Refining the N index to determine the risk of nitrate contamination of surface and groundwater for Ontario soils

Transcription

1 Refining the N index to determine the risk of nitrate contamination of surface and groundwater for Ontario soils C.F. Drury, G.W. Parkin, W.D. Reynolds, J. Saso J. Lauzon, T.Q. Zhang, C.S. Tan, J.Y. Yang, X.M. Yang, T.W. Welacky, and K. Reid AAFC Harrow and the University of Guelph

2 Objectives Evaluate N leaching in 5 dominant soil types in Ontario which represent hydrologic soil groups A,B, C (2 soils) and D. Evaluate the impact of tile drainage on nitrate and chloride loss from the Brookston clay loam (HSG-D) and Perth clay loam (HSG-C) soils. Compare nitrate movement in soils with a non-reactive tracer (Chloride). Determine the extent of N leaching and denitrification losses from swine manure and calcium nitrate amended soils in a column study. A non-reactive tracer (chloride) will also be used.

3 Criteria for Placement of Hydrologic Soil Groups (adapted from USDA, Natural Resource Conservation Service, Technical Release 55) Hydrologic Soil Group (HSG) Group A (primarily sand, loamy sand and sandy loam soils coarse texture) Group B (primarily silt loam and loam soils well structured) Primary Placement Criteria Ksat 3 x 1-3 cm s -1.* Excessively drained to well drained. 3 x 1-4 Ksat < 3 x 1-3 cm s -1. Well drained to moderately drained. Group C (primarily clay loam and sandy clay loam soils - poor structure) 3 x 1-5 Ksat < 3 x 1-4 cm s -1. Moderately drained. Group D (primarily soils with substantial silt and/or clay contents poor structure and/or swelling, e.g. silty clay loams, sandy clays, clays) Ksat < 3 x 1-5 cm s -1. Poorly drained. *minimum Ksat in top 5 cm (or top 1 cm).

4 Field study Field sites (7) - established fall 27 Fox sandy loam (HSG A) no tiles Guelph loam (HSG B) with tiles Maryhill loam (HSG C) with tiles Perth clay loam (HSG C) no tiles Perth clay loam (HSG C) with tiles Brookston clay loam (HSG D) no tiles Brookston clay loam (HSG D) with tiles

5 Ontario Soils HSG & Acreage Soil HSG Land Area (ha) Land Area (% of agr. land) Brookston D 957, 17.5 Perth C 561, 1.3 Otonabee B 542, 9.9 Harriston B 446, 8.2 Bondhead B 428, 7.8 Grenville B 419, 7.7 Huron C 389, 7.1 Brighton A 279, 4.9 Fox A 245, 4.5 Gobles C 195, 3.6 Lincoln D 177, 3.2 Maryhill C Guelph B

6 Field study (cont d) Treatments (4) kg N/ha + 1 kg KCl/ha 1 kg N/ha + 1 kg KCl/ha 2 kg N/ha + 1 kg KCl/ha 2 kg N/ha + kg KCl/ha Replicates (4)

7 Inorganic N Recovery (-8 cm depth) Perth Clay Loam Tiled kg N/ha 1 kg N/ha 2 kg N/ha Brookston Clay Loam Tiled 1 8 NH 4 + -N + NO3 - -N (kg N ha -1 ) Not Tiled Not Tiled Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

8 5 4 Inorganic Chloride Recovery (-8 cm depth) Perth Clay Loam Tiled Chloride Tracer No Chloride Tracer Brookston Clay Loam Tiled 3 2 Chloride (kg Cl/ha) 1 4 Not Tiled Not Tiled Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

9 Inorganic N and Chloride Recovery (-8 cm depth) 25 2 Fox sandy loam kg N/ha 1 kg N/ha 2 kg N/ha 5 4 Fox sandy loam kg N/ha 1 kg N/ha 2 kg N/ha NH 4 + -N + NO3 - -N (kg N ha -1 ) Guelph loam Chloride (kg Cl ha -1 ) Guelph loam 2 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Maryhill loam 4 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Maryhill loam Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

10 Inorganic Nitrogen vs Depth Perth Clay Loam 2 weeks 8 weeks 32 weeks 54 weeks 1 2 Not Tiled Depth (cm) kg N/ha 1 kg N/ha 2 kg N/ha Tiled Depth (cm) NH + 4 -N + NO - 3 -N (mg N kg -1 soil)

11 Inorganic Chloride vs Depth Perth Clay Loam 2 weeks 8 weeks 32 weeks 54 weeks 1 2 Not Tiled Depth (cm) Chloride Tracer No Chloride Tracer Tiled Depth (cm) Chloride (mg kg -1 soil)

12 Inorganic Nitrogen vs Depth Brookston Clay Loam 2 weeks 8 weeks 32 weeks 54 weeks 1 Not Tiled Depth (cm) kg N/ha 1 kg N/ha 2 kg N/ha Tiled Depth (cm) NH 4 + -N + NO 3 - -N (mg N kg -1 soil)

13 Inorganic Chloride vs Depth Brookston Clay Loam 2 weeks 8 weeks 32 weeks 54 weeks 1 2 Not Tiled Depth (cm) Chloride Tracer No Chloride Tracer Tiled Depth (cm) Chloride (mg kg -1 soil)

14 Inorganic Nitrogen vs Depth 3 weeks 8 weeks 32 weeks 47 weeks 1 Maryhill loam Guelph loam Depth (cm) Depth (cm) kg N/ha 1 kg N/ha 2 kg N/ha NH 4 + -N + NO 3 - -N (mg N kg -1 soil)

15 Inorganic Chloride vs Depth 3 weeks 8 weeks 32 weeks 47 weeks 1 Maryhill loam Guelph loam Depth (cm) Depth (cm) kg N/ha 1 kg N/ha 2 kg N/ha

16 Inorganic N and Chloride vs depth Fox soil 2 weeks Inorganic N and Chloride Fox sandy loam 8 weeks 29 weeks 54 weeks 1 2 Depth (cm) kg N/ha 1 kg N/ha 2 kg N/ha weeks NH + 4 -N + NO - 3 -N (mg N kg -1 soil) 8 weeks 29 weeks weeks 2 Chloride Tracer No Chloride Tracer Depth (cm) Chloride (mg kg -1 soil)

17 Chloride and Inorganic N Loss (%) Chloride Loss Inorganic N Loss Fox (A) Guelph (B) Maryhill (C) Perth (C) Brookston (D)

18 Nitrate and Chloride Leaching Summary A vast majority (>6%) of the applied nitrate and chloride leached through the Maryhill (C), Guelph (B) and Fox (A) soils 6 months after application. Nitrate leaching was reduced in the Perth and Brookston soils which were not tiled compared to tiled soils. Chloride leaching generally follows HSG howevr nitrate losses were also influenced by biological processes (mineralization, immobilization, denitrification) as well as tile drainage.

19 12 Chloride and Inorganic N Losses after 6 months 1 Inorganic N =.577(Chloride) r 2 =.62 Maryhill (C) Inorganic N Loss (%) Brookston (D) Perth (C) Fox (A) Guelph (B) Chloride loss (%)

20 Intact Soil Columns and Soil Cores Intact Soil Columns (2 cm diameter; -6 cm depth) were collected for detailed & controlled laboratory measurements of: - nitrate and chloride leaching - greenhouse gas emissions - soil water movement/distribution Intact Soil Cores (1 cm diameter; -1 cm, 2-3 cm, 4-5 cm depths) were collected for detailed laboratory measurement of: - hydraulic conductivity, Ksat (soil water infiltration rate) - water release curve (soil water-air storage characteristics) - bulk density (soil strength/hardness/compaction)

21 Intact Soil Columns and Soil Cores Field Location Soil Type (HSG) Under Drainage Intact 2 cm x 6 cm Soil Columns Intact 1 cm x 1 cm Soil Cores 6 cm 1 cm 2 3 cm 4 5 cm Harrow Elora Elora Malden Malden Woodslee Woodslee Fox SL (A) Guelph L (B) Maryhill L (C) Perth CL (C) Perth CL (C) Brookston CL (D) Brookston CL (D) Tiled Tiled Tiled Tiled Not Tiled Tiled Not Tiled Totals

22 Soil Column Insertion

23 Soil Column Extraction Backhoe used to open an access trench. Columns retrieved by hand.

24 Intact Soil Cores Collected from wall of column extraction pits using stainless steel rings Grab samples collected for OC and PWP determination

25 HSG Class A B C D The T bars indicate geometric standard error (n = 1 for -1 cm; n = 5 for 2-3 cm; n = 3-4 for 4-5 cm). The upper case letters indicate Hydrologic Soil Group (HSG).

26 Key Soil Hydraulic Property Results 1. Impacts on Hydrologic Soil Group Soil Type Published HSG Ksat Derived HSG* Fox SL A A Guelph L B B Maryhill L C A-B (A-B)/C Brookston CL Not Tiled D D Brookston CL Tiled D C (C/D) *based on minimum Ksat in top 5 cm

27 Key Soil Hydraulic Property Results 2. Under-Drainage Effects on Brookston CL Installation of tile had a double effect on the internal drainage of Brookston clay loam soil - improved drainage due to presence of tile - improved drainage by due to increased Ksat Tile drainage increased Ksat by a factor of 1 in -1 cm depth and by a factor of 1 in the 2-3 cm and 4-5 cm depths. The factor of 1-1 increase in Ksat is consistent with the apparent increase in rate of chloride (and possibly nitrate) leaching through the crop root zone (and potentially into tile drainage water).

28 Appreciation is expressed to the Nutrient Management Joint Research Program for providing funding for this study and for expert technical assistance provided by Wayne Calder, Dr. Tom Oloya,Vic Bernyk, Mary-Anne Reeb Karl Rinas, Joann Gignac and for ERCA for providing access to the land for the Perth clay loam sites