Rotating crops to a new area each year assists in preventing disease and reduces insect pests. It may also prevent the depletion of nutrients in the soil, as each crop has its own requirements for nutrients. The Penn State Extension office recommends rotating crops on a three-year cycle. However, there may be times when crop rotation poses difficulties and proves a disadvantage for some gardeners.
For those growing vegetables in a small area, rotating large plants, such as corn or pole beans, may pose a problem. These crops tend to obstruct the sunlight from smaller plants and are typically grown on the west side of gardens while smaller crops occupy the eastern side. Small areas may not support rotation for these large plants.
In home gardens, it is not unusual for selected areas of the garden to have shallow soil. This can occur if ledge or rocky deposits rest under the garden area. In these instances, only vegetables with shallow root systems, such as salad greens and radishes, can survive in shallow soil. Large rooted crops, such as tomatoes, potatoes and corn, can not be grown in shallow soil. This limits the gardener's ability to rotate crops as recommended.
Trellises and Fences
Crops such as pole beans, peas and other vining crops are often grown on trellises or fences. Many gardeners prefer to erect permanent structures to provide support for these vegetables. Rotating crops require moving the support systems for these plants and creates a disadvantage to crop rotation.
For commercial farms, growing several crops and practicing crop rotation may not be practical in terms of profitability because it may limit production of the most profitable crop. It also requires an investment in a range of machinery and equipment to tend to multiple crops. According to the Dairy Science Department at the University of Wisconsin, growing multiple crops also requires more knowledge and better management skills. Some commercial farmers solve this issue by allowing some fields to lie fallow for a season and rotating the main crop to a new field. This does, however, require the farmer to manage more farm land than is required for the crop production itself.