Quantifying ammonia (NH₃) flux following fertilizer and manure nitrogen (N) application is crucial to develop sound management practices. Traditional methods used for obtaining these measures are expensive, inefficient, or inaccurate. The objective of this study is to develop a method using a passive dosimeter and a semi-open static chamber to provide an economical and simple solution to measure NH₃ loss following nitrogen application. Dosimeter tubes were commercially developed to measure ammonia exposure, providing a time-weighted average. In this study, chicken manure was applied to short grass and the ppm h reading obtained using the dositube ammonia method was calibrated against a reference measure of NH₃ loss (kg N ha^-1) using a wind tunnel and acid trap method. A calibration was developed (Estimated Total Loss (kg N ha^-1) = (0.217Dw) - (0.034D) 0.71), which requires the dositube (D, ppm h) to be read every 24 h and placed at a height of 0.15 m in the dositube chamber, with wind speed (w, m s^-1) measured at a height of 0.3 m and averaged over the coinciding time period. This calibration may also be applied where dositubes are read every 48 h; however, 24 h periods are recommended to achieve the greatest accuracy.

Increasingly, poor soils are used for plant cultivation involving chemical fertilizer (CF) usage which in turn lowers soil quality. To improve the quality of poor soils, promote plant growth, and reduce CF use, bio-organic-mineral fertilizer (BF) was introduced to poor soil to examine its effects on both soil and plants. Organic fertilizer (OF), CF, and mineral powder (MP) were applied as controls. When cotreating water spinach with fertilizer, the soil quality was improved with the increased doses of BF, OF, and MP. The BF treatment produced the most pronounced improvement. Applying CF reduced the soil quality. Under the CF treatment the largest plant-growth-promoting effect was observed within 30 d, whereas plants treated with BF showed the most favorable growth after 50 d. Moreover, for BF, plants’ nutritional quality was also higher, particularly in the long term. When poor soil was treated with fertilizer without plants, the soil quality changed as in the previous treatment; however, the change in this treatment was more pronounced and the remaining available elements in soil were higher, particularly in the case of CF treatment. These results indicate that BF treatment without CF can be applied to improve the quality of poor soil, and meanwhile promote plant growth and quality.

Earthworm abundances were tracked from 1997 to 2012 in established tillages (since 1983) and recently imposed tillages (since 1997) from a Brookston clay loam soil (Orthic Humic Gleysol) at Woodslee, ON. The tillages included the following systems: long-term fall moldboard plowing (CT83) and its 1997 conversion to no tillage (NT97-CT83), long-term no tillage (NT83) and its conversion to moldboard plowing (CT97-NT83), long-term ridge tillage (RT83) and its conversion to moldboard plowing (CT97-RT83), and long-term bluegrass sod (BG83) and its conversion to moldboard plowing (CT97-BG83). Lumbricus terrestris and Aporrectodea turgida were the most abundant of six species identified. The NT83 system had the greatest earthworm numbers except for 2012 when RT83 had equal abundance because of increased Ap. turgida juveniles. Populations in NT97-CT83 increased significantly from 1997 to 2012 because of reduced mechanical disturbance and greater surface residues. During 1997, 1999, and 2003, mean abundance in CT97-BG83 was not different from that of BG83, which likely occurred because buried sod continued to provide ample food. The CT97-RT83 system showed a decline in earthworm populations relative to RT83. The CT97-NT83 treatment had the most significant earthworm decline, reflecting a substantial increase in soil disturbance. Characterizing tillage system effects on earthworm dynamics (e.g., diversity, occurrence, adult, and juvenile abundance) will provide essential data for landscape models.

Managing nitrogen (N) inputs to sustain high yields while minimizing losses to adjacent environments remains among the foremost aims in agroecosystems. We studied the N balance in a study established in 1911 at Lethbridge, AB, Canada. The experiment includes three cropping systems — continuous wheat (W), fallow–wheat–wheat (FWW), and fallow–wheat (FW) — with a factorial of two N rates (0 and 45 kg N ha^-1) and two phosphorus (P) rates (0 and 20 kg P ha^-1) superimposed beginning in 1967. In unfertilized subplots, grain yields generally increased for the first eight decades, but then declined, perhaps partly because of growing N deficiency. Yield response to N increased over time, especially under continuous cropping and when co-applied with P. Soil N concentration in the surface 15 cm declined in the first few decades, and then approached an apparent steady state. Application of N increased soil N, roughly in proportion to the amount of residue returned. For the first half-century (1911–1967), N removal was approximately equivalent to the loss of soil N in the surface 15 cm. Since then, however, when the soil organic N was near steady state, removals of N in grain exceeded N inputs by approximately 20–30 kg N ha^-1 yr^-1, suggesting an input from outside sources, perhaps partly from atmospheric NH₃. This study demonstrated the importance of long-term experiments in evaluating the N balance of cropping systems, and indicated the potential significance of non-fertilizer N inputs from outside sources in such ecosystems.

Surface mining of oil sands in northeastern Alberta is a large-scale disturbance affecting over 900 km² so far. Extraction companies are required by law to return the environment to “equivalent land capability”, but this has been challenging to quantify. To date, only one site has been certified as reclaimed. Restoring ecosystem function, including nutrient availability and uptake, might be a more realistic goal of reclamation. We tested the effect of admixing subsoil with peat and peat biochar on bioavailable nutrients, foliar nutrient concentration, and aspen (Populus tremuloides Michx.) productivity in a greenhouse study. Brunisols and luvisols, found in upland boreal forests of the Athabasca oil sands region, have high mineral soil content compared with the commonly used peat. Charcoal is a native component of boreal forest soils in northern Alberta and affects a variety of soil characteristics. In two separate tests, we compared different peat–subsoil admixtures and biochar-amended peat–subsoil admixtures with forest floor–mineral mix (FFM). Seedling productivity increased with admixing subsoil in both experiments with and without biochar, and there was an overall positive effect of amendment with biochar when comparing all treatments of both experiments using multivariate statistics, with biochar being more similar to FFM. Our findings suggested that peat–subsoil mixes did not provide sufficient amounts of P and Cu to seedlings. A lower K and Mn availability in peat–subsoil mixes was also identified and needs to be evaluated in further studies.

Understanding soil erosion processes under different land uses is important for predicting and controlling watershed soil losses, especially in karst areas. Five soil profiles and 55 soil samples were collected from soils that were under different land uses in a typical karst catchment, Southwest China. The total contents of rare earth elements (REE) are significantly lower (<100 mg kg^-1) than the average value of soils in China (181 mg kg^-1). The enrichment degree of REE in heavy REE is much higher than that of light REE in all soil samples. A positive Ce anomaly (~1.4) and a slightly negative Eu anomaly (~0.95) were found. The enrichment and release of REE are partly controlled by pH, distribution of REE in bedrocks, contents, and adsorption ability of organic matters in weathering profiles.

Nitrogen (N) deposition and precipitation changes can strongly influence soil microbial properties in arid and semiarid regions. Here, we examined these effects on soil samples from the Inner Mongolia desert steppe of northern China after 7 yr of consecutive simulated N deposition by adding NH₄NO₃ and manipulation of precipitation, using a dilution plate method, PCR analysis, and 18S rRNA sequencing. The experimental treatments were as follows: control (CK), N addition ( N), N and water addition ( N W), and N addition plus water reduction ( N-W). In this study, 14 genera and 32 fungal species were isolated, and Penicillium was determined to be the dominant fungal group. Treatment N-W significantly increased (by 94.8%) the number of cultivable fungi as compared with CK. Compared with the CK community, fungal communities exposed to the three treatments, especially N W and N-W, showed shifts in the relative abundances of cultivable fungi. Treatment N-W significantly enhanced species richness compared with N at the 0–2 cm soil depth. However, N addition and manipulation of precipitation did not influence species richness, the Shannon–Weiner index, or evenness at the 0–30 cm soil depth. This study can provide insight into how fungal composition and diversity respond to climate change scenarios.

Chemical form of phosphorus (P) in soils influences both plant accessibility and solute transport of P. Soil P speciation receiving inorganic and organic fertilizers is extensively studied to address a range of agronomic and environmental concerns. It is known inorganic P sources react over long time scales in soils, but relatively few studies have focused upon long-term P speciation changes in soils receiving organic amendments. This study was conducted to address this gap by providing detailed information on the speciation of P in agricultural soils from short- (2 yr) and long-term (11 yr) applications of liquid hog manure (LHM) and solid cattle manure (SCM) made at a field research site. Chemical speciation was performed with a combination of laboratory-based soil test P extraction methods and solid-state synchrotron-based techniques. There was clear evidence that initial phosphate minerals in the manures rapidly transform into new phases after short-term soil application. The X-ray absorption near edge spectroscopy results for SCM soil samples were consistent with high solubility (likely Mg-substituted) dicalcium phosphate minerals and phosphate (PO₄) adsorption species present after short-term period, whereas long-term SCM application resulted in transformation of soil phosphate into more crystalline calcium phosphate minerals. In contrast, phosphate speciation after short term of LHM application revealed predominantly magnesium phosphate and adsorbed P compounds. Soils under long-term LHM amendment still had phosphate speciation dominated by poorly crystalline dicalcium phosphate minerals. This suggests that the manure form plays a strong role not only in short-term plant availability but also in long-term P speciation.

Studies of soil nutrients in revegetated land have often not provided the sampling positions on a scale of individual trees and shrubs, suggesting that nutrients were assumed to not vary substantially at fine scales. This assumption, however, conflicts with the “fertile island” theory for arid and semi-arid areas. We assessed the importance of sampling position on nutrient contents in 0–100 cm soil profiles by examining differences between soils under and outside the canopies of Armeniaca sibirica and Caragana korshinskii on a slope on the Loess Plateau, China. Soil organic carbon, total nitrogen (TN), total phosphorus, ammonium N, and extractable P did not differ significantly under and outside the canopies, except for nitrate N (NO₃^--N). The differences between these two canopy positions were significantly larger for C. korshinskii than A. sibirica for TP, significantly larger on upper than middle and lower slope sections for TN and NO₃^--N. The NO₃^--N content varied with sampling position around individual trees and shrubs, and trail tests about sampling position can be conducted around individual leguminous plants, in flatter areas, and in topsoil.

Understanding nutrient cycling under different land uses can improve agricultural management practices. In southwestern Saskatchewan, long-term land use as annual cropland, native grassland pasture, tame (planted) crested wheatgrass grasslands, or roadsides altered soil physical and chemical properties based on the intensity and frequency of disturbance, with cropland > roadsides > tame grassland > native grassland. The majority of significant differences were detected at the soil surface (0–7.5 cm); few significant differences below 15 cm suggested that the soils were not significantly different prior to changes in land use. Bulk density was increased in cropland soils compared with native grassland, probably from compaction from farm equipment, and in tame pastures due to their past use as croplands. Croplands also had decreased carbon and organic phosphorus (P) and increased Olsen P compared with grasslands, from crop removal and fertilizer inputs. Roadsides, an important but poorly studied land use in Saskatchewan, had increased clay and Olsen P concentrations compared with native grassland. Roadsides were disturbed during road building and remained disturbed because of runoff from adjacent fields and dust from roads. These results on soil chemical and physical properties, combined with soil microbiology information, will help to improve land management and nutrient use efficiency in soils of this region.

Soil organic carbon (SOC) plays a critical role in revegetation of semi-arid areas. The accurate estimation of SOC under various land-use types is fundamental to sustain ecosystem productivity. Thus, the dominant factors of the spatial distribution of SOC in shallow soil layers were determined at hillslope scale. The state-space modeling approach was used to quantify the relationship between SOC stock and land-use type, soil properties, topographic features, and fine root biomass (FRB) at 0–20 and 20–40 cm soil layers of a hillslope on the Loess Plateau. The best state-space models explained more than 96% of the variations in SOC stocks on the hillslope. The best multivariate state-space models including land-use type, FRB, soil pH, and total nitrogen were optimal for 0–20 and 20–40 cm soil layers. Land-use type was the dominant factor for identification of localized variation in SOC in the 0–40 cm soil layer. The results underscored the importance of land-use type in SOC variation on the hillslopes of the Loess Plateau. It also provided a useful insight into the accurate estimation of SOC using state-space modeling approach driven by other easily obtainable variables.

Phosphorus (P) can be a limiting nutrient in terrestrial ecosystems and adding biochar or wood ash can increase plant-available P. We added wood ash and biochar to microcosms containing three acidic Ontario soils planted with red pine or sugar maple seedlings and observed seedling growth responses, as well as amendment-induced changes in soil P pools, microbial P, and enzyme activity. Neither ash nor biochar consistently increased seedling growth; instead sugar maple and red pine seedlings often had opposing responses to the same amendment–soil combination. Overall, these results indicate that it is important to carefully consider both the chemical and physical characteristics of the soil and the ash or biochar, as well as the nutrient requirements of the target tree species, to effectively use these amendments to reduce P limitation.

The Environmental Policy Integrated Climate (EPIC) model was updated with relevant weather, tillage, and crop management operations from the 1994 to 2013 Alternative Cropping Systems study to assess simulations of annual and long-term yield of wheat, barley, and canola. Linear regression and coefficients of determination (R²), root mean square error of prediction (RMSE), the d index, and paired sample t-test were used to assess the relationship between simulated and experimental values. Simulations indicated that the model captured long-term yield trends but was less accurate at predicting annual variations. These variations were due to variability of soil properties at the research field, terrain attributes, extreme weather events, and the model’s overestimation of available nitrogen (N) under low-N input systems. The R², RMSE, and the d index values on long-term yield were R² = 0.74, RMSE = 205 kg ha^-1, and d = 0.75 for wheat; R² = 0.90, RMSE = 226 kg ha^-1, and d = 0.73 for barley; R² = 0.98, RMSE = 238 kg ha^-1, and d = 0.76 for canola, indicating good model performance. The EPIC model effectively simulated crop yields affected by agricultural inputs and cropping diversity, and may be used to assess future cropping decisions and agronomic management.

Salinity is the major stress factor that limits crop cultivation, especially in developing countries. A randomized complete block, factorial (3-factor) experiment was conducted on Sudan grass grown on nonsaline and saline soils to assess humic substances with or without foliar spraying Moringa leaf extract (MLE). Factors were (i) soil (three different levels of salinity), i.e., S₁: nonsaline [electrical conductivity (EC) = 3.01 dS m^-1], S₂: medium saline (6.12 dS m^-1), and S₃: highly saline (12.33 dS m^-1); (ii) humic substances, i.e., B₀: no addition, B₁: humic acid (HA) as potassium (K) humate, B₂: fulvic acid (FA) as K fulvate, and B₃: HA and FA; (iii) foliar spray with MLE, i.e., C₀: nontreated and C₁: foliar spray. Results indicated that total chlorophyll, nutrient uptake, available nitrogen (N), phosphorus (P), and K significantly decreased within each humic substances application, and MLE with increasing salinity concentration. The highest values of fresh, dry weight, total chlorophyll, and NPK uptake under different salinity levels were observed with application of substances and MLE. Spraying of MLE increased cumulative yield and nutrient uptake by Sudan grass compared with the untreated ones. The treatment of HA and FA with or without spraying MLE gave the highest values of available NPK under the salinity levels.

Cold winters and short, warm summers in the Canadian prairies pose a challenge for the effectiveness of on-farm biobeds for degrading agricultural pesticides. A thermo-gradient plate was used to evaluate the effect of temperature on the dissipation kinetics of seven commonly used herbicides applied to a biobed matrix composed of materials typically available on a farm. The dissipation of all seven herbicides increased with increasing incubation temperature and duration. 2,4-D, bromoxynil, and thifensulfuron-methyl dissipated completely during the 35 d incubation at 13 and (or) 20 °C. Tribenuron-methyl, pyrasulfotole, thiencarbazone-methyl, and metsulfuron-methyl dissipated 93%, 70%, 64%, and 34%, respectively, at 20 °C. The order of decreasing dissipation in the biobed matrix reflected the relative soil half-lives and soil sorption coefficients of the herbicides. Metsulfuron-methyl and thiencarbazone-methyl had the lowest activation energies and temperature quotients and were the least sensitive to increases in incubation temperature. At 20 °C, the half-lives of all herbicides were <70 d. However, 10 yr average soil temperatures to 1 m depth from a site in Saskatoon, SK, were considerably <20 °C for much of the growing season. Assuming soil temperatures to be a proxy for expected temperatures of on-farm biobeds, biobed temperatures would not be high enough for a long enough period of time to achieve complete dissipation of some herbicides. Consequently, biobeds in the Canadian prairie provinces may require supplemental heating, especially in spring and late fall, to maintain incubation temperatures of approximately 20 °C to optimize the degradation of herbicides used in prairie crop production.

Agroforestry systems play an important role in the sequestration of carbon (C) to reduce atmospheric carbon dioxide (CO₂) levels. However, the extent of long-term C sequestration will depend on physical stabilization of the sequestered C. This study determined the influence of six major shelterbelt species on soil organic carbon (SOC) distribution in the light- and heavy-density fractions of bulk soil compared with adjacent agricultural fields. Soil samples were collected from the shelterbelts and adjacent agricultural fields and were separated into light and heavy fractions using sodium iodide solution (NaI, density = 1.6 g cm^-3) and analyzed for their organic C stocks. Both the light and heavy fractions to a 50 cm soil depth contained higher SOC stocks for the shelterbelts (21 and 91 Mg C ha^-1, respectively) compared with the adjacent agricultural fields (14 and 81 Mg C ha^-1, respectively). Most SOC added at the 0–10 cm soil depth was in the form of labile light fraction (92%), whereas heavy fraction contributed to 70% of the increase in the SOC stocks at the 10–30 cm soil depth. Increase in light-fraction SOC stocks was higher for coniferous species compared with hardwood species, and accounted for 48%–50% and 28%–31% of the increase in SOC stocks for coniferous and hardwood shelterbelts, respectively. This trend was attributed to the differences in the amount and quality of litter between coniferous and hardwood species.

Soil fertility decline is encountered in intensively managed low-residue systems. This long-term study (1998–2015) characterized soil organic matter (SOM) changes in the province of Prince Edward Island (PEI), Canada. The sampling locations were based on the 4 km × 4 km National Forest Inventory grid. Five subsamples were collected within a radius of 1–6 m from the centre location at the intersecting points on the grid and at locations 100 m in each cardinal direction covering the whole province every 3 yr, for a total of six cycles. The interpolation used the regression kriging method. Means ranged from 2.8% to 3.6%, coefficients of variation ranged from 0.22 to 0.28, and residual nugget and sill values were 0.03 and 0.06, respectively. From cycle 1 to cycle 6, acreage with 2%–3% SOM increased from 10% to 73% of the total area, acreage with 3.1%–4% SOM declined from 70.6% to 24% of the total area, and acreage with >4% SOM declined from 19% to 0.8% of the total area. Areas with a history of intensive agricultural activity were associated with the lowest SOM levels (2%–3%) at the beginning of the study, and SOM levels in those areas either remained unchanged or declined (<2%) at the end of the study, suggesting a predominance of recalcitrant SOM fractions with a longer turnover rate. This long-term study highlights the need to put in place strategies to increase levels of SOM to sustain PEI soil productivity.

Reclamation practices in the oil sands region of Alberta involve the reconstruction of soil profiles using a combination of salvaged mineral substrates and organic-matter-rich surface materials, including peat–mineral mix (PM) and forest floor – mineral mix (FFM). The successful re-establishment of vegetation on reclaimed sites is for a large part dependent on the nutrients these materials can provide. Hence, the overall objective of this study was to compare carbon (C), nitrogen (N), and phosphorus (P) release rates from PM and FFM materials used to cap reconstructed sandy soils. A 325 d laboratory incubation was conducted to measure these rates. The two materials released comparable amounts of N on a per kilogram of soil basis (111–118 mg N kg^-1). However, when results were normalized based on each material’s organic C content, N release was six times greater for FFM than for PM, in accordance with results of previous studies. In addition, overall C mineralization and P release rates were over one order of magnitude higher with FFM than with PM. As opposed to N, however, P release seemed to be controlled more by abiotic processes than by organic matter mineralization. While the FFM material overall released more N and P, it also degraded faster; in comparison, PM may provide a smaller but more stable release of N.

A 2-yr study was conducted on a loamy sand soil to compare short-term persistence of ammonium-N in an annual (ACS) and a perennial (PCS) cropping system following pig manures application as a possible explanation for the reduced nitrate leaching from perennial forage grasses. In spring 2014 and 2015, nitrogen-based application rates of liquid (LPM) and solid (SPM) pig manure were broadcast on PCS and ACS plots with incorporation of the manures for ACS plots alone. Following manure applications, soil samples were taken at 0–15 and 15–30 cm depths seven times (2014) and six times (2015) over 2–3 wk period for ammonium-N and nitrate-N concentrations. Ammonium-N (0–15 cm) with LPM peaked 4 d after manure application in ACS (18–29 kg ha^-1) and PCS (50–74 kg ha^-1) in both years. In both years, persistence of ammonium-N at 7 d was 46%–77% in LPM-amended PCS and 8%–14% in LPM-amended ACS. Ammonium-N measured in SPM-amended ACS and PCS was low after manure application in both years. There was lower accumulation of nitrate-N in PCS than ACS of LPM- and SPM-amended treatments in both years. The greater persistence of ammonium-N in the LPM-amended PCS than ACS coupled with lower percentage increase in nitrate-N in the PCS may account for lower nitrate leaching previously observed for perennial forage grasses at the study location.

Selected soil properties were compared after 2–6 yr of grassland set-aside (GLSA) management and an annual cropping system (potato). In general, GLSA and nearby arable cropping fields had similar soil properties, with some improvements of aeration porosity, aggregate stability, bulk density, and mechanical resistance following short-term GLSA management.

In two prairie wetlands, mean available phosphate was six times greater at 0–15 cm in Ca-depleted recharge soil (57.3 mg kg^-1) versus Ca-rich discharge soil (13.0 mg kg^-1) highlighting the importance of wetland chemistry when characterizing P availability and nutrient loss potentials of prairie wetland soils.

Construction removes soil from one site to another site. The aim of this study was to compare soil carbon of fill material and buried soil. The fill had topsoil and subsoil layers over a buried soil. The buried soil had significantly higher organic carbon (22.7 g kg^-1) than the fill had (12.4 g kg^-1).

We measured soil greenhouse gas fluxes and nutrient pools in a nitrogen (N)-polluted north-temperate forest and report relatively small N₂O effluxes and high CH₄ uptake. Six years after application, non-N fertilizers (P K, lime) did not significantly reduce soil respiration or increase N₂O efflux; however, rates of CH₄ oxidation were significantly suppressed.

Agronomists in Manitoba, Canada, are willing to reduce soil nitrous oxide emissions. They consider: enhanced efficiency fertilizers if cost effective; both crop yield and financial returns to be important for application rate; preferred fall application instead of spring because of operational advantages; and using banding placement if appropriate equipment is available.