Elliott Hildebrand and Jeff Schoenau. ASA, CSSA and SSSA Long Beach, CA November, Dept. Soil Science University of Saskatchewan

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Central Saskatchewan Elliott Hildebrand and Jeff Schoenau ASA, CSSA and

1 Relationships Among Soil Properties, Crop Yield, Protein, and Response to Nitrogen Fertilizer Application in an Undulating Landscape in South Central Saskatchewan Elliott Hildebrand and Jeff Schoenau ASA, CSSA and SSSA Long Beach, CA November, 2014 Dept. Soil Science University of Saskatchewan

2 Context 4 Rs of Nitrogen (N) Management Goal to increase N-use efficiency (NUE) Global NUE for cereal production < 50%

3 Context Precision Agriculture GPS guidance Sectional control Variable Rate (VR) N Fertilizer Application Concept: Match N rates to varying production potentials in a field Does it work?

4 Context In theory VR N should: Improve yield and N-use efficiency However, improvements at the farm level have been difficult to document Reflects knowledge gaps of: Temporal and spatial variation in soil properties controlling yield Environmental controls How this affects response to applied N (Cassman et al., 2002)

5 Context In practice: Many farmers apply the same fertilizer rate across a whole field regardless of variability in yield potential Why? Efficient means are needed to create a variable application map Cost to ID, sample and predict crop response in separate zones Uncertainty surrounding benefits to be achieved Challenge: ID efficient reliable mechanisms to make VR map

6 Research Questions What is the effect of soil properties on crop yield and protein in a typical landscape in southern SK? Will protein concentration of crops help delineate effective fertilizer management zones?

7 Research Question Yield Can establish how much N it takes to produce a target yield Protein Reflects balance of N to other yield limitations

8 Yield vs Protein Curve Spring Wheat (adapted from Engel et al., 1999)

9 Study Objectives Summer 2012 Typical southern Saskatchewan undulating farm field Determine relationships between: Crop yield Crop protein Soil landscape properties Salinity Organic matter ph Soil nutrients

10 Study Objectives Summer 2013 Use these relationships to: 1) develop VR N prescription 2) compare performance to constant rate Side by side comparison

12 SW W3 (2012) PEAS CANOLA WHEAT

13 SW W3 (2013) WHEAT WHEAT CANOLA

14 Variable N Rates Strategy: Increase N rates where previous crop had low or medium protein Decrease N rates where previous crop had high protein

15 Wheat on Canola Stubble Fertilizer Rates Transect 1 Control 50 kg N ha -1 (109 kg ha -1 ) 9m Variable Rate 40 (87) 40 (87) 70 (152) 0 70 (152) 60 (130) 40 (87) 60 (130) 9m Transect Point WC1 WC2 WC3 WC4 WC5 WC6 WC7 WC Canola HP MY LP HY MP LY LP LY LP MY MP MY HP LY MP MY Transect 2 Variable Rate 40 (87) 70 (152) 0 70 (152) 60 (130) 60 (130) 60 (130) 0 9m Control 50 kg N ha -1 (109 kg ha -1 ) 9m Transect Point WC9 WC10 WC11 WC12 WC13 WC14 WC15 WC Canola HP LY LP MY LP LY LP MY MP HY MP HY MP HY LP LY

16 Wheat on Pea Stubble Transect 1 Control N Rate Varied N Rates N July 3/2013

17 Relationship of Canola Yield and Protein to Soil Properties Canola: Soil Relationships Organic carbon (%) (0-30 cm) Base Year Variable N Constant N Protei Yield Protein Yield n Yield Protein ns r=0.65* ns ns r=0.57* ns EC (ds m -1 ) (0-30 cm) 2013 Soil Moisture Spring (30-60 cm) ns ns r=0.51* ns ns ns ns ns ns ns ns r=-0.50* * indicates significant correlation at p < 0.05

18 Relationship of Wheat Yield and Protein to Soil Properties Wheat: Soil Relationships Base Year Wheat on Canola Stubble Wheat on Pea Stubble Variable Constant Variable Constant Yield Protein Yield Protein Yield Protein Yield Protein Yield Protein Organic Carbon (%) (0-30 cm) 0.74* ns 0.51* ns ns ns ns ns ns ns EC (ds m -1 ) (0-30cm) ns 0.51* ns ns ns ns -0.52* ns -0.51* ns 2013 Soil Moisture Spring (30-60 cm) ns ns ns ns ns -0.60* ns ns ns * indicates significant correlation at p < 0.05 ns

19 Yield (kg ha -1 ) Crop Yield (kg ha -1 ) No significant differences at p< Canola on Wheat Wheat on Canola Wheat on Peas Varied Control Constant

20 Protein (%) Crop Protein (%) No significant differences at p< Canola on Wheat Wheat on Canola Wheat on Peas Varied Control Constant

21 Did protein help create N zones? Increasing N rates: Generally a positive yield and protein response where previous crop was low or medium protein Low and medium protein good indicator that more N was required Decreasing N rates: Generally a negative yield and protein response where previous crop was high protein High protein a less reliable indicator that N could be reduced

22 Conclusions Surface soil organic carbon content was sometimes positively related to yield and protein of canola and wheat Reflects variation in OM and N supply from mineralization Varied from year to year and field to field Surface soil electrical conductivity (salinity) was positively related to protein content, often negatively with yield Greater soil moisture at depth = lower protein

23 Conclusions Average yield and protein across the landscape in varied N rate and constant N rate were similar Since similar total amounts of N fertilizer were used in each, no difference in economic return Same results for each crop Prescription approach needs refining? What can be improved? Be careful about reducing N rates in a VR prescription!

24 Thank You! Questions?

25 Supplemental Slides

26 SW W3 High ground Bathtub ring salinity Old rail line Saline depression

27 Precipitation Rainfall (mm) Month April May June July Aug Sept Oct Total (mm) Total (inches)

28 Context Current methods to create VR maps include: Soil electrical conductivity (EC) maps Satellite imagery Elevation maps Yield maps Soil surveys All reveal variability in many different aspects

29 Soil Association Kh4:l- Ad5:l Ga3:St2 (Ayres et al., 1985)

30 Harvest 2013 Results Wheat on Pea Stubble Transect 1 Control N Rate Varied N Rates N August 23/2013

31 Wheat on Canola Stubble Control Varied N Rates

32 Acknowledgements Case New Holland Jim Henry Joel Gervais Ross Welford Software

33 Why no significant differences? Mean Impact of Variable Rate N Strategy versus Constant N Rate on Yield and Protein VR Strategy Canola on Wheat Wheat on Canola Wheat on Peas Decrease N Rate Yield (kg ha -1 ) Protein (%)

34 Variable Rate Seeding 2014 VR Strategy Increase N rate where previous crop Low protein Medium protein Keep N rate constant where previous crop High protein Harvest completed; anticipating results!

35 Protein Sensor

36 Seeding Outfit 2013

37 Relationship of EC to Soil N Canola on Wheat Field Area 1 EC 0-30cm (µs cm -1 ) EC 30-60cm (µs cm -1 ) Wheat on Canola Field Area 2 EC 0-30cm (µs cm -1 ) EC 30-60cm (µs cm -1 ) Wheat on Peas Field Area 3 EC 0-30cm (µs cm -1 ) EC 30-60cm (µs cm -1 ) Extractable NO N AEM NO N Depth (cm) Spring Fall * (0.02) 0.68 (0.004) 0.52 (0.05) 0.57 (0.02) 0.53 (0.04) (0.05) 0.52 (0.04) (0.003) (0.04) (0.002)

38 Soil Association Kh4:l- Ad5:l Ga3:St2 (Ayres et al., 1985)

Virtual Soil Testing What Is It?

Virtual Soil Testing What Is It? Rigas E. Karamanos 1 and Karen Cannon 2 1 Western Cooperative Fertilizers Limited, 2 Conservation and Development Branch, Alberta Agriculture, Food and Rural Development