This Is AuburnElectronic Theses and Dissertations

Potassium Movement and Uptake as Affected by Potassium Source and Placement




Young, Bradford

Type of Degree



Agronomy and Soils


Although downward loss of anions such as nitrate has been well-studied in high-sand turfgrass putting greens, leaching of cations such as potassium (K) has received less study. Moreover, turfgrass research with K has largely focused on two soluble forms of K: potassium chloride (KCl) and potassium sulfate (K2SO4). Thus, the objectives of this research project were to: 1) examine the effect of K fertilizer sources on bentgrass (Agrostis palustris Huds.) performance, 2) determine K levels in soil and plant tissue, and, 3) trace downward movement of K via incremental depth sampling. The 2 yr study was conducted on a 5 yr old existing bentgrass putting green (cv 'G2'), with treatments arranged in a randomized complete block design with 4 replications of each treatment. Treatments were K sources: 1) potassium chloride - KCl, 2) potassium sulfate - K2SO4, 3) resin-coated K2SO4, 4) potassium thiosulfate (KTS), and, 5) potassium nitrate - KNO3. All K treatments were applied quarterly, with treatments applied according to the initial recommended soil-test level of 56 kg ha-1 K2O. Treatments were applied either by a broadcast application or a vertical 'band' treatment. For the band treatment plots were first core aerified (1 cm diam. x 10 cm deep), and applied fertilizer was swept into aerification holes, followed by a sand topdressing. Broadcast treatments were also aerified, with topdress sand first applied, and K fertilizer then surface applied. Collected data included monthly clipping yield, monthly K content in clippings, monthly soil K (0-7 cm sampling depth), quarterly shoot density, and quarterly root mass. Extractable soil K over a 0-30 cm depth was also collected quarterly, with samples collected every 5 cm of depth. Over the 2 year study potassium application had no beneficial effects on turfgrass performance, and acceptable performance was achieved across a wide gradient of K content in soil and leaf tissue. Regardless of soil test K level, no deficiency symptoms were observed.