|LARCO, HANDELL - Oregon State University|
|STRIK, BERNADINE - Oregon State University|
|SULLIVAN, DAN - Oregon State University|
Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2013
Publication Date: 12/1/2013
Citation: Larco, H., Strik, B.C., Bryla, D.R., Sullivan, D.M. 2013. Mulch and fertilizer management practices for organic production of highbush blueberry. II. Impact on plant and soil nutrients during establishment. HortScience. 48(12):1484-1495.
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). This paper reports on the impacts of each treatment on soil and plant nutrients during the first 2 years after planting. Fish emulsion, weed mat, and compost were generally the most favorable practices in terms of plant and soil nutrition. Fish emulsion and weed mat reduced soil pH and had the highest availability of plant-available N, but fish emulsion increased leaf K to marginally high levels and weed mat reduced soil organic matter content. Compost covered with sawdust, on the other hand, increased soil pH and organic matter and resulted in higher levels of soil nutrients than sawdust alone and higher levels of levels of leaf K and B. Given the impact of each practice on soil pH and/or plant and soil K, further investigation is needed to determine whether these practices are sustainable over the long term for both conventional and organic production of highbush blueberry.
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’). Bed type affected most leaf nutrients measured in one or both cultivars during the first year after planting, including N, P, K, Ca, Mg, B, Mn, and Zn, but had less of an effect on leaf nutrients and no effect on soil pH, organic matter, or soil nutrients measured the following year. Feather meal contained 12 times more Ca and seven times more B than fish emulsion and resulted in higher levels of soil Ca and soil and leaf B in both cultivars, while fish emulsion contained three times more P, 100 times more K, and 60 times more Cu and resulted in higher levels of soil P, K, and Cu, as well as a higher level of leaf P and K. Fish emulsion also reduced soil pH. Compost+sawdust, on the other hand, increased soil pH and organic matter and resulted in higher levels of soil nitrate-N, P, K, Ca, B, Cu, and Zn than sawdust alone and higher levels of leaf K and B. Weed mat, in contrast, resulted in the lowest soil pH among the mulches and had the highest availability of ammonium-N. Weed mat also reduced soil Ca and Mg, but its effects on leaf nutrients were variable. Only leaf Ca, Mg, and B were below levels recommended for blueberry the first year and only when plants were fertilized with fish emulsion. Leaf N was also low or deficient on average the following year when feather meal was applied, leaf B was low again in all treatments, and leaf Cu was marginal. Leaf K, conversely, continued to increase from the previous year and was becoming marginally high with fish emulsion. Fish emulsion, weed mat, and compost were generally the most favorable practices in terms of plant and soil nutrition, but further investigation is needed to determine if these practices are sustainable.