Cover Crops For Orchards - Washington State University

Cover Crops forOrchardsDavid GranatsteinWSU CSANRWenatchee, WAIn collaboration with Joan Davenport,Elizabeth Kirby, Michel Wiman, AmosKukes, Kent Mullinix

Apple Root DensityNeilsen and Neilsen, 2003

Mini Tatura Trellis on M.9WashingtonStandard SystemHerbicide strip, grass alley

Orchard Cover CropsCover crops affect: Weeds Soil and orchard temperature Soil moisture, physical properties Soil C, N, other nutrients (root exudates) Soil biology, food web Tree performance Pests (insect, disease, rodents) N fixation (legumes)

Cover Crop ChoicesAge of orchard, rootstockFruit harvest dateIrrigation system, waterAlley, tree row, ‘Sandwich’Legume, grass, broadleafSpecies, cultivarAnnual or perennialNematode host?Insect pest host?Mulch?

Orchard Floor Management ReviewMicroclimate: soil temperature inverse to the amount of herbageor mulch plant mulch dampens extremes of daily soiltemperature plant cover reduces minimum air temperature by0.5-1.0oC bare, compacted wet soil raised minimum airtemperature by as much as 2oC effects on humidity and disease? Russet?(Skroch & Shribbs, 1986)

Orchard Floor Management ReviewSoil quality: avoid cultivation favorable soil effects: legumes grass mulch bare ground cultivationWater: soil moisture availability: mulch bare soil minimal cultivation grass legumes continuous cultivation mowing decreases water use(Skroch & Shribbs, 1986))

WA Peach5 yr old trees Orchard grass – mowed late May Alfalfa – mowed late May, mid-summer Rye (winter cc) – disked late May, summer cult Vetch (winter cc) - disked late May, summer cult Mulch under tree Herbicide Alfalfa delayed maturity Highest yield with mulch N, water effects(Proebsting, 1958)

MI Tart CherryCover crop mix – crimson cl, annual ryegrass/hardfescue, berseem clover; no herbicides, mowed,irrigated Highest yields – mulch Cover crops, compost improved soil quality Fewest pest mites in cover crop; beneficial mitesall year in red clover Cover crop fertigation was among mostprofitable Nitrate leaching – most in season-long herbicide(Edson et al., 2003)

MI Tart Cherry(Edson et al., 2003)

NZ Apple 8 yr old apple trees Several species mixes Fixed N can replace harvest and leachingremoval (15N method)Annual N fixed by understorykg N/haRed clover33-84Herb ley12-105(Goh et al., 1995)

NZ Apple Legumes – increased fruit N, delayedmaturity; lower Brix and firmness than grass Mow and blow provided large inputs ofnutrients; increased tree growth and fruityield; did not increase fruit disorderspHN (%)P (ppm)K (ppm)Ca (ppm)Mg (ppm)Mow6.10.242861218Mow & blow6.80.3337301535(Marsh et al., 1996)

Legume Cover CropsRio Negro, Argentina5 yr old apple; 3.2 m drive alleys, mowed twice ayearLeaf N(%)TCSA Fruit Yield(cm2) (tons/ha)Strawberry Clover1.98 a113 a54 aAlfalfa/fescue1.85 b108 a58 aVetch2.00 a105 a57 aControl1.86 b94 b45 b2 tons/ha 5-5-5 fertilizer(Sanchez et al., 2007)

WA - White cloverliving mulch In-row Recycles P, K Root N contributions,but N fix suppressed Suppresses weeds Saves waterFall-planted Dwarf white clover

Grow Your Own NNitrogen release over 3 weeks from ambientsoil with and without clover, root exclusiontubes, and tube covers.kg N/haSoil 2001ABCDEA – control plot; tube cover; no cloverF46% of clover NmineralizedTree growth,fruit yieldenhancedD – clover plot; tube – cover,clover clippings addedB – control plot; tube cover; clover clippings added. E – control plot; no tubeC – clover plot; tube cover, clover clippings added F – clover plot, no tube

Late summer 2000Early spring 2002Rodents – the weak link for clover.

Vole Trail LengthWA IMM Trial, Winter 05/06(Winter 06/07, too few to analyze)350Other livingmulches2trail length (cm/m )300250200Galium (sweetwoodruff)1501005011/05 trails2/06 trailsWWCTLCWLNSWLSWNLLMLML0

Sweet Woodruff(Galium odoratum)Wenatchee areaThyme

Mow and Blow Alley Cover Crop

2008 Trial – Qunicy, WA Legumes direct seeded in drivealley (4’ swath) – May 19 Alfalfa cv. RadiantJumbo Ladino white cloverKura cloverBirdsfoot trefoil cv. Norcen SPRAY or NO SPRAY prior toseeding Mow and blow before appleharvestNo-till drill

Alfalfa afterseeding

Drill - 8” spacing;narrower wouldbe betterSingle passDouble pass

Before mowingAlfalfa tractorAlfalfa no tractor

Year 1SprayLadinocloverNo spray

Ladino Clover – May, Yr 2

Alfalfa – May, Yr 2

Mow and BlowLegume residue in tree row after mow and blow

Legume Biomass(Yr 2, 2009, 4 cuttings)Biomass (DM kg/ha)120010008006004002000Alfalfa% N of DM4.1%Trefoil3.4%27-MayLadinoKuraGrass3.9%1-Jul 10-Aug3.1%1-Oct2.3%

Effect of Pre-seedingTreatment on BiomassSum of 8/08, 7/09,8/09 cuttingsLegume only, 7/09SprayedSprayedUnsprayedUnsprayed- - - - - - - - - Dry matter (kg/ha) - - - - - - - -Alfalfa759 a685 a157 a105 bLadino701 a719 a191 a131 bTrefoil783 a716 a141 a74 bKura476 a486 a56 a18 a

Year 3, 2010AlfalfaTrefoil39 days after mowing

Cover Crop Biomass, Yr 3Morgan Orchard, Cover Crop Biomass 2010- Spray20001800Biomass (DM -May14-JunLadino12-Jul24-AugKura24-SepGrass

Morgan OrchardCumulative Cover Crop BiomassCover Crop Biomass, 2008-103000Biomass DM refoilAlfalfaGrassSprayKuraNo spray200820092010LadinoTrefoil

Morgan Orchard 2008-10, Kura cloverMorgan Orchard 2008-10, Alfalfa100100Spray90Kura cloverNo Spray80807070Ground Cover (%)Cover (%)AlfalfaSpray90No Spray60504030206050403020101000June - Oct2008May - Oct2009April - Aug2010June - Oct2008May - Oct2009April - Aug2010% Cover of Legumes in Drive AlleyMorgan Orchard 2008-10, Ladino cloverMorgan Orcahrd 2008-10, Birdsfoot trefoil100100Spray90TrefoilLadino clover90No Spray808070Cover (%)Cover (%)70605040605040303020201010SprayNo Spray00June - Oct2008May - Oct2009April - Aug2010June - Oct2008May - Oct2009April - Aug2010

Grower Application Grafted ‘Fuji’ Young apple block Seeded mid May of 2010 Direct seed drill directly into existing vegetationof grasses and weeds (flailed before seeding)-- double pass, high seeding rate Excellent establishment; 7’ swathAlfalfaWhite cloverPhotos June 16, 2010

Direct-seeded AlfalfaJune 23, 2010

Red CloverTilled and seededJune 14, 2010

N ContributionBiomassN 2009Soil PRS2009Ave. DryMatter*2009Tissue NAve. NAdded(lb N/ac)(ppm NO3N)(ton/ac/yr)(%)(lb Grass151033.282.3024.2*Ave. 2009 and 2010. Yield on a full acre basis; actual strips are 0.16 ofarea (2.2’ strip)

EconomicsCosts per acre of orchard, 4’ al7.1514.8529.7032.0083.90Planting good for at least 5 yr - 21/yr costAlfalfa – 3.5 ton/ac/yr @ 4% N 280 lb NWidthN contentFert. Valuea5’4’3’1018159 71 57 41Over 4 yr, 84 cost / 130 lb Nb 0.65/lbaEstimateN fertilizer at 0.70/lbb40% avail., accounting for Nmin (50-70%), losses[ 4’ swath, 81 lb N/yr x 4 yr x 0.4 avail 130 ]

SamplingPercent coverPoint intersect – stiff wire with 20 pts; place at45o to seeding rows; at least 3 representativespots per plotBiomassQuadrat frame – 3-4 representative samples perplot; cut at mower height; dry, weigh; convert tolb/ac DM; can weigh wet sample first formoisture content estimate and future wet basissampling

See OSU cover cropsampling instructions

SamplingNitrogenIdeal – C,N analyzer, by combustionMow and Blow trial, Year 1 Tissue Kura2.8314.9Grass2.1518.8Non-legume2.3217.7

SamplingNitrogenIdeal – C,N analyzer, by combustionTotal N analysis – reported as %N; e.g. alfalfa 4.11%N content 0.0411 x 7120 lb/ac DM 293 lb N/acNeed to adjust for area – 4’ strip, 14’ row spacing;4/14 0.2857 x 293 83.6 lb N/ac of orchardNeed to adjust for N mineralizationGet C:N from tissue test e.g. alfalfa 10.683.6 lb x 0.40 33 lb avail N/ac orchard

http://smallfarms.oregonstate.edu/calculator

PAN (% of cover crop total N)100100Vetch Phacelia MixVetch Oat Mix808060604040202000-20-20-40-4028 d70 d-60-6012341234Cover crop mix total N (% of dry wt)Equation: Vigil and Kissel (1991) SSSAJ 55:757Courtesy: N. Andrews

Couldperennial cover crop roots contributemore available nitrogen? Residues on surface, not incorporated. After 40 days surface applied legumesprovided about 20% of the nitrogen providedby incorporated legumes. Orchard floor PAN release is probably lowerthan calculator estimates. Less control over timing of PAN release, e.g.decomposition slower on dry surface.Courtesy: N. Andrews

MaterialHairy vetch topsHairy vetch rootsBreak even point for short term NmineralizationC/N1025-30 20Adapted from Kuo et al (1997). Soil Science Society of America Journal, 61:1392-1399.Courtesy: N. Andrews

Perennial Cover Crops– mowed, left on surface Legume C/N 10-15 Cereal C/N 20-40 Mixtures 15-25 Suggests that orchardfloor residues maylose 0-5% of the total%N as NH3Dutch lab research, 37 day duration.Ruijter et al (2010). Atmospheric Environment 44, 3362-3368.Courtesy: N. Andrews

What we learned so far Need multiple years to assess species;many novel species to test Shade, traffic affecting growth Spraying out grass helped, but alllegumes had reasonable stands;compensate with double pass, higherseed rate Need greater growing surface to boostN contribution; net 3’ with tires Combinations ? Alfalfa ladino kura?Thanks to USDA Organic ResearchSpecial Grant for funding.

ResourcesUC Davis SAREPhttp://www.sarep.ucdavis.edu/ccrop/- Cover Cropping in VineyardsMidwest Cover Crops Councilhttp://www.mccc.msu.edu/USDA SARE Programhttp://www.sare.org/- Managing Cover Crops ProfitablyWSU- EB 2010 – Cover Crops for PNW Vineyards- Orchard floor rchard Floor

clover clippings added B - control plot; tube cover; clover clippings added. E - control plot; no tube C - clover plot; tube cover, clover clippings added F - clover plot, no tube Nitrogen release over 3 weeks from ambient soil with and without clover, root exclusion tubes, and tube covers. 7/31/2001 46% of clover N mineralized