Soil and Water Conservation Research under Intensive Potato Production Systems in New Brunswick

Transcription

1 Agri-Food Soil and Water Conservation Research under Intensive Potato Production Systems in New Brunswick T. L. Chow 1, H.W. Rees 1, and J.-L, Daigle 2 Quebec New Brunswick Technical Exchange Workshop Saint-Hyacinthe, Quebec January 20-21, Potato Research Centre, AAFC, Fredericton, NB 1 2 Eastern Soil and Water Conservation Centre, Grand Falls, NB

2 Agri-Food Cooperators: NB Dept of Agriculture, Fisheries and Aquaculture Eastern Soil and Water Conservation Centre Environment (pesticides) Health (pathogens) New Brunswick Department of Environment University of New Brunswick (modeling) Various farm agencies and associations Potatoes New Brunswick New Brunswick Soil and Crop Improvement Association Individual farmer/producers

3 Agri-Food Content: Introduction Factors causing soil erosion by water Materials and Methods Magnitude of the Problem Management Considerations Conclusions

4 Agri-Food Quebec Black Brook Experimental Watershed Potato Producing Areas - 20,000 ha annually % of total farm cash receipts Maine USA New Brunswick Prince Edward Island Nova Scotia Bay of Fundy Water Erosion

5 Agri-Food Natural Factors Shallow Soils Sloping Topography Major Rain Storms Snow Melt SOIL EROSION

6 Agri-Food Intensification of agricultural practices Continuous potato production Extensive tillage Heavy machinery Changing field sizes s 2000 s 1980 s

7 Agri-Food Soil Erosion Research in Potato Production in New Brunswick Rainfall simulator plots (1m x 1m); On-farm Permanent runoff-erosion plots (10m x 30m); Paired drainage basins benchmark sites (2-5 ha); Off-farm Experimental watersheds (15 and 340 km 2 ) 11

8 Agri-Food Rainfall simulator plots (1m x 1m) Guelph Rainfall Simulator II Not weather dependent Allows for numerous treatment comparisons and replicates 12

9 Agri-Food Permanent runoff-erosion plots (10m x 30m) Seven hydrologically isolated plots. Collection trough at lower end. Three above-ground over-flow tanks. Insulated for year-round data collection. 13

10 Agri-Food Paired drainage basins (2-5 ha) Soil Quality Monitoring Benchmark Sites 14

11 Agri-Food Experimental watersheds Little River Watershed (2000): Size : 340 km 2 Land use: Agriculture 15% Forestry 85% Black Brook Watershed (1992): Size : 14.5 km2 Land use: Agriculture 64% Forestry 36% Monitoring stations on Little River 19

12 Agri-Food Magnitude of the problem Soil Loss (t/ha/yr) Potential soil loss from various crops planted up-and-down 5-10% slope Potato Barley Clover Tolerable Crop 6 CROP ROTATION CROP ROTATION CROP ROTATION 28

13 Agri-Food Timing of the problem Annual value (%) Seasonal distribution soil loss/runoff under potato, Grand Falls, N.B. Erosivity (MJ mm ha -1 h -1 ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month ( ) 0 Soil Loss Cropping Season Runoff Non-cropping Season 28

14 Agri-Food Magnitude of the problem COMPOSITION OF ERODED SEDIMENTS % Sand Silt Eroded sediments Clay Plow layer OM

15 Agri-Food Magnitude of the problem % Soil Org. C Change in SOC (0-15cm) Potato Up and Down Slope Crop Legend B Barley P Potato C Clover R Ryegrass O Oats r ryegrass underseeded 1.85 P/O R P P B P B-C C P P Br 1989 Crop 1999

16 Agri-Food Magnitude of the problem Nutrient Losses from potato planted up & down 8% slope Kg Ha -1 N P 2 O 5 K 2 O Ca Mg

17 Agri-Food Magnitude of the problem

18 Agri-Food Magnitude of the problem Off-Farm Implications Stream water quality Sediment in road ditches

19 Agri-Food Magnitude of the problem Surface Water Quality SEDIMENT CONC ('000 ppm) WEIR # JULIAN DAY NITRATE CONC (ppm) WEIR # JULIAN DAY

20 Agri-Food Impact of potato production on soil profile characteristics Wang et al % HFP 7% DYB 50 cm Forest soil Cultivated soil, potato rotation 42 cm 27% HFP 22% DYB 51% HR SUBSOIL

21 Agri-Food Research on potato production cultural practices that impact on soil erosion

22 Agri-Food Some management considerations Stones are a liability, but are they also an asset?

23 Agri-Food Some management considerations Effects of Coarse Fragment Content on Soil Loss Soil Loss Ratio (%) Coarse Fragment (2-5 cm dia, % vol) Some farmers no longer remove stones. Stones brought up in the harvester are crushed (< 2.5 cm dia.) and return to the field.

24 Agri-Food Some management considerations Since potato produces limited crop residue (< 1 t ha -1 ) for ground cover, alternate means of enhancing SOC are considered. Fall application of 4.5 t ha -1 hay mulch with shallow incorporation into the plow layer prior to planting the following spring acts as both a surface mulch during the winter and a soil amendment during the growing season. Soil loss is reduced by up to 90%.

25 Agri-Food Some management considerations Pulp Fibre 20 t ha -1 dry pulp fibre added as a soil amendment reduced runoff and soil loss to 65 and 43% of control

26 Agriculture and Agri-Food Some management considerations Underseeding grains with a grass or legume increases soil organic matter in a Potato-Grain rotation

27 Agri-Food Some management considerations Chisel Plowing vs Moldboard Plowing Additional surface residues left by chisel plowing reduced runoff by 20% and soil loss by 62% on 11% slopes in grain production.

28 Agri-Food Some management considerations Effects of potato hilling on soil loss Potatoes are hilled: - for weed control - to reduce the amount of soil to be handled when harvesting - to prevent sun scalding

29 Agri-Food Some management considerations Effects of potato hilling on soil loss Hilling increased soil loss 4x. The USLE C-Factor used for continuous potato is Our research determined a value closer to 2.00 To reduce impact of hilling: - reduce time soil is hilled - reduce hill side-slope angle - reduce number of hills

30 Agri-Food 2005 BMP Implementation Sub-basins #6 & 7 Grassed Riparian Buffer Zones 5-15 m grassed buffers Existing Weir Grassed Buffer Zone Grassed Waterway New Weir After Before

31 Agri-Food Vegetated Buffer Strip 30 min Intensity (mm/hr) Discharge Rate (l/s) June 21, 2006 Cumulative Rainfall = 6.9 mm Before buffer strip After 15 m buffer strip Time (min)

32 Agri-Food Vegetative Buffer Strip Buffer Strip June 21, 2006 Before Concentration (mg/l) After g/l ug/l 1 2P Element NO3 K Ca Mg Sed

33 Agri-Food Vegetated Buffer Strip 30 min Intensity (mm/hr) Discharge Rate (l/s) Cumulative Rainfall = 28.5 mm July 10, 2006 Before buffer strip After 15 m buffer strip Time (min)

34 Agri-Food Some management considerations Contour cultivation -not always logistically possible (complex slopes) Up-and-down slope cultivation Contour cultivation - longer field slope lengths reduce effectiveness 24.3 t ha -1 vs 1.2 t ha -1 (soil loss based on 30 m slope length erosion plots)

35 Agri-Food Some management considerations Variable grade diversions and grassed waterways

36 Agri-Food Some management considerations Rainfall Intensity (mm/h) Discharge Rate (l/s) June 19, Flood Prevention Time of Day (minutes) Up-and-down slope cultivation Diversion terraces and grassed waterway

37 Agri-Food Some management considerations Benefits of variable grade diversions and grassed waterway conservation systems in potato production Up and Down Variable Grade Diversions Slope Cultivation and Grassed Waterways - 5% slope - 6.4% slope m slope length - 66 m between diversions Soil Loss / /- 0.6 (t ha -1 yr -1 ) Runoff (cm) / /- 1.2 (% of May to (29%) (4%) Nov. Rainfall.)

38 Agri-Food Total Available N and P Losses (Potato 1994) kg/ha Total N 1.7 Up-Down Cultivation Total P 0.4 Diversions/Waterway

39 Agri-Food Area of fields protected by terraces/grassed waterways: ha (16% of farm land) ha (35% of farm land)

40 Agri-Food Black Brook Experimental Watershed Surface water monitoring sites Automated stage height recording and water sampling for flow, ph, conductivity, sediment loading, N, P, K, Ca, Mg

41 Agri-Food Impacts of Terracing on Stream Discharge Black Brook Watershed Discharge as a % of Precipitation Black Brook Watershed Stream Discharge % Cubic meters ('000,000) Year Period

42 Agri-Food Impacts of Terracing on Stream Sediment Load Black Brook Watershed Sediment per unit Erosivity Black Brook Watershed Sediment Yield Ton/MJ mm/ha hr yr Impacts of Construction Ton Year Period

43 Agri-Food Conclusions: Landscape, soil and climate conditions of NB are susceptible to soil erosion by water; Intensive potato production enhances the erosion processes; Soil erosion induces on-farm and off-farm impacts; Soil conservation practices (BMPs) reduce these impacts; Soil conservation should consider a group of BMPs rather than any single practices; Watershed studies indicate positive returns of BMPs in term of discharge and sediment loading; BMPs are the key solution to the sustainable potato production in NB

44 Agriculture and Agri-Food THANK YOU 31