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Climate change has resulted in warmer average temperatures and is predicted to result in reduced
water available for irrigation, even as growing season droughts are expected to increase. Climate models
indicate that the area suitable for production of sweet cherries in the BC interior has already increased
northward and in elevation. As opportunities arise for expanding production of perennial horticultural crops in
the BC interior due to climate change, it is important to consider soil and water resources in site selection to
optimize fruit production. Using sweet cherry as a key indicator crop, we assessed the impact of mulch,
compost and postharvest deficit irrigation on water use efficiency, soil water holding capacity and crop
production in two newly-planted north Okanagan orchards and one well-established south/central Okanagan
orchard. Soil was collected from six sites newly designated as climatically suitable for cherry production and
from twelve older orchards throughout the Valley. Using greenhouse bioassays of cherry seedlings in ‘old’ and
‘new’ soils, we determined whether soil chemistry and indigenous soil microbial populations (plant parasitic
nematodes, mycorrhizal fungi, soil bacterial and fungal populations) placed any restrictions on expanding
cherry production into the newly designated areas.
Surface application of compost increased soil and leaf nutrient status in both newly-cultivated and
older orchard soils and showed potential to improve fruit quality. Compost application may also maintain soil
health, and mitigate future soil-borne disease in newly established orchard soils that have never cropped
sweet cherry or other tree fruits. Woodchip mulch had no effect on soil nutrient status and soil biology after
three growing seasons, but increased foliar P at two sites. It may have benefits longer term in enhancing soil
organic matter and improving soil water holding capacity. Cost/benefit analysis suggests that compost
amendment has greater potential for benefits to be realized in the short term than mulch, but the costs may
outweigh the benefits to be gained. Overall, we conclude that the use of organic amendments may be an
effective tool to maintain and/or restore soil organic carbon in perennial horticulture and to enhance sweet
cherry production.
Postharvest deficit irrigation with a 25% reduction in water application had no detrimental effects on
soil physiochemical or biotic properties, on tree growth, tree water stress, foliar nutrient status, fruit yield or
quality in the two years following its implementation. Water use efficiency increased with its implementation.
Cost/benefit analysis suggests that adoption of postharvest irrigation would be beneficial as costs of
implementation are minimal and water usage is decreased without loss of sweet cherry productivity.
However, there is little incentive presently for growers to adopt this management practice as current water
allocations are sufficient to meet grower needs.
The bioassay indicated that new orchard soils were more ‘biologically suitable’ for planting sweet
cherry than old orchard soils, and the lower plant growth observed in old orchard soils may have been the
result of detrimental changes in the microbial community, rather than from abiotic elements in the soil
environment. Orchard management practices that maintain soil organic carbon levels, and stimulate an active
microbial community will benefit growth of cherry trees in both new and old orchard soils
water available for irrigation, even as growing season droughts are expected to increase. Climate models
indicate that the area suitable for production of sweet cherries in the BC interior has already increased
northward and in elevation. As opportunities arise for expanding production of perennial horticultural crops in
the BC interior due to climate change, it is important to consider soil and water resources in site selection to
optimize fruit production. Using sweet cherry as a key indicator crop, we assessed the impact of mulch,
compost and postharvest deficit irrigation on water use efficiency, soil water holding capacity and crop
production in two newly-planted north Okanagan orchards and one well-established south/central Okanagan
orchard. Soil was collected from six sites newly designated as climatically suitable for cherry production and
from twelve older orchards throughout the Valley. Using greenhouse bioassays of cherry seedlings in ‘old’ and
‘new’ soils, we determined whether soil chemistry and indigenous soil microbial populations (plant parasitic
nematodes, mycorrhizal fungi, soil bacterial and fungal populations) placed any restrictions on expanding
cherry production into the newly designated areas.
Surface application of compost increased soil and leaf nutrient status in both newly-cultivated and
older orchard soils and showed potential to improve fruit quality. Compost application may also maintain soil
health, and mitigate future soil-borne disease in newly established orchard soils that have never cropped
sweet cherry or other tree fruits. Woodchip mulch had no effect on soil nutrient status and soil biology after
three growing seasons, but increased foliar P at two sites. It may have benefits longer term in enhancing soil
organic matter and improving soil water holding capacity. Cost/benefit analysis suggests that compost
amendment has greater potential for benefits to be realized in the short term than mulch, but the costs may
outweigh the benefits to be gained. Overall, we conclude that the use of organic amendments may be an
effective tool to maintain and/or restore soil organic carbon in perennial horticulture and to enhance sweet
cherry production.
Postharvest deficit irrigation with a 25% reduction in water application had no detrimental effects on
soil physiochemical or biotic properties, on tree growth, tree water stress, foliar nutrient status, fruit yield or
quality in the two years following its implementation. Water use efficiency increased with its implementation.
Cost/benefit analysis suggests that adoption of postharvest irrigation would be beneficial as costs of
implementation are minimal and water usage is decreased without loss of sweet cherry productivity.
However, there is little incentive presently for growers to adopt this management practice as current water
allocations are sufficient to meet grower needs.
The bioassay indicated that new orchard soils were more ‘biologically suitable’ for planting sweet
cherry than old orchard soils, and the lower plant growth observed in old orchard soils may have been the
result of detrimental changes in the microbial community, rather than from abiotic elements in the soil
environment. Orchard management practices that maintain soil organic carbon levels, and stimulate an active
microbial community will benefit growth of cherry trees in both new and old orchard soils
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