Date of Award

12-2010

Degree Name

MS in Agriculture - Crop Science

Department

Horticulture and Crop Science

Advisor

John Phillips

Abstract

Tillage and subsequent bare soil have been linked to erosion, nutrient leaching, reduced biological diversity, loss of organic matter, and release of CO2 into the atmosphere (Brady and Weil, 2004). The usefulness of an organic no-till system for transplanted vegetables was explored over two growing seasons. In 2007-2008, in a randomized complete block design, treatments of tilled and no-till (T and NT, respectively) were seeded to a dense grain and legume winter cover crop. Tilled plots were mown and disk-ploughed two times; NT plots retained a mow-killed mulch on the soil surface. There were less weeds in NT plots. A corollary experiment was conducted in 2007-2008 to help determine the best cover crops for a no-till system. There was no difference in the amount of biomass produced by the different cover crops, although anthesis for ‘Juan’ triticale (Triticum X Secale) was 12 days later than for ‘Montezuma’ red oats (Avena sativa). In 2008-2009, a completely randomized experimental design was used to test the effect of tillage on bell pepper yield, weed suppression, plant height, and total soil carbon. The treatments were tilled and no-till (T and NT, respectively). A winter cover crop was seeded. Tilled plots were mown, hand-forked and roto-tilled; NT plots retained a killed mulch on the soil surface. Although T plots yielded more bell peppers, NT plots had more weed suppression. There was no difference between the treatments in the change of total soil carbon over the 1 year period, although both treatments experienced overall gains. The present study will add to the growing body of research on the possibility of organic no-till vegetable farming for small- to mid-sized growers located on the central coast of California.

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