NOVEMBER/DECEMBER 2003

BY Will Brinton & Alan York

In France, what is known today astraditional viticulture evolvedafter thousands of years of trialand error that created a basic

understanding of the nature of theplant and its relationship to a site (soiland climate).

A review of the soil characteristicsof the world’s most recognized vine-yards is very revealing in regard to soilquality. This became the basis by whicha system of classification was devel-oped known as AOC (Appellationd’Origine Contrôlée) in France. TheAOC system evolved into a nationalreality in the 1930s as a result of vari-ous factors including economic depres-sion, widespread cultivation of hybrids,and uncontrolled wine blending.

Presently, AOC regulations overseeproduction areas, vine varieties,ripeness and alcoholic strength, yields,viticulture (vine density, pruning, vinetraining system, and irrigation), andwinemaking and distillation.

According to Richard Smart and JohnGladstone, “Old World opinions —especially in France — stronglyemphasize soil effects. It is a principalbasis for the concept of terroir, whichunderlies the official French AOC sys-tem. New World opinion has tended tominimize the role of soil and instead tostress major differences in regionalclimate, or macroclimate.”20

Terroir may be grasped as “authenticfertility” — the reliance principally onwhat the deep soil profile within alandscape offers. An additional aspect,which bridges tradition with the mod-ern ecology of recycling, is that thislocal, site-specific quality is fostered byrecycling of the vineyard’s ownresidues and nutrients, supplementedonly to the extent needed (see Part I,PWV Sept/Oct 2003) to make compost-ing successful.

The question is: With an under-standing of the nature of the grapeand its traditional predilection fordeep-soil, low-nutrient conditions,how to best use and apply compost tofoster balanced vine growth? Cancompost use be overdone? If so, how?Visual indicators of excessive supplyof nutrients are often the best refer-ences.

It is necessary to first examine whatis referred to in modern terms as soilquality. Soil quality is defined as thecombined effects of biological, chemi-cal, and physical properties.1 Compostcontributes indirectly and holisticallyto this aggregate of soil quality in ways

that are hard to quantify. These includesoil nutrient adsorption, water-holdingcapacity, and biological disease sup-pression traits.

Wine grape culture defies, to alarge extent, knowledge we havefrom common agronomic rules forfertilization and attainment of yieldand the approach taken to site-ori-ented production. Within the frame-work of wines for mass consumption,based on high-yielding grape vines,the agronomic model may havegreater validity.

A case where a positive trait of com-post may be a negative in viticulture isin the behavior of rootlets. Roots lovecompost and may come to the surfaceif compost has been layered heavily onthe soil. The shock to the grapes comeslater, under dry conditions, when theseroots cannot survive.

From years of experience, it hasbeen found that heavy applications ofcompost (more than 10 tons/acre) alltoo easily encourage surface feeding. Itwould be better for vines to seek outwater and deeper layer minerals,which better fits the concept of soil andsite-specific management.

Low input, site-specificA significant body of evidence sup-

porting the concept of local soil qual-ity is seen in long-term fertility stud-ies. In Leigh and Johnston’s work(1994), the basis of long-term soil pro-ductivity is revealed by examiningfield research plots that have been run

PART II

SUSTAINABLE

compostingIN THE VINEYARD

Figure I: Average composition of finished compost

Stones, Sand,

Silt, Clay 40.1%

Plastic+Glass (depending on source)

1.5%

Organic Matter / Stable Humus

37.1%

Extractable Humic+Fulvic

Acids 5.6%

(Mineral Elements): N-P-K-Ca-Mg-Fe-

Al-Zn-Cu 15.2%

Microbial Biomass

0.6%

continuously for 150 years inRothamsted, England.2

One finding is that conservativeadditions of manure over decades sup-port soil improvements that persist longafter the amendments are discontinued.In contrast, long-term grass plots receiv-ing no fertilizer stabilized at sustainable,low yields, with roots colonized to aconsiderable soil depth. The grasseswere apparently drawing on the incalcu-lably large but only slightly availablereserves in the deep profile.

The work of Bordeaux researcherDr. G. Seguin provides an excellentbasis for appreciating the complexvalue of soils.5 He stresses that the bestsoils for wine quality have the follow-ing characteristics: • Moderately deep to deep;• Fairly light-textured, often with

gravel through much of the profileand at the surface;

• Free draining;• Sufficiently high in organic matter

to give soil friability, a healthyworm population, and adequatenutrient-holding capacity, but not,as a rule, particularly high inorganic matter;

• Relatively infertile overall, supply-ing enough mineral elements forhealthy vine growth, but onlyenough nitrogen early in the seasonto promote moderate vegetativevigor.The combination of all factors —

the gradual and very slight naturalweathering of soil minerals, deposi-tion of wind and rain-borne nutri-ents, and microbial symbioses such

as mycorhizal relationships whichare very common in grapes — aids aplant’s ability to extract sufficientnutrients for ongoing yields with sur-prisingly little inputs. These observa-tions partly explain the success oflow-input viticulture.

Low-input sustainable approachesneed not be thought of as exclusive topremium wines, as research willattest. Comprehensive farm studiesin Austria support a “farm-organ-ism” concept in general agriculture.There, researchers asked what factorscontributed most to quality and per-formance of the farms. They gatheredsoil and crop data across four geo-graphical regions and correlatedthese with quality indicators.

The results indicated that themore management moved a soilaway from its typical natural state(such as with heavy liming, mineralbalancing, and high nutrient inputs),the less satisfactory was the overallquality.3 This may be partly due tothe well-known fact that over-limingsignificantly reduces trace elementavailability.

While these studies are not specific tograpes, there is no reason to believe thatresults in vineyards would be any differ-ent. John Reganold, working atWashington State University-Pullman, hasrecently shown that apple flavor improveswith sustainable soil practices.22 The sameauthor, working in New Zealand, com-pared paired groups of farms using con-ventional and biodynamic practices. Thelatter group, with significantly fewerinputs, had lower yields but scored higheron a soil-quality index scale.21

Evidence increasingly suggests afundamental contrast exists between

the attainment of high yield, whichrequires increased soil manipulationand inputs, and “sustainable yield,”represented by lower yields andfewer inputs but higher quality.However, there is no simple, singleformula to strike a balance. For vine-yards, the low-input approach fits thesite-specific scheme closely.

Compost, a balanced approachAs pressure for sustainable prac-

tices and recycling increases, the bene-fits of compost come more into focus.However, there is a danger in treatingcompost like a silver bullet. Benefits ofcompost should not be seen as isolatedfrom but rather in addition to theinherent qualities of the site and soils.As noted in Part I, the mandate to“reduce and recycle” does not auto-matically result in great soil amend-ments.

Compost should be handled withquality control practices, just as anyother agricultural product. The bene-fits must be viewed in context of rea-sonable application rates related toappropriate effort and costs involved,along with the expected outcome.

Over-rating the benefits of compostmay serve the interests of the organiccommunity as a New York Times article,“A Magic Organic Elixir” suggests.14

When sensational or panacea-likeattributes are assigned to an organicinput, especially compost, consumersand growers may be misled. Growersmay adopt practices that are costlyand don’t produce the benefitsexpected. Or the benefits varygreatly by location in ways that arenot described. The following mayresult:

NOVEMBER/DECEMBER 20032

W I N E G R O W I N G

Table II: Nutrient mineral composition of pomace composta

IN COMPOST Organic Total- Potash Calcium Phosphorus Matter Nitrogen (K) (Ca) (P)

lbs/ ton as isb 460 23 28 27 5Per 4 tons 1840 92 112 111 20Per 10 tons 4600 230 280 278 50

(a) Compost prepared at Benziger Family Vineyards, Glen Ellen, CA. (b) Average of three batches.

Table I: Choosing Compost

■ Make it yourself, if possible,■ If you have to buy in compost,

consider asking the following: • What are source ingredients? • Has it been tested by a lab familiar

with compost? • Is a sample available to examine?

■ You should also find out:• Are grower reports on use of the

product available?• Is the supply seasonal? How so?

• Applying too much compost withan imbalance of growth resulting.

• Using compost at the wrong time,to no benefit.

• Not checking the ingredients orquality of compost sufficiently, andfinding contamination later.

• Overlooking subtle uses that bringimportant benefits, such as thevalue of light applications.The largest uncertainty about com-

post is whether benefits are purely ofa microbial nature. Stating that thepurpose of compost is to providemicrobes to the soil can be misleading.Recent scientific reports show thatmicrobial populations and ratios insoil are highly stable, and are mostlydependent on geological and physicaltraits.17

Moreover, these reports indicatethat microbe populations in soils donot appear to be appreciably influ-enced by temporal practices such astillage and application of organicmatter.18 These findings are consis-tent with some observations fromlow-input vineyards that have beensuccessful for generations. The dis-covery that indigenous soilmicrobes are very stable supportsthe notion that the native soil hasmuch to offer.

Microbes in compost cannot beignored, however. An example of thehard-to-quantify benefits from com-post is in the area of plant diseasesuppression, a controversial topic.Working with grape powderymildew (Uncinula necator) in Alsationvineyards, we have shown that avariety of compost applications maysignificantly reduce the fungal inci-dence.9

When compost is broadcastdirectly onto the soil surface, itapparently aids in the decay of thelitter, and competes with disease-causative fungi harbored there.Laboratory studies have confirmedthat compost microbes inhibit fungalconidia germination. Field plot stud-ies in vineyards have confirmed thatthis reduces ascospore production

the following spring, resulting fromoverwintering of spores on litter andprunings.8

Unfortunately, these positive ele-ments of compost all depend on theconfounding relationship of diseasepressure to meteorological eventsand vineyard management and com-post quality. As a further caution, itis generally true that the more dis-ease pressure there is, the lesschance that compost will have a sat-isfactory controlling influence.

A German summary of vineyardmicrobial compost shows the bestresults to be expected for Uncinulanecator, with variable results fromPlasmopara viticola, and unsatisfac-tory control of Botrytis cinerea.16 Arecent study reported in Oregonwith compost extracts (tea) used forBotrytis in vineyards producedinconclusive findings.25

Predicting microbial benefits ofcompost can be frustrating. For exam-ple, on a pound-for-pound basis, com-post does not necessarily containmore microorganisms than healthysoil does, which is usually in the

range of one million to 100 millionper gram. Each laboratory techniquefor determining soil microbial diver-sity produces its own numericalresults, and interpretation schemesvary tremendously.12

Can a healthy soil be successfullyinoculated with compost microbes?

Microbes and organic matter incompost are food for healthy soilmicrobes. In the case of an impover-ished soil, there could be apprecia-ble benefits, but we do not knowhow to determine this. Growersneed to be guided by experience. Weare very suspicious of ideal ratios orquantities of microorganisms in asoil that can be managed. To ourknowledge, this has never beenproven.

Woods End Lab has attempted toinoculate compost with selectedmicrobes. The result has been thatthe introduced bacterial species suc-cumb very quickly to pressure fromexisting populations. Apparently,these introduced microbes areunable to compete with the better-established, indigenous community.10

NOVEMBER/DECEMBER 2003 3

W I N E G R O W I N G

Table III: Worksheet for Whole Vineyard Nutrient Budget with Composting

INPUT SIDE N – K – Ca – OM OUTPUT SIDE N – K – Ca – OMBased on 3 ton yield + manure Based on 3 ton/acre grape yield

Pomace + 49, 62, 59, 1000 Wine grape removal 14, 15, 15, –Manure (a)

Lost only in juice (b) 6, 9, 9, –Deposition (c) 11, 0, 2,100 Erosion (d) 5, 8, 20, 300N-fixation(e) 10, 0, 0, 100 Leaching & 15, 5, 0, 1200

mineralization(f)Supplements + 10, 5, 5, 0 Prunings not 6, 7, 14, –Soil tillage (g) recycled (h)Total Input 80, 67, 66, 1200 Total Removal 31, 29, 43, 1500Est. available(i) 38, 57, 56, 1200

Notes to Worksheet: (a) 3 tons yield = 1.1 tons pomace + 1 ton manure (as is)(b) estimate using 150 gals/juice/ton and nutrient fractioning into wet/solid portions(c) Estimates for wet & dry precipitation, CA-EPA(d) 10 ton/acre loss rate, from NRCS Soil Loss tables.(e) assuming cover crop in 1/2 rows at 1/3 field density(f) OM mineralization of 2%/yr of 3%OM soil(g) tilling releases more N, based on experience(h) UC-Davis estimate of 1,300-1,500lb/a canes(i) compost availability N=15%, K & Ca = 85%

Still, others have reported some suc-cesses.

The variable results are not surpris-ing; they match recent reports fromEuropean microbial research. The ideaof importing microbes from someexternal source, and thereby signifi-cantly improving or altering a soil orcompost, seems naive. However, wewon’t deny there are important dis-coveries to be made here.

Balancing nutrients andcomposts

It is important to not lose sight ofthe nutrients that occupy a signifi-cant fraction of compost (see FigureI). Table II shows the composition offinished grape pomace compost,made according to the recipe fromPart I (PWV, Sept/Oct 2003).

A single ton of pomace compostprovides a significant amount of N-P-

K-Ca. The majority of the P-K-Ca willbe readily available, since there areno factors in compost that hold ontothese elements strongly. However, itis uncertain how much nitrogen willbe made available — the more agedand mature the compost, generallythe less N is available.

The moisture content of the soilwhere compost is applied also playsa large secondary role in the actualrelease rate. But if only one-fifth ofthe nitrogen is made available, then4 tons of compost provides 20 lbs ofavailable N. In contrast, a 3-toncrop of grapes removes approxi-mately 14 lbs/N.15 Below are otherfactors that must be known beforeconcluding this is the right amountof nutrient.

The low rate of N release fromcompost may be fortuitous, since itis essentially what is desired in avineyard; otherwise, one could noteven apply one ton of compostwithout potentially stimulatingexcessive vigor. Trial and error arerequired to set the application rateto match the vigor.

We have been involved withsites, such as the McNab Ranch(Ukiah, CA), where vigor is suchthat applying even one ton/acre ofpomace compost is unnecessary.Other similar sites are foundthroughout wine growing regions.

The primary way to reduce soilvigor is to use grass cover crops toabsorb nitrogen and water and thenreduce or eliminate tillage and irri-gation. Theoretically, if there is toomuch N-release from a compost, itcan be managed with these tools.

These facts about compost andnutrient release may seem a curiouscontradiction to sustainable man-agement and compost recycling.Nevertheless, truly “natural” viti-culture will always mean using thesoil’s best abilities to produce acrop. Compost can be a way to care-fully supplement with site-specificnutrients covering short and longerterm depletion from grape removal.

NOVEMBER/DECEMBER 20034

W I N E G R O W I N G

Conservative recycling of com-post — returning pomace year afteryear via composting to the site whereit came from — thus leads to auniquely genuine form of nutrientsupport for grape yields and flavorwhich is highly site-specific.

Vineyard nutrient budgetsWith these points in mind, the

new vineyard input formulabecomes: soil reserves released bynatural weathering + available nutri-ents in entire soil-profile + microbialaugmented release of nutrients +added nutrients from recycled com-post + other supplements, N-fixationinputs, wind deposits, rain depositednutrients + reduced disease pressure= total input factors for plant devel-opment. Most of these can be quanti-fied.

Table III shows a nutrient budgetwith the input and outputs for themajor nutrients plus organic mattercompared side by side.

In preparing a nutrient budget,many assumptions must be madeand then adjusted for a particularvineyard and location. There is noideal budget or single scheme. It issomewhat analogous to preparing abusiness plan, and then substitutingactuals for projections as informationbecomes available.

In Table III, actual analyses ofpomace compost are used. Themodel assumes a 3-ton/acre grapeyield. Clearly, the only substantialnutrient removal is in the pressedjuice. However, not all nutrients injuice are actually removed, as somereturn in the pomace, and thereforego back into the input side of theequation.

It is assumed that all pomace afterpressing is composted using the for-mula of a 50% addition of manure tobalance the pomace, which results inan increase of the nutrient input.Thus, from a wet yield of 6,000lbs/acre of grapes, one ton of wetpomace results after pressing, whichis combined with approximately one

ton of mixed manure. The modelassumes this amount is then re-applied to each acre, although thismay not necessarily apply in everysituation.

In addition to assuming a certainyield and recovery, several estimatesof probable losses plus other gainsare predicted. Environmental gainsand losses in a growing system areclearly variable and sometimes veryhigh.24 Many remain largelyunknown in the absence of a goodway to measure them.

This is where, in the end, carefulvisual observation of vigor and qual-ity are important — the model getsadjusted accordingly, up or down.Up if the predictions are too pes-simistic, and down if too optimistic.With experience, it is easy to deter-mine if a budget model is relevant ornot.

Note: Even where there are num-bers, a nutrient budget is never anexact science. But neither is soil test-ing. Soil chemical tests give nutrientvalues by a particular extraction for athin topsoil layer, even though rootsmay be exploiting much deeper lay-ers.

Tissue testing is often done, and isthought of as sharpening estimatesmade from a soil test. However, tis-sue concentrations must be inter-preted by comparing them to tablesfor the appropriate variety andregion, if available. In this way, allmodels have validity but also limita-tions.

We are cautious about the value ofsoil and tissue tests in establishedvineyards. These are tools that arevery valuable for start-up years andwhere deficiencies are observed.

Using the whole-system budgetapproach, some surprising conclu-sions result. In the example pro-vided, the end-effect of compostingpomace from a 3-ton grape yield isthat there are enough inputs to offsetthe calculated nutrient removal andestimated losses for N-K-Ca for allsources. Net loss of organic matter

by natural mineralization is alsoclosely covered. Soil cover crops con-tribute organic matter and were notadded in this model.

Note that the total-nitrogen inputin the model using compost appearshigh compared to its removal.However, only a fraction of the totalN from natural sources is plant-available in any season. We assumed15% availability in the first year aftercompost application.

A UC Davis study comparing thenitrogen benefits in vineyards fromvarious cover crops and compostranked compost on the low end.13

Therefore, on light soils where N-supply is very critical, it is importantto know more precisely the potentialN-release for a compost. There arelab tests to measure N-mineraliza-tion from compost. Since site and cli-mate have so much to do with per-formance, trial and error in thevineyard will be essential, however.

ConclusionThe satisfying finding here is that

the system represented in this modeldoes not appear to be too far off.Remove one or another factor, espe-cially the recycled pomace, and itchanges enormously. Increase theproduction demand and eliminatenutrient recycling from the pomace,and this worksheet quickly turnsinto red ink!

If one is not recycling one’s ownpomace via compost, then purchases

NOVEMBER/DECEMBER 2003 5

W I N E G R O W I N G

Monitoring active compost for temperature(long-stemmed probe) and oxygen (digitalmembrane meter). If the temperature isvery high and/or oxygen is very low(under 2%), the pile may be turned.

NOVEMBER/DECEMBER 20036

W I N E G R O W I N G

of compost should be tied to a grapeproduction model, otherwise theinputs may be too high or too low.This is why we recommend assessingthe production objectives beforeapplying a model. True, it is anexploratory process, requiring someexperimentation.

The important caveat, to adapt anold saying, is: An ounce of visualobservation of the grapes may beworth a pound of input of compost.■

William F. Brinton, Ph.D. studiedagronomy and environmental scienceand is founder and director of WoodsEnd Research Laboratory, Mt. Vernon,Maine with a branch office in Europe.

Alan York, past president of theBiodynamic Agricultural Association, isa trained horticulturist and is an inter-national consultant for wine grapegrowers.

References1. Doran, J.W., D.F. Bezdicek, D.C.

Coleman, and B.A. Stewart (1994). “DefiningSoil Quality for a Sustainable Environment.”Soil Sci. Soc. Amer. Spec. Publ.# 35 , Madison,WI.

2. Leigh, R.A., A.E. Johnson (1994). Long-term Experiments in Agricultural and EcologicalSciences. CAB International, London.

3. Schiller, H., J. Gusenleiter, E. Lengauer, B.Hofer (1967). Fruchbarkeitstörungen bei Rindernin Zusammenhang mit Düngung, Flora undMineralstoffgehalt des Wiesenfutters. LinzAgricultural Experiment Station, Linz Austria.

4. Robinson, J. Ed. (1999). The OxfordCompanion to Wine 2nd Edition. Oxford Univ.Press.

5. Seguin, G. (1986) “Terroirs– A pedol-ogy of wine growing.” Experientia, 42: 861-872.

6. Larney, F. J., L. J. Yanke, J. M. Miller,T. A. McAllister (2003). “Fate of ColiformBacteria in Composted Beef CattleFeedlot Manure.” J. Environ. Qual.32:1508-1515.

7. Brinton, W. (2003). “Complexity andCharade in the World of Soil Microbes: APlea for Balance.” Journal Biodynamics Vol.2.

8. Brinton, W., and A. Traenkner (1996).“Investigations into Liquid CompostExtracts.” Biocycle. 37:68-71.

9. Brinton, W. (1997). “Compost forControl of Grape Powdery Mildew.” JrnlBiodynamics Vol 3.

10. Droffner, M. and W. Brinton (1994).“Microbial Approaches to the Character-ization of Composting Process.” CompostSci. Util. Vol. 2.

11. Droffner, M. and W. Brinton (1995).“Evidence for the Prominence of WellCharacterized Mesophilic Bacteria inThermophilic Composting Environments.”Biomass & Bioenergy 8:191-195 Elsevier SciLtd.

12. Dunbar, J. et al., (2002). “Empiricaland Theoretical Bacterial Diversity in FourArizona Soils.” Appl. Env. Microbiol. 68:3035-3045.

13. Hirschfelt, D., W. Peacock, P.Christensen (1992). “The Effects of CoverCrops and Compost on GrapevineNutrition and Growth.” Univ. California-Davis SAREP.

14. Homeyer, H. (2003). “A MagicalOrganic Elixir Goes High-Tech.” New YorkTimes. Jan. 5, 2003.

15. LIVE (2000). “Soil and Fertilizers.”In Low Input Viticulture and Enology. OregonState Univ. http://berrygrape.oregonstate.edu/LIVE/.

16. Fischer, B. (1996). Beiträge-zurEntwicklung Umweltschonender Pfanzen-schutzsysteme im Weinbau. “Contributionsto Environmental Pest Control in Vine-yards,” Univ. Bonn Dissertation

17. Girvan, M., et al. (2003). “Soil TypeIs the primary Determinant of the Compo-sition of the Total and Active BacterialCommunities in Arable Soils.” Appl. Env.Microbiol. 69:1800-1809.

18. Sessitsch, A., et al. (2001). “MicrobialPopulation Structures in Soil Particle SizeFractions of a Long Term Fertilizer FieldExperiment.” Appl. Env. Microbiol. 67: 4215-4224.

19. Odell, R. T., W. M. Walker, L.V.Boone, and M. G. Oldham (1983). “TheMorrow Plots: A Century of Learning.”Illinois Agric. Exp. Stn. Bull. 775.

20. Smart, R. E. and J. Gladstones(1999). “Soil and Wine Quality.” In TheOxford Companion to Wine. 2nd Edition. J.Robinson (Ed) Oxford Univ. Press.

21. Reganold, J. P., A. S. Palmer, J. C.Lockhart, and A. N. Macgregor (1993).“Soil Quality and Financial Performance ofBiodynamic and Conventional farms inNew Zealand.” Science. 260: 344-349.

22. Reganold, J. P., J. D. Glover, P. K.Andrews, and H. R. Hinman (2001).“Sustainability of Three Apple ProductionSystems.” Nature. 410: 926-930.

23. Blanchard, C. H., M. and S.Tanenbaum, (1996). Regional Estimatesof Acid Deposition Fluxes in California.Air Resources Board, CA-EPA. No. 96-13.

24. Soule, J. J., J. Piper (1992). Farming inNature’s Image; An Ecological Approach toAgriculture. Island Press.

25. SARE (2003). “Control of Botrytis byCompost Tea Applications on Grapes inOregon.” Western Region SARE ProjectSW00-039. http://wsare/usu.edu.

Reprinted from:

58 Paul Drive, Ste. D, San Rafael, CA 94903 • 415-479-5819

Visit our website:www.practicalwinery.comto learn more about PWV.