Comparison of Root Measurements for Kentucky Bluegrass Sod Establishment

Sod establishment is often gauged utilizing dry weight measurements even though other root parameters such as root length have been shown to more directly affect nutrient uptake.  Therefore, two methods for measuring sod rooting, root dry weight and root architecture were compared.  Kentucky bluegrass (Poa pratensis L.) (KGB) sod was harvested and re-established in April 2006 and 2007.  Roots were collected pre-harvest (P-H) and biweekly for 8 weeks after sod re-establishment (WAE) and analyzed for total root length (TRL), surface areas (SA) and dry weight.  Pre-harvested roots served as controls and represented mature KBG root systems.  Total root length and SA of rooting sod returned to P-H levels within 6 to 8 WAE, whereas, root dry weights constituted only 46 and 54 % of P-H levels at 8 WAE in 2006 and 2007, respectfully.  Roots during sod re-establishment had small root diameters but greater specific root length and specific surface area compared to mature KBG roots.  This shows carbon allocations were used to construct finer roots during establishment compared to a mature KBG root system. Use of dry weight to assess sod rooting rather than root architectural parameters may result in over application of inputs during KBG sod re-establishment.