Nitrogen and P leaching losses from fertilized turfgrass remain an environmental concern. In the present study, we examined the effects of sod type, fertilization, and irrigation on turf quality, NO3–N and PO4–P leaching following St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] sod installation. Treatments included muck‐ vs. sand‐produced sod, no fertilization, fertilization with 4.9 g N m−2 at installation or at 30 d after installation (DAI), and routine irrigation or irrigation at stress from 30 to 60 DAI. Drainage was collected from lysimeters installed in each plot and analyzed for NO3–N and PO4–P to determine total leaching losses. Across all treatments, drainage averaged 290, 902, and 604 mm during each of the three trials. Fertilization at 30 DAI significantly reduced PO4–P leaching losses compared to fertilization at 0 DAI. Muck sod type significantly reduced the quantity of NO3–N leached. Muck sod also significantly reduced PO4–P leached and resulted in better turf quality in two of the three trials. In the context of minimizing nutrient leaching, these results support the use of muck‐grown sod established during low rainfall periods with fertilization delayed at least 30 DAI and with judicious use of irrigation.

Abstract:To conserve natural water resources, athletic fields may be mandated to follow phase water restrictions. In order to optimize irrigation reduction, early plant responses to water stress need to be identified to avoid loss in turfgrass performance and the requirement of additional irrigation to overcome water stress. Current irrigation scheduling based on using potential evapotranspiration (ET) and water stress indices are not suitable for all growing conditions, especially in the water repellent sand soils of South Florida. This experiment was conducted to use spectral reflectance as a means to document normal and progressive water stress in 'Tifgreen' bermudagrass (Cynodon dactylon (L.) Pers. X Cynodon transvaalensis Burtt Davy) grown on a native water repellent sand soil. Three consecutive trials were conducted, in which bermudagrass was subjected to either no irrigation until severe visual wilt (non-irrigated) or irrigated daily (irrigated) over a dry down period. Visual assessment of turf quality and localized dry spot occurrence verified that bermudagrass receiving daily irrigation was not water-limited and bermudagrass receiving no irrigation was experiencing increased water stress over time. An experimentally active near-IR/red sensor was used to monitor changes in plant architecture as a means to determine early water stress. Monitoring near-IR/red ratios determined mid-day depression when water demand is at the highest as well as overnight rehydration in both bermudagrasses. At the end of the dry down period, pooled trial morning near-IR/red ratios-afternoon near-IR/red ratios from non-irrigated bermudagrass was significantly greater than irrigated bermudagrass (P D 0Ð0035), documenting severe water stress from the non-irrigated bermudagrass. Spectral reflectance allows real-time, site-specific bermudagrass water stress evaluation before it is visually identifiable. Using spectral reflectance as an early warning detection tool can be used for better irrigation decisions including pre-emptive irrigation to avoid water stress, compared to models based on predetermined ET and water stress indices.

A field scale facility was constructed to investigate the impact of a wide range of potential management parameters on nitrate (NO 3 -N) leaching from St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] turf. The facility was built to identify and quantify background NO 3 -N sources and concentrations before turf cultural management factors were applied, and to examine how establishment of sod with two contrasting soil organic matter (SOM) contents influence NO 3 -N concentrations in percolate and leachate. The performance of the facility's irrigation and vadose zone percolate sampling units were evaluated and found acceptable. St. Augustinegrass sod with a 2.5 cm rootzone containing either 4% or 10% SOM was installed and maintained at this facility. The NO 3 -N amounts in percolate and leachate were nearly proportional to the amount of SOM associated with the sod rootzones at 4% and 10%, respectively. Based on this investigation, SOM content in the rootzone attached to sod and within the soil which sod is placed influences NO 3 -N concentration in the rootzone and leachate. Therefore, SOM should be considered in best management practices for lawncare. This facility will allow for future investigations on cultural management strategies aimed at decreasing the potential for NO 3 -N leaching from St. Augustinegrass lawns.