Soil Nitrate Levels After Legume Cover Crops. Becky Maden January 24, 2017 VVGBA Cover Crop Conference

Transcription

1 Soil Nitrate Levels After Legume Cover Crops Becky Maden January 24, 2017 VVGBA Cover Crop Conference

2 The Issue: Soil Phosphorus Accumulation on Vegetable Farms Annual applications of Manure to meet N needs Analysis varies widely (apx ) To apply 80 lbs N/ acre, you need apx 8 tons manure. This adds apx 32 lbs P 2 O 5 / acre

3 Annual applications of Compost to meet N needs-- analysis varies widely (apx 1-1-1) To apply 80 lbs N/ acre, you need 4 tons of finished compost, or apx 10 yd 3. This adds apx 80 lbs P 2 O 5 / acre

4 Annual applications of Composted Chicken Manure to Meet N needs To apply 80 lbs N/ acre, you need 8 tons of Kreher s This adds 64 lbs P 2 O 5 / acre

5 # of Fields 40 Soil P levels from 11 Vermont Vegetable Farms (2015) < Soil Phosphorus levels (ppm)

6 Comparing N Costs (estimates)* Kreher s Composted Chicken Manure (5-4-3) $5/ lb N Chilean Nitrate (16-0-0) $6/ lb N Feather Meal (12-0-0) $8/ lb N Peanut Meal (8-2-1) $8/ lb N Soybean Meal (7-2-1) $5/ lb N Urea (46-0-0) $1/ lb N Legume Cover Crop $2-$4/ lb N *Costs depend on volume, trucking, and source

7 Legume Cover Crops Source of N with no additional P Many other soil health benefits

8 Legume Cover Crops for N Timing and duration of availability in VT? When to incorporate? When is best time to take a PSNT for veg? Best legumes/ mixes for veg cash crops? Costs per lb of N provided by legume cover crops?

9 Nodules on Spring Planted Field Peas

10 N Uptake Rate (Broccoli) Mark Gaskell and Richard Smith Hortechnology Oct 2007

11 *

12 Mark Gaskell and Richard Smith HortTechnology October-December 2007 vol. 17 no

13 2016 Legume Nitrate Study 11 VT veg farms Sampled cover crops already seeded on the farms Farmers maintained usual practices including fertilization and irrigation. Farmer participation Monthly PSNT samples from pre-incorporation through October

14 PSNT Pre Sidedress Nitrate Test Developed by UVM s Fred Magdoff for use in field corn Measures available soil nitrate levels Helps determine if N sidedress would offer yield/ economic gains 30 ppm is suggested threshold for sidedressing N for most vegetables

15 Cover Crops Sampled Spring planted Oat-Pea (five farms) Fall planted Rye-Vetch (four farms) Spring planted Field pea Fall planted Oat Vetch Fall planted Red clover/ Timothy Fall planted Yellow clover/ Winter rye Spring planted triticale Spring planted mixed grasses/ Timothy

16 Spring seeded Pea oats

17 Spring Seeded Oat/ Peas

18 Soil NItrate (ppm) 120 Soil Nitrate Levels Following Oat Pea Cover Crop Days after Incorporation

19 Fall seeded rye & vetch

20 Soil Nitrate (ppm) 120 Soil Nitrate Levels Following Rye Vetch Cover Crop Days After Incorporation

21 Fall seeded vetch & (winter-killed) oats

22 Soil Nitrate (ppm) Soil Nitrate Levels Following Oat Vetch Cover Crop Days After Incorporation

23 Fall Seeded Yellow Clover/ Winter Rye Fall Seeded Red Clover/ Timothy Grass

24 Use of Legume covers crops in mulch

25 Soil Nitrate (ppm) Soil Nitrate Levels After Red Clover/ Timothy Cover Crop Days After Incorporation

26 Soil Nitrate (ppm) Soil Nitrate Levels After Mixed Grasses/ Timothy Cover Crop Days after Incorporation

27 Days After Incorporation Soil Nitrate Levels Following Yellow Clover/ Rye Cover Crop Days After Incorporation

28 Spring seeded Field Pea

29 Soil Nitrate Levels (ppm) Soil Nitrate Levels After Field Pea Cover Crop Days After Incorporation

30 Soil Nitrate (ppm) 120 Soil Nitrate After Triticale Cover Crop Days After Incorporation

31 Fall planted Rye, Spring planted peas

32 Findings Fall planted Rye Vetch and Spring planted Oat Pea are most reliable sources of PAN for vegetable crops Role of grains in sustaining nitrate levels Annual rainfall and temperature major factor in nitrate availability More research needs to be done to determine reliability of predicting nitrate availability from legumes 2 year SCBG to do further research

33 10% 2016 Vermont Rainfall Percent Deviation of Rainfall from Average 0% -10% Burlington Newport Bennington -20% -30% -40% -50% -60% -70% April May June July August September

34 Thank you Farmers!

35 Spencer Blackwell, Elmer Farm

36 Luke Jonas and Nic Cook, Cedar Circle Farm

37 David Marchant, River Berry Farm

38 Jake Guest, Killdeer Farm

39 Hank Bissell, Lewis Creek Farm

40 Melissa Jacobs, Pete s Greens

41 Aly Martelle, Intervale Community Farm

42 Thank you Farmers! Cedar Circle Farm Clearbrook Farm Diggers Mirth Collective Farm Elmer Farm Intervale Community Farm Pete s Greens Killdeer Farm Lewis Creek Farm New Leaf Organics Pete s Greens River Berry Farm Singing Cedars Farmstead

43 Thank you funders! VVGBA Research fund New England Vegetable and Berry Growers Association Research Fund UVM Extension