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NWGICSpring Vine Health Field Day
Queensland
Soil Health – a Review
byProfessor Emeritus Robert White
10 November 2010
What is ‘soil health’?
A popular term synonymous with ‘soil
quality’ , which describes a soil’s
fitness for purpose
Soil health tends to emphasize the living organisms in the soil
Soil quality depends on the interaction
of chemical, physical and biological properties
Properties Processes Functions
to promote healthy vines producing quality fruit
Information on soil quality (= health) derived from
national and international literature
views of scientists, growers and industry
personnel
Important to recognize soil quality depends on
‘inherent’ and ‘dynamic’ factors
The ‘inherent’ factors are
parent material (geology))
climate (rainfall and temperature)
organisms (good and bad)
topography (up and down), and
time (ageing!)
Some examples
Deep red loam(Ferrosol) formedon basic rocks inthe King Valley,NE Victoria
Infertile podzolic soil (Podosol) formed on old sandstone rocksin central NSW
The Jory soil in the Willamette Valley, Oregon (Ferrosol)
Red Cambrian soil, Heathcote
(Ferrosol)
Soil animals mix organic matter deeply in a Chilean soilPeriglacial deposits
under vineyards in Chile
A young soil forming on fissile slate deposits in the Collio del Friuli, Italy
Ancient weatheredlateritic soil underlyingmore recent alluvialsediments in theRiverina
Grey Vertosol formed onQuaternary alluvium in theRiverina
Red Chromosol formed onQuaternary alluvium in theRiverina
What are the key ‘dynamic’ soil properties that
affect soil quality and vineyard performance?
Some examples
Soil organic matter (SOM) is beneficial for
Soil structure (aggregation)
Soil organisms (their food)
Nutrient turnover, cation exchangecapacity, and
Improving soil water storage
Increase SOM through composts, manures,cover crops and mulches
Build up of SOM in a degraded granitic soil18 months after 100 cubic metres per ha of compostedstraw + chicken manureon a vineyard near Young, NSW
Benefits of cover crops are
(a) Protection of the mid-rows from erosion, especially on slopes (see Hunter Valley)
(b) Improving soil structure and making themid-rows more trafficable under wet conditions
(c) Reducing excess vigour in vines on fertilesoils
(d) Adding organic matter to the soil, dependingon the type of cover crop (grasses vs legumes)
Mixed species cover crop at AtaRangi, Martinborough NZ
Winter cereal cover cropnear Stellenbosch,South Africa
Composted grape marc
Potential disadvantages of cover crops are
(a) Compete with the vines for water in dry-grownvineyards
(b) May predispose to frost damage in spring ifnot mown
(c) May harbour certain pests and diseases,e.g. the light brown apple moth
In-row mulch in the Barossa –build up of SOM,earthworms, conserving water
Light texturedover-cultivated soil in Bordeaux, France
Management Practice Earthworm biomass
(kg/ha)
Mulch of grape marc 220
Ryegrass cover crop, slashed and
thrown under the vines
300
Bare soil, surface application of lime 340
Straw mulch 450
Straw mulch plus lime 700
From White (2003); original data from Buckerfield and Webster (2001)
Effect of mulch on earthworm biomass in a Barossa soil
SOM can be increased in vineyards, more easily in cool, moist regions than hot and dry regions
What is realistically achievable?
Data for C inputs in an organic vineyard on the Californian central & north coast
MaterialOrganic/Biodynamically farmed
(kg C/ha)
Prunings 1,000
Leaves 1,400
Weeds, cover crops 1,200-12,000
Compost 2,300-6,900
Total C input 5,900-22,500
Topsoil (0-0.3 m) Subsoil (0.3-0.6 m)Treatment Organic C
(%)
Extra available water (mm)
Organic C
(%)
Extra available water (mm)
Control – no amendment
0.63 - 0.44 -
10 t/ha/yr fresh cow manure
0.92 5.1 0.52 1.8
8 t/ha/yr spent mushroom compost
0.96 5.1 0.46 1.5
20 t/ha/yr fresh cow manure
1.21 7.5 0.58 1.5
16 t/ha/yr spent mushroom compost
1.34 7.5 0.64 0.9
Soil (86% sand) in Loire Valley after 28 years of organic inputs
Big difference between ‘conventional’ and‘organic’ viticulture is in the amount oforganic inputs and the use of syntheticchemicals for pest and disease control
Many growers are adopting the best practicesfrom both systems (‘integrated’) – terms organicand conventional have become less relevant
‘Biodynamic’ viticulture (BD) same as organic,provided organic inputs are maintained (BD preparations have no significant effect)
For example - Take prep. 500 sprayed on at
80 g/ha to stimulate soil biological activity
Due to competitive pressure with resident soil
organisms, the chances of the added
‘bugs’ surviving in the top 15 cm of soil is
between 1 and 25 million to one!
Soil chemical properties – some issues
soil sampling – location, soil variability,
depth?
soil testing – what to measure, which lab?
vine nutrition – visual signs, petiole tests?
salinity and sodicity
What to measure and which lab?
pH, EC, organic C, exchangeable Na+
soil biological tests, e.g. microbial biomass C
Location MB-C (mg/kg)
MB-C (g/m2) MB-C (kg/ha 15 cm depth)
Barossa 25-35 50-70
Alsace 600-740 1200-1480
Marlborough 40-105 400-1050
Soil salinity – soil /water extraction or
SoluSamplers
Sodicity – exchangeable Na+
percentage (ESP) >6
As ESP increases, clays
are likely to disperse and
aggregates become less
stable
Increased salinity predisposes to an increase
in soil sodicity
Irrigation inevitably means an increase in soil
salinity, unless there is a sufficient leaching
fraction LF - irrigation in early winter with good
quality water or sufficient winter rainfall
LF between 0.1 and 0.15
Fe deficiency, St Emilion, France
Zn deficiency, Rueda, SpainVisual symptoms
Macronutrient
Element
Very
Deficient
Deficient Low to
Marginal
Adequate High to
Excessive
N (total) <0.7 0.7-0.89 0.9-1.2 >1.2
P <0.15 0.15-0.19 0.2-0.24 0.25-0.5 >0.5
K (with
adequate N)
<1.0 1.0-1.7 1.8-3.0 >3.0
Ca <1.2 1.2-2.5
Mg <0.3 0.3-0.4 >0.4
Na >0.5
Cl >1.0
Macronutrient concentrations (%) in petioles
Micronutrient
Element
Deficient Low to
Marginal
Adequate High to
Excessive
Fe 25-30 >30
Cu <3 3-5 6-11 >40a
Zn <15 15-25 26-150 >450a
Mn <20 20-29 30-60 >500a
B <25 25-34 35-70 >100
Mo <0.05 0.05-0.19 0.20-99 >100
Micronutrient concentrations (mg/kg or ppm) in petioles
aMay indicate spray contamination
Plant analysisThis can be repeated season after season to compile a record of the vines’ nutritional status(crop logging)
Soil physical properties
Soil depth – depth of rooting, subsoil
constraints (compaction)
Soil structure and water - plant available water
rate of supply, drainage, and
Soil strength – trafficability and ease of root
penetration.
Generally more difficult to measure than chemical
properties
Benchmarking soil quality
Based on soil/vine properties for soil
quality, or
Based on cultural practices that improve
soil qualityExample of the former – Cornell Soil HealthAssessment System(http://soilhealth.cals.cornell.edu)
Example of the latter – Californian SustainableWinegrowing Program(www.sustainablewinegrowing.org)
Factor Indicators Value Rating ConstraintPh
ysic
alAggregate stability (%) 22 25 Aeration, infiltration, rooting
AWC (mm/m) 180 63Surface hardness (psi) 107 78
Subsurface hardness (psi)
400 13 Subsurface pan, compaction
Bio
logi
cal
Organic matter (%) 2.1 14 Energy storage, C sequestration, water retention
Active C (ppm) 462 21 Soil biological activityPotentially mineralizable N (mg N/g soil/week)
2.0 0 N supply
Root health (1-9) 2.3 88
Che
mic
al
pH 8.3 0 Toxicity, nutrient availability
Extractable P (ppm) 9.5 100Extractable K (ppm) 20 11 Plant K availabilityMinor elements 56
Overall quality score out of 100 39.1 Very low
0
0.005
0.01
0.015
0.02
0.025
0 20 40 60 80 100 120 140 160
Frequency distribution for soil K values from a large number of sites
Rating – too low
Optimum
Rating – too high
Soil test values in mg/kg
A benchmarking system for Australian vineyardswould require
1. Selection of key soil properties2. Review of existing data on soil quality3. Identification of benchmark values (ranges)for the main regions and soil types4. Identification of knowledge gaps5. Research to ‘plug the gaps’6. Collaborative approach between scientists and growers7. ‘Packaging’ of information for extension togrowers
Conclusion
Improvement in soil quality may be limited by
inherent factors (geology, climate, age etc), but
A focus on dynamic soil properties can improve
vineyard performance and resilience, e.g.
soil organic matter and organisms, soil depth,
soil structure, soil nutrient supply
Growers should adopt the best practices from
‘conventional’ and ‘organic systems’ – integrated,
sustainable systems
Full report available on GWRDC websitewww.gwrdc.com.au
See also the Soil Health Knowledge Bank atwww.soilhealthknowledge.com.au(maintained by the Grains R and D Corporation),and
Soils for Fine Wines (2003), Oxford UniversityPress, New York
Understanding Vineyard Soils (2009), OUP,New York