Predictors of post-thrombotic syndrome in a population with a first deep vein thrombosis and no primary venous insufficiency.

BACKGROUND: Post-thrombotic syndrome (PTS) is the most frequent complication of deep vein thrombosis (DVT). Its diagnosis is based on clinical characteristics. However, symptoms and signs of PTS are non-specific, and could result from concomitant primary venous insufficiency (PVI) rather than DVT. This could bias evaluation of PTS. METHODS: Using data from the REVERSE multicenter study, we assessed risk factors for PTS in patients with a first unprovoked unilateral proximal DVT 5-7 months earlier who were free of clinically significant PVI (defined as absence of moderate or severe venous ectasia in the contralateral leg). RESULTS: Among the 328 patients considered, the prevalence of PTS was 27.1%. Obesity (odds ratio [OR] 2.6 [95% confidence interval (CI) 1.5-4.7]), mild contralateral venous ectasia (OR 2.2 [95% CI 1.1-4.3]), poor International Normalized Ratio (INR) control (OR per additional 1% of time with INR < 2 during anticoagulant treatment of 1.018 [95% CI 1.003-1.034]) and the presence of residual venous obstruction on ultrasound (OR 2.1 [95% CI 1.1-3.7]) significantly increased the risk for PTS in multivariable analyses. When we restricted our analysis to patients without any signs, even mild, of contralateral venous insufficiency (n = 244), the prevalence of PTS decreased slightly to 24.6%. Only obesity remained an independent predictor of PTS (OR 2.6 [95% CI 1.3-5.0]). Poor INR control and residual venous obstruction also increased the risk, but the results were no longer statistically significant (OR 1.017 [95% CI 0.999-1.035] and OR 1.7 [95% CI 0.9-3.3], respectively). CONCLUSIONS: After a first unprovoked proximal DVT, obese patients and patients with even mild PVI constitute a group at increased risk of developing PTS for whom particular attention should be paid with respect to PTS prevention. Careful monitoring of anticoagulant treatment may prevent PTS.

Risk of post-thrombotic syndrome after subtherapeutic warfarin anticoagulation for a first unprovoked deep vein thrombosis: results from the REVERSE study.

BACKGROUND: Risk factors for post-thrombotic syndrome (PTS) remain poorly understood. OBJECTIVES: In this multinational multicenter study, we evaluated whether subtherapeutic warfarin anticoagulation was associated with the development of PTS. METHODS: Patients with a first unprovoked deep venous thrombosis (DVT) received standard anticoagulation for 5-7 months and were then assessed for PTS. The time in the therapeutic range was calculated from the international normalized ratio (INR) data. An INR below 2, more than 20% of the time, was considered as subtherapeutic anticoagulation. RESULTS: Of the 349 patients enrolled, 97 (28%) developed PTS. The overall frequency of PTS in patients with subtherapeutic anticoagulation was 33.5%, compared with 21.6% in those with an INR below two for ≤ 20% of the time (P = 0.01). During the first 3 months of therapy, the odds ratio (OR) for developing PTS if a patient had subtherapeutic anticoagulation was 1.78 (95% confidence interval [CI] 1.10-2.87). After adjusting for confounding variables, the OR was 1.84 (95% CI 1.13-3.01). Corresponding ORs for the full period of anticoagulation were 1.83 (95% CI 1.14-3.00) [crude] and 1.88 (95% CI 1.15-3.07) [adjusted]. CONCLUSION: Subtherapeutic warfarin anticoagulation after a first unprovoked DVT was significantly associated with the development of PTS.

Comparison of the Villalta post-thrombotic syndrome score in the ipsilateral vs. contralateral leg after a first unprovoked deep vein thrombosis.

BACKGROUND: Post-thrombotic syndrome (PTS) is the most frequent complication of a deep vein thrombosis (DVT). International guidelines recommend assessing PTS with the Villalta scale, a clinical measure that incorporates venous symptoms and signs in the leg ipsilateral to a DVT. However, these signs and symptoms are not specific for PTS and their prevalence and relevance in the contralateral leg have not previously been studied. METHODS: Using data from the REVERSE prospective multicentre cohort study, we compared the Villalta total score and prevalence of venous signs and symptoms in the ipsilateral vs. contralateral leg in patients with a first, unilateral DVT 5 to 7 months previously. RESULTS: Among the 367 patients analyzed, the mean Villalta score was higher in the ipsilateral than in the contralateral leg (mean ± standard deviation [SD] 3.7 [3.4] vs. 1.9 [2.5], respectively; P<0.0001). Villalta scores in the ipsilateral and contralateral legs were strongly correlated (r=0.68; P<0.0001). Ipsilateral PTS (defined by a Villalta total score >4) was present in 31.6% (n=116) of patients. Among these, 39.7% (n=46) of patients had a Villalta score >4 in the contralateral leg, and the distribution of Villalta symptoms and signs components was similar between the legs. CONCLUSIONS: Villalta scores in the ipsilateral and contralateral legs are strongly correlated. Almost half of cases considered to be PTS might reflect pre-existing symptomatic chronic venous disease. Alternatively, patients with pre-existing chronic venous disease might be more prone to developing PTS after a DVT. Performing a bilateral assessment of Villalta scores at the acute phase of DVT could be of clinical interest from a diagnostic, prognostic and therapeutic point of view.

Residual vein obstruction as a predictor for recurrent thromboembolic events after a first unprovoked episode: data from the REVERSE cohort study.

OBJECTIVES: There is growing interest in using residual vein obstruction (RVO) to guide the duration of oral anticoagulant therapy (OAT) for unprovoked deep vein thrombosis (DVT). We sought to determine if RVO as determined by compression ultrasonography (CUS) after completion of 5-7 months of anticoagulation for unprovoked DVT is associated with an increased risk of recurrent venous thromboembolism (VTE). MATERIALS AND METHODS: This was a multicentre multinational prospective cohort study undertaken in tertiary care centers. Patients with a first 'unprovoked' major VTE were enrolled over a 4-year period and completed a mean 18-month follow-up in September 2006. All 452 patients with DVT had baseline CUS at inclusion to assess any RVO before stopping OAT at 5-7 months. During follow-up off OAT, all episodes of suspected recurrent VTE were independently adjudicated with reference to baseline imaging. RESULTS: Forty-five out of 231 patients with abnormal CUS (19.5%) had recurrent VTE during follow-up, as compared with 32 out of 220 patients with normal CUS (14.6%), and one patient had inadequate CUS. There was no significant association between an abnormal CUS at inclusion and the risk of recurrent VTE: hazard ratio 1.4 (95% confidence interval, 0.9-2.1), P=0.19. None of the different degrees of clot resolution on baseline CUS was statistically significantly associated with the risk of recurrent VTE. CONCLUSION: In our study, the presence of RVO at the time of OAT withdrawal was not associated with a statistically significant higher risk of recurrent VTE. RVO assessment may not be useful to guide duration of anticoagulation.

Patients with a first symptomatic unprovoked deep vein thrombosis are at higher risk of recurrent venous thromboembolism than patients with a first unprovoked pulmonary embolism.

BACKGROUND: Previous studies are mixed as to whether patients with unprovoked pulmonary embolism (PE) have a higher rate of venous thromboembolism (VTE) recurrence after anticoagulation is discontinued than patients with unprovoked deep vein thrombosis (DVT). OBJECTIVES: To determine whether patients with unprovoked PE have a higher rate of VTE recurrence than patients with unprovoked DVT in a prospective multicenter cohort study. PATIENTS/METHODS: Six hundred and forty-six patients with a first episode of symptomatic unprovoked VTE were treated with heparin and subsequent oral anticoagulation for 5-7 months, and were followed every 6 months for recurrent VTE after their anticoagulant therapy was discontinued. RESULTS: Of 646 patients, 194 had isolated PE, 339 had isolated DVT, and 113 had both DVT and PE. After a mean of 18 months of follow-up, there were 91 recurrent VTE events (9.5% annualized risk of recurrent VTE in the total population). The crude recurrent VTE rate for the isolated PE, isolated DVT and DVT and PE groups were 7.7%, 16.5% and 17.7%, respectively. The relative risk of recurrent VTE for isolated DVT vs. isolated PE was 2.1 (95% confidence interval 1.2-3.7). CONCLUSIONS: This study has demonstrated that patients with a first episode of unprovoked isolated DVT are 2.1 times more likely to have a recurrent VTE episode than patients with a first episode of unprovoked isolated PE. These findings need to be considered when determining the optimal duration of anticoagulant therapy for patients with unprovoked VTE.

Recurrent venous thromboembolism after surgery-provoked versus unprovoked thromboembolism.

SUMMARY BACKGROUND: The incidence of recurrent venous thromboembolism (VTE) varies depending on the nature of the initial provoking risk factor(s). OBJECTIVES: To compare the incidence and time course of recurrent VTE after unprovoked VTE vs. VTE provoked by nine different types of surgery. METHODS: Retrospective analysis of linked California hospital and emergency department discharge records. Between 1997 and 2007, all surgery-provoked VTE cases had a first-time VTE event diagnosed within 60 days after undergoing a major operation. The incidence of recurrent VTE was compared during specified follow-up periods by matching each surgery-provoked case with three unprovoked cases based on age, race, gender, VTE event, calendar year and co-morbidity. RESULTS: The 4-year Kaplan-Meier cumulative incidence of recurrent VTE was 14.7% (95%CI: 14.2-15.1) in the matched unprovoked VTE group vs. 7.6% (CI: 7.0-8.2) in 11 797 patients with surgery-provoked VTE (P < 0.001). The overall risk reduction was 48%, which ranged from 64% lower risk (P < 0.001) after coronary bypass surgery to 25% lower risk (P = 0.06) after disc surgery. The risk of recurrent VTE 1-5 years after the index event was significantly lower in the surgery group (HR = 0.47, CI: 0.41-0.53). Within the surgery-provoked group, the risk of recurrent VTE was similar in men and women (HR = 1.0, CI: 0.8-1.3). CONCLUSIONS: The risk of recurrent VTE after surgery-provoked VTE was approximately 50% lower than after unprovoked VTE, confirming the view that provoked VTE is associated with a lower risk of recurrent VTE. However, there was appreciable heterogeneity in the relative risk of recurrent VTE associated with different operations.

Risk of stroke after surgery in patients with and without chronic atrial fibrillation.

SUMMARY BACKGROUND: The extent to which chronic atrial fibrillation affects the risk of postoperative stroke is largely unknown. OBJECTIVES: We sought to determine the 30-day rate of stroke among patients with and without chronic AF who underwent 10 different types of surgery. PATIENTS/METHODS: The crude incidence of stroke was retrospectively determined using a population-based linked administrative database of hospitalized patients who underwent specified operations between 1 January 1996 and 30 November 2005. The risk of stroke in patients with AF was adjusted for age, race, sex, presence of diabetes, heart failure, hypertension and prior stroke. RESULTS: The overall 30-day rate of stroke in 69 202 patients with chronic AF was 1.8% (95% CI, 1.7-1.9%) vs. 0.6% (CI, 0.58-0.62%) in 2 470 649 patients without AF. The risk-adjusted odds of a postoperative stroke in patients with chronic AF were 2.1 (CI, 2.0-2.3). The highest incremental difference in the crude rate of stroke was observed in patients undergoing neurologic or vascular surgery, with a difference of approximately 2%. CONCLUSION: Patients with chronic AF had twice the risk of postoperative stroke. Randomized trials are needed to determine if aggressive perioperative anticoagulation can reduce the incidence of postoperative stroke in patients with AF.

Biosolid and alum effects on runoff losses during turfgrass establishment.

Large, volume-based rates of composted biosolids (CB) enhance turfgrass establishment and soil properties, but nonpoint-source runoff losses could occur during production and after transplanting of sod. The objective was to evaluate runoff losses of N, P, sediment, and organic C during establishment of sprigs or transplanted sod of Tifway bermudagrass (Cynodon dactylon L. Pers. X C. transvaalensis Burtt-Davey) with and without CB and aluminum sulfate (Alum). Four treatments comprised Tifway sprigged in a sandy loam soil with and without incorporation of 0.25 m(3) CB m(-3) soil and Alum. In four additional treatments, sod transplanted from Tifway grown with and without CB was established with and without a surface spray of Alum. During early establishment, CB incorporated in soil before sprigging reduced runoff loss of sediment and total N to amounts comparable to transplanted sod. In contrast, mean runoff losses of total dissolved P and soluble-reactive P (SRP) were more than 50% greater for CB-amended sod than for fertilizer-grown sod or Tifway sprigged in soil with or without CB. Yet, the surface spray of Alum reduced runoff loss from sod more than 88% for SRP and 41% for dissolved organic C. Both surface sprays and incorporation of Alum effectively reduced SRP runoff loss from CB, soil, and turfgrass sources during turfgrass establishment.

Validation of a diagnostic approach to exclude recurrent venous thromboembolism.

SUMMARY INTRODUCTION: The diagnosis of recurrent venous thromboembolism (VTE) is a challenge in clinical practice. Our objective was to evaluate the safety of a diagnostic strategy utilizing comparison of diagnostic test results with baseline imaging results to rule out suspected recurrent VTE. METHODS: The REVERSE study was a prospective cohort study whose primary aim was to develop a clinical prediction rule for recurrent VTE. We included and followed patients who completed 5-7 months of anticoagulant therapy after a first unprovoked VTE. Suspected cases of recurrent VTE were assessed according to standardized diagnostic criteria based on comparison of diagnostic test results with those obtained at the time of anticoagulant treatment withdrawal. RESULTS: Out of the 398 suspected events, a recurrent VTE was diagnosed in 106 cases (26.6%) and excluded in 292 cases. In 76 cases (19%), the diagnosis of recurrent VTE was excluded on the basis of the fact that no significant change on diagnostic imaging was detected when compared to baseline imaging. During the ensuing 3 months, six patients received anticoagulant therapy after recurrent VTE was excluded, and two were lost to follow-up. Eight of 284 remaining patients in whom recurrent VTE had been excluded, who were not treated and who were not lost to follow-up were diagnosed with subsequent VTE (3-month risk, 2.8%; 95% confidence interval, 1.4-5.5%). Six of these eight patients with subsequent recurrent VTE had a known superficial or distal thrombosis at the time of initial suspected recurrent VTE. CONCLUSION: A diagnostic strategy comparing diagnostic test results obtained at the time of the suspected recurrent event with those obtained at baseline can safely and effectively rule out recurrent VTE in a significant proportion of patients. Registered at http://www.clinicaltrials.gov identifier: NCT00261014.

The incidence of venous thromboembolism among patients with primary lung cancer.

BACKGROUND: The incidence of venous thromboembolism (VTE) by lung cancer histology and stage is unknown. OBJECTIVES: To determine the incidence of VTE and the risk factors associated with development of VTE in a large population-based study of patients with non-small cell and small cell lung cancer. METHODS: The California Cancer Registry was merged with the Patient Discharge Data Set to determine the incidence of VTE among lung cancer cases diagnosed between 1993 and 1999. RESULTS: Among 91 933 patients with newly diagnosed lung cancer, the 1-year and 2-year cumulative VTE incidences were 3.0% and 3.4%, respectively, with a person-time rate of 7.2 events/100 patient-years during the first 6 months. The 1-year incidence of VTE was significantly increased in comparison to the general population [standardized incidence ratio = 21.2, 95% confidence interval (CI) = 20.4-22.0]. In a multivariate model, significant predictors of developing VTE within 1 year of non-small cell lung cancer (NSCLC) diagnosis were: younger age, the number of chronic medical comorbidities [hazard ratio (HR) = 2.8 if 3 vs. 0, 95% CI = 2.5-3.1], advancing cancer stage (HR = 4.0 for metastatic vs. local disease, 95% CI = 3.4-4.6) and adenocarcinoma histology (HR = 1.9 vs. squamous cell, 95% CI = 1.7-2.1). In multivariate models, VTE was a significant predictor of death within 2 years for both NSCLC and small cell lung cancer (SCLC), HR = 2.3, 95% CI = 2.2-2.4, and HR = 1.5, 95% CI = 1.3-1.7, respectively. CONCLUSIONS: Approximately 3% of lung cancer patients developed VTE within 2 years. The diagnosis of VTE was associated with a higher risk of death within 2 years for NSCLC and SCLC.

Structure of an amide bond forming F(420):gamma-glutamyl ligase from Archaeoglobus fulgidus -- a member of a new family of non-ribosomal peptide synthases.

F(420) is a flavin-like redox-active coenzyme commonly used by archaea and some eubacteria in a variety of biochemical reactions in methanogenesis, the formation of secondary metabolites, the degradation of nitroaromatic compounds, activation of nitroimidazofurans, and F(420)-dependent photolysis in DNA repair. Coenzyme F(420)-2 biosynthesis from 7,8-didemethyl-8-hydroxy-5-deazariboflavin (Fo) and lactaldehyde involves six enzymatic steps and five proteins (CofA, CofB, CofC, CofD, and CofE). CofE, a F(420)-0:gamma-glutamyl ligase, is responsible for the last two enzymatic steps; it catalyses the GTP-dependent addition of two L-glutamate residues to F(420)-0 to form F(420)-2. CofE is found in archaea, the aerobic actinomycetes, and cyanobacteria. Here, we report the first crystal structure of the apo-F(420)-0:gamma-glutamyl ligase (CofE-AF) from Archaeoglobus fulgidus and its complex with GDP at 2.5 A and 1.35 A resolution, respectively. The structure of CofE-AF reveals a novel protein fold with an intertwined, butterfly-like dimer formed by two-domain monomers. GDP and Mn(2+) are bound within the putative active site in a large groove at the dimer interface. We show that the enzyme adds a glutamate residue to both F(420)-0 and F(420)-1 in two distinct steps. CofE represents the first member of a new structural family of non-ribosomal peptide synthases.

Runoff water quality from turfgrass established using volume-based composted municipal biosolids applications.

Municipal programs for turfgrass establishment recommend large volume-based application rates of composted municipal biosolids (CMB). This study compared runoff water quality among combinations of two common turfgrass establishment practices and two CMB sources. Bryan- or Austin-CMB were incorporated into 5 cm of soil at a rate of 12.5 or 25% by volume (v/v) on an 8.5% slope. Tifway bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy, var. Tifway] sprigs were planted and established; sod, produced at a separate site using either CMB amendment at the 25% v/v rate, was transplanted to the runoff plots on the same day. A mature stand of bermudagrass was used as a control. Runoff water was collected after each of eight natural rain events during the sampling period. Total runoff water loss (mm) was similar for the CMB-amended sprigged and transplanted sod stands. The concentration of total dissolved P (TDP) in runoff water was greatest from the transplanted sod in the first seven rain events (4.1 to 7.5 mg L(-1)). The concentration of TDP in runoff water was similar at both the 12.5 and 25% v/v incorporation rates. Regression analysis indicated Mehlich-3-extractable soil test P concentrations in soil amended with CMB were positively correlated to concentration and mass loss of dissolved P in runoff. At similar application rates, dissolved P loss in runoff water was reduced by incorporating CMB into the soil on site rather than transplanting sod produced with CMB.

High risk for venous thromboembolism in diabetics with hyperosmolar state: comparison with other acute medical illnesses.

BACKGROUND: Diabetes mellitus is generally not recognized as an important risk factor for venous thromboembolism (VTE). However, clinical observations and case reports have suggested that patients with diabetes and hyperosmolarity may be at increased risk for VTE. OBJECTIVES: To determine the risk of VTE in patients hospitalized for diabetes with hyperosmolar state compared to patients with other acute medical illnesses. PATIENTS/METHODS: The California Patient Discharge Data Set was used to determine the incidence of first-time VTE in all patients admitted between 1995 and 2000 for diabetes with hyperosmolarity and 11 other acute medical conditions. Proportional hazard modeling was used to adjust for age, race, gender, and prior hospitalization within 3 months. RESULTS: Among 2859 patients with diabetes and hyperosmolarity, 34 (1.2%) developed VTE during the hospitalization and 14 (0.5%) developed VTE within 91 days after discharge. In an adjusted multivariate model comparing the risk of VTE to cases with depression, patients with hyperosmolarity had a significantly higher risk of VTE [hazard ratio (HR) = 16.3; 95% confidence interval (CI): 10-25] comparable to the risk associated with sepsis (HR = 19.3; 95% CI: 13-29) or acute connective tissue disease (HR = 21; 95% CI: 15-31). Compared to uncomplicated diabetes, patients with hyperosmolarity had a significantly higher risk of VTE (HR = 3.0; 95% CI: 2.1-4.5) whereas patients with ketoacidosis were not at higher risk (HR = 1.2; 95% CI: 0.8-1.7). CONCLUSIONS: Patients hospitalized for diabetes with hyperosmolarity are at increased risk for developing VTE both during their inpatient stay and in the 3 months after discharge. Thromboprophylaxis in these patients appears warranted, and extended prophylaxis for after hospital discharge should be studied.

Assessment of manure phosphorus export through turfgrass sod production in Erath County, Texas.

A best management practice (BMP) for exporting manure phosphorus (P) in turfgrass sod from the North Bosque River (NBR) watershed in central Texas was assessed using a geographic information system (GIS). The NBR watershed has a mandate to reduce the total annual P load to the NBR by 50% as a result of total maximum daily load regulation. Since dairy waste applications to fields are identified as the major nonpoint source of P to the river, innovative BMPs, such as export of manure P in turfgrass, will be needed to achieve the 50% reduction. However, methods are needed to evaluate the feasibility of these innovative management practices prior to their implementation. A geospatial database of suitable turfgrass production sites was developed for Erath County using GIS. Erath County largely encompasses the upper portion of the NBR watershed. Information from field experiments, production practices, and ground-truthing was used to search, analyze, and verify a geospatial database developed from national and regional sources. The integration and analyses of large databases supports the search by turf producers for sites suitable for turfgrass sod production in Erath County. In addition, GIS enables researchers and regulators to estimate manure P exports and reduced P loading due to implementation of the manure export BMP on a county scale. Under optimal conditions 198,000 kg manure P yr(-1) could be used and 114,840 kg manure P yr(-1) exported from the NBR watershed through implementation of a system using dairy manure to produce turfgrass sod. This is the equivalent of the manure P applied from 10,032 dairy cows yr(-1) and exported from 5808 dairy cows yr(-1). Application of GIS to large-scale planning and decision-making transcends traditional field-scale applications in precision agriculture.

Effect of age on the incidence of venous thromboembolism after major surgery.

BACKGROUND: Most guidelines for administration of thromboprophylaxis after major surgery use age as a major predictor of postoperative venous thromboembolism (VTE). We sought to quantify the effect of age on the risk of symptomatic VTE after a spectrum of surgical procedures. METHODS: Using the California Patient Discharge Data Set and specific ICD-9-CM surgical procedure codes, we retrospectively determined the incidence of VTE diagnosed within 91 days after 40 different urgent or elective surgeries performed in the hospital between 1992 and 1996. Logistic regression was used to quantify the effect of age on the incidence of postoperative VTE and to adjust for other risk factors. RESULTS: 1,464,452 cases underwent one of 40 different procedures (mean cases per procedure = 35,718, range 4500-145 500). There was a significant interaction between age and the type of surgery performed (P<0.0001). Qualitative analysis of the effect of age on the incidence of VTE stratified by the presence or absence of malignancy revealed three general patterns: a steady increase in the incidence of VTE with age, exemplified by appendectomy or cholecystectomy; an increase in VTE up to approximately age 65 with no increase thereafter, exemplified by total hip arthroplasty; and no effect of age on the incidence of VTE, exemplified by vascular surgery. CONCLUSIONS: The relationship between age and the risk of VTE after surgery is complex and depends on the nature of the surgery and the underlying pathologic process. Advancing age was a significant predictor for VTE following surgeries performed for conditions not inherently associated with significant comorbidity. Conversely, advancing age was not associated with a higher incidence of VTE after surgeries performed for conditions strongly associated with serious underlying comorbidity, such as a malignancy or severe peripheral vascular disease.

Runoff losses of phosphorus and nitrogen imported in sod or composted manure for turf establishment.

Nutrient loading on impaired watersheds can be reduced through export of sod grown with manure and export of composted manure for turf production on other watersheds. Effects of the sod and manure exports on receiving watersheds were evaluated through monitoring of total dissolved phosphorus (TDP) and N concentrations and losses in runoff from establishing turf. Three replications of seven treatments were established on an 8.5% slope of a Booneville soil (loamy-skeletal, mixed, superactive Pachic Argicryolls). Three treatments comprised imported 'Tifway' bermudagrass [Cynodon dactylon (L.) Pers. x C. transvaalensis Burtt-Davy) sod grown with composted dairy manure (382 or 191 kg P ha(-1)) or fertilizer (50 kg P ha(-1)). Three treatments were sprigged with Tifway and top-dressed with either composted manure (92 or 184 kg P ha(-1)) or fertilizer (100 kg P ha(-1)). The control was established bermudagrass [Cynodon dactylon (L.) Pers. var. Guymon]. During eight fall rain events, mean TDP concentration in runoff (7.8 mg L(-1)) from sprigged Tifway top-dressed with manure (84 kg P ha(-1)) was 1.6 times greater than sod imported with 129 kg manure P ha(-1). During the first fall event, mass losses of TDP (232 mg m(-2)) and total Kjeldahl nitrogen (TKN) (317 mg m(-2)) from sprigged treatments top-dressed with manure or fertilizer were nearly three times greater than manure-grown sod. Percentages of manure P lost as TDP in runoff from imported sod were 33% of percentages lost from sprigged treatments top-dressed with manure. Sod grown with manure P rates of 190 kg P ha(-1) can be imported without increasing runoff losses of TDP compared with conventional fertilization of establishing turfgrass.

Export of manure phosphorus and nitrogen in turfgrass sod.

Regulatory mandates have increased demand for best management practices (BMPs) that will reduce nutrient loading on watersheds impaired by excess manure P and N. Export of manure P and N in turfgrass sod harvests is one BMP under consideration. This study quantified amounts and percentages of P and N removed in a sod harvest for different rates of manure and inorganic P and N. Six treatments comprised an unfertilized control, two manure rates with and without supplemental inorganic N, and inorganic P and N only. The treatments were applied to 'Tifway' bermudagrass (Cynodon dactylon L. x C. transvaalensis Burtt-Davey), '609' buffalograss [Buchloe dactyloides (Nutt.) Engelm.], and 'Reveille' bluegrass (Poa arachnifera Torr. x P. pratensis L.) under field conditions. Comparisons among treatments revealed small variations of P and N content in clippings and the plant component of sod, but large variations in the soil component of sod for each turf species. In addition, 2 to 10 times more P and 1.3 to 5 times more N was removed in soil than in plant components of sod for the two manure rates with and without added inorganic N. Percentages of applied P and N in harvested sod were similar for the two manure rates with and without added N for each species, but differed among turf species for each P (46 to 77%) and N (36 to 47%). The large amounts and percentages of manure P and N removed by sod harvest support the feasibility of this BMP in efforts to reduce nutrient loads on watersheds.