Soil Management for Orchards and Vineyards
No-Till versus Tilled Orchards and Vineyards
Whether to cultivate is perhaps the first and most important choice to make in choosing a cover crop strategy for an orchard or vineyard. Choosing a cover cropping farming system will depend on the relative vigor of the site; water availability in the soil; management objectives (increasing or decreasing vegetative growth); and erosion control. Following are discussions of several different approaches to managing cover crops in orchards or vineyards.
Annually Seeded and Tilled Cover Crops
Some growers use this system choose it to conserve moisture in their orchards or vineyards. Cover crops are planted in the fall, allowed to grow until some point in the spring when the ground can be easily tilled, and then tilled into the soil as a “green manure” cover crop. This operation is often timed when the cover crop is flowering, as it will decompose easily at this stage. Although disking destroys organic matter, the periodic addition of organic matter enhances soil microbes, improving soil structure and nutrient cycling.
No-Till Cover Crop Systems
No-till practices were first introduced as a soil conservation tool and to decrease labor requirements and fuel use. Another benefit is firm footing in wet weather. Numerous studies have shown that soil is more protected from erosion and run-off in no-till systems and that yields in no-till systems can be as good or better than with conventional tillage. Soil carbon and other soil quality parameters (aggregate stability, microbial activity, earthworm populations) can increase significantly after switching from annual tillage to no-till.
No-Till with Annual Cover Crops
In a no-till system with annual cover crops, orchards or vineyards are tilled initially and seeded with species that will reseed themselves on an annual basis. Tillage is restricted to only beneath the trees or vines. Orchards and vineyards are mowed in spring and early summer which helps increase heat absorption and reradiation for frost protection. Mowed residue left on the soil surface helps suppress summer weeds and will decompose by harvest. Fall weather may not favor the germination of winter annual species that reseed themselves.
No-Till with Perennial Cover Crops
Perennial grasses and legumes are most commonly used in orchards or vineyards planted on fertile sites. Many of the perennial grasses are very competitive with plant roots, and will have a devigorating effect on the orchard or vineyard. This may be desirable if tree and vine growth is excessive. There is a range of cover crops that vary from being slightly competitive to very competitive. Cover crop selections of perennial rye grass, tall fescue, and orchard grass are the most competitive, and can have a tremendous impact on orchard or vineyard vigor.
Tilled and No-Till Floor Management Systems
Some growers use different floor management systems in alternate tractor rows to moderate vigor, incorporate compost, provide diverse habitat, or for aesthetic reasons. One system commonly employed uses a no-till approach of self-reseeding annuals for three years in alternate tractor rows, with annually planted and plowed down cover crops in other tractor rows. After three years, the planting systems are switched to alternate tractor rows. Perennial species are also used in this way.
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