EFFECT OF SHEEP GRAZING ON COVER CROPS, SOIL HEALTH AND WINE GRAPE VINE PERFORMANCE IN A BIODYNAMICALLY FARMED VINEYARD IN THE NORTH COAST OF CALIFORNIA, USA EFECTO DE PASTOREO DE OVEJAS EN CULTIVOS DE COBERTURA, SALUD DEL SUELO, Y RENDIMIENTO DE VID DE UVA DE VINO EN UN VIÑEDO CULTIVADO BIODINAMICAMENTE EN LA COSTA NORTE DE CALIFORNIA, EE.UU.

MCGOURTY, Glenn1*; GREYDANUS-IRWIN, Jaime2; KEIFFER, Ryan1 1 University of California Cooperative Extension, Mendocino County, Ukiah, California USA 2 KAOS Sheep Outfit, Clearlake, California USA *Corresponding Author: gtmcgourty@ucanr.edu

Abstract: In this study, a 5 ha vineyard planted with annual cover crops was divided into 2 treatments: intensive grazing with lambs (average weight 32 kg) @ 100 animals per ha for 3 days, and an ungrazed control. Fourreplications of each treatment were made, with an area of 0.6 ha for each replicated plot. Portable electric fences were used to separate the plots. Animals grazed for 3 days removing most of the cover crop. Cover crops included a mix of annual oats (Avena sativa), common vetch (Vicia sativa), bell bean (Viciafaba), and field pea (Pisumsativum). The ungrazed areas produced an average of 1855 kg/ha of forage per ha. Sheep removed an average of 858 kg of forage per ha and left 746 kg/ha residual vegetation. It is estimated thatanimals gained an average of 0.23 kg per day, for a total of 105 kg of live weight during the experiment. They also produced 545 kg of manure per ha containing 7.6 kg of N, 6.5 kg of K2O and 2.7 kg of P2O5. No significant differences in soil density or porosity were measured. Organic matter following tillage was slightly higher in the ungrazed areas. No differences were found in N, P or K levels in the soils of the grazed and ungrazed areas. There were also no differences in vine yield or fruit chemistry at harvest between treatments.

Keywords: Sheep grazing, biodynamic vineyards
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