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University of California Cooperative Extension # Tulare County.A�,% Grape Notes .4 January 2002 San Joaquin Valley Table Grape Seminar ` Wednesday,February 20,2002 Visalia Convention Center 303 East Acequia• Visalia, California See enclosed program and registration form. Amending Soil and Water Chemistry in Drip-Irrigated Vineyards The first California drip systems were installed in the root system is effectively wetted during summer 1969 in citrus groves located in San Diego County. months. The shape of the wetted zone beneath Growers were searching for a way to save water and emitters depends on the unsaturated flow character- reduce exorbitant water costs. Their pioneering istics of the soil and the rate of water application. effort paid off and news of this new irrigation Salts in the soil move towards the periphery of the technology soon spread. In 1972, the first drip wetted zone and towards the surface in row mid- system was installed in a vineyard in Tulare dles. County. Today, drip irrigation is widely used by growers in the San Joaquin Valley,and the technol- Under drip irrigation,the vine's water and nutrient ogy has evolved in all areas from irrigation schedul- requirements are mined by roots from a limited soil ` ing and engineering to managing soil and water volume compared to furrow/flood irrigations. In chemistry. addition,amendments and fertilizers are applied to this limited soil volume.This magnifies the impacts Hydraulic gradients and soil-water movement with on the soil chemical and physical properties.Prob- drip are distinctly different than furrow/flood lems with soil acidification and water infiltration irrigation.Both drip and furrow irrigated vineyards are more common with drip irrigation, and the ` begin the growing season with 100% of the soil unique soil water and salt distribution in the soil profile wetted by rainfall (except during drought under drip affect vine nutrition. years).But differences in soil water and salt distri- bution within the profile occur soon after irrigation Acidification: The effect of adding acid or acid- begins.With furrow/flood irrigation,the entire root forming compounds on soil pH is determined by the system is periodically rewetted by irrigations, and soil's buffering capacity. Soils of the southern San L salts are uniformly moved downward in the profile. Joaquin Valley are generally well buffered. Soils In contrast,with drip only a fraction(20 to 50%)of are predominately alkaline in reaction (pH greater L 4437-B South Laspina Street,Tulare,California 93274 • Telephone:(559)685-3303 • Web Site: cetulare.ucdavis.edu U.S.Deparunent of Agriculture,University of California,and Tulare County Cooperating