Soil quality assessment and nitrogen managment. Dan M. Sullivan Crop & Soil Science, OSU

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1 Soil quality assessment and nitrogen managment Dan M. Sullivan Crop & Soil Science, OSU

2 Nitrogen mineralization (Nmin) test concept Nitrate NO3 - Plant Uptake Ammonium NH 4 + Organic Nitrogen

3 Cumulative available N from an organic source Year 1 = available N

4 Mineralization series estimate cumulative N availability Cumulative N mineralized (% of annual N applied) Fresh manure % of remaining N Compost % of remaining N Year of continuous application

5 Available N: Long term After 5+ yr of consistent organic inputs Approach equilibrium N into soil = available N After soil N mineralization capacity built up, it may be difficult to match timing of mineralized N to crop needs

6 Nitrogen management for organic potatoes: in the OSPUD project Dan Sullivan, John McQueen, Alexandra Stone, Lane Selman, Don Horneck Oregon State University and 11 cooperating organic farms in OR and WA 2006 and 2007

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8 OSPUDers

9 Inputs Farm scale nutrient cycling Outputs Within-farm (cover crop)

10 Building, mining or maintaining nutrients? Nutrients Higher equilibrium Lower equilibrium Time

11 N Inputs Farm Boundary Compost or feedstocks Chicken litter Specialty organic fertilizers Legume cover crops compost N outputs Veggies for sale

12 Soil ph Ospud farms Soil ph Farm 1 Farm 2 Farm 3 Farm 4 Farm 5 Farm 6 Farm 7 Farm 8 Farm 9 Farm 10 Farm 11

13 Soil test OM and texture 8 7 Organic matter (%) Organic Matter (%) Farm 1 Sand (%) Farm 2 Farm 3 Farm 4 Farm 5 Farm 6 Farm 7 Farm 8 Farm 9 Farm 10 Farm 11 Sand (%) Farm 1 Farm 2 Farm 3 Farm 4 Farm 5 Farm 6 Farm 7 Farm 8 Farm 9 Farm 10 Farm 11

14 Soil test P and K 200 Soil test P (Bray P1) Phosphorus (P) Soil test K (ppm) Farm 1 Farm 2 Farm 3 Farm 4 Farm 5 Farm 6 Farm 7 Potassium (K) Farm 8 Farm 9 Farm 10 Farm 11 0 Farm 1 Farm 2 Farm 3 Farm 4 Farm 5 Farm 6 Farm 7 Farm 8 Farm 9 Farm 10 Farm 11

15 Nutrient uptake for sweet Spanish onions In: Nutrient Management for Onions in the PNW PNW Extension publication 546

16 Organic amendment Total N Total P Total K lb per dry ton broiler litter separated dairy solids yard trimmings compost pelleted fish fertilizer canola meal

17 Soil Quality Test for Nmin Soil (0-12 inch samples) N mineralization in moist soil at room temperature in the laboratory

18 Does soil organic matter correlate with N mineralized from soil OM? Soil N mineralization rate (ppm N per day) OSPUD, 2006 "spring" soil N min samples Soil organic matter (%)

19 Is baseline soil N min rate the same for spring and summer soil samples? Summer soil N min rate (ppm N per day) OSPUD, Spring soil N mineralization rate (ppm N per day)

20 1.0 Soil N min rate (ppm N per day) spring OSPUD, 2006 summer 0.2 spring summer OSPUD, 2007 fall

21 OSPUD Grower zero N plots Grower N management No nitrogen plots Tuber yield (tons/acre) Nicola Tuber yield (tons/acre) Yellow Finn Days after planting Days after planting At six farm locations, crop N uptake from an unfertilized crop was always above 100 lb N per acre.

22 Zero N experiment across six farms: Crop Nitrogen Uptake (lb/acre) whole plant N uptake Potato Crop Nitrogen uptake zero N applied in 2006 Linear regression across all farms = approx. 2 lb N per acre per day from soil organic matter mineralization Farm 2 Farm 1 Farm 6 Farm 3 Farm 4 Farm Days after planting

23 OSPUD Nmin summary Lab and field data point in same direction. Soils with history of organic inputs have high N mineralization rate in both field and laboratory: Field: plants took up N from soil at rate of 2 lb N per acre per day from zero N plots (no N fertilizer applied). Lab: N mineralization rate (0.6 ppm N per day at 72 o F) is roughly equal to 2 lb N/acre/day in top foot of soil (0.6 ppm N x 3.5 million lb soil/acre-ft)

24 Laboratory Incubations (22 o C or 72 o F) organic vs. conventional history Typical N min rate for organic farm soil: 0.5 to 1.3 mg N/kg (ppm) per day Typical N min rate for conventional soil 0.3 to 0.5 ppm per day Represents baseline Nmin rate Doesn t include effect of recent organic matter additions (crop residues, cover crops, etc)

25 Effect of organic matter addition history on soil N mineralization rate NItrate-N (mg kg -1 ) Days at 22 o C Dairy solids each spring (2001-4) Dairy solids spring 2004 only No dairy solids Median 2005 organic farms Separated dairy solids applied in May (OSU Veg Farm) Soils collected in Sept from the field Soil samples incubated at 22 o C Loamy textured soils

26 Benton Soil Quality Project Soils with high N mineralization rate also generally had: High active carbon soil test High soil test P and K (because soil building done with manures and composts that supply more P and K than plants can use)

27 Practical application of knowledge of soil N mineralization rate

28 OSU Pub# EM9010-E at a computer near you Sweet corn (western Oregon) Hart, Sullivan, Myers, Peachey (2010)

29 Test soil in June for summer vegetable crops. If N mineralization rate is high, reduce N fertilizer inputs

30 PSNT vs. Sweet Corn Ear Yield (2011) Coho Basin OSU recommended PSNT rates

31 Mid-season soil nitrate test as a soil quality indicator How it works NO3-N lost by leaching in winter, resetting the system N mineralization happens in spring in response to soil conditions (substrate, temperature and moisture) Soil nitrate-n in early summer (June) used as criteria for N rate applied (side-dress) for vegetable crops

32 Mid-season soil nitrate-n vs. broccoli yield Fresh broccoli yield (% of max) Max yield = 12.5 Mg/ha (fresh wt) fallow oat oat + vetch phacelia phacelia + vetch vetch Soil Nitrate-N (mg/kg) Sampled 65 days after cover crop incorporation No feather meal N added

33 Sweet corn, mid-season soil nitrate-n vs. yield 110 Ear yield (% of maximum) Pre-sidedress nitrate-n (mg/kg) data point= site-yr for a preplant compost or manure application

34 Soil nitrate-n vs. table beet yield Table beet yield (Mg/ha) MF Farm Fallow Fallow + feather meal Phacelia Vetch (PV) PV + feather meal Rye Vetch (RV) RV + feather meal Vetch (V) V + feather meal Soil nitrate-n (mg/kg) on May 18, 2009

35 Conclusions Soil-building works. Add fresh OM, it mineralizes and builds soil baseline N mineralization rate. Lab incubations of N mineralization potential are helpful in determining the cumulative effects of soil management practices on N mineralization rate, and provide opportunity to reduce expensive N inputs Baseline soil N mineralization rates are elevated on local organic farms, approx 2x that of conventional farms on same soils Best test for Nmin done in field (PSNT; June) Lab tests: High soil N min rate is usually associated with high active C in soil. Active C a better predictor of soil N min than Total C or Organic Matter. But, I think direct measurement of soil Nmin (aerobic incubation) is the best predictor.