Plant Nutrition

Phosphorus use in cranberry nutrient management.  Over the past several years, we have developed a body of research data supporting a new set of Best Management Practices (BMP) recommendations for the use of phosphorus in cranberry fertilizer programs. 

You can find the full nutrient management BMP at this web address:
www.umass.edu/cranberry/pubs/bmps.html   Select: Nutrient Management (2010)

Our current recommendation is to use no more than 20 lb/A of actual P and to use less than that if tissue P is sufficient, especially on native varieties.

Based on results in surveys for our SARE project (as reported in 2009), at least half of MA growers were implementing some form of P reduction by the end of the 2008 season.  After the 2009 season, growers were surveyed by CCCGA -- 65% identified themselves as practicing phosphorus reduction.

As growers have adopted reduced P management, we have worked at 7 sites to follow the change in yield and water quality as P was reduced below 20 lb/A.  At the 7 sites, reduced P was NOT related to reduced yield.  At the sites with long term P reduction, water quality has improved (less P in discharge water).  Flood discharges are the highest source of P export, with harvest floods a greater source than winter floods.

Current plot-scale research on Howes and Stevens follows up on the use of reduced P, looking at various P sources and slow release materials while holding N application rates constant.  In general, best results are with 5-10 lb/A P and at least some of the season’s applications as slow release materials.  The only site that responded to higher P rates was a newly renovated bed.

SARE funded project to look at sustainable cranberry canopy management.  The primary goal of this 4-year project (ended in spring 2009) was to develop, demonstrate, and implement grower-identified practices on MA cranberry farms that would improve water and plant canopy management to reduce costs and improve pest management.  The UMass team for this project included Sandler, Caruso, Averill, and Vanden Heuvel (first 2 years).  In consultation with a team that included 5 farmers, we identified sanding, pruning, fertilizer use, irrigation, and drainage as the most importance practices to study during this project.  During the project we found that while the practices studied and adopted (especially drainage improvement) had some potential to impact pest management, they had even greater potential for reducing costs, reducing nutrient pollution, conserving water, and sustaining productivity.  We identified five practices that could improve nutrient, water, and canopy management from environmental and/or cost perspectives -- pruning (as an alternative to sanding), reduced phosphorus fertilizer, irrigation scheduling with water floats or sensors, installation of drainage tiles, and cycling sprinklers on and off during frost protection (in most cases using automation).
During the 4 years of this project, we held 6 on-farm workshops (4 at grower team member farms); participated in 3 grower panel discussions at UMass and grower organization workshops - attendance 524; presented project results at 3 UMass winter grower meetings; conducted two replicated trials (one at a grower site) of pruning; evaluated pruning at 10 grower demonstration sites; established grower demonstration sites for irrigation scheduling (6) and drainage improvement (6); worked with 7 growers to study the changes associated with the reduction in phosphorus fertilizer; began a study of the economics of periodic mowing for canopy management with 5 growers; produced 2 journal articles; and published 7 newsletter articles relevant to the project.

By the end of this project, 197 growers attended on-farm demonstrations; 1340 attended workshops to learn about water, nutrition, and canopy management; 6 established demonstration research areas on their farms; and 6 participated in panel discussions on nutrient management, water conservation, or irrigation scheduling.

In our final survey of 102 growers, representing 5520 acres (~40% of the total acres in MA), 51% reduced P use and 21% had adopted the use of floats or sensors for irrigation scheduling.  We also interviewed 28 growers who self-identified in 2006 as interested in this project and representing 3100 acres (~22% of total).  Of those growers, 75% reduced P use, 39% use sensors or floats to schedule irrigation, 54% have added drainage to their bogs, 25% cycle sprinklers in frost protection, and 46% would substitute pruning for sanding.  Full report may be found at: http://www.sare.org/reporting/report_viewer.asp?pn=LNE05-217&ry=2009&rf=1

See Also: Dr. Carolyn DeMoranville Bio