High Biomass Cover Crops and Organic Mulch Effects on Yields, Soil Carbon, & Weed Populations during No-Till Herbicide-Free Collard Production Michael J. Mulvaney Auburn University

Introduction Conservation tillage offers: –↓ Erosion –↑ SOM –↑ Soil moisture –Improved soil structure –Soil temperature moderation Kip Balkcom, 2008

Problem #1 problem: Weed suppression How to suppress weeds without tillage or herbicides?

Solution? High biomass cover crops (killed mulches) Mulch Ted Kornecki, 2008

Rationale Combine cover crops and mulches Improve soil quality on productive field Effects on: –Yields, soil, weeds

Objective Determine the effects of organic mulches and forage soybean as a summer cover crop on: SOC C mineralization Total soil N Aggregate stability Collard yield Weed populations in a no-till system without the use of herbicides during limited-input fall collard production

Methods 3 years: Central-Eastern AL 2x4 RCB: 2 summer cover crops: –Forage soybean, weed fallow 4 organic mulches: –Lespedeza, mimosa, straw, control –6.7 Mg ha -1 yr -1 (3 t/ac/yr)

Cropping Schedule JanFebMarMayJunJulSepAprOctNovDecAug Soybean or Control CollardsRye Mulch application

Methods C & N: –Dry combustion C mineralization: –Lab incubation –NaOH trap Aggregate stability: –Water immersion Yield: –65 DAP –2.8 m 2 (30 ft 2 )

Methods Weed coverage –Transects 50 count transects 2x per plot Classified: –Broadleaves –Grasses –Sedges –Soil –Identified to species level 2x in 2008

Statistics SAS: –Proc Means: Means and standard errors –Proc Glimmix: Model variable selection –95% CL for treatment comparisons

SOC after 3 yrs ABCBCC

Soil organic carbon

ABCBCDD

Other results C mineralization –No treatment differences, 0-10 cm depth –Ave: 12.1 mg C kg -1 soil day -1 over ºC Aggregate stability –No treatment differences 0-5 cm depth –Ave: 91% stable

Yields Collard Yields: –No treatment differences –Ave in SC (2001) 12,000 lbs/ac –Ave: 17,900 kg ha -1 = 16,000 lbs/ac –Assuming 25% waste & 1.1 lbs/bunch: ATL market, Nov. 18, 2009: –25 lbs/ctn: $12/ctn $5,760/ac – No premium assumed

Conclusions: Soils Conversion to no-till increased SOC Forage soybean did not affect SOC, TSN Forage soybean decomposes quickly C mineralization, aggregate stability, yields not affected by mulching or forage soybean

Conclusions: Weeds Forage soybean does not effectively suppress weeds Broadleaves and sedges suppressed under high biomass no-till Grasses control: highly variable Population shifts from broadleaves toward grasses

CARBON AND NITROGEN MINERALIZATION AND PERSISTANCE FROM ORGANIC RESIDUES Objective: –To quantify mass loss and nutrient release rates from decomposing organic residues under conservation and conventional tillage.

Methods E.V. Smith Research Center Plant Breeding Unit –S. Tallassee, AL –Wickham fine sandy loam, 0 to 2 % slope –3 yrs in no-till Lespedeza, Mimosa, Oat Straw, Soybean Packed into litterbags –6.7 Mg/ha (3 t/ac)

Methods Randomized split-plot design Buried or surface-placed Retrieved periodically –0, 3.5, 7, 14, 28, 56, 112, 224, & 364 days after Oct. 7, 2007 Samples dried, weighed, analyzed for C and N Ash-free dry weight

Statistics –SAS Proc Mixed, Proc GLM –95% Confidence Level Regression: –Sigmaplot –Double exp. decay: Y = Ae -k1t + Be -k2t Time Mass or nutrient remaining

Mass remaining

Carbon remaining

Nitrogen remaining

LespedezaMimosaStrawSoybean Buried Season Surface Season Seasonal N Mineralization (kg ha -1 ), May 1 – Oct. 7

Assumes decay models valid >1yr LespedezaMimosaStrawSoybean Buried Season Season Surface Season Season

LespedezaMimosaStrawSoybean Buried Season Season Season Surface Season Season Season Seasonal N Mineralization (kg ha -1 ), May 1 – Oct. 7 Assumes decay models valid >1yr

LespedezaMimosaStrawSoybean Buried Season Season Season Year 3 total Surface Season Season Season Year 3 total Seasonal N Mineralization (kg ha -1 ), May 1 – Oct. 7 Assumes decay models valid >1yr

Conclusions Mass/nutrient loss is faster with buried residue Surface residue may act as slow-release fertilizer More OC & N accumulation from surface residue over time Nutrient fate is not determined in this study

Acknowledgements Dr. Wes Wood Committee: –Dr. Kip Balkcom –Dr. Joe Kemble –Dr. Dennis Shannon Dr. Andrew Price SARE Auburn University

Part II: Qualifications SANREM CRSP Phase IV: Increase smallholder food security through conservation agriculture production systems.

Goals Develop conservation agriculture production systems for rain-fed, staple crop, smallholder production systems; and Identify and test effective strategies through which smallholders can transition to sustainable CA.

Qualifications PhD, Agronomy & Soils  No-till crop production  Vegetables & agronomic crops  Soil fertility management  C and N cycling in agroecosystems  Limited-input, smallholder food systems  BS, Organic chemistry  Knowledge of C rxns

Outside of dissertation  Soil H 2 O retention under no-till cover crops  Alley cropping  Gas emissions  J. Environ. Qual. 37:2022–2027 (2008)  Consulting, Agroinnovations, Inc.  C & H 2 O inventories on landscape levels  Sludge application  Land use maximization

Outside of dissertation  Auburn Community Garden Coordinator  Vegetable production for food insecure

International Development Agricultural Extension Volunteer U.S. Peace Corps, Bolivia: Jan May 2002 –Managed, implemented ag projects in Quechua villages –Wrote grants, budgets & progress reports

Animal Husbandry Vaccination of cattle, sheep & goats throughout region Castration of pigs and bulls

Pit Latrines ApicultureEducationGreenhouses

Water Systems Gravity systems built for 51 families in 2 communities Water used for irrigation &/or personal use

Central China May-June 2009 Northwestern A&F University

International experience 40+ countries on 5 continents

Foreign Languages English (Native speaker) Spanish (Proficient) Quechua (Working knowledge) Vietnamese (One year university level)

Conservation Agriculture Conservation tillage Alley cropping Limited input agriculture Nutrient management Water management Crop rotations Weed management Pest management Gas emissions

Soil C Sequestration/Cycling Developed soil C inventories Modeled C sequestration in no-till systems Organic C decomposition Knowledge of organic C rxns

Communication Skills Peer reviewed publications: Michael J. Mulvaney*, A.J. Price, and C.W. Wood. Cover crop residue and organic mulches provide herbicide-free weed control during no-till collard production. Currently under review, Journal Sustainable Agriculture. Michael J. Mulvaney*, K.A. Cummins, C.W. Wood, B.H. Wood, & P.J. Tyler Ammonia emissions from field-simulated cattle defecation and urination. Journal Environmental Quality 37(6): S.A. Pratt, M.F. Goble, M.J. Mulvaney & P.G.M. Wuts Dialkylhydrazides for directed orthometalations. Tetrahedron Letters 41: more pubs from dissertation

Conference Presentations Mulvaney, M.J., C.W. Wood, and B.H. Wood Conservation tillage effects on carbon, nitrogen and mass loss from organic residues. ASA-CSSA-SSSA International Annual Meetings, Pittsburgh, PA. Nov. 1-5, “Food Insecurity and the Auburn Community Garden” Seminar Series on Hunger Research and Intervention. Dept. of Nutrition and Food Science, Auburn University, Auburn, AL. Oct. 14, Mulvaney, M.J., C.W. Wood, and B.H. Wood Persistence and nutrient release from organic mulches and cover crops. 106 th Southern Assoc. of Agricultural Scientists, Atlanta, GA. Feb. 1-3, “Food Security Issues Facing the Rural South” Panel presentation at the Professional Agricultural Workers Conference. Committee on the Role of Faith Based Organization in Rural Community Development, Tuskeegee University, Tuskeegee, AL. Dec. 8, Mulvaney, M.J., C.W. Wood, B.H. Wood, K.S. Balkcom, J. Kemble, and D. Shannon High biomass cover crops and organic mulch effects on soil moisture and weed distribution during collard production. ASA-CSSA-SSSA Joint National Conference, Houston, TX. Oct. 5-9, Mulvaney, M.J., C.W. Wood, and B. Wood Nutrient release rates from organic mulches and cover crops. Proc. 8th Annual Conservation Production Systems and Training Conference, Tifton, GA. July 29-31, 2008.

Conference Presentations Mulvaney, M.J., C.W. Wood, K.A. Cummins, B.H. Wood and P.J. Tyler Ammonia emissions from grazing cattle. 18 th GSC Research Forum, Auburn, AL. Mar , Mulvaney, M.J., K.A. Cummins, C.W. Wood, B.H. Wood and P.J. Tyler Ammonia volatilization from field-simulated cattle defecation and urination. 105 th Southern Assoc. of Agricultural Scientists, Dallas, TX. Feb. 2-5, Mulvaney, M.J., C.W. Wood, K.S. Balkcom, B. Meso, and B. Wood Effects of tillage, location and variety on nitrogen release from peanut residue. 17 th GSC Research Forum, Auburn, AL. Mar. 7-8, Mulvaney, M.J., K.S. Balkcom, C.W. Wood, B. Meso, and B. Wood Effects of nitrogen, tillage and variety on nitrogen release from peanut residue under field conditions. Proc. 104th Southern Association of Agricultural Scientists, Mobile, AL. Feb. 3-6, Mulvaney, M.J., C.W. Wood, K.S. Balkcom, and B. Meso Nitrogen release from peanut residue. In R.C. Schwartz, R.L. Baumhardt, and J.M. Bell (eds.) Proc. 28th Southern Conservation Systems Conf., Amarillo, Texas. June 26-28, 2006, USDA-ARS Conservation and Production Research Laboratory Report No. 06-1, Bushland, TX.

Awards  First Place, Graduate Oral Competition, Soils Division. Southern Assoc. of Agricultural Scientists. Atlanta, GA, Feb. 2, 2009  A. L. Smith Outstanding Graduate Student Award, Ph.D. candidate category, Dept. of Agronomy & Soils. Auburn University, AL. Jan. 16, 2009  Soil Science Society of America Graduate Student Award National Competition, Soil & Water Management & Conservation Division. Houston, TX, Oct. 6, 2008  First Place, Graduate Oral Competition, Soils Division. Southern Assoc. of Agricultural Scientists. Dallas, TX, Feb. 5, 2008  First Place, Graduate Oral Competition, Soils Division. ASA, Southern Branch. Mobile, AL, Feb. 6, 2007

Approved Grants $2,529, International Scholars Program, “Professional Collaboration between Auburn University and the Pan- American Agricultural School”, Honduras, 9/08 $1,149,000, Transportation Enhancement Program, “Wire Road Bicycle Facilities” 11/07 $10,000, SARE (Sustainable Agriculture Research & Education) Graduate Student Grant, “Organic mulches and high residue no-till for collard production in Alabama” 8/05 $3,500, Peace Corps Agricultural Extension Partnership Grant, “Community greenhouses and rural water systems” 9/00

Summary PhD Soil Science 2.5 yrs experience in int’l agricultural development Soil C cycling/sequestration Conservation agriculture English, Spanish & others U.S. citizen

Summary Proven publication record Successful grant writing Award-winning communication skills Team management Media relations Self-motivated Resourceful

Thank you