What Does A Biodiverse Farm Look Like

Agricultural practices that increase the abundance and diversity of above-and below-ground organisms strengthen your crops' abilities to withstand pests. In the process, you also improve soil fertility and crop productivity. Diversity on the farm includes the following components:

■ Spatial diversity across the landscape (within fields, on the farm as a whole and throughout a local watershed)

■ Genetic diversity (different varieties, mixtures, multilines, and local germplasm)

Temporal diversity, throughout the season and from year to year (different crops at different stages of growth and managed in different ways)

How diverse is the vegetation within and around your farm? How many crops comprise your rotation? How close is your farm to a forest, hedgerow, meadow or other natural vegetation? All of these factors contribute to your farm's biodiversity.

Ideally, agricultural landscapes will look like patchwork quilts: dissimilar types of crops growing at various stages and under diverse management practices. Within this confusing patchwork, pests will encounter a broader range of stresses and will have trouble locating their hosts in both space and time. Their resistance to control measures also will be hampered.

Plant diversity above ground stimulates diversity in the soil. Through a system of checks and balances, a medley of soil organisms helps maintain low populations of many pests. Good soil

Robert L. Bugg, Univ. of Calif.

Robert L. Bugg, Univ. of Calif.

a rosemary cash crop teams with flowering buckwheat, which improves the soil and attracts beneficials, in a Brentwood, calif., apricot orchard.

caution!:

increasing biodiversity takes a lot of knowledge and management, as it can backfire. Some cover crops can provide pest habitat, and mulches can boost populations of slugs, cutworms, squash bugs and other pests.

YEAR-ROUND in Oregon's Willamette Valley, Larry Thompson's 100-

BLOOMING acre fruit and vegetable farm blossoms with natural

--insectaries. "To keep an equilibrium of beneficials and

CYCLE

--pests and to survive without using insecticides, we

ATTRACTS have as much blooming around the farm as we can,"

BENEFICIALS he says.

Thompson uses cover crops to recruit ladybugs, lacewings and praying mantises in his battle against aphids. overseeded cereal rye is already growing under his lettuce leaves before he harvests in late summer and fall. "it creates a nice habitat for overwintering beneficials and you don't have to start over from ground zero in the spring," he says.

Between his raspberry rows, Thompson lets his dandelions flower into a food source for nectar- and pollen-seeking insects before mowing them down. Forced out of the dandelions that nurtured them in early spring, the beneficials pursue a succession of bloom. They move first into his raspberries, then his marionberries and boysenberries.

Later in the year, Thompson doesn't mow his broccoli stubble. instead, he lets the side shoots bloom, creating a long-term nectar source into early winter. "The bees really go for that," he says.

Jerry DeWitt, iowa State Univ.

Jerry DeWitt, iowa State Univ.

The next generation of farmers? Students learn about ecological farm design from Oregon fruit and vegetable grower Larry Thompson.

tilth and generous quantities of organic matter also can stimulate this very useful diversity of pest-fighting soil organisms.

As a rule, ecosystems with more diversity tend to be more stable: they exhibit greater resistance — the ability to avoid or withstand disturbance — and greater resilience — the ability to recover from stress.

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