Closing the Knowledge Gap on Wisconsin Hop Fertility · Closing the Knowledge Gap on Wisconsin Hop...

Closing the Knowledge Gap on Wisconsin Hop Fertility

C h r i s t o p h er A . B ax t e r, P h . D.

Pro fe s s o r & S o i l Fe r t i l i t y a n d N u t r i e nt M a n a g e m e nt S p e c i a l i s t

U W - P l a t tev i l l e a n d U n i ve rs i t y o f W i s co n s i n M a d i s o n - E x te ns i o n

Hop Production for the Wisconsin Craft Brew Industry, February 29, 2020 Christopher A Baxter

Summary of Recent Hop Fertility Work in Wisconsin2016 – Collected preliminary data on yield, nutrient removal and soil test levels.

Verified P and K removal were within UW estimatesIndicated need for further evaluation of recommended N rates

2017&2018 – Conducted study to evaluate effect of nitrogen rate and timing on hop biomass and cone yield. Incorporated petiole nitrate tissue and sap testing.

https://buffalo.extension.wisc.edu/agriculture/barley-and-hops/

2019 – Initiated a 2-year study to determine optimum N rates for Wisconsin growers.

Included 5 N ratesContinued petiole tissue and sap testingIncluded post harvest soil nitrate samplingEvaluate effect of N rate on hop quality parameters

https://buffalo.extension.wisc.edu/agriculture/barley-and-hops/


2019 N Rate TrialsSame locations as used in 2017 and 2018

Tomah, WI : Centennial and Cascade

Waterloo, WI: Chinook, Tahoma

Rosholt, WI: Magnum, Nuggett

Nitrogen TreatmentsPlots consisted of 5 “plants”

N rates: 0, 50, 100, 150, 200 lbs N/ac

All N rates split applied: at training and after majority of bines reached top wire.

N source: ammonium nitrate

Used maintenance rates of P, K, Zn, and B


Data CollectionSoil samples collected and plots harvested at discretion of the grower (July-Sept).

Whole plants weighed before machine picking. Subsamples of machine-picked cones and bines collected for determination of moisture and nutrient content.

Soil samples collected from a subset of plots to investigate for determination of profile nitrate.


2019 Biomass and Cone Yield Results

Variety significantly affected bine and cone yield

0

1000

2000

3000

4000

5000

6000

7000

0 50 100 150 200

Cascades

Centennial

Chinook

Magnum

Nugget

Tahoma

Bine DM Yield

lbs/

ac

0

200

400

600

800

1000

1200

1400

1600

0 50 100 150 200

Cone Yield (adj. 10% moist.)

Suffered from Anthracnose


Significance of N rate effect on Bine and Cone YieldLocation Variety N treatment

effect on Bine DM yield P-value

N treatment effect on Cone

yield P-value

Tomah Cascades 0.001 0.099

Tomah Centennial 0.012 0.023

Rosholt Magnum 0.015 0.077

Rosholt Nugget <0.001 0.004

Waterloo Chinook 0.014 0.37

Waterloo Tahoma 0.772 0.633

P values less than 0.05 generally indicate significant effect of N treatment.


Overall Effect of N rate on Average Bine and Cone Yield

N Rate (lb N/ac)

Bine DM (lb/ac)

Cone Yield (adj. 10% moisture, lb/ac)

0 2735 C 841 C

50 3480 B 944 CB

100 4191 A 1141 BA

150 4430 A 1226 A

200 4501 A 1188 AMeans that do not share a letter are significantly different.


Biomass and Cone Yield affect on N Removal

Cone yield was not a good predictor of N removal

N removal is well correlated with biomass yield

y = 0.0181x + 4.3093R² = 0.70090

50

100

150

200

0 2000 4000 6000 8000 10000

N r

emo

val (

lb/a

c)

Biomass yield (lb DM/ac)

Whole plant Biomass (DM) yield vs N removal

y = 0.0685x + 18.767R² = 0.3788

0

50

100

150

200

0 500 1000 1500 2000 2500

N r

emo

val (

lb/a

c)

Cone yield (lb DM/ac)

Cone yield vs N removal


Petiole Tissue and Sap testing

Potentially a valuable tool for hop growers

Samples collected when bines are ½ - ¾ to top of trellis

Allows for in-season adjustment of N rates

Recommend applying 50-70% of N recommendation prior to petiole test

General Guidelines (adapted from PNW recommendations)

0-6000 ppm : Apply recommended rate plus additional 30-50lbs N

6000-10000 ppm: Apply recommended N rate

10000+ ppm: no additional N necessary

y = 1.3237x - 947.53R² = 0.7686

0

2000

4000

6000

8000

10000

12000

14000

16000

0 2000 4000 6000 8000 10000 12000Pet

iole

Tis

sue

NO

3-N

(p

pm

)

Petiole Sap NO3- (ppm)

Tissue Vs. Sap - All 2019 Samples

y = 1.0832x - 124.69R² = 0.7773

0

2000

4000

6000

8000

10000

12000

0 2000 4000 6000 8000 10000Pet

iole

Tis

sue

NO

3-N

(p

pm

)

Petiole Sap NO3- (ppm)

Tissue Vs. Sap-All Treatment Yards Excluding >10,000 ppm


Effect on Hop Quality Parameters

3 varieties sampled for hop quality parameters, analyzed by AAR Labs

Variety significantly affected HSI, total Oils, Total A-acid, Cohumulone, Total B-acid, Colupulone, and A/B ratio. (P<0.0001)

N rate did not have a effect on any quality parameter except Colupulone. (P=0.02).

Colupulone (as % of BA) decreased steadily with N rate in the Chinooks, but this decrease was not observed in Cascade or Magnum varieties.

Variety HSI Oils (mg/100g)

Cohumulone(% of AA)

A-Acid(%)

Colupulone(% of BA)

B-acid(%)

A/B

Cascade 0.24 0.19 32.45 1.41 54.14 0.98 1.55

Chinook 0.26 0.62 30.55 2.83 55.27 0.73 3.87

Magnum 0.27 0.86 25.92 4.57 45.97 2.12 2.15


Effect of N rate on Colupulone(as % of BA) in Chinook

200150100500

58

57

56

55

54

53

Nrate

Co

lup

ulo

ne

Interval Plot of Colupulone vs Nrate95% CI for the Mean

The pooled standard deviation is used to calculate the intervals.


N treatment effect on Soil testN treatment had no significant effect on soil test P or organic matter, but significantly (P<0.001) affected pH and soil test potassium

On average pH dropped 0.5 units and K dropped 45 ppm in 200lb/ac N rate plots compared to the 0 N plots.

4

4.5

5

5.5

6

6.5

7

7.5

0 50 100 150 200

Cascades

Centennial

Chinook

Magnum

Nugget

Tahoma

0

50

100

150

200

250

0 50 100 150 200

Soil pH Soil Test K (ppm)


Deep Soil Nitrate samplingCollected from three varieties; Cascades (Tomah), Chinook (Waterloo), and Nugget (Rosholt).

Used truck-mounted probe to collect samples to a depth of 7-8 ft (or refusal)

Collected samples in row, ¼ distance between row, and ½ distance between row.

Sampled 0, 100, and 200 lb N/acre plots.


Rosholt-Nugget

0 2 4 6 8

0-1

1-2

2-3

3-4

4-5

5-6

6-7

Row

0 2 4 6 8

0-1

1-2

2-3

3-4

4-5

5-6

6-7

7-8

¼ Distance between rows

0 10 20

0-1

1-2

2-3

3-4

4-5

5-6

6-7

0

100

200

½ Distance between rows

Nitrate-N (ppm)


Waterloo-Chinook

0 2 4 6 8

0-1

1-2

2-3

3-4

4-5

5-6

Row ¼ Distance between rows ½ Distance between rows

0 2 4 6 8

0-1

1-2

2-3

3-4

4-5

5-6

0 2 4 6 8

0-1

1-2

2-3

3-4

4-5

5-6

0

100

200


Tomah-Cascade

0 5 10 15

0-1

1-2

2-3

3-4

4-5

Row ¼ Distance between rows ½ Distance between rows

0 2 4 6

0-1

1-2

0 1 2 3 4

0-1

1-2

0

100

200

Rocky subsoil prevented coring at most locations.


SUMMARY2019 growing season data suggest, on average, N rate above 150 lb/ac did not increase cone yield.

Cone yield doesn’t appear to be a good predictor of optimum N rate.

Fine-tuning N rate for hop will likely involve variety-specific adjustments for biomass production.

Petiole testing has promise for in-season adjustments of N rate – proper sampling time is important.

Most quality parameters don’t seem to be affected by N rate, but data suggest that N fertility decreases colupulone in at least one variety

Managing lime and K inputs are important considerations for hop growers

End-of season soil nitrate-N concentrations were generally low, and didn’t appear to reflect N rate.


AcknowledgementsHannah McWhirter - UW Platteville, Class of 2019.

Fine Bine Farms – Randy and Peggy Urness

Bohica Hop Farm – Bob, Jim, & Sherry Conant

Davali Ridge Hops – Dave and Ali Buss

Carl Duley – UWEX, Buffalo County

Jerry Clark – UWEX, Chippewa County

Bill Halfman – UWEX, Monroe County

Ken Schroeder – UWEX, Portage County

George Koepp – UWEX – Columbia County

NRCS Soil Scientists – Chris Miller, Karla Petges, Natalie Irizarry

Hop harvest helpers: Walt Rasmussen, Ashley Olson, Ashley Blackburn, Kaitlyn Lance

Closing the Knowledge Gap on Wisconsin Hop Fertility · Closing the Knowledge Gap on Wisconsin Hop...

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