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United States Department of Agriculture

Agricultural Research Service

Research Project: Determining Impact of Soil Environment and Root Function on Horticultural Crop Productivity and Quality

Location: Horticultural Crops Research

Title: Mulch and fertilizer management practices for organic production of highbush blueberry. I. Plant growth and allocation of biomass during establishment

Authors
item Larco, Handell -
item Strik, Bernadine -
item BRYLA, DAVID
item Sullivan, Dan -

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 9, 2013
Publication Date: October 1, 2013
Citation: Larco, H., Strik, B.C., Bryla, D.R., Sullivan, D.M. 2013. Mulch and fertilizer management practices for organic production of highbush blueberry. I. Plant growth and allocation of biomass during establishment. HortScience. 48(10):1250-1261.

Interpretive Summary: A long-term field study is being conducted to evaluate management practices for organic production of highbush blueberry. The cultivars include Duke (early-season) and Liberty (mid- to late-season) and the practices include flat or raised planting beds, two fertilizers (feather meal and fish emulsion fertilizer applied at low and high rates), and three different types of mulch (sawdust, yard debris compost covered with sawdust, and weed mat). The planting was established in October 2006 and was certified organic in 2008. This paper reports on the results from the first 2 years after planting. The greatest growth and yield after two seasons were found when plants were 1) grown on raised beds, 2) fertilized with a low rate of fish emulsion or a high rate of feather meal, and 3) mulched with either compost+sawdust or weed mat. The use of raised beds and weed mat is becoming popular for organic blueberry production in the Pacific Northwest, in part as a result of this study. Both practices increase growth and early production of the crop and the later improves weed control and increases economic returns. Next, we will evaluate the impacts of each treatment on soil and plant nutrients and irrigation requirements.

Technical Abstract: A systems trial was established to evaluate management practices for organic production of highbush blueberry. The practices included two bed types (flat and raised), two sources and rates of fertilizer (feather meal and fish emulsion applied at 29 and 57 kg/ha N), three mulches [sawdust, compost topped with sawdust (compost+sawdust), or weed mat], and two cultivars (‘Duke’ and ‘Liberty’). The planting was established in October 2006 and was certified organic in 2008. After two growing seasons, total plant DW was 19% greater on raised beds than on flat beds and 17% greater with fish emulsion than with feather meal. Yield in year 2 was also 33% higher on raised beds than on flat beds and 36% higher with weed mat than with sawdust mulch. Plants on raised beds allocated more biomass to roots than those on flat beds in year 1, but after two growing seasons, there was no effect of bed type on DW allocation. However, plants allocated more biomass to root and crown tissue and less to wood and leaves both years with feather meal than with fish emulsion. Plants also allocated more biomass to roots and the crown at lower fertilizer rates and with sawdust or sawdust+compost mulch than with weed mat. After two seasons, shoots and leaves accounted for 60% to 77% of total plant biomass, roots accounted for 7% to 19%, and fruit accounted for 4% to 18%. The impact of these organic practices on growth, yield, and biomass allocation may affect sustainability of production over time, as high yielding plants with low root:shoot ratios, such as those with weed mat, may be more sensitive to cultural or environmental stresses.

Last Modified: 8/19/2014
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