Iowa Learning Farms Webinar June 28, Marshall on Twitter

Transcription

1 Burying tea to dig up soil health Iowa Learning Farms Webinar June 28, 2018 Marshall on Twitter

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3 Overview I. Definition of soil health, and reason why the emphasis on soil biology II. Current soil health tests why, how, and where/who III. Bury tea to assess soil health IV. Conclusions and questions

4 Soil Health is now trending, and so are soil health tests But what exactly is soil health? Can you define human health?

5 Human Health Health is the level of functional and metabolic efficiency of a living organism. In humans it is the ability of individuals or communities to adapt and self manage when facing physical, mental, psychological and social changes with environment Wikipedia Soil Health Soil health, also referred to as soil quality, is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans. Natural Resource Conservation Service (NRCS) Only living things can be healthy Soil Tilth Soil Quality Soil Health

6 Soil biology regulate many of these soil functions we care about as agronomists. Microbes are the engine that drive N, P, and S cycling in soils

7 A soil is composed of 25% 45% Mineral Particles Air 25% Water 5% 5% Soil Organic Matter 80% Decomposed SOM 10% Organisms 10% Roots

8 The living SOM

9 How can we increase soil health? 1. Control traffic on soil 2. Minimum tillage 3. Manure use 4. Cover crops 5. Increase residue cover 6. Crop rotations increase crop variety (i.e. diversity)

10 Why bother with soil health tests? 1. Comprehensive assessment of a soil s productivity and sustainability 2. Help agronomists evaluate effect of management practices on soils, and provide incentives for keeping soils healthy 3. May help assess land value (similar to CSR2) 4. Public and private soil health initiatives are sweeping the nation California s Healthy Soils Action Plan Maryland House Bill 1063 Maryland Healthy Soils Program

11 less money spent on N fertilizer! Franzluebbers et al. 2018

12 Ingredients in a good soil health test Soil health test should be based in rigorous research Be broadly applicable across soil types Incorporate physical, chemical, and biological aspects of soil health Should have consistent, robust methods across laboratories Should relate to yield! Should be relatively inexpensive

13 Adapted from: Al Kaisi and Kwaw Mensah (2016)

14 Who is measuring soil health? Organization/Test Range in Cost (per sample) Cornell Comprehensive Assessment of Soil Health (CASH) $60 $170 Woods End Laboratories $60 $90 Ward Laboratories, Inc. $25 $60 Midwest Laboratories $55 $65 Average $50 $96

15 The soil is so [healthy] that it would eat almost anything thrown at it from a gunny bag to corn stover. Farmer quoted in Pay Dirt (1959)

16 Can we bury tea to get at their health?

17 Soil Decomposition Index (SDI) with two tea bags to measure Soil Health Less healthy Soil Healthy Soil Rooibos Green C:N = 43 C:N = Relative Mass Remaining (%) o 80 F 80 o 60 F 60 o 40 F 80 o 20 F Time (days) = Rooibos Tea Time (days) = Green Tea Data adapted from Keuskamp et al. (2013)

18 Calculating SDI with two tea types Less healthy Soil Healthy Soil Relative Mass Remaining (%) Time (days) Time (days) = Rooibos Tea = Green Tea The closer to 1, the more healthy the soil is

19 Benefits of SDI with two teas It s very inexpensive!!! Tea is in a convenient litter bag Using two teas, with Green Tea as the baseline, might correct for any temperature or moisture variability Integrated measure of soil biological activity and resources available to soil microbes (carbon and nutrients) ~$20 for 60 pyramids Rooibos Green C:N = 43 C:N = 12

20 Teresa Middleton

21 Preliminary Results from PFI Farms = Replicated Strip Trials (n = 10) (cover crop vs. no cover) 2 soil samples Soil temp. & moisture Other soil health measurements Source: crop affect corn soybean yields/ = Farmer collected data (n = 10) Voluntary soil samples Recorded observations

22 Focused Study on Replicated Cover Crops Farm Years in CC # of strips Dominant Soil Series Cash crop in 2017 CC Seeding Rate/Method (lbs ac 1 ) NFertilizer Method/Rate and Source Other Mgmt Practices A 1 5 Brownton silty clay loam Corn???/Aerial Split/200 manure, 70 AA Strip till B 1 4 Webster clay loam Corn 56/Drill Split/?????? C 1 4 Ladoga silt loam Corn 50/Drill Pre plant/ 110 manure??? D 1 5 Marshall silty clay loam Corn 56/Drill Split/20 30 manure banded, 6 UAN (side dress) E 8 5 Kalona silty clay Soybean 56/Drill?????? F 8 4 Colo silty clay loam Soybean 56/Drill?????? G 9 3 Nicollet loam Corn 60/Drill Banded pre plant/??? AA??? H 9 4 Kenyon loam Soybean 56/Aerial Banded/98 manure No till I 15 5 Clarion loam Corn 70/Drill Split/200 UAN No till???

23 TB Decomposition Methods 1. Twelve tea bags ( 6 Green and 6 Rooibos tea) buried 3.5 deep, between May and June 2. Retrieved tea bags at 4, 7, 14, 30, 68 and 130 days of decomposition. 3. Dry tea bags 4. Weighed the mass loss of tea 3.5

24 Preliminary Data from PFI Farms % Mass Remaining Farm BI Day No Cover Crop (Green) Cover Crop (Green) No Cover Crop (Red) Cover Crop (Red)

25 7/9 farms have higher SDI with cover crops, but a lot of variability 0.6 No Cover Cover Crop Soil Decomposition Index ** 0.2 A B C D E F G H I Ave. (1) (1) (1) (1) (8) (8) (9) (9) (15) Farm (and years in cover crop) ** = P < 0.05

26 Soy and Corn SDI does somewhat relate to yield % Change in Yield from Cover Crop r 2 = 0.46 P = Cover Crops -10 decrease SDI Cover Crops increase SDI Change in SDI (Cover SDI No Cover) Farm F Farm H Farm DI Farm BD Farm B

27 State of Soil Health Tests Some limitations to this method More research needs to be done on using decomposition as an indicator of soil health Which tests can be done in field vs. laboratory? How should we weight each indictor in a test? Scientifically robust is important, but inexpensive is key Focus should be on biological, they are most sensitive to management practices. decomposi on should be included!

28 Citizen science can lead to a greater understanding of soil health, and increased adoption of conservation practices ~$8 for 40 pyramids $12 ~$20 to assess soil health $0.20 $1 per sample

29 Acknowledgements: ISU Team: Teresa Middleton, Mitchell Roush, Steve Potter, Tom Kaspar, Keith Kohler PFI Collaborators: Stefan Gailans, Sarah Carlson, and many PFI cooperators. Funding from the Leopold Center for Sustainable Agriculture

30 @Soil_Plant_IXNS on Twitter