Rootzone pH and Penn A-4 Creeping Bentgrass Root Growth.

Rootzone pH highly influences nutrient availability and root growth during both establishment and maintenance of creeping bentgrass (Agrostis stolonifera L. ‘Penn A-4’) putting greens (PGs). While the optimal pH range for creeping bentgrass is generally considered to be 5.5–6.5, PG sand rootzones across the Mid-Atlantic and Midwest regions frequently contain calcite and are buffered to higher pH values. Further alkalinization, via topdressing sand and/or irrigation water inputs, offsets natural acidification processes at the PG surface. Meanwhile, our understanding of how supraoptimal rootzone pH influences Penn A-4 root growth remains limited. A greenhouse study evaluated Penn A-4 root growth, viability, and distribution over an array of rootzone pH levels (5-7.5), yet otherwise receiving ample maintenance fertilization. Furthermore, rootzone samples collected from PG field studies conducted in 2007, 2011, and 2012 were analyzed for soil pH (1:1 DI-H2O), root length density, specific root length, and specific fork number (forks/g). A ‘metadata’ analysis approach, using these and other published findings, generates a more specific soil pH range for optimal root growth of Penn A-4 creeping bentgrass maintained as PGs.