Organic Hobby Farming. Andy Tomolonis

      Air drainage is important in the summertime as well as during cold weather. Tomato vines can succumb to midsummer fungal diseases if they aren’t given enough space between rows. Remember, those tiny transplants. will eventually grow into big, bushy plants.

      Understanding Microclimates

      Not only will you have to think about the general climate of the area in which you’ll farm, you’ll also need to understand and account for the effects of microclimates (climates that differ from those of the surrounding areas). Features of the land are responsible for numerous microclimate changes. For example, sometimes lowlands can collect and hold cold air, creating early and late frosts. This is known as lowland chill.

      Have you ever stood at the top of a mountain and looked down at fog blanketing the valley below? It’s an illustration of simple physics: Hot air rises and cold air sinks. And fog in the valley forms because water vapor condenses in the cold air that settles against the ground. You can sometimes see these effects in early fall, when driving through areas with hills and valleys: Trees in the lowest-lying areas show the first foliage colors. That’s because cool air sinks and flows like a slow-moving river downhill, settling into valleys—especially on calm, clear nights. Understanding this downward flow of cool air, called air drainage, will help you take advantage of microclimates caused by physical attributes of the land.

      Farmers who are tending fields at the bottom of a valley might find their plants nipped by an unexpected frost, while plants growing at a higher elevation remain unharmed. Even if you’re not at the bottom of a hill, buildings, hedges, a row of trees, or other physical obstructions can block the streams of cold air. This can be a problem for vegetable gardeners who are stretching the season in spring or fall. Fruit growers, who tend orchards on sloping land, can suffer crop losses when trees on south-facing slopes bloom early after a streak of sunny days, then get hit by a late spring frost. The cold can damage blossoms and reduce fruit set.

      Air drainage isn’t just a desirable thing in fall and spring. During the summer, a good flow of air between rows of tomatoes will help deter fungal diseases, which multiply under warm, moist conditions and stagnant air.

      If you’re buying a piece of property in a northern climate, it pays to make sure the topography provides ample air drainage. If you already own the land and want to take advantage of air drainage, look around your property for obstacles that prohibit airflow. The best time to detect such an impediment is at dawn on a morning when ground fog is apparent. Go to the highest point on your property and take note of spots where the fog collects. Then walk through the fog banks looking for barriers. If there are no obstacles and the fog is moving, make a mental note of its path so you can avoid creating future blockades. When you find an obstacle to air drainage, remove it, create a larger area for the air to collect, or create a different route for the cold air to flow downhill.

      Taming the Wind

      Airflow is good, but too much can be a problem. A large area of flat land without windbreaks can lead to erosion, which is one reason why so much valuable farmland has disappeared. Soil that’s left unplanted or that has been recently plowed or tilled can become airborne under dry, windy conditions. And most of the material that gets picked up and carried away is organic matter or fine silt, both of which help conserve moisture and retain nutrients in. the soil.

      In most of the country, the prevailing wind blows west to east, but storms and other weather patterns can temporarily alter wind direction. Winter winds tend to blow from the northwest, and summer winds from the southwest. Consider the prevailing directions when scouting out a property. To avoid wind erosion, choose a farm site that receives some shelter from the prevailing winds. A ridge, hill, or line of trees can slow down the steady wind. If you’ve already chosen or purchased your site, plant trees and shrubs yourself to disrupt the continuous flow of wind. Just beware of wind funnels, which can occur when prevailing winds are channeled between hills, ridges, buildings, or wooded areas.

      Windbreaks can also come in handy if properties adjacent to yours are or will be used for non-organic farming. To be certified as organic with non-organic farming next door, you’ll need to create buffers between your farming operation and any property that is sprayed with chemicals. You could, for example, plant a windbreak or create a roadway around the perimeter. Keeping a row of trees, some tall grasses, or a meadow between you and your neighbor are a few other ways of creating buffers that will minimize chemical drift. Talk with an organic certifier to generate more ideas.

      The Effects of Slope

      The slope of a property can also enhance the sun’s power. Land that is slightly graded toward the south and southwest catches more direct rays from the sunlight, which warms the earth faster, allowing an earlier planting time. Too much slope, however, will create problems. At a grade of 3 percent or more, some drip irrigation systems don’t perform at their optimum efficiency. And at grades of 5 percent or more, water runoff can be fast enough to cause soil erosion.