Sustainable Production Systems for Vegetables

Sustainable Production Systems for Vegetables

Summary

Rationale:
Conventional vegetable production systems rely extensively on off-farm purchased inputs such
as inorganic fertilizers and synthetic pesticides. These inputs can be reduced or replaced using
crop rotation, allelopathic rye relay crops and green manures, along with integrated pest
management. Use of alternative production systems may offer an economical and
environmentally sound approach to vegetable farming. These systems will become common if
they are shown to offer advantages and are more sustainable than conventional production
systems. Alternative vegetable cropping systems could also offer opportunities for
diversification of small to moderate sized farms.

Objectives:
1) Develop sustainable production systems for small- to moderate-sized fresh market vegetable
farms.
2) Evaluate the constraints (including economics) of alternative vegetable production systems.
3) Disseminate information on sustainable vegetable production to potential users.

Methods:
An alternative system for vegetable production was developed using interseeded hairy vetch and
rye as a green manure to supply nitrogen and allelopathic weed control. The experimental design
included a three year rotation of cabbage, snapbeans, and tomatoes with the green manure. The
green manure was managed using two methods. The first method maximized the incorporation

of hairy vetch into the soil, resulting in improved soil tilth and providing nitrogen to the crop.
The second method maximized the allelopathic potential of the rye for weed control and
provided a reduced tillage approach to minimize soil erosion. Data on production costs, pest
levels, and yield was compiled and used to develop an economical analysis. Information from
this study was disseminated by various means, including field days, cooperative extension
publications, television, press releases, and grower association meetings and workshops.

Results:
Overall, the soil fertility was adequate in all the plots. There were differences in plots in the
amounts of nitrogen. Nitrogen as ammonia was initially low in all plots and as the season
progressed, ammonia remained consistent. Ammonia was higher in the rye and hairy vetch plots
than bare ground plots at 8 and 14 weeks after planting. Nitrate was initially higher in the bare
ground plots because of excessive fertilization. The cover crop plots had about 1/3 of the nitrate
of the bare ground for most of the growing season. The soil pH was similar in the three
treatments. Initially phosphorous and potassium was higher in the bare ground soil, but the soil
from all three treatments were similar later in the growing season.

Tissue analysis of the crop plants indicated that the soil in the cover crop plots provided
acceptable levels of fertility, while the bare ground soil fertility tended to be excessive. The
growth of crops differed between the three systems. The greatest growth of snapbeans was in the
rye mulch killed with glyphosate, and the smallest plants were initially in the bare ground.
Cabbage had its greatest growth in the bare ground and plots where rye mulch was killed with
glyphosate. The tilled rye plots consistently had smaller sized cabbage. Initially, tomato growth
was greater in the rye mulch killed with glyphosate, but by harvest, tomatoes in the bare ground
and rye mulch killed with glyphosate plots were similar in size.