Published online 7 November 2007
Published in Crop Sci 47:2521-2528 (2007)
© 2007 Crop Science Society of America
677 S. Segoe Rd., Madison, WI 53711 USA
TURFGRASS SCIENCE
Nitrate Leaching in Overseeded Bermudagrass Fairways
Laosheng Wua,*,
Robert Greenb,
Marylynn V. Yatesa,
Porfy Pachecoa and
Grant Kleinb
a Dep. of Environmental Sciences, Univ. of California, Riverside, CA 92521
b Dep. of Botany & Plant Sciences, Univ. of California, Riverside, CA 92521
* Corresponding author (laosheng.wu{at}ucr.edu).
 |
ABSTRACT
|
|---|
Maintaining high visual quality of turfgrass requires intensive management. Nitrogen fertilizer inputs in golf-course turfgrass have raised some concerns regarding potential nitrate leaching into groundwater. This study investigated nitrate leaching from an overseeded bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy) managed as a golf course fairway (mowing height in 1.3 cm). The study was conducted from 1994 to 1997, with two soil types (sandy loam and loamy sand), two irrigation regimes, and two N fertilization programs representing the typical resort-turfgrass management practices in the semiarid southern California. Leachate was collected and its volume was measured from lysimeter assemblies each consisting of five metal cylinders. Results showed that the nitrate concentration and mass of the leachate from the loamy sand was lower than that from the sandy loam soil. The difference was attributed to N immobilization and clipping removal. The volume of leachate was greater in the loamy sand than in the sandy loam due to the higher water holding capacity of the latter. Average nitrate concentration of the leachate was lower than that of the irrigation water in five out of the six seasons, implying that if turfgrass is properly managed, it may provide an opportunity to mitigate nitrate loading to surface and ground waters, even when N application rate is high.
Abbreviations: MCL, maximum concentration level • TKN, soil total N
Nitrate Leaching in Overseeded Bermudagrass Fairways
Laosheng Wua,*,
Robert Greenb,
Marylynn V. Yatesa,
Porfy Pachecoa and
Grant Kleinb
a Dep. of Environmental Sciences, Univ. of California, Riverside, CA 92521
b Dep. of Botany & Plant Sciences, Univ. of California, Riverside, CA 92521
* Corresponding author (laosheng.wu{at}ucr.edu).
Maintaining high visual quality of turfgrass requires intensive management. Nitrogen fertilizer inputs in golf-course turfgrass have raised some concerns regarding potential nitrate leaching into groundwater. This study investigated nitrate leaching from an overseeded bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy) managed as a golf course fairway (mowing height in 1.3 cm). The study was conducted from 1994 to 1997, with two soil types (sandy loam and loamy sand), two irrigation regimes, and two N fertilization programs representing the typical resort-turfgrass management practices in the semiarid southern California. Leachate was collected and its volume was measured from lysimeter assemblies each consisting of five metal cylinders. Results showed that the nitrate concentration and mass of the leachate from the loamy sand was lower than that from the sandy loam soil. The difference was attributed to N immobilization and clipping removal. The volume of leachate was greater in the loamy sand than in the sandy loam due to the higher water holding capacity of the latter. Average nitrate concentration of the leachate was lower than that of the irrigation water in five out of the six seasons, implying that if turfgrass is properly managed, it may provide an opportunity to mitigate nitrate loading to surface and ground waters, even when N application rate is high.
Abbreviations: MCL, maximum concentration level • TKN, soil total N
|
INTRODUCTION
|
|---|
SOUTHERN CALIFORNIA is home to more than 500 (18-hole equivalent size) golf courses. Nitrogen management is the most important aspect of fertilization in maintaining a high quality turfgrass. The typical N application rate on bermudagrass (Cynodon spp.) fairways is approximately 20 to 40 kg ha–1 growing mo–1 (Beard, 2002). Under conditions where leaching is not required, nitrate leaching loss is minimal under various management scenarios (Bushoven et al., 2000; Lee et al., 2003; Petrovic, 2004; Mangiafico and Guillard, 2006). For irrigated soils in arid climates, however, leaching is often required to control salinity in the rootzone to ensure acceptable turfgrass growth and/or appearance.
Many studies have been conducted to evaluate N fate in turfgrass systems. These projects evaluated the effect of fertilizer types, application rates, application frequency, and irrigation management on N fate. Geron et al. (1993) found more N leached from sodded than seeded plots and attributed it to less rooting in sodded plots. Using two genotypes of creeping bentgrass (Agrostis palustris Huds.) in a column lysimeter study, Bowman et al. (1998) found that deep-rooted turfgrass can absorb N more effectively than the shallow-rooted varieties. In addition, they observed that management practices affecting rooting depth and density can affect N uptake and nitrate leaching. Turfgrass cultivars can also affect N leaching. Based on measured nitrate concentrations and model simulation of water percolation, Liu et al. (1997) concluded that N leaching among different cultivars was significantly different.
Several studies were conducted to evaluate N leaching in bermudagrass. Snyder et al. (1977) found that N source and application rates significantly affected nitrate leaching in bermudagrass. Differences in nitrate leaching due to N fertilizer forms varied by as much as 30 fold (Guillard and Kopp, 2004). Miltner et al. (1996) used 15N labeled urea in Kentucky bluegrass (Poa pratensis L.) and found that a well-maintained turfgrass could intercept and immobilize N quickly, making leaching unlikely.
The extent of nitrate leaching from golf courses under arid–semiarid climate with intensive irrigation, however, is largely unknown. The fate and transport of nitrate in irrigated soil is affected by the leaching fraction. With progressively higher leaching fractions, more nitrate will be leached, which decreases N use efficiency and increases nitrate contamination potential (Pang et al., 1997a,b). Due to increasingly stricter water quality regulations, N loss via leaching is a primary concern in irrigated turfgrass systems. Excess water application in urban lawns can result in substantial nitrate leaching (Exner et al., 1991). Overwatering in conjunction with fertilization can generate significantly higher nitrate loss in irrigated soils (Morton et al., 1988). To determine the amount of nitrate leaching out of the root zone, nitrate concentration is often measured in leachate collected in lysimeters and suction lysimeters (Gross et al., 1990).
Besides management practices such as irrigation and leaching, nitrate leaching in turfgrass is also greatly affected by site-specific environmental conditions. Compared to other regions, relatively little is known about nitrate leaching under conditions representative of arid/semiarid climate and heavily irrigated turfgrass, in particular, long-term field observations of nitrate leaching in an overseeded bermudagrass fairway, maintained under representative management practices in the southwestern United States. Thus, the main objectives of this study were to determine (i) the amount of nitrate leaching from an overseeded bermudagrass fairway during cool- and warm-seasons and (ii) the influence of soil types, irrigation scheduling, and fertilization on nitrate leaching.
|
MATERIALS AND METHODS
|
|---|
This study was conducted at the University of California at Riverside fairway lysimeter facility. The site, which was constructed in 1991, consists of 24 plots (3.66 m by 3.66 m), 12 each of two different soil types: a Hanford fine sandy loam (coarse-loamy, mixed, superactive, nonacid, thermic Typic Xerorthents; 70.7% sand, 19.8% silt, and 11.3% clay), and an imported loamy sand (84.2% sand, 9.8% silt, and 7.7% clay).
Individual plots were separated by plywood. A lysimeter assembly consisting of five metal cylinders (diam. = 56 cm) with a combined surface area of 1.23 m2 (13.2 ft2) was pre-assembled and then transported into the center of each plot (Fig. 1
). The top 89 cm of the cylinders was hand-packed to the same bulk density as the external surrounding soils. A 7.5-cm layer of pea gravel was placed in the bottom of the cylinders to facilitate leachate collection. A metal drain pipe extended from the bottom of each cylinder to a retaining wall. Each lysimeter assembly was capable of collecting all leachate from the 1.23 m2 surface area.
View larger version (23K):
[in this window]
[in a new window]
|
Figure 1. The five-cylinder lysimeter assembly used in the study to collect leachate. Depth of the soil in the cylinders was 89 cm and the gravel was 7.5 cm.
|
|
In summer 1994, the fairway sod was removed, and the surface leveled. ‘Tifway II’ bermudagrass (Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy) was sodded on 8 September, and the fairway was overseeded with ‘Brightstar’ (for first 2 yr) and ‘Seville’ (for the last year) perennial ryegrass (Lolium perenne L.) at a rate of 586 kg ha–1 on 21 Oct. 1994, 13 Oct. 1995, and 8 Oct. 1996, respectively. Specifically, for cool-season transition, 1 to 2 wk before overseeding, the plots were mowed at a 1-cm mowing height and were verticut (Ryan Ren-O-Thin, Ryan Inc., St. Paul, MN) in three to five directions with blades set to slightly engage soil surface. The plots were swept several passes with a power sweeper to pick up all debris. The plots were then mowed again in two directions before seed was spread and raked into soil surface by hand. The mowing and verticutting procedure for the warm-season transition was the same as for the cool-season transition. The fairway was mowed three times per week (Monday, Wednesday, and Friday) at a 13-mm mowing height with clippings removed throughout the 3 yr of research.
Two irrigation treatments were used: one representing optimal (100% crop evapotranspiration, ETcrop), and the other representing overwatering (130% ETcrop). For determining irrigation amounts, the plots were managed for cool-season turfgrass (i.e., the cool-season turfgrass crop coefficient was used) from mid-October to late April the next year, and for warm-season turfgrass (i.e., the warm-season turfgrass crop coefficient was used) from late April to late September. Beginning and ending dates for irrigation treatments were different for each year. Weekly irrigation amount was calculated for each plot by:
where ETo is weekly reference crop evaporation, which was determined using an on-site California Irrigation Management Information System (http://www.cimis.water.ca.gov) weather station that uses a modified Penman equation with a wind function; Kc is the monthly crop coefficients (Meyer et al., 1985) that were developed in Irvine, CA, which is about 45 km from the study site; and DU represents the coefficient of variation uniformity for each plot, which was calculated as (1 – coefficient of variation in the plot). The weekly irrigation amount was corrected for precipitation and was equally divided into three irrigations applied on Monday, Wednesday, and Friday. Spray pattern of the sprinklers (Rain Bird 1800 Series pop-Up Spray Heads. Rain Bird Corp., Azusa, CA) was checked monthly to ensure maximum DU.
The two N fertilization treatments (440 and 488 kg ha–1 yr–1, Table 1
), although higher than the national average, were based on a 1994 survey of 15 southern California resort golf course superintendents, and represented the typical N application amount in overseeded bermudagrass fairways in southern California at the time of the survey. According to the survey, different N sources, application time, and application rates for cool and warm seasons were used for the two N programs, A and B (Table 1). The two irrigation treatments and two N application programs were randomly assigned to the two soil treatments, which resulted in a 2 x 2 x 2 factorial design. The eight treatment combinations were replicated three times and were arranged in a random complete block design.
View this table:
[in this window]
[in a new window]
|
Table 1. Fertilization programs and N sources used for the overseeded fairway N leaching study for the cool and warm seasons in 1994 to 1997.
|
|
All leachate from the lysimeter assemblies was collected weekly from each plot. Leachate from the five cylinders of each lysimeter assembly at the plot was combined (composited). Leachate volumes (for convenience, leaching volume from each lysimeter assembly was divided by its surface area and reported in leaching depth) were measured and recorded, and a subsample of 125 mL was taken using a 200-mL plastic test tube, acidified with 1 mL of 1 M sulfuric acid, and placed in ice to be transported to the laboratory for analysis. The samples in plastic test tubes were kept refrigerated until analysis. A blank (irrigation water) was also collected at a spigot located on the plot each time when leachate was collected from the lysimeters. Nitrate concentration of the leachate and irrigation water was determined using an Alpkem flow-through analyzer (Alpkem Corp., Clackamas, OR). The seasonal cumulative leachate depth, flow-volume weighted mean concentration, and seasonal cumulative loss (mass) of nitrate were calculated to assess the characteristics of nitrate leaching under heavily irrigated warm seasons and less irrigated cool seasons. For quality assurance purposes, duplicate analyses were done once in every 20 samples.
Clipping yield was measured every Friday during the first season only (11 Nov. 1994 to 22 Mar. 1995) since the original experiment was not designed to evaluate the yield difference among the treatments. The total area of yield collection was 7.88 m2. Clippings were placed in paper bags and dried for 48 h in a forced-air oven at 70°C, and the results were reported as g m–2 d–1 of dry matter.
A composite bulk soil samples was collected using an Oakfield soil sampling tube with an inner diameter of 2.5 cm for each of the two soils twice in the first (including the prior-experiment sampling) and second year, and three times in the third year. Soil total N (TKN) was determined by the Kjeldahl method (Bremner and Mulvaney, 1986). Paired t test was conducted to compare if TKN was significantly different in the two soils during the experiment.
Analysis of variances (ANOVAs) were performed using SAS (SAS Institute Inc., Cary, NC) for several variables: weekly nitrate concentration, leaching depth, and clipping yield; and cumulative (over seasons and years) nitrate mass, leaching depth, flow-volume weighted mean concentration, and percent of applied N. Overall ANOVAs also were conducted and included year and season as factors. ANOVAs for years and seasons in this study were individually reported since the overall ANOVAs indicated that the interactions with year and season were significant.
|
RESULTS AND DISCUSSION
|
|---|
Nitrate leaching from a turfgrass area should be evaluated in terms of both concentration and total mass. Our statistical analyses showed that the N application rates did not have a significant effect on nitrate leaching, except for the cool season of Year 1. The exception is attributed to the soil disturbance, early stage of turf system, and large amount of precipitation during the cool season in Year 1. Besides the effect of irrigation and soil interaction on leaching depth, the statistical analyses also showed that the interaction between irrigation and soil, soil and fertilization, irrigation and fertilization, and interaction among soil, irrigation and fertilization were all not significant (Table 2
) in terms of nitrate leaching. Thus our following discussion is focused mainly on the effect of soil textural types on nitrate leaching.
View this table:
[in this window]
[in a new window]
|
Table 2. Seasonal totals of nitrate in leachate and leaching depth in the lysimeters for two irrigation amounts and two soil types during 3 yr of the study.
|
|
Nitrate Concentration in Leachate Collected from the Two Soils
Except for the first year cool season, the seasonal average (flow-volume weighted) nitrate concentration in the leachate from the loamy sand was 0.1 to 0.2 mg L–1 NO3––N (Table 2). During the same period, the leachate from the sandy loam had a seasonal average concentration of NO3––N ranged from 3.2 to 6.3 mg L–1. Nitrate-N concentration of the leachate from both soils was lower than the maximum concentration level (MCL) of 10 mg L–1 set by the USEPA (Fig. 2
, middle plot), except for the first cool season. The results from this experiment agree with the observation by Geron et al. (1993), who found that early in their study, N leaching losses from all treatments exceeded the MCL (10 mg L–1 nitrate N) level, but none of their treatments had a N level exceeding the MCL in the second year when the turfgrass was more mature, and therefore, more representative of a typical turfgrass system. Qian et al. (2003) also predicted that minimal nitrate leaching occurred throughout their long-term model simulation (100 yr) if clippings were removed. In our experiment, the fairway was sodded on 8 September and overseeded on 21 Oct.1994. The first pre-treatment N application was on 16 September and the first N treatment application was on 4 Nov. 1994, while leaching monitoring started on 5 Nov. 1994. Thus, the nitrate concentration in the leachate for the first few weeks did not accurately reflect the treatment effect, since (i) it took some time for the applied N to move through the soil profile (even though there was some rain during the period); and (ii) the turfgrass might not have a developed root system. For example, it takes about one year for Festuca to develop roots in the 15 to 20 cm layer (Boeker, 1974). Therefore plant uptake of N during the early turfgrass establishment period would be low. It has been shown that root length can affect nitrate leaching (Bowman et al., 2002), and shallow rooted turfgrass in its early establishment stage may have a greater potential for nitrate leaching due to limited water and nutrient uptake (Walker and Branham, 1992).
View larger version (31K):
[in this window]
[in a new window]
|
Figure 2. Depth (top) and nitrate concentration (middle) of leachate in the sandy loam and loamy sand soils, and precipitation (bottom) during the 3 yr (1994–1997) of N leaching study. NS = not significant between the two soils, Fisher's protected LSD test (P  0.05).
|
|
In contrast to most other observations that the nitrate is more susceptible to leaching in coarse textured soils than in fine textured soils (Rauschkolb and Hornsby, 1994), this experiment showed that the nitrate concentration of the leachate from the sandy loam was consistently higher than that from the loamy sand during the entire 3-yr experiment (Table 2 and Fig. 2). However our observation agrees with Mancino and Pepper (1994) who found both ammonium and nitrate concentration of leachate from a sandy loam soil was greater than that from a silt loam soil. Soil analysis showed that before initiating the experiment, the total soil N in the 0 to 12 cm layer was essentially the same (0.023 and 0.026% TKN for the loamy sand and the sandy loam, respectively). The paired t test indicated that the mean values of TKN in subsequent years in the sandy loam (0.048%) were significantly greater than in the loamy sand (0.024%). Higher soil N indicates a greater potential for nitrate leaching, and differences in nitrate leaching in the sandy loam and the loamy sand can be partially attributed to the difference in soil N. Other factors can also affect nitrate leaching in a turfgrass system. For example, N immobilization through plant uptake can reduce nitrate concentration in the leachate. Our limited clipping yield data showed that the amount of clippings removed during the first season was significantly higher (P < 0.05) in the loamy sand (2.16 g m–2 d–1) than in the sandy loam (1.70 g m–2 d–1).
To further help explain the difference in nitrate leaching in the two soils, root distribution between the two soils was determined outside the lysimeters 14 mo after the leaching study was finished (data not shown). The root density samples were taken at depths of 0 to 30, 30 to 60, 60 to 90, and 90 to 120 cm using a 2-cm diam. tube sampler (Allmaras et al., 1996). During the post-experiment period, the fairway was not overseeded but maintained at the same mowing height with a N application rate of 20 kg ha–1 growing-mo–1. Therefore we expected that the post-experiment management did not alter the treatment effects significantly. Statistical analysis shows that the root density in the loamy sand was significantly higher than in the sandy loam in each of the three sampled layers (Table 3
). Since both soils received the same fertilizer treatment and other management practices during and after the experiment, the difference in root density can be safely attributed to the difference in soils. For the same plant species, a higher root density has the potential to extract more N from soil, and consequently reduce nitrate leaching. Bowman et al. (1998) indicated that management practices that affect rooting depth and density could affect N uptake and nitrate leaching.
Leachate from the loamy sand had a lower seasonal-averaged concentration of nitrate N than found in the irrigation water: 0.1 to 0.2 mg L–1 nitrate N for the leachate vs. 3.9 to 5.1 mg L–1 nitrate N for the irrigation water. The amount of N added to the soil through irrigation water in this study ranged from 13.5 to 51.5 kg ha–1, which is equivalent to 3 to 11% of the required N for a typical fairway turfgrass. Nitrogen in irrigation water may have some effect on N fertilizer treatment, but the quality of irrigation water in southern California does not vary substantially, thus it still represents the typical local condition. Weekly measured nitrate concentrations of the leachate were consistent during the entire three years of experiment except for the first few weeks (Fig. 2), as was discussed previously. A high clipping yield, plus the fact that N content is usually higher if the yield is higher for the same species, suggests more N uptake in the loamy sand than in the sandy loam, which is in agreement with our observation that nitrate concentrations in the leachate collected from the loamy sand were significantly lower than those in the leachate from the sandy loam (Table 2 and Fig. 2). Except for the warm season in Year 3, the concentration was still much higher in sandy loam (although the differences were not statistically significant) in both cool and warm seasons for the entire 3 yr.
Leaching Volume and Nitrate Mass in the Leachate
The seasonal cumulative leaching volume (measured by depth in mm) collected from the loamy sand was significantly greater (P < 0.01) than from the sandy loam during the entire three years, except for the cool season first year (Table 2). With the same irrigation application rate and frequency for both soils, it is reasonable to expect that more water would be leached out in the loamy sand than in the sandy loam due to the lower water holding capacity of the loamy sand soil.
The mass of nitrate leached out the root zone reflects a combination of the concentration and the leaching volume (depth) of the leachate. Seasonal cumulative nitrate (mg m–2) collected in the lysimeters was significantly greater (P < 0.01) in the sandy loam than in the loamy sand in five of the six seasons, with the exception of the first season (Table 2). At the beginning of the experiment, the mass of nitrate leached in the loamy sand was greater than in sandy loam, but the difference was not statistically significant.
Irrigation treatment (100 vs. 130% ETcrop) showed a significant effect on the leaching volume (reported in depth) during the last five seasons of the experiment. The interaction of irrigation and soil was significant in the first two warm seasons (Table 2). However, N application rate (439 kg ha–1 vs. 488 kg ha–1) showed a significant effect on nitrate leaching only in the first cool season, not in the last five seasons in either soil. Since no significant difference was observed (Table 2), we used the average N application rate to calculate the percent of N loss (i.e., NO3–N in leachate/N application rate). In the first season, the leaching loss of N was 4.9 and 7.6%, respectively, in the sandy loam and loamy sand. In the subsequent five seasons, the leaching loss represents 3% or less of the applied N (Table 2), which agrees with the previous reports that, under proper management, leaching in turfgrass did not carry significant amounts of nitrate to groundwater (Barton and Colmer, 2006), in spite of our heavy irrigation.
|
SUMMARY
|
|---|
A three-year field lysimeter experiment was conducted to investigate nitrate leaching in overseeded bermudagrass fairways in southern California which represents the typical arid/semiarid climatic conditions. The irrigation treatments in the experiment represent the optimal (100% ETo) and overwatering (130% ETo) irrigation. The N application rates in our experiment were higher than the average N application rates across the country (
200 kg ha–1) in golf course fairways, but they represented those typically used in southern California resort golf courses at the time. The rates are also close to the range of 200 to 434 kg N ha–1 yr–1 for overseeded bermudagrass fairways as suggested by Beard (2002).
Our research indicated that nitrate leaching in overseeded bermudagrass fairways was minimal in a sandy loam and a loamy sand soil, even when the amount of N in the irrigation water was not figured in as one of the N sources. It is interesting to note that the concentration and mass of nitrate in the leachate from the loamy sand was lower than from the sandy loam. The difference was mainly attributed to plant uptake and clipping removal. Although the clipping yield was only measured for a period of 4.3 mo, and root density was measured 14 mo after the end of the experiment, the consistently and significantly higher clipping yield and root density in the loamy sand than in the sandy loam strongly support that there was more N uptake and consequently N removal in the loamy sand than in the sandy loam, which resulted in lower nitrate leaching in the loamy sand than in the sandy loam. However, other factors such as irrigation and rainfall, and denitrification in the soil may also affect N leaching.
The same irrigation management regimes (amount, rate, and frequency) were followed in the two soils. As expected, the leaching volume (measured in depth) was greater in the loamy sand than in the sandy loam due to the higher water holding capacity of the latter. We observed that the average nitrate concentration of the leachate was lower than that of the irrigation water in five out of the six seasons.
|
NOTES
|
|---|
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.
Received for publication January 24, 2007.
|
REFERENCES
|
|---|
- Allmaras, R.R., S.M. Copeland, P.J. Copeland, and M. Oussible. 1996. Spatial relations between oat residue and ceramic spheres when incorporated sequentially by tillage. Soil Sci. Soc. Am. J. 60:1209–1216.[Abstract/Free Full Text]
- Barton, L., and T.D. Colmer. 2006. Irrigation and fertilizer strategies for minimizing nitrogen leaching from turfgrass. Agric. Water Manage. 80:160–175.[CrossRef]
- Beard, J.B. 2002. Turf management for golf courses. A publication of the United States Golf Association. Ann Arbor Press, Chelsea, MI.
- Boeker, P. 1974. Root development of selected turfgrass species and cultivars. In E.C. Roberts (ed.) Proc. of 2nd Int. Turfgrass Res. Conf., Blacksburg, VA. June 1973. ASA and CSSA, Madison, WI.
- Bremner, J.M., and C.S. Mulvaney. 1986. Nitrogen: Total. In A.L. Page (ed.) Methods of soil analysis: Part 2. Chemical and microbiological properties. Agron. Monogr. 9. ASA and SSSA, Madison, WI.
- Bowman, D.C., C.T. Cherney, and T.W. Rufty, Jr. 2002. Fate and transport of nitrogen applied to six warm-season turfgrasses. Crop Sci. 42:833–841.[Abstract/Free Full Text]
- Bowman, D.C., D.A. Devitt, M.C. Engelke, and T.W. Rufty, Jr. 1998. Root architecture affects nitrate leaching from bentgrass turf. Crop Sci. 38:1633–1639.[Abstract/Free Full Text]
- Bushoven, J.T., Z. Jiang, H.J. Ford, C.D. Sawyer, R.J. Hull, and J.A. Amador. 2000. Stabilization of soil nitrate by reseeding with perennial ryegrass following sudden turf death. J. Environ. Qual. 29:1657–1661.[Web of Science]
- Exner, M.E., M.E. Burbach, D.G. Watts, R.C. Shearman, and R.F. Spalding. 1991. Deep nitrate movements in the unsaturated zone of a simulated urban lawn. J. Environ. Qual. 20:658–662.[Web of Science]
- Geron, C.A., T.K. Danneberger, S.J. Traina, T.J. Logan, and J.R. Street. 1993. The effects of establishment methods and fertilization practices on nitrate leaching from turfgrass. J. Environ. Qual. 22:119–125.[Abstract/Free Full Text]
- Gross, C.M., J.S. Angle, and M.S. Welterlen. 1990. Nutrient and sediment losses from turfgrass. J. Environ. Qual. 19:663–668.[Abstract/Free Full Text]
- Guillard, K., and K.L. Kopp. 2004. Nitrogen fertilizer form and associated nitrate leaching from cool-season lawn turf. J. Environ. Qual. 33:1822–1827.[Abstract/Free Full Text]
- Lee, D.J., D.C. Bowman, D.K. Cassel, C.H. Peacock, and T.W. Rufty, Jr. 2003. Soil inorganic nitrogen under fertilized bermudagrass turf. Crop Sci. 43:247–257.[Abstract/Free Full Text]
- Liu, H., R.J. Hull, and D.T. Duff. 1997. Comparing cultivars of three cool-season turfgrasses for soil water NO3–concentration and leaching potential. Crop Sci. 37:526–534.[Abstract/Free Full Text]
- Mancino, C.F., and I.L. Pepper. 1994. Irrigation of turfgrass with wastewater. p. 174–191. In Wastewater reuse for golf course irrigation. USGA, Lewis Publ., Boca Raton, FL.
- Mangiafico, S.S., and K. Guillard. 2006. Fall fertilization timing effects on nitrate leaching and turfgrass color and growth. J. Environ. Qual. 35:163–171.[Abstract/Free Full Text]
- Meyer, J.L., V.A. Gibeault, and V.B. Youngner. 1985. Irrigation of turfgrass below replacement of evapotranspiration as a means of water conservation: Determining crop coefficient of turfgrasses. p. 357–364. In F. Lemaire (ed.) Proc. of the 5th Int. Turfgrass Res. Conf., Avignon, France. July 1985. INRA Publications, Versailles, France.
- Miltner, E.D., B.E. Branham, E.A. Paul, and P.E. Rieke. 1996. Leaching and mass balance of 15N-labeled urea applied to a Kentucky bluegrass turf. Crop Sci. 36:1427–1433.[Abstract/Free Full Text]
- Morton, T.G., A.J. Gold, and W.M. Sullivan. 1988. Influence of overwatering and fertilization on nitrogen losses from home lawns. J. Environ. Qual. 17:124–130.[Abstract/Free Full Text]
- Pang, X., J. Letey, and L. Wu. 1997a. Irrigation quantity and uniformity and nitrogen application effects on crop yield and nitrogen leaching. Soil Sci. Soc. Am. J. 61:257–261.[Abstract/Free Full Text]
- Pang, X., J. Letey, and L. Wu. 1997b. Yield and nitrogen uptake prediction by CERES-Maize model under semiarid conditions. Soil Sci. Soc. Am. J. 61:254–256.[Abstract/Free Full Text]
- Petrovic, A.M. 2004. Nitrogen source and timing impact on nitrate leaching from turf. Acta Hortic. 661:427–432.
- Qian, Y.L., W. Bandaranayake, W.J. Parton, B. Mecham, M.A. Harivandi, and A.R. Mosier. 2003. Long-term effects of clipping and nitrogen management in turfgrass on soil organic carbon and nitrogen dynamics: The CENTURY model simulation. J. Environ. Qual. 32:1694–1700.[Web of Science][Medline]
- Rauschkolb, R.S., and A.G. Hornsby. 1994. Nitrogen management in irrigated agriculture. Oxford Univ. Press, New York.
- Snyder, G.H., E.O. Burt, and B.L. James. 1977. [isobutylidene diurea] Nitrogen fertilization of bermudagrass [Cynodon dactylon] turf in south Florida with urea, UF [ureaformaldehyde] and IBDU. Proc. Fla. State Hortic. Soc. 89:326–330.
- Walker, W.J., and B. Branham. 1992. Environmental impacts of turfgrass fertilization. p. 105–219. In J.C. Balogh and W.J. Walker (ed.) Golf course management and construction: Environmental issues. USGA, Lewis Publ., Chelsea, MI.
This article has been cited by other articles:
|
|
|
|
 
B. G. Wherley, W. Shi, D. C. Bowman, and T. W. Rufty
Fate of 15N-Nitrate Applied to a Bermudagrass System: Assimilation Profiles in Different Seasons
Crop Sci.,
October 22, 2009;
49(6):
2291 - 2301.
[Abstract]
[Full Text]
[PDF]
|
|
|
TOP
ABSTRACT
INTRODUCTION
