Using runoff-erosion plots (10 m wide × 30 m long), the effects of cropping practices on surface runoff and soil loss were examined on a Hommesville gravelly loam soil to evaluate the applicability of the Universal Soil Loss Equation in New Brunswick. The amount of water runoff and soil loss from continuous fallow, up-and-down slope planting of potatoes (Solanum tuberosum), and clover (Trifolium pratense) on 8 and 11% slopes were measured from 1983 to 1985. In addition, runoff and soil loss from contour planting of potatoes were measured on the 11% slope. Slope planting of potatoes resulted in higher runoff and soil loss than on fallow plots. There was considerable reduction in runoff and soil loss when potatoes were planted along the contour. Runoff and soil loss under clover were negligible. Rainfall erosion index (R) and slope length and steepness (LS) correlated well with the measured soil losses. However, both the measured soil credibility factor (K) and the cover and management factor (C) deviated markedly from the current values used for conservation planning. Key words: Universal Soil Loss Equation, rainfall erosion index, topographic factor, soil erodibility factor, cover and management factor, support practice factor

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 Z. Zhao et al. 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.

(Fig. l).The Holmsville series is the most common soil in the study area (Langmaid et al. 1976). Some typical pedons are described in Table l The land form of the area is mostly gently rolling with long, simple 5-97o slopes.General characteristics of the soil and site of the 10 transects are shown in Table 2. METHODSSimilarities in parent material and landform between forost sites and potato sites were the major criteria in selecting the transe"cts. For cultivated sites (transects 4 to t0) da€ of clearance and years in continuous potato crops were also considered.On each transect, from crest to toe, 10 equally spaced soil pedons were exposed. Each pedon was described according to Day (1983). Soil samples were taken for chemical and physical analyses. At the forest sites, the top 10 cm (the minimum thickness of the Podzolic B horizon is l0 cm) of the B horizon of every profile were sampled; occasionally lower B and C horizons were also sampled. At the potato sites, both the plowed layer (Ap) and the top 10 cm (many had no B horizons) immediately below the Ap horizon were sampled in every pedon; occasionally samples from the C horizons were taken. AnalysesAll samples were analyzed according to McKeague (1978). Numerical references to these methods are indicated in parentheses: pH in 0.01 M CaCl, (3.11); organic carbon by dry combustion (3.611); particle size distribution by the pipette procedure after peroxide and dithionite treatment (2.11) and Al + Fe by Napyrophosphate extraction (3.53). RESULTS Field ObserYationsFoResr srrEs (TRANSECTS 1 ro 3) However, the variation within each transect was again much wider (Table 3).About half (34 of 70) the pedons observed had Ap horizons underlain by B horizons (Table 3)

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We investigated the effects of soil and water conservation practices on mean and variance of potato (Solanum tuberosum L.) yield across 267 fields in northwestern New Brunswick, Canada, from 1988 to 2010. A stochastic production function method was used to account for seven soil and water conservation practices in addition to farm inputs, potato varieties, technological change, site characteristics, and seasonal climate effects. Overall, soil and water conservation structures had mixed effects on potato yield. While spring tillage and terracing increased mean potato yield, grassed waterways, drainage, chisel plowing, and other practices had the opposite effect. Rock management did not impact mean potato yield. Most practices did not impact yield variance. While soil and water conservation practices can be effective farm management tools for maintaining soil fertility and enhancing potato yields, there are no one-size-fits-all prescriptions to enhance yield.