The effect of returning grass clippings on turfgrass growth and quality has not been thoroughly examined. The objective of this research was to determine the effects of returning grass clippings in combination with varying N rates on growth, N utilization, and quality of turfgrass managed as a residential lawn. Two field experiments using a cool‐season turfgrass mixture were arranged as a 2 × 4 factorial in a randomized complete block design with three replicates. Treatments included two clipping management practices (returned or removed) and four N rates (equivalent to 0, 98, 196, and 392 kg N ha−1). Soils at the two sites were a Paxton fine sandy loam (coarse‐loamy, mixed, active, mesic Oxyaquic Dystrudepts) and a variant of a Hinckley gravelly sandy loam (sandy‐skeletal, mixed, mesic Typic Udorthents). Returning clippings was found to increase clipping dry matter yields (DMYs) from 30 to 72%, total N uptake (NUP) from 48 to 60%, N recovery by 62%, and N use efficiency (NUE) from 52 to 71%. Returning grass clippings did not decrease turfgrass quality, and improved it in some plots. We found that N fertilization rates could be reduced 50% or more without decreasing turfgrass quality when clippings were returned. Overall, returning grass clippings was found to improve growth and quality of turfgrass while reducing N fertilization needs.

Various N fertilizer sources are available for lawn turf. Few field studies, however, have determined the losses of nitrate (NO3–N) from lawns receiving different formulations of N fertilizers. The objectives of this study were to determine the differences in NO3–N leaching losses among various N fertilizer sources and to ascertain when losses were most likely to occur. The field experiment was set out in a completely random design on a turf typical of the lawns in southern New England. Treatments consisted of four fertilizer sources with fast‐ and slow‐release N formulations: (i) ammonium nitrate (AN), (ii) polymer‐coated sulfur‐coated urea (PCSCU), (iii) organic product, and (iv) a nonfertilized control. The experiment was conducted across three years and fertilized to supply a total of 147 kg N ha−1 yr−1 Percolate was collected with zero‐tension lysimeters. Flow‐weighted NO3–N concentrations were 4.6, 0.57, 0.31, and 0.18 mg L−1 for AN, PCSCU, organic, and the control, respectively. After correcting for control losses, average annual NO3–N leaching losses as a percentage of N applied were 16.8% for AN, 1.7% for PCSCU, and 0.6% for organic. Results indicate that NO3–N leaching losses from lawn turf in southern New England occur primarily during the late fall through the early spring. To reduce the threat of NO3–N leaching losses, lawn turf fertilizers should be formulated with a larger percentage of slow‐release N than soluble N.

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Carbon‐13 discrimination (Δ) and water use efficiency (WUE) have been largely ignored in turfgrass. Turfgrass performance under drought may be improved by selecting for low Δ, which has been shown to be negatively correlated with WUE. The objectives of this 2‐yr greenhouse study were (i) to compare Δ and WUE in 12 genotypes of Kentucky bluegrass (Poa pratensis L.) with evapotranspiration (ET) and rooting for assessing turf performance under drought, and (ii) to determine the relative importance of ET in drought resistance by comparing diverse ET genotypes (6 low and 6 high) during drydown. Clipping dry weight to ET ratio (WUE) was evaluated with sand‐filled weighing lysimeters (20‐cm diam. by 65‐cm depth) during two 4‐d periods (Days 1 to 4 and 5 to 8) in 2002 and 2003. Carbon (13C/12C) analysis of leaf clippings was used to derive Δ values. Time domain reflectometry (TDR) was used to measure changes in volumetric soil moisture content (VSMC) at the 8.25‐, 17.5‐, 35.0‐, and 52.5‐cm depths to indicate moisture uptake and rooting activity. Drought resistance was visually assessed as wilt and leaf‐firing symptoms. Low‐ and high‐ET genotypes were similar in wilt and leaf firing, suggesting low ET may not be relevant in drought survival. Deep rooting at the 52.5‐cm depth and higher ET as soils dried were associated with less leaf firing. The WUE at Days 5 to 8 was comparable in some years with rooting. The Δ was not always reliable in assessing WUE, but turf performance under drought was correlated with Δ. Low Δ values were associated with less wilt (r = 0.59, P ≤ 0.05) and leaf firing (r = 0.58, P ≤ 0.05), suggesting that Δ may be a useful selection criterion for superior performance under limiting soil moisture.

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