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.

Assessment of a turfgrass sod best management practice on water quality in a suburban watershed.

The disposal of manure on agricultural land has caused water quality concerns in many rural watersheds, sometimes requiring state environmental agencies to conduct total maximum daily load (TMDL) assessments of stream nutrients, such as nitrogen (N) and phosphorus (P). A best management practice (BMP) has been developed in response to a TMDL that mandates a 50% reduction of annual P load to the North Bosque River (NBR) in central Texas. This BMP exports composted dairy manure P through turfgrass sod from the NBR watershed to urban watersheds. The manure-grown sod releases P slowly and would not require additional P fertilizer for up to 20 years in the receiving watershed. This would eliminate P application to the sod and improve the water quality of urban streams. The soil and water assessment tool (SWAT) was used to model a typical suburban watershed that would receive the sod grown with composted dairy manure to assess water quality changes due to this BMP. The SWAT model was calibrated to simulate historical flow and estimated sediment and nutrient loading to Mary's Creek near Fort Worth, Texas. The total P stream loading to Mary's Creek was lower when manure-grown sod was transplanted instead of sod grown with inorganic fertilizers. Flow, sediment and total N yield were the same for both cases at the watershed outlet. The SWAT simulations indicated that the turfgrass BMP can be used effectively to import manure P into an urban watershed and reduce in-stream P levels when compared to sod grown with inorganic fertilizers.

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.

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.

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.

The use of vegetation to remediate soil freshly contaminated by recalcitrant contaminants.

The use of vegetation to remediate soil contaminated by recalcitrant hydrocarbons was tested under field conditions. Specifically, an evaluation was made of the effectiveness of deep rooting grasses, Johnsongrass and Canadian wild rye in the dissipation of TNT and PBB's in the soils freshly contaminated to an initial concentration of 10.17+/-1.35 for TNT and 9.87+/-1.23 mg/kg for PBB. The experiment used 72 (1.5m long and 0.1m diameter) column lysimeters with four treatments: Johnsongrass; wild rye grass; a rotation of Johnsongrass and wild rye grass; and unplanted fallow conditions. In the laboratory, immunoassay test procedures determined the TNT and PBB concentrations in the soil, leachate, herbage and root samples. The root characteristics such as total root length, rooting density, and root surface area were quantified to a depth of 1.5m. Changes in microbial biomass were assessed for both rhizosphere soil and the bulk soil during the 2-year study. The largest and most rapid loss in soil chemical concentration was for TNT, which decreased to less than 250 microg/kg, the detection limit, by 93 days after germination. The PBB was at or near the detection limit of 500 microg/kg by 185 days after germination. There was no perceptible difference in contaminant concentration in the soil between the vegetation treatments and/or with depth.

Response of turf and quality of water runoff to manure and fertilizer.

Manure applications can benefit turfgrass production and unused nutrients in manure residues can be exported through sod harvests. Yet, nutrients near the soil surface could be transported in surface runoff. Our research objective was to evaluate responses of bermudagrass [Cynodon dactylon (L.) Pers. var. Guymon] turf and volumes and P and N concentrations of surface runoff after fertilizer or composted manure applications. Three replications of five treatments were established on a Boonville fine sandy loam (fine, smectitic, thermic Vertic Albaqualf) that was excavated to create an 8.5% slope. Manure rates of 50 and 100 kg P ha(-1) at the start of two monitoring periods were compared with P fertilizer rates of 25 and 50 kg ha(-1) and an unfertilized control. Compared with initial soil tests, nitrate concentrations decreased and P concentrations increased after two manure or fertilizer applications and eight rain events over the two monitoring periods. The fertilizer sources of P and N produced 19% more dry weight and 21% larger N concentrations in grass clippings than manure sources. Yet, runoff volumes were similar between manure and fertilizer sources of P. Dissolved P concentration (30 mg L(-1)) in runoff during a rain event 3 d after application of 50 kg P ha(-1) was five times greater for fertilizer than for manure P. Observations during both monitoring periods indicated that total P and N losses in runoff were no greater for composted manure than for fertilizer sources of P at relatively large P rates on a steep slope of turfgrass.

The use of box lysimeters with freshly contaminated soils to study the phytoremediation of recalcitrant organic contaminants.

The potential for phytoremediation of soil contaminated by trinitrotoluene (TNT) and 2,2',5,5'-tetrabromobiphenyl (PBB was used as a surrogate for PCBs) was examined in a 2-year study using box lysimeters under field conditions. The treatments were a warm season grass, Johnson grass, and a cool season grass, Canadian wildrye, and a rotation of Johnson grass and wildrye plus a fallow condition. The experiment was conducted using 12 large (1.50 m x 1.50 m x 0.75 m), in-ground, box lysimeters filled with a Weswood silt-loam soil freshly spiked with the TNT and PBB compounds to a concentration of 10 mg kg(-1) for each chemical. The lysimeters were sheltered to permit controlled applications of water. A total of five sampling rounds were conducted where soil, herbage, and leachate samples were collected for laboratory analysis. TNT and PBB concentrations were determined using the U.S. EPA approved immunoassay test procedures. In the soil, TNT concentrations dropped below the detection limit of 0.25 mg kg(-1) by day 92 and PBB concentrations dropped below the detection limit of 0.50 mg kg(-1) by day 184. There were no significant differences in chemical concentrations among any of the vegetated or fallow treatments at a significance level of alpha < 0.05. However, PBB soil concentrations rebounded above the 0.50 mg kg(-1) level by day 720 for all treatments. No detectable concentrations of TNT or PBB were found in any of the herbage samples or in the leachate.

Plant contamination by organic pollutants in phytoremediation.

Phytoremediation is a remediation technique that involves plant uptake, transformation, accumulation, and/or volatilization of soil- and aqueous-phase contaminants or by the stimulation of microbial cometabolic activity in the rhizosphere of the plant. Even when the principal mechanism is by stimulation of bacteria, any resultant plant contamination cannot be overlooked. For the purpose of modeling, a two-compartment plant model has been developed. The model divides the plant into the shoot compartment (which can be harvested) and the root compartment (into which contaminants can accumulate). Numerical experiments were conducted to investigate model behavior and to determine important parameters affecting plant contamination. Johnsongrass [Sorghum halepense (L.) Pers.] was used to evaluate the model behavior. The contaminants TNT (2,4,6,-trinitrotoluene) and chrysene were selected on the basis of their contrasting aqueous-phase solubilities. The results indicate that plant contamination and soil remediation by plants depend on soil properties such as soil organic carbon content, the physicochemical properties of the contaminants such as the octanol-water partition coefficient, and plant properties. The most important factor affecting plant contamination is bioavailability. As bioavailability increased, the concentrations in root and shoot compartments were predicted to increase. Microbial activities and plant contamination are closely related, which suggests that plants and microorganisms can have complementary roles in phytoremediation.