Coastal soils: Issues with salinity Mark Battany, Viticulture/Soils Farm Advisor San Luis Obispo & Santa Barbara Counties

Quick review of salinity Water + salts Pure water Irrigation Evapotranspiration Salts in root zone Vineyard soil Leaching Salts below (or away from) root zone

Three salinity situations Restricted drainage Salts can accumulate to high levels No leaching of rootzone Free drainage conditions, occasional leaching Salts can increase, but to some limit Will still affect vineyard performance

Restricted drainage East of Mendoza, Argentina

Limited natural rainfall leaching Elqui Valley, Chile; source: http://www.astro.cl/en/astro-tours/tour-elqui-valley-and-mamalluca-observatory Valle del Elqui, Chile

Occasional leaching

Effects on soil chemistry Electrical conductivity (ECe) Plant growth decreases as soil EC increases Sodium Degrades soil structure, toxicity at high levels Chloride, boron Toxicity at high levels Bicarbonate Increases soil physical degradation pH Nutrient availability

Salt source: groundwater Data from 56 wells in the Paso Robles area Source: Paso Robles Groundwater Basin Study Increasing problem potential Major problem potential

Vine productivity vs. soil EC 100% Relative growth or yield 0% 0 1 2 3 4 5 6 7 8 9 10 Soil EC (dS/m)

Specific toxicity

Sodium Sodium salts; disperse organic matter & clay Calcium salts; from amendments

Soil structure degradation Effects of sodium and bicarbonate Vine growth, yield Soil degradation >>>

Paso Robles salinity survey Soil EC (dS/m) 6.5 5.4 4.2 3.0 1.8 2006 data 0.6

2006-2009 salinity surveys

Soil EC values (2007)

Deeper soil salt fate Samples taken in May 2010, after relatively wet winter

Irrigation water analysis meq/L mg/L pH ECw SAR Ca Mg Na Cl HCO3 B 7.8 1.81 4.6 3.4 6.0 9.9 6.4 4.8 0.93 Each season of irrigation water (1.25 ft) applies about 775 lbs of sodium per acre, and about 3.1 lbs of boron per acre Bicarbonate hazard low: Ca + Mg > HCO3

Sample site: Clay content Percent clay Sample site: Clay content

Soil pH Sample site: pH

Electrical conductivity Sample site: ECe

Sodium Sample site: Sodium

Chloride Sample site: Cl

Boron Sample site: Boron

Managing vineyard salinity Measure soils and water; heed recommendations Correct any drainage problems Adjust water chemistry Apply gypsum (or acid) as needed Leach with irrigation when rainfall insufficient Use tolerant rootstocks, varieties

Field salinity measurement

Drainage

Adjust water chemistry Acidification Acid injection Sulfur burner Critical to manage waters with high pH and bicarbonates Blending with better water if available Reverse osmosis not feasible economically Miracle devices...magnets, electrodes, etc.

Gypsum Helps displace sodium Counteracts bicarbonate Can use acid instead if soil has “free lime” Still need leaching water to remove sodium Gypsum will raise soil EC slightly

Additional leaching

Use more tolerant rootstocks 100% 1103P, 140R Salt Creek Relative growth or yield 0% 0 1 2 3 4 5 6 7 8 9 10 Soil EC (dS/m)

Use more tolerant varieties Example: Syrah vines in a block of Cabernet Sauvignon

Summary Central Coast salinity conditions are manageable (for the most part) but will require attention to keep impacts from becoming economically damaging Thanks: American Vineyard Foundation ASEV Grower support on Central Coast

Retrofitting with sprinklers

Salt toxicities