Cold-air drainage and soil quality have significant effects on the profitability of an orchard. An ideal site is on the upper side of a gradual (4 to 8 percent) slope, on rolling or elevated land. Low-lying areas, where cold air can accumulate during a calm, clear night, are prone to spring frost damage. Hilltops or ridges may expose trees to excessive winds or to arctic air masses. A preferred orchard soil is a deep (at least 1 meter), well-drained, and aerated loam. Detailed soil appraisals should be conducted several years in advance of planting.
A grower begins by obtaining a soil map and by digging test holes to examine the soil profile. Soil maps provide useful information on soil texture, parent material, native fertility, erosion levels, and waterholding capacity. Test holes reveal impervious layers and water-related problems. If checked several times during a rainy period, the pits will yield valuable information on the soil water table. Topsoil and subsoil samples also are collected at this time for analysis of pH, nutrient deficiencies and toxicities, and organic matter content. Separate samples are collected for evaluation of replant disease factors, such as nematodes and herbicide residues. Additional site considerations include access to water for irrigation and spraying, the presence of weeds that serve as reservoirs for plant viruses, and the potential for hail or other weather-related disasters.
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