Winter-Kill Cover-Cropping for Erosion Control in Mechanically-Cultivated Organic Garlic

Commodities

• Vegetables: garlic

Practices

• Crop Production: conservation tillage, cover crops, no-till
• Production Systems: organic agriculture
• Soil Management: green manures, soil quality/health

Within organic garlic cultivation, there are three commonly-used
weed-control methods: 1. Plasticulture 2. mulching with straw 3.
bare-earth cultivation. Growing garlic in plastic creates
unnecessary plastic waste and micro plastics contamination. Straw
mulch in our area is not readily available and costly, its
application is labor intensive and when applied thick enough for
effective weed control interferes with the operation of an
undercutter that we use for harvesting. Bare-earth growing with
mechanical cultivation provides successful, cost-effective weed
control, but leaves fields vulnerable to erosion during the
winter months. We think cover crops can fix this issue. This
research seeks to determine the level of cover-crop biomass at
which erosion control is effective, and mechanical cultivators
may still be used without obstruction from cover crop mulch. By
planting a mixed oats and peas cover crop at successively later
dates in the season, the cover crop will winter-kill at
successive levels of biomass and therefore residue. By planting
directly into this cover crop without tillage and using the same
mechanical weed control methods on each planting, we will be able
to determine at what biomass level mechanical cultivation is
still possible, as well as the effectiveness of the erosion
control provided by the cover crop at successive planting stages.
Cover crop height will be measured, and qualitative visual
inspections and photo documentation will be used to measure the
effectiveness of the mechanical cultivator and the extent of
erosion.

The objective of this project is to find the ideal time to plant an
oat/pea cover crop before no-till planting garlic into it. The
ideal planting time maximizes biomass production up to the point of
cover crop residue makes mechanical cultivation of weeds
unfeasible. To determine the ideal planting time we will plant 4
successions (spaced 3 weeks apart) of oat-pea cover crop and a
bare-earth control. Then we will document the differences in
erosion control, weed suppression, feasibility of mechanical weed
control, and yield.