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Zhao Z.,University of New Brunswick | Benoy G.,Agriculture and Agri Food Canada | Chow T.L.,Agriculture and Agri Food Canada | Rees H.W.,Agriculture and Agri Food Canada | And 2 more authors.
Water Resources Management | Year: 2010

Digital elevation model (DEM) is often used for hydrologic modeling, land use planning, engineering design and environmental protection. Research is required to assess the need of updating existing conventional DEM using higher resolution and more accurate DEMs, including light detection and ranging (LiDAR) DEM. The objective of this study was to evaluate effects of DEM accuracy and resolution on hydrologic parameters and modeling in an agriculture-dominated watershed. DEMs compared included 1 m and 10 m LiDAR based DEMs, and a conventional 10 m DEM obtained with aerial photogrammetry method. Hydrologic parameters assessed included elevation, sub-basin area and boundaries, drainage networks, slope and slope length. DEM derived hydrological parameters were used to estimate soil loss in Black Brook Watershed, New Brunswick using Revised Universal Soil Loss Equation (RUSLE). Results indicated that DEM resolution had substantial influence on the sub-basins boundaries, sub-basin area, and distribution of water flow lines. Field investigation confirmed that most of the water flow lines derived from 1 m LiDAR based DEM were accurate and a number of flow diversion terraces (FDT) failures had been identified with help of LiDAR 1 m DEM. Both conventional and LiDAR based 10 m DEM could not identify the impacts of soil conservation structures such as diversion terraces. The RUSLE predicted soil loss using 1 m LiDAR based DEM was considered to be better because both conventional and LiDAR based 10 m DEMs could not reflect the impact of FDTs on reducing soil loss. © 2009 Springer Science+Business Media B.V.

Chow L.,Agriculture and Agri Food Canada | Xing Z.,Agriculture and Agri Food Canada | Benoy G.,Agriculture and Agri Food Canada | Rees H.W.,Agriculture and Agri Food Canada | And 3 more authors.
Journal of Soil and Water Conservation | Year: 2011

Impacts of suspended sediment and agrochemicals on water quality comprise one of the dominant environmental concerns affecting the agricultural sector today. Three subwatersheds within the Little River watershed (New Brunswick, Canada) were instrumented to continuously monitor discharge and sample water for suspended sediment and agrochemical analysis with the objective of determining the impacts of different agriculture and forestry intensities on water yield and quality on a long-term basis. The subwatersheds included (1) Black Brook watershed (BBW), a predominantly agricultural (65%) watershed with potato as the major crop; (2) Little River watershed (LRW), a combination of forest (77%) and agricultural (16%) land uses; and (3) Upper Little River watershed (ULRW), a forest- and wetland-dominated watershed (94%). Data from 2003 to 2007 showed that average water yields were 0.588, 0.849, and 0.901 million m3 km-2 y-1 (53.78, 77.65, and 82.41 million ft3 mi-2 yr-1) for the BBW, LRW, and ULRW, respectively, indicating that water yield decreased with increasing agricultural intensity. Average suspended sediment yield in the receiving water decreased from high agricultural intensity to low agricultural intensity, with values of 181.60, 121.60, and 57.00 Mg km-2 y-1 (470.34, 314.94, and 147.63 tn mi-2 yr-1) for the BBW, LRW, and ULRW, respectively, as did flow-weighted sediment concentration (0.33, 0.13, and 0.06 mg L -1 for the BBW, LRW, and ULRW, respectively). Average flow-weighted nitrate-nitrogen concentration in the water of the BBW was 4.39 mg L -1 compared to 1.24 mg L-1 in the LRW and 0.45 mg L -1 in the ULRW; ortho-phosphorus in the BBW was 56.43 μg L -1 compared to 24.29 μg L-1 in the LRW and 19.56 μg L-1 in the ULRW Major ions such as potassium, magnesium, and calcium followed similar trends to those observed for suspended sediments and dissolved nutrients across the watersheds. Water pH showed little variation among watersheds, but water conductivity and water temperature were highly related to the intensity of agriculture. While the differences across the watersheds were generally consistent, differences among years -were variable-dependent. Except for the ortho-phosphorus load, chemical loads of nitrogen, potassium, calcium, and magnesium were closely related to annual precipitation, but chemical concentrations did not show much correlation with either rainfall amount or erosivity. The robust time-series data available for this study enabled meaningful assessment of agricultural impacts at a landscape scale.

Rees H.W.,Agriculture and Agri Food Canada | Chow T.L.,Agriculture and Agri Food Canada | Zebarth B.,Agriculture and Agri Food Canada | Xing Z.,Agriculture and Agri Food Canada | And 3 more authors.
Canadian Journal of Soil Science | Year: 2014

The effect of timing of supplementary poultry manure applications on potato (Solanum tuberosum L.) yield and quality and soil properties of degraded soils in the New Brunswick potato belt were assessed. Four treatments on an 11% slope consisted of a control (11% - Ctrl) and applications of 4 Mg ha-1 of fresh broiler poultry manure applied either in late fall (11% - F), pre-planting (11% - PP) or pre-hilling (11% - PH). Similar treatments were set out on an 8% slope with exception of the pre-planting treatment. Manure applications enhanced potato plant N status as measured by petiole NO-3 concentration. Over the 3-yr experiment, poultry-manured treatments averaged 13 to 17% more annual total tuber yield and 19 to 34% more annual marketable tuber yield than the unmanured control. Poultry-manured treatments had fewer tubers in the small category and increased the proportion of tubers in the No. 1 and 10 oz. categories. Tuber yields were similar with fall-applied manure and with manure applied at pre-hilling. Manure did not induce either scab or hollow heart. Manure reduced tuber specific gravity. After three annual applications of poultry manure, soil P, K, B, Cu, Na, S and Zn increased significantly. Soil organic carbon did not change significantly after three annual poultry manure applications, but there was an increase in soil CO2 concentrations, earthworm populations and infiltration. Repeated manuring did not improve saturated hydraulic conductivity, matrix bulk density, field capacity, available-water-holding capacity or wet aggregate stability, and no consistent response in soil temperature or soil water content occurred. We conclude that low, repeated applications of poultry manure would benefit tuber yield and soil biological properties, but soil physical properties would be slower to change.

Rees H.W.,Agriculture and Agri Food Canada | Chow T.L.,Agriculture and Agri Food Canada | Zebarth B.J.,Agriculture and Agri Food Canada | Xing Z.,Agriculture and Agri Food Canada | And 2 more authors.
Canadian Journal of Soil Science | Year: 2011

Soil erosion is a major threat to the economic viability of potato production in northwestern New Brunswick. One option for growers to increase soil organic matter and improve soil quality in potato fields is through poultry manure application. While poultry manure may be beneficial for soil quality, there are also potential risks to surface water quality associated with manure application. This study evaluated the effects of time of poultry manure application on potato fields in northwestern New Brunswick on soil erosion and runoff water quality. Seven permanent Wischmeier-like erosion plots, established in 1982, were used. Treatments consisted of a control (Ctrl) with no manure applied, and applications of 4 Mg ha-1 of fresh poultry broiler manure in late fall (F), pre-planting (PP) and pre-hilling (PH) on 11% slope plots and a Ctrl, F and PH treatments on 8% slope plots. All poultry manured treatments increased potato total yield with a general trend of Ctrl

Yang Q.,University of New Brunswick | Benoy G.A.,Agriculture and Agri Food Canada | Chow T.L.,Agriculture and Agri Food Canada | Daigle J.-L.,Eastern Canada Soil and Water Conservation Center | And 2 more authors.
Journal of Environmental Quality | Year: 2012

Runoff from crop production in agricultural watersheds can cause widespread soil loss and degradation of surface water quality. Beneficial management practices (BMPs) for soil conservation are often implemented as remedial measures because BMPs can reduce soil erosion and improve water quality. However, the efficacy of BMPs may be unknown because it can be affected by many factors, such as farming practices, land-use, soil type, topography, and climatic conditions. As such, it is difficult to estimate the impacts of BMPs on water quality through field experiments alone. In this research, the Soil and Water Assessment Tool was used to estimate achievable performance targets of water quality indicators (sediment and soluble P loadings) after implementation of combinations of selected BMPs in the Black Brook Watershed in northwestern New Brunswick, Canada. Four commonly used BMPs (flow diversion terraces [FDTs], fertilizer reductions, tillage methods, and crop rotations), were considered individually and in different combinations. At the watershed level, the best achievable sediment loading was 1.9 t ha -1 yr -1 (89% reduction compared with default scenario), with a BMP combination of crop rotation, FDT, and no-till. The best achievable soluble P loading was 0.5 kg ha -1 yr -1 (62% reduction), with a BMP combination of crop rotation and FDT and fertilizer reduction. Targets estimated through nonpoint source water quality modeling can be used to evaluate BMP implementation initiatives and provide milestones for the rehabilitation of streams and rivers in agricultural regions. © 2012 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

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