John D. Lauzon

Transformations and losses of swine manure 15N as affected by application timing at two contrasting sites.

An improved understanding of the fate of manure N is necessary for developing efficient manure management plans that ensure adequate crop nutrition and minimum environmental problems. This study quantified the fate of 15N-labelled liquid swine manure applied at three different times (late-fall, spring pre-plant and side-dress) on two soil types (a well-drained fine sandy loam and an imperfectly drained silt loam). Manure N uptake by corn (Zea mays L.) was significantly lower with fall application than with two spring applications (14-18% vs. 30-38% of applied N) in both soil types. Manure application increased total N leaching (30-43 vs. 27 kg N ha-1 yr-1 in the control), especially with fall application. Manure N contributed 18-25% of the total N leached in the fine sandy loam and 8-10% of the total N leached in the silt loam. Application timing did not affect manure N leaching in the silt loam, which ranged between 3 and 5% of applied N. In the fine sandy loam, fall application resulted in significantly...

Nitrogen application rate, timing and history effects on nitrous oxide emissions from corn (Zea mays L.)

Roy, A. K., Wagner-Riddle, C., Deen, B., Lauzon, J. and Bruulsema, T. 2014. Nitrogen application rate, timing and history effects on nitrous oxide emissions from corn (Zea mays L.). Can. J. Soil Sci. 94: 563-573. Nitrous oxide (N2O) emissions resulting from application of nitrogen (N) fertilizer contribute to the greenhouse gas footprint of corn production. In eastern Canada, corn is a major crop with most N fertilizer applied pre- or at planting. This timing of application results in a lack of synchrony of soil N supply and crop N demand. Matching the amount and timing of application to crop uptake has been suggested as a mitigation measure to reduce N losses, and is an integral part of the 4R Nutrient Stewardship program. This study examined the effect of timing, rate and history of urea-ammonium nitrate application on N2O emissions in corn in 2011 and 2012 at Elora, ON, Canada. Treatments were three N rates (30, 145 and 218 kg N ha-1); two timings (N injected in mid-row at planting and at the 8th leaf stage, V8); two histories (short-term: applying N rate treatments on plots that had received 145 kg N ha-1 in the previous year, and long-term: applying the same N rate to a given plot over the duration of the trial). N2O emissions were measured using static chambers. History of N application did not have an effect on N2O emissions or grain yield. In both years, cumulative N2O emissions during the growing season and corn yields increased significantly with increasing N application rates. In 2011, cumulative N2O emissions were significantly lower when N was applied as side-dress at V8 (0.88 kg N ha-1) compared with planting (2.12 kg N ha-1), with no significant impact on corn grain yield (average 9.1 Mg ha-1). In contrast, in 2012, limited rainfall reduced both N2O emissions and corn grain yield, and neither N2O emission (average 0.17 kg N ha-1) nor grain yield (average 6.7 Mg ha-1) was affected by timing of N application. Applying N as side-dress at V8 instead of at planting and using the recommended N rate were shown to be effective N2O emission mitigation practices without affecting corn yield during a typical wet spring in Ontario.

Effect of nitrogen fertilization and topography on soft red winter wheat yield and protein content in two Ontario landscapes

Identification of suitable management units for the variable application of fertilizer N is an essential component of a site-specific N management program. Topography and/or soil N test results are examples of two parameters that could potentially delineate N management units for improved grain yield or protein concentration. Field studies were conducted on soft red winter wheat (Triticum aestivum L.) to examine the effects of mineral soil N, soil organic carbon (SOC), and N fertilization on grain yields and protein concentrations in two variable landscapes in southwestern Ontario, Canada. Six N rates (0 to 145 kg N ha-1) were applied to plots (3 × 400 m long), arranged in a randomized complete split block design with four replicates. Sampling on a 3 × 20 m grid indicated slope position affected soil nitrate (NO3-N) and SOC levels at site 1, but not at site 2. The range of spatial correlation for NO3-N was 11.5 m at both sites and for SOC was 16.0 m and 32.4 m at site 1 and 2, respectively. Yields decreas...

Solute dynamics and the Ontario nitrogen index: II. Nitrate leaching 1

Abstract: Nitrogen (N) leaching from soil into surface and ground waters is a concern in humid areas of Canada. As a result, N management protocols, including the Ontario N Index, are widely used to identify N leaching risk, although field assessment remains limited. Nitrogen fertilizer and chloride (Cl) tracer were fall-applied to five agricultural soils in Ontario with different textures and hydrologic soil groups (HSG) to assess the Ontario N Index and characterize inorganic N movement over 1 yr. The treatments included three N rates (0, 100, and 200 kg N ha-1) plus Cl tracer and 200 kg N ha-1 rate without Cl. After spring thaw, N loss from the crop root zone (top 60 cm) ranged from 68% for Brookston clay loam to 99% for Harrow sandy loam. A strong linear relationship between apparent N recovery and apparent Cl recovery indicated that N loss from the root zone occurred primarily by downward leaching. Leaching was controlled by the minimum measured saturated hydraulic conductivity (Ksat), and good estimates of N leaching were obtained using a quasi-theoretical relationship between N loss and Ksat. We concluded that Ontario N Index estimates of N leaching risk might be improved by including site-specific measurements of Ksat.

Assessing the temporal stability of spatial patterns in crop yields using combine yield monitor data

Using previous years’ yield patterns may be one method of breaking a field into management zones for the purpose of site-specific management. For this method to be useful there must be temporal stability of yield patterns and there must be a sound method of assessing the spatial-temporal stability of yield in a field. To this end, a method was developed to give a non-biased estimate of the within-field spatial-temporal stability of yield. The method determined the probability that the normalized yield for all years available at a given location in the field fit within the accuracy limits of the combine. Combine accuracies of ± 2.5%, 5% and 10% of the field mean yield and gridded data of 3 m, 6 m, and 9 m cell sizes, as well as crop choice were all included in the model to assess its sensitivity to changes in these factors. The resulting spatial-temporal stability maps were well correlated with visual estimations of the spatial yield patterns. The model results were highly influenced by the inputted combin...

Temporal and Spatial Variability of Water Surplus in Ontario, Canada

The temporal variability in estimated water surplus in 12 climatic regions of the province of Ontario, Canada, and its spatial distribution throughout most of the province are discussed in this paper. Surplus water is that which results from precipitation that runs off the land surface and that which drains through the soil profile to the water table and through subsurface drainage. A one-dimensional, deterministic model (DRAINMOD) that simulates soil water flow, including plant uptake, evapotranspiration, and freeze/thaw conditions, was used to estimate the water surplus. Simulations were performed using daily climatic data from January 1954 to December 2001 for each region. A reference corn crop and the predominant local soil conditions in each region, with the hydraulic properties for each layer in the soil profile, were used as model inputs. There was considerable year-to-year variability in annual water surplus in all regions caused by both precipitation and soil conditions. It was the least (~150 mm) in three regions and it exceeded 350 mm in another three regions, where winter snowfall is the greatest as a result of these regions being in the lea of one of the Great Lakes. The variability in water surplus generally increased as average water surplus increased.

Solute dynamics and the Ontario nitrogen index: I. Chloride leaching1

Abstract: The nitrogen (N) index for humid temperate southern Ontario, Canada (Ontario N index) incorporates previous and current crop type, fertilizer and (or) manure management, and hydrologic soil group (HSG) to estimate risk for contamination of tile drainage water and groundwater by nitrate leached below the primary crop root zone (top 60 cm of soil). The Ontario N index has received limited ground-truthing, and the leaching component was assessed using chloride tracer (ClTR) on five soils (one sandy loam, two loams, and two clay loams) representing four HSG-based risk levels (HSG-A, high risk; HSG-B, medium risk; HSG-C, low risk; HSG-D, very low risk). A square-wave pulse of ClTR was applied to the soil surfaces in fall 2007 as KCl, and movement and loss of ClTR was tracked over 1-1.2 years using monthly soil core samples collected from the top 60-80 cm. For all five soils, 60-96% of ClTR was leached out of the primary crop root zone (below 60 cm depth) during the noncropping period (October 2007 to March 2008 inclusive), and >80% was leached out of the root zone within 1 year. The percentage of ClTR that leached did not correlate with precipitation or HSG designation, but produced significant (P < 0.05) power function regressions with minimum and harmonic mean saturated soil hydraulic conductivity (Ksat) measured in the top 50-60 cm. ClTR leaching rate appeared to be controlled primarily by Ksat in a manner consistent with infiltration and solute transport theory. It was consequently proposed that solute leaching loss versus Ksat relationships may improve N index risk estimates for both southern Ontario and other humid temperate regions.

A decision tree-based approach to calculate nitrous oxide fluxes from chamber measurements1

Abstract: Soil nitrous oxide (N2O) fluxes are commonly measured with nonsteady state chambers using slope values derived from linear or quadratic regression, fitted to the change in N2O concentration over time (dC/dt); however, these methods frequently underestimate N2O flux values. Here, we propose a decision tree-based model (DTBM) to better match curve shape with linear and nonlinear models to estimate dC/dt. The DTBM was compared with linear, quadratic regression, and the Hutchinson–Mosier (H–M) equation. The objectives were to (i) evaluate curve shape classification; (ii) evaluate dC/dt response to uncertainty, and (iii) determine method effect on cumulative N2O emissions and emission factor. Curve shapes with increasing N2O concentration over time had the highest proportion of data (52%–55%). Mean N2O flux calculated with DTBM showed to be less responsive to data variability, and therefore, more stable than the other methods. Data classification included in DTBM offered an improved method for calculating cumulative N2O emissions in low-flux situations, whereas under a high-flux situation, all methods tested were acceptable to calculate N2O emissions. The DTBM proved to be a robust method of matching each data type with the best model for calculating an individual flux and to accurately calculate cumulative N2O emissions.

Impact of manure storage conditions and time on decomposition of and losses from liquid dairy manure stored in a temperate climate

Abstract: Large volumes of generated animal manures necessitate knowledge of how its production and storage affects composition, losses, and utilization potential. Stratification of liquid dairy manure was the main source of observed variability within outdoor uncovered manure storage, during a yearlong monitoring of 24 physicochemical manure parameters. Coefficient of variation (CV) ranged from 4% to 24% for plant nutrients and 33% to 89% for biogas feedstock parameters. Nitrogen (N) volatilization losses during storage between manure additions were ?10% mo-1 of total Kjeldahl nitrogen (TKN). Acetic acid was up to 100% of total volatile fatty acid concentration. Bioavailability and solubility of manure parameters, reflected in ratios of volatile solids to total solids (VS:TS), total ammoniacal nitrogen to total Kjeldahl nitrogen (TAN:TKN), and dissolved phosphorus to total phosphorus (O-PO4:TP) ratios, was high. There was substantial pathogen survival during the study, with an increased count with added manure. Manure temperature changes and precipitation levels likely played a major role in mineralization and volatilization rates of nutrients and reduction of solids, especially in surface levels of manure in storage. Study results underline the importance of sampling method, timing, and location within stored manure to obtain representative samples unless thorough mixing is previously applied.