 10–15° (17.7–26.3%), respectively, compared with flat land. Crop yield was strongly negatively correlated (R2 = 0.79, P < 0.001, n = 138) with erosion severity. Due to pedological translocation, non-eroded Dystric Albeluvisols had relatively little clay and silt in eluvial (E) soil horizons, with their relative accumulation in illuvial (Bt) horizons . Thus, severely eroded soils had argillaceous top soils, due to exhumation of Bt horizons. The suggested classification system enables rapid assessment of past soil erosion severity and may have broader applicability in areas of Podzolic soils. Key words: Dystric Albeluvisols, soil erosion severity, slope steepness, soil properties, pedology
Earthworms and agricultural systems: Status of knowledge and research in Canada
Authors: Tomlin A. D. , Fox C. A.
Published: April 2011

Since the ratification of the United Nations Convention on Biological Diversity, there has been increased interest in issues related to biodiversity, particularly with respect to soil biodiversity and the influence of agricultural practices. This paper is one of a series of papers contributing to a state of the art review initiated by Agriculture and Agri-Food Canada on the status of soil biodiversity research in Canada, particularly with respect to agroecosystems. The objectives of this paper are to provide an overview of earthworm species distribution in Canada by province and territory, and to review research that illuminates our understanding of the ecological relationships of earthworms in agricultural systems. Most Canadian earthworm species are considered exotics having generally been dependent on human activity for their introduction and dispersal throughout the Canadian landscape. Twenty-seven earthworm species have been identified so far in Canada; of these, eight species are native to North America. Suggestions for future research on earthworm biodiversity within an agricultural context are discussed including: the need for increased spatial and temporal information on earthworm distributions across Canada, particularly with respect to Canada’s varied agroecosystems and landscapes; information on the ecology of earthworms with respect to their contributions to the soil system and their interactions with other soil fauna; the need for ecosystem process models relating earthworm contributions to soil structure formation and transport of materials and nutrients within the soil system; and the need to determine threshold levels of earthworm species associations in order to optimise effectively their contributions to soil quality and plant growth. To facilitate these studies, expansion of taxonomic expertise and capability across Canada will be required. Key words: Earthworms, agroecosystems, ecology, species distribution, soil biodiversity
The influence of rotation, tillage and row spacing on near-surface soil temperature for winter wheat in southern Alberta
Authors: Larney F. J. , Ren T. , McGinn S. M. , Lindwall C. W. , Izaurralde R. C.
Published: April 2011

Soil and crop management practices and their effects on surface residue levels can modify soil temperature. Our study investigated the effect of rotation, tillage and row spacing on near-surface (0.025 m) soil temperature under winter wheat (Triticum aestivum L.) in 1993-1994 and 1994-1995. The main treatment was winter wheat rotation: continuous winter wheat (WW); winter wheat-canola (Brassica campestris L.) (WC) or winter wheat-fallow (WF)] with tillage sub-treatments of conventional tillage (CT) vs. zero tillage (ZT) and row spacing treatments of uniform row (UR) vs. paired row (PR) spacing. From fall 1993 to spring 1994, ZT was cooler than CT by 1.2°C on the WC rotation, 1.1°C on WW and 0.4°C on the WF rotation. From fall 1994 to spring 1995, the magnitude of tillage differences was lower on all three rotations with ZT being cooler than CT by 0.1–0.9°C. The magnitude of the row spacing effect on soil temperature was less than that of the tillage effect. Extreme differences in soil temperature due to tillage were generally higher (1.0–4.9°C) on the WW and WC than the WF rotation (0.6–2.5°C) due to the presence of more crop residue. Results demonstrate that while ZT promotes overall cooler soils under winter wheat from fall to late spring, especially on continuously cropped (WW, WC) rotations, it also allows moderation of soil temperatures during extremely cold periods. Key words: Soil temperature, winter wheat, rotation, tillage, row spacing
Temporal trends in soil properties at a soil quality benchmark site in the Lower Fraser Valley, British Columbia
Authors: Kenney E A , Hall J W , Wang C.
Published: April 2011

A national soil quality monitoring program was established in 1990 to address concerns that the quality of Canada's agricultural soils was in decline. The British Columbia benchmark site (01-BC) was established in 1991 and is located on the Pelly soil series (Orthic Humic Gleysol) supporting a corn-forage-pasture rotation in the Lower Mainland ecoregion. The objectives of this study were to report on the differences in: (1) the measured soil properties for the 5-yr period between baseline data collection in 1991 and resampling in 1996 and (2) the properties measured annually as indicators of soil compaction. A 25-m (25-m grid was used at the site to locate sampling points for bulk density and collecting soil samples of the Ap, BCg, and Cg horizons, as well as the measurement locations for saturated hydraulic conductivity and penetration resistance. A 5-yr interval sampling regime was used to sample the Ap, BCg, and Cg horizons and bulk density. Saturated hydraulic conductivity and penetration resistance were sampled annually from 1992 to 1998. Between 1991 and 1996 in the A horizons, pH, available P, C:N ratio and bulk density increased by 4.6, 7.8, 2.5, and 8%, respectively, and available K, total C and total N decreased by 21, 16.5, and 18.3%, respectively. In the BCg horizon, pH, available P and C:N ratio increased by 5, 126, and 8%, respectively, and the available K and total N both decreased by 21%. Bulk density remained unchanged. The assumption that the soil chemical properties in the Cg horizon would remain stable during the study period did not hold. The trends detected for the Cg horizon were similar to those measured for the upper two horizons. However, only the reductions in available K and total N and increases in C:N were significant. The changes in the soil physical properties measured at this site indicate that some soil compaction has occurred. Both bulk density at 20 cm and penetration resistance increased at all depths between 1994 and 1998, which coincided with the time period that grazing was included in the crop rotation. Field saturated hydraulic conductivity at 25 cm (Ap2 horizon), although highly variable from year to year also tended to be lower during the pasture rotation. The penetration resistance measurements, which detected changes at all depths, appeared to be a more sensitive indicator of soil compaction than either bulk density or field saturated hydraulic conductivity. Key words: Soil quality, soil monitoring, soil properties, soil compaction, temporal change
Spacial patterns of soil temperature and moisture across subalpine forest-clearcut edges in the southern interior of British Columbia
Authors: Redding T. E. , Hope G. D. , Fortin M. -J. , Schmidt M. G. , Bailey W. G.
Published: April 2011

To investigate if timber harvesting influences spatial patterns of soil micro climate, forest floor soil temperature and moisture were examined across forest-clearcut edges. Transects were sampled during the 2000 growing season across a 1-ha clearcut at a subalpine forest site in the southern interior of British Columbia, Canada. Forest floor temperature measurements were made twice, once under sunny and once under overcast conditions. Moisture status, measured under wet and dry conditions, was expressed as gravimetric and volumetric moisture content and matric potential. Wavelet analysis was used to detect and compare the location of edges in soil properties, and variance partitioning was used to examine the environmental and spatial sources of variability in temperature and moisture. Based on the wavelet analyses, the transition zone, in both temperature and moisture between forest and clearcut occurred at 7–15 m into the clearcut from the south edge and at 8–18 m into the forest from the north edge. Spatial patterns were consistent between clear and overcast conditions and wet and dry conditions. Distance from the edge was a minor source of spatial variability in temperature and moisture relative to the strong contrast between forest and clearcut conditions. The edge influences may have implications for nutrient cycling, plant available water and forest regeneration. Key words: Soil temperature, soil moisture, forest floor, subalpine forest, wavelet analysis, edge effects
Long-term effects of liquid hog manure on the phosphorus status of a silt loam cropped to corn
Authors: Royer I. , Simard R. R. , Barnett G. M. , Cluis D. , Angers D. A.
Published: April 2011

Repeated application of animal manure or mineral P fertilizer can significantly increase soil P content and enhance the risk of water contamination. The objectives of this study were to evaluate the long-term (8 yr) effect of liquid hog manure (LHM) applied at high rates and its timing of application on the soil P status and on the risk index of water contamination by P. Spring (S), fall (F), or spring + fall (SF) applications of LHM on a silt loam (Humo Ferric Podzol) were compared to recommended application rates of mineral fertilizer (MF) in a continuous corn (Zea mays L.) system. Total P applied ranged from 7 to 34 kg P ha-1 yr-1 in the MF treatment and from 106 to 150 kg P haP ha-1 yr-1 in the LHM treatments. Soil samples were collected to 1.0-m depth after one, six and eight annual applications. Applying high rates of LHM for 8 consecutive years resulted in a significant (P ≤ 0.10) enrichment in total soil P content relative to MF at the 0- to 20-cm soil depth. The effects of LHM on labile P forms (water soluble P, Pw and Mehlich-III extractable P, M3P) were also restricted to the 0- to 20-cm depth with values as high as 11 mg kg-1 for Pw and 241 mg kg-1 for M3P in the LHM plots. The degree of soil P saturation, evaluated as Pox/(Alox+Feox), increased to 15% in the 0- to 20-cm depth after 6 to 8 yr of LHM application. Saturation values of 12 to 15% were also found at the 80- to 100-cm depth in some LHM plots. The P index rating was always medium (109 to 216) in soil receiving MF but was high (217 to 432) after 6 to 8 yr of heavy LHM applications, which indicates a high potential risk of soil P transfer to surface water. The results of this study showed that timing of application had little influence on long-term soil P status. Overall, applying LHM at high rates greatly increased total soil P, the degree of soil P saturation, and the labile P forms in the surface horizons but had little effects below 20 cm. Key words: Hog manure, soil P, long-term effects, labile P, P saturation
Shoot-to-root ratios and root biomass of cool-season feed crops in a boreal Podzolic soil in Newfoundland
Authors: Kwabiah A B , Spaner D. , Todd A G
Published: April 2011

Barley (Hordeum vulgare L.) and oat (Avena sativa L.) crops are grown as feed grains by Newfoundland (NL) dairy farmers. The cereals are either grown as monoculture or intercropped with field pea (Pisum sativum L.) with or without N fertilization. Two experiments were conducted in both 2000 and 2001 to evaluate the shoot-to-root (S:R) weight ratios and root biomass in these production systems. Experiment 1 involved monocultures of pea sown at 150 kg ha-1, and barley and oat each sown at 170 kg ha-1. For pea-barley and pea-oat intercrops, pea was sown at 150 kg ha-1 and each cereal component was sown at either 85 and 170 kg ha-1. The seven treatments were referred to, respectively, as pea150, barley170, oat170, pea150-barley85, pea150-oat85, pea150-barley170, and pea150-oat170. Experiment 2 evaluated factorial combinations of two barley seeding rates of 107 kg ha-1 (low) and 157 kg ha-1 (high) and three N rates (0, 30 and 60 kg ha-1) applied at Zadok’s Growth Stage (ZGS 30). Root biomass was sampled from soil (30-cm depth) and determined at about the anthesis stage of oat and barley and the shoot biomass at maturity (ZGS 90). In exp.1, the S:R ratios of oat170 and pea150-oat85and pea150-oat170 ranged from 8.1 to 8.8 and were lower than barley170, pea150, pea150-barley85and pea150-barley170 which ranged from 10.0 to 12.5. Barley170 had the highest root biomass of 835 kg ha-1 followed by pea150-barley170 (745 kg ha-1) and pea150-oat170 (765 kg ha-1). Intercropping pea with cereals increased root biomas s by 31% for pea150-barley85and 48% for pea150-oat85compared to pea150. However, root biomass increased by 109% for pea150-barley170 and 104% for pea150-oat170, indicating that the cereal component of the intercrops contributed more to the root biomass than the pea at the higher seeding rate of the cereal crop. In exp. 2, the 0 kg N ha-1 rate produced the lowest S:R ratios irrespective of the barley seeding rate. When N was applied, both the shoot biomass and root biomass appeared to be increased at the high barley seeding rate. The feed grain production practice in Newfoundland could affect root biomass production in soil. High cereal seeding rates in either monoculture and intercrop systems are required to maximize root biomass production and therefore increase C inputs into the soil. Key words: Shoot-to-root (S:R) ratios, root biomass, intercrops, barley, oat, pea, seeding rate
Soil phosphorus depletion capacity of arbuscular mycorrhizae formed by maize hybrids
Authors: Liu A. , Hamel C. , Begna S. H. , Ma B. L. , Smith D. L.
Published: April 2011

The ability of arbuscular mycorrhizal (AM) fungi to help their host plant absorb soil P is well known, but little attention has been paid to the effect of AM fungi on soil P depletion capacity. A greenhouse experiment was conducted to assess, under different P levels, the effects of mycorrhizae on extractable soil P and P uptake by maize hybrids with contrasting phenotypes. The experiment had three factors, including two mycorrhizal treatments (mycorrhizal and non-mycorrhizal), three P fertilizer rates (0, 40, and 80 mg kg-1) and three maize hybrids [leafy normal stature (LNS), leafy reduced stature (LRS) and a conventional hybrid, Pioneer 3979 (P3979)]. Extractable soil P was determined after 3, 6 and 9 wk of maize growth. Plant biomass, P concentration and total P content were also determined after 9 wk of growth. Fertilization increased soil extractable P, plant biomass, P concentration in plants and total P uptake. In contrast to P3979, the LNS and LRS hybrids had higher biomass and total P content when mycorrhizal. Mycorrhizae had less influence on soil extractable P than on total P uptake by plants. The absence of P fertilization increased the importance of AM fungi for P uptake, which markedly reduced soil extractable P under AM plants during growth. This effect was strongest for LNS, the most mycorrhizae-dependent hybrid, intermediate for LRS, and not significant for the commercial hybrid P3979, which did not respond to AM inoculation. Key words: Arbuscular mycorrhizal fungi, extraradical hyphae, maize hybrid,plant biomass, P uptake, soil extractable P
Impact of incorporated hay mulch on selected physical, chemical and microbiological properties of a loam soil in Atlantic Canada after five years of continuous potato production
Authors: Rees H. W. , Chow T. L.
Published: April 2011

Maintenance of soil quality and crop productivity is a major concern under intensive potato (Solanum tuberosum L.) production. The effects of four consecutive annual applications of 0.00, 2.25, 4.50 and 9.00 t ha-1 wet hay on growing season soil moisture and thermal regimes, soil quality and yield were evaluated on a loamy Orthic Humo-Ferric Podzol between 1995 and 1999. Hay mulching increased soil moisture at the beginning of the growing season by 6.5 to 12.7%, with increases significant until June 24, September 07 and September 20 for the 2.25, 4.50 and 9.00 t ha-1 treatments, respectively. Growing season soil temperature of the 4.50 and 9.00 t ha-1 treatments were lower than control, but only by −0.2 and −0.8°C, respectively. Hay mulching increased soil organic carbon (SOC) of the plow layer (0–25 cm), which increased biological activity resulting in better soil aggregation with more macropores, faster saturated hydraulic conductivity and reduced bulk density. Soil air CO2 concentration was significantly correlated to SOC content, aggregation, porosity and saturated hydraulic conductivity. Hay mulching at 2.25 and 4.50 t ha-1 increased total potato yield over that of the unmulched control by 11–14%, but was insufficient to maintain soil productivity. Hay mulching at 9.00 t ha-1 may have been excessive in terms of crop yield as it showed no total yield benefits. Key words: Organic carbon, CO2 concentration, aggregates, porosity
Cover crops and nitrogen fertilization effects on soil aggregation and carbon and nitrogen pools
Authors: Sainju U. M. , Whitehead W. F. , Singh B. P.
Published: April 2011

Cover crops and N fertilization rates may influence soil aggregation and associated C and N pools, thereby affecting soil quality and productivity. We compared the effects of legume [hairy vetch (Vicia villosa Roth) and crimson clover (Trifolium incarnatum L.)] and nonlegume [rye (Secale cereale L.)] cover crops and N fertilization rates {half N rate [HN: 90 kg N ha-1 yr-1 for 3 yr of tomato (Lycopersicon esculentum Mill.) followed by 80 kg N ha-1 yr-1 for eggplant (Solanum melogena L.)]} and full N rate [FN: 180 kg N ha-1 yr-1 for 3 yr of tomato followed by 160 kg N ha-1 yr-1 for eggplant]} on soil aggregation and C and N pools in whole-soil and aggregates. The pools were organic C, total N, potential C mineralization and potential N mineralization (PCM and PNM), microbial biomass C and microbial biomass N (MBC and MBN), and particulate organic C and particulate organic N (POC and PON). Field experiment was conducted in a Greenville fine sandy loam (fine-loamy, kaolinitic, thermic, Rhodic Kandiudults) from 1995 to 2000 in Fort Valley, Georgia, USA. While the amount of soil present in aggregates decreased with decreasing size class, the amount was greater with nonlegume and FN than with HN and legume cover crops in the 2.00- to 0.85-mm size class. Organic C, PCM, and MBC contents in whole-soil were greater with nonlegume, but MBN and PON were greater with legumes than in the control with no cover crop or N fertilization. Organic C and total N concentrations in aggregates were greater in 2.00- to 0.50-mm than in 4.75- to 2.00-mm, <0.25-mm, or <4.75-mm (whole-soil) size classes, but PNM and MBN were greater in <0.50- or <4.75-mm than in 4.75- to 2.00-mm size classes. As POC and PON decreased with decreasing aggregate-size class, POC in the <0.85-mm size class was greater with nonlegume and PON in the 2.00- to 0.85-mm size classes was greater with legumes than with the control and N rates. Nonlegume may increase soil aggregation, microbial activities, and C sequestration, but legumes may increase N mineralization in the soil compared with no cover crop. Nitrogen fertilization also may improve soil aggregation. Nitrogen mineralization and C and N sequestration may be greater in aggregates <2.00 mm diameter. Cover crops and N fertilization may improve soil quality and productivity, particularly in intermediate and small size (<2.00 mm) aggregates. Key words: Cover crop, nitrogen fertilization, soil aggregation, soil carbon, soil nitrogen
Copper and zinc amounts and distribution in soil as influenced by application of animal manure in east-central Saskatchewan
Authors: Qian P. , Schoenau J. J. , Wu T. , Mooleki S. P.
Published: April 2011

Increasing use of animal manures in Saskatchewan requires information on the fate and distribution of residual manure Cu and Zn in Saskatchewan soils. To address this issue, the amounts of soil Cu and Zn in various inorganic and organic fractions were investigated in a field crop research plot (Cudworth Association soil) with a 5-yr history of annual application of liquid swine manure and solid cattle manure, and in two grassland field research plots (Meota and Oxbow Association soils) that had received annual application of liquid swine manure for 3 yr. The annual rates of manure application were based on N contents in the manures, and were equivalent to approximately 0, 100, 200 and 400 kg total N ha-1 yr-1 in the field crop plots, and 0 and 100 kg total N ha-1 yr-1 in grassland plots. In both the field crop and grassland manured plots there were no substantial increases in total Cu an d Zn in soils associated with manure application. Some increases in the moderately labile Cu and Zn fractions were observed in treatments with large amounts of animal manures applied every year. The liquid swine manure had less effect than cattle manure on increasing labile Cu and Zn fractions. These results indicate that annual addition of animal manures at rates of approximately 100 kg N ha-1 for 3 to 5 yr does not constitute an environmental risk from Cu and Zn loading in these soils. Key words: Cu fraction, Zn fraction, sequential Cu extraction, sequential Zn extraction, urea, swine manure, cattle manure
Influence of soil texture on fertilizer and soil phosphorus transformations in Gleysolic soils
Authors: Zheng Z. , Parent L. E. , MacLeod J. A.
Published: April 2011

The P dynamics in soils should be quantified in agricultural soils to improve fertilizer P (FP) efficiency while limiting the risk of P transfer from soils to water bodies. This study assessed P transformations following FP addition to Gleysolic soils. A pot experiment was conducted with five soils varying in texture from sandy loam to heavy clay, and receiving four FP rates under barley (Hordeum vulgare L.)-soybean (Glycine max L.) rotations. A modified Hedley procedure was used for soil P fractionation. Soil resin-P and NaHCO3-Pi contents were interactively affected by texture and FP. The NaHCO3-Po, NaOH-Po, HCl-P and H2SO4-P were only affected by soil texture. Proportions of 78 and 90% of the variation in labile and total P were, respectively, related to soil clay content. The FP addition increased resin-P, NaHCO3-Pi and NaOH-Pi and -Po contents in coarse-textured soils, but the amount added was not sufficient to mask the initial influence of soil texture on the sizes of soil P pools. Plant P uptake was proportional to FP rate but less closely linked to clay content. The average increase in labile P per unit of total FP added in excess of plant exports was 0.85, 0.8 2 , 0.73, 0.55 and 0.24 for the sandy loam, loam, clay loam, clay and heavy clay soil, respectively. The results of this study stress the important of considering soil texture in Gleysolic soils when assessing P accumulation and transformations in soils, due to commercial fertilizers applied in excess of crop removal. Key words: P fractions, clay content, fertilizer P, plant P uptake, soil texture
Influence of paper mill sludges on corn yields and N recovery
Authors: N’Dayegamiye A. , Huard S. , Thibault Y.
Published: April 2011

Mixed paper mill sludges are an important source of N for crop production. An estimate of direct and residual N recovery is necessary for their efficient management. A 3-yr field study (1997-1999) was conducted in central Quebec, Canada, to evaluate mixed paper mill sludges (PMS) effects on corn (Zea mays L.) yields and N nutrition, N recovery and N efficiency. The effects of PMS on soil NO3-N and total N levels were also determined. The study was situated on a silt loam Baudette soil (Humic Gleysol). The treatments included 3 PMS rates (30, 60 and 90 t ha-1 on wet basis) applied alone or in combination with N fertilizer (90 and 135 kg N ha-1, respectively, for 60 and 30 t ha-1). Treatments also included a control without PMS or N fertilizer, and a complete mineral N fertilizer (180 kg N ha-1) as recommended for corn. The previous plots were split beginning with the second year of the experiment, for annual and biennal PMS applications. Similar treatments as above were made on an adjacent site to evaluate N recovery under climatic conditions in 1999. In all years, PMS applied alone significantly increased corn yields by 1.5–5 t ha-1, compared to the unfertilized control. However, corn yields and N uptake were highest from the application of PMS in combination with N fertilizer. Biennial PMS applications at 60 to 90 ha-1 significantly increased corn yields and N uptake, which suggest high PMS residual effect; however, these increases were lower than those obtained with annual PMS applications. The N efficiency varied in 1997 from 13.0 to 15.4 kg grain kg N-1 for mineral N fertilizer and ranged from 3 to 13.7 kg grain kg N-1 for PMS, decreasing proportionally to increasing PMS rates. Apparent N recovery ranged from 1 3 to 19% in 1997 and from 10 to 14% in the residual year (1998), compared to 30 and 49%, respectively, for mineral N fertilizer. Depending on the PMS rate, N recovery varied from 13 to 21% in 1999. The results indicate high N supplying capacity and high r esidual N effects of PMS, which probably influenced corn yields and N nutrition. Annual PMS applications alone or combined with mineral N fertilizer had no significant effect on soil NO3-N and total N levels. This study demonstrates that application of low PMS rate (30 t ha-1) combined with mineral N fertilizer could achieve high agronomic, economic and environmental benefits on farms. Key words: Mixed paper mill sludges, corn yields, N uptake, N efficiency, residual effects, soil N
Cropping, soil type and manure application effects on phosphorus export and bioavailability
Authors: Michaud A. R. , Laverdière M. R.
Published: April 2011

A simulated rainfall study was conducted on an array of 36 runoff plots (6 m2 each) deployed on three benchmark soil series of the Missisquoi region in southwestern Québec. The split-plot experimental design tested the effects and interactions of pig slurry treatment as main plots (check vs. 59 kg P ha-1) and cropping (tilled vs. hay) as subplots, on runoff volume and concentrations in total suspended sediment (TSS), tot al phosphorus (TP), dissolved reactive soluble P (DRP), particulate P (PP) and bioavailable P (BioP). TP concentration in runoff ranged from a low of 1.17 mg L-1 average on non-amended Bedford hay, to a peak concentration average of 9.55 mg L-1 on manured and tilled Saint-Sébastien plots. Variance analysis indicated significant contributions of treatments in explaining TP concentration in runoff as follows: Soil type effect > Cropping effect > Soil × Cropping interaction > Manure effect. Erosion and sediment transport processes were identified as prime vectors of TP export . Manure effect alone accounted for 35% of overall DRP variability, while soil type alone accounted for 70% of variability in particulate P bioavaibility (BioP/PP). Among practical implications of this study is the importance of assessing PP bioavaibility to adequately predict the adverse impact of runoff on aquatic ecosystems. The high level of interaction among cropping and manure treatment and the site- specific influence of soil physical and chemical properties also calls for a holistic approach to nonpoint P risk assessment and management, that focusses on timely manure P management, control of soil P build-up and agricultural practices minimizing surface runoff. Key words: Phosphorus, P-index, rainfall simulation, runoff, erosion, bioavailability, sediment
Erosion-preventive crop rotations and water erosion rates on undulating slopes in Lithuania
Authors: Jankauskas B. , Jankauskiene G. , Fullen M. A.
Published: April 2011

A combination of perennial grass species and selected crop rotations can help prevent soil erosion in upland regions and minimize the risk of soil erosion and associated water pollution (to both terrestrial and aquatic ecosystems). Research data were obtained on sandy loam Eutric Albeluvisols at the Kaltinenai Research Station of the Lithuanian Institute of Agriculture on the undulating hilly topography of the Zemaiciai Uplands of Western Lithuania. The aim was to identify crops and crop rotations that would minimize soil erosion. Measured water erosion rates over 18 yr of field experiments were: 3.2–8.6 m3 ha-1 yr-1 under winter rye, 9.0–27.1 m3 ha-1 yr-1 under spring barley and 24.2–87.1 m3 ha-1 yr-1 under potatoes. Perennial grasses completely prevented water erosion, while the erosion-preventive grass-grain crop rotations (>50% grass) decreased soil losses on arable slopes of 2–5°, 5–10° and 10–14° by 75–80%. The grain-grass crop rotation (<50% grass) decreased rates by 23–24% compared to the field crop rotation. The main attributes of the proposed soil conservation systems were the careful selection of optimum erosion-preventive ecosystems (sod-forming perennial grasses or erosion-preventive crop rotations) with high erosion-resisting capabilities. These selected systems varied in response to slope gradient and thus assist erosion control and ecological stability of the undulating topography of Lithuania. These results may have wider applicability on the undulating landscapes of the temperate agricultural zone. Key words: Undulating upland topography, water erosion rates, erosion-preventive crop rotations, temperate climate
Soil properties influencing compactability of forest soils in British Columbia
Authors: Krzic M. , Bulmer C. E. , Teste F. , Dampier L. , Rahman S.
Published: April 2011

The widespread use of heavy machinery during harvesting and site preparation in timber plantations in British Columbia (BC) has led to concerns that compaction causes a reduction in long-term soil productivity. Impacts of properties such as total C, water content, and texture on compactability of forest soils in BC were assessed. Two compactability indices were used: maximum bulk density (MBD) and susceptibility to compaction (SC) determined by the standard Proctor test. Soil samples were collected from 16 sites throughout BC covering a wide range of biogeoclimatic zones. Soils varied in texture (12 to 87% sand, 9 to 76% silt, and 2 to 53% clay) and organic matter content (18 to 76 g kg-1 total C). A strong negative correlation was observed between MBD and gravimetric water content at which MBD was achieved (WMBD) and between MBD and total C. Similarly, WMBD and total C had strong effects on SC. The estimation of either MBD or SC values was not substantially improved by including texture parameters to the regression equations in addition to the total C. The implication of the relationships observed in this study is that increases in soil organic matter reduce the risk of compactability, which is particularly important for forest soils where compaction is generally not corrected by implements after tree planting. The information is also useful for assessing the extent of compaction on soils affected by machine traffic. Key words: Soil compaction, Susceptibility to compaction, maximum bulk density, Proctor test, total carbon
Predicting nitrogen fertilizer requirements for corn by chlorophyll meter under different N availability conditions
Authors: Rashid M. T. , Voroney Paul , Parkin G.
Published: April 2011

Nitrogen management strategies that enhance fertilizer use efficiency and maximize profitability in corn require a rapid and accurate method to determine the crop N needs of current hybrids. The objective of this study was to evaluate the potential of a portable chlorophyll meter for predicting N fertilizer requirements for corn grown under varying levels of N availability. Several crop management treatments were imposed in an attempt to create conditions ranging from low N availability (oily food waste application in spring and fall, application at different rates in spring) to high N availability (continuous fertilized corn, winter wheat cover crop). Different corn hybrids were sown at different sites (21 site yr) and varying N fertilizer application rates were applied. Chlorophyll meter readings (CMR) were taken at the 5th to 6th leaf stage (V6) using a SPAD-502 chlorophyll meter. The crop management treatments, corn hybrids and their interaction significantly affected the chlorophyll meter readings. A high inverse correlation between chlorophyll meter readings and maximum economic rate of nitrogen (MERN) was observed (r = −0.87). The main new and unique aspect of our research is the development of a linear model for using chlorophyll meter measurements to make N fertilizer recommendations (MERN = 348.47 − 8.5304 × CMR ) for corn production under varying degrees of N availability in Southern Ontario. Key words: Chlorophyll meter, soil organic carbon, nitrogen application
Impacts of potential climate change on selected agroclimatic indices in Atlantic Canada
Authors: Bootsma A. , Gameda and D.W. McKenney S.
Published: April 2011

Agroclimatic indices (heat units and water deficits) were determined for the Atlantic region of Canada for a baseline climate (1961 to 1990 period) and for two future time periods (2010 to 2039 and 2040 to 2069). Climate scenarios for the future periods were primarily based on outputs from the Canadian General Circulation Model (GCM) that included the effects of aerosols (CGCMI-A), but variability introduced by multiple GCM experiments was also examined. Climatic data for all three periods were interpolated to a grid of about 10 to 15 km. Agroclimatic indices were computed and mapped based on the gridded data. Based on CGCMI-A scenarios interpolated to the fine grid, average crop heat units (CHU) would increase by 300 to 500 CHU for the 2010 to 2039 period and by 500 to 700 CHU for the 2040 to 2069 period in the main agricultural areas of the Atlantic region. However, increases in CHU for the 2040 to 2069 period typically varied from 450 to 1650 units in these regions when variability among GCM experiments was considered, resulting in a projected range of 2650 to 4000 available CHU. Effective growing degree-days above 5°C (EGDD) typically increased by about 400 units for the 2040 to 2069 period in the main agricultural areas, resulting in available EGDD from 1800 to over 2000 units. Uncertainty introduced by multiple GCMs increased the range from 1700 to 2700 EGDD. A decrease in heat units (cooling) is anticipated along part of the coast of Labrador. Anticipated changes in water deficits (DEFICIT), defined as the amount by which potential evapotranspiration exceeded precipitation over the growing season, typically ranged from +50 to −50 mm for both periods, but this range widened from +50 to −100 mm when variability among GCM experiments was considered. The greatest increases in deficits were expected in the central region of New Brunswick for the 2040 to 2069 period. Our interpolation procedures estimated mean winter and summer temperature changes that were 1.4°C on average lower than a statistical downscaling procedure (SDSM) for four locations. Increases in precipitation during summer and autumn averaged 20% less than SDSM. During periods when SDSM estimated relatively small changes in temperature or precipitation, our interpolation procedure tended to produce changes that were larger than SDSM. Additional investigations would be beneficial that explore the impact of a range of scenarios from other GCM models, other downscaling methods and the potential effects of change in climate variability on these agroclimatic indices. Potential impacts of these changes on crop yields and production in the region also need to be explored. Key words: Crop heat units, effective growing degree-days, water deficits, climate change scenarios, statistical downscaling, spatial interpolation
Combined de-inking paper sludge and poultry manure application on corn yield and soil nutrients
Authors: Michel C. Nolin Bernard Gagnon, , Cambouris Athyna N.
Published: April 2011

Application of combined de-inking paper sludge and poultry manure may be an appropriate way to dispose of these residues and restore fertility of highly degraded soils. An experiment was initiated to determine the effects of a single application of this material, using two different application techniques, on corn yield and soil properties of two 12-ha fields of contrasting textures located in the Nicolet watershed in the province of Québec, Canada. De-inking paper sludge was mixed with poultry manure (PP) at a ratio of 25:1 and strip-applied before corn seeding. The study included three treatments: untreated control, a constant application rate, and variable application rates according to initial soil organic C content. The variable application rates were 10, 20 and 30 Mg dry weight ha-1. The strips were randomized within blocks, and the strips ran lengthwise in the blocks. Soil N immobilization and P release occurred on both sites at least 2 mo after PP incorporation, as measured at the corn eight-leaf and silk apparition stages by the anion-exchange membranes. Despite early N immobilization, grain yield was not affected whereas plant P uptake was increased by PP. At both sites, a single application of PP increased soil pH and major nutrient levels at harvest but had no significant effect on soil organic C. The application of PP also increased P saturation indices but the measured values were well below critical thresholds above which environmental risks would be high. The variable application rate treatment did not differ from the equivalent constant rate treatment for improving soil status and crop growth. This study indicates that mixing de-inking paper sludge and poultry manure may provide a cost-effective and environmentally friendly approach to land disposal of these wastes. Key words: Corn, paper sludge, poultry manure, precision farming, soil nutrients
Tillage, crop residue and crop sequence effects on nitrogen availability in a legume-based cropping system
Authors: Soon Y. K. , Arshad M. A.
Published: April 2011

A field study was conducted to determine the effects and interactions of crop sequence, tillage and residue management on labile N pools and their availability because such information is sparse. Experimental treatments were no-till (NT) vs. conventional tillage (CT), and removal vs. retention of straw, imposed on a barley (Hordeum vulgare L.)-canola (Brassica rapa L.)-field pea (Pisum sativum L.) rotation. 15N-labelling was used to quantify N uptake from straw, below-ground N (BGN), and fertilizer N. Straw retention increased soil microbial biomass N (MBN) in 2 of 3 yr at the four-leaf growth stage of barley, consistent with observed decreases in extractable soil inorganic N at seeding. However, crop yield and N uptake at maturity were not different between straw treatments. No tillage increased soil MBN, crop yield and N uptake compared to CT, but had no effect on extractable soil inorganic N. The greater availability of N under NT was probably related to soil moisture conservation. Tillage effects on soil and plant N were mostly independent of straw treatment. Straw and tillage treatments did not influence the uptake of N from its various sources. However, barley following pea (legume/non-legume sequence) derived a greater proportion of its N from BGN (13 to 23% or 9 to 23 kg N ha-1) than canola following barley (nonlegumes) (6 to 16% or 3 to 9 kg N ha-1). Fertilizer N constituted 8 to 11% of barley N uptake and 23 to 32% of canola N uptake. Straw N contributed only 1 to 3% of plant N uptake. This study showed the dominant influence of tillage on N availability, and of the preceding crop or cropping sequence on N uptake partitioning among available N sources. Key words: Crop residue, crop sequence, labile nitrogen, nitrogen uptake, pea, tillage
Potential replacements for rockwool as growing substrate for greenhouse tomato
Authors: Allaire Suzanne E. , Caron Jean , Ménard Claudine , Dorais Martine
Published: April 2011

The greenhouse industry needs renewable, cheap, and available substitutes for rockwool. The physical properties and performance of rockwool substitutes such as low grade peat, composted bark white spruce and fir, shavings, sawdust, and peat-bark mixtures were compared during two greenhouse experiments with tomato grown in plastic bags. Air and water filled porosities greatly differed between substrates, particularly for sawdust and shavings. Relative gas diffusivity (Ds/ Do) and the hydraulic conductivity were less different between substrates. The physical properties of the substrates changed over a production cycle but the changes were small compared to treatment differences. Yields in peat-bark substrates were similar to rockwool substrates during both the short and long experiments but were lower in sawdust and shavings during the long experiment. The yield differences expected between media were less than the differences between some substrate physical properties of the various media. Yields were positively related to easily available water (EAW) and negatively related to Ds/ Do and airfilled porosity (AFP). This indicated excessive drainage for the low-yielding substrates. In plastic bags, media properties related to aeration were not good indicators of production because the plants adapted to the lack of aeration by modifying their root distribution. White spruce and fir bark alone or mixed with low-grade peat showed high potential for greenhouse tomato production and represent an environmental sound alternative to rockwool. Key words: Gas diffusivity, water retention, peat, potting media, sawdust, bark