Strawberries and Fall Nitrogen
As summer weather begins to wane giving rise to cooler daytime temperatures it’s time to either get strawberries planted for spring or maintain carry over strawberries which means it’s time to think about fall nitrogen application. The success of a spring strawberry crop hinges on the preparatory measures taken in the preceding fall. Nitrogen plays a central role in plant growth and development. Fall nitrogen fertilization equips strawberry plants with the resources they need for vigorous growth, flowering, and fruiting in the subsequent growing season.
Carry Over Plants
If you have not already done so, make sure to have leaf tissue samples analyzed to base your nitrogen and other nutrients applications off of. Generally, 40-60 lb per acre N are recommended as a fall nitrogen dose. During the fall, strawberry plants exhibit heightened nutrient absorption and storage mechanisms. As temperatures drop and daylight decreases, plants shift their focus from vegetative growth to nutrient uptake and storage. Applying nitrogen during this period facilitates its absorption and conversion into storage forms, such as proteins and amino acids, which are crucial reservoirs for subsequent spring growth. Split applications of N are recommended because strawberries have shallow root systems and are typically grown on lighter, sandier soils, which are prone to leaching. Fertigation is the best way to fertilize because it allows for smaller doses of nitrogen to be applied compared to broadcasting N. It's recommended to administer nitrogen six weeks before the first expected frost.
Annual Systems
For annual production systems that will not be carried over nitrogen application prior to planting is even more critical. Two thirds of all the N for the planting should be applied in the fall. New plastic mulched beds should be planted ideally in early to mid-September. Fertigate using 60-70 pounds N one week prior to planting.
Nitrogen Source
Nitrate-N fertilizers are recommended because strawberry plants utilize Nitrate-N over Ammonium-N which must be converted into Nitrate-N by soil microbes and therefore, takes longer to become accessible to strawberry plants. Additionally, most Ammonium-N sources acidify soil more quickly than Nitrate-N sources.
Conclusions Importance of Fall Nitrogen
Nitrogen availability in the fall primes strawberry plants for successful flower bud initiation. Well-nourished plants are more likely to produce higher numbers of well-formed flower buds, demonstrate improved stress tolerance, and withstand cold stress and potential frost damage. Although additional nitrogen is recommended in spring at or before bloom for strawberries, missing, late or inadequate application of fall N will seriously limit strawberry yield for the following spring.
This article appears in August 2023, Volume 14, Issue 6 of the Vegetable and Fruit News.