Blueberry Root Dynamics and Nutrient Management Under Organic and Conventional Production

Two principal differences that differentiate organic from conventional production in blueberry are nutrient management and weed control.  Use of nutrient amendments, such as fish emulsion, feather meal, and yard debris compost, and weed control methods, such as surface sawdust mulch and black landscape fabric (weed mat), create rhizosphere conditions that differ from conventional systems.  Organic soil amendments have a unique influence on soil chemical and biological properties, including soil pH, electrical conductivity (salinity), and the structure of microbial populations and fungal symbionts (ericoid mycorrhizae).  Likewise, weed mat often increase soil temperature while sawdust reduces it, influencing various soil-temperature-dependent processes associated with microbial activity and root function (e.g., growth, respiration, nutrient uptake).  Thus, to better predict crop growth and productivity in organic systems, proper understanding of the belowground processes is critical.  However, while roots have been well studied in several major fruit crops, including apples, grapes and citrus, belowground research in blueberry is comparatively new and little is known about the timing of new root production, root lifespan, or root turnover in either organic or conventional systems.  Preliminary results from two studies, an organic trial and a conventional trial, examining blueberry roots will be discussed in this presentation.  Blueberry root dynamics were monitored using minirhizotrons and examined in relation to soil pH and soil electrical conductivity.