Browsing by Subject "Phosphorus"
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Item Agricultural phosphorus in an integrated crop/livestock system in the Texas High Plains(Texas Tech University, 2003-12) Collins, Jennifer L.This study Is a component of a project designed to develop a productive and environmentally sustainable integrated crop/livestock system that will assure the viability of agricultural activities in the Texas High Plains. The integrated crop/forage livestock system consists of (1) a Conventional Irrigated Cotton (Gossypium hirsutum) System and (2) an Alternative Integrated Crop/Forage/Livestock System with 1-paddock of Old World Bluestem (Bothiiochloa bladhii) and a 2-paddock rotation of rye {Secale cerea/e)/cotton/wheat (Tiiticum aestivum), and wheat/fallow/rye. Cattle sequence grazed the forages. The objective of this study was to evaluate changes in soil phosphorus (P) concentrations between the Conventional and Alternative Systems. Each system was replicated three times In a complete randomized block design. Soil samples were collected in 1997 and 2002 at multiple locations within each paddock by compositing three cores at each of the following depths: 0-15 cm, 15-30 cm, and 30-45 cm. Available P was determined using the Olsen bicarbonate extraction method.Item Amending constructed roadside and urban soils with large volume-based compost applications: effects on water quality(Texas A&M University, 2007-04-25) Hansen, Nels EdwardMineral nutrients imported in composted dairy manure (CDM) and municipal biosolid (CMB) amendments for highway-rights-of-way and urban landscapes can pose a threat to surface water quality. Treatments were developed to evaluate recommendations for amending roadside and urban soils with compost at large volumebased rates. Texas Department of Transportation (TxDOT) recommendations were evaluated in 2002 and 2003. Municipal recommendations were evaluated in 2004. Treatments were imposed on 4 by 1.5-m field plots on a constructed soil with an 8.5% slope. Three TxDOT compost application methods were tested; incorporation at 25% by volume (CMT), topdressing over vegetation (GUC), and topdressing a 5-cm compost woodchip mix over bare soil (ECC). In 2003, a 12.5% CMT treatment was substituted for the GUC, and two contrasting composts were compared. In 2002, soil test phosphorus (STP) concentrations (mg kg-1) were 291, 360, 410, and 1921 mg kg-1 in the 0 to 5-cm layer of a course textured CMT, fine textured CMT, GUC, and ECC treatments, respectively using CDM. In 2003, STP concentrations were 264, 439, 496,623, 1115, and 2203 mg kg-1, in the 0 to 5-cm layer after incorporation of CDM and CMB at the 12.5 and 25% volume-based rates, and topdressing the 5-cm CDM- or CMB-woodchip mix over bare soil, respectively. In 2004, contrasting CMB products, relatively low or high in total phosphorus (TP) were incorporated into the soil at 12.5 and 25% by volume, or imported in transplanted sod at the 25% by volume rate. The STP concentrations were 87, 147, 180, 301, 322, and 544 mg kg-1, respective to the previously defined treatments. Runoff water from 14, 10, and 8 natural rain events was used to characterize nutrient and sediment transport in 2002, 2003, and 2004, respectively. Concentration of TDP in runoff water was highly variable for roadside treatments across rain events. Mass losses of TDP were similar after CDM or CMB were incorporated into the soil at 12.5 and 25% by volume. Compost incorporation was the most effective method for limiting TP loss in runoff. Roadway and urban soils are expected to contribute greater TP losses as P concentration increases in soils.Item Deposition and properties of Co- and Ru-based ultra-thin films(2009-12) Henderson, Lucas Benjamin; Ekerdt, John G.Future copper interconnect systems will require replacement of the materials that currently comprise both the liner layer(s) and the capping layer. Ruthenium has previously been considered as a material that could function as a single material liner, however its poor ability to prevent copper diffusion makes it incompatible with liner requirements. A recently described chemical vapor deposition route to amorphous ruthenium-phosphorus alloy films could correct this problem by eliminating the grain boundaries found in pure ruthenium films. Bias-temperature stressing of capacitor structures using 5 nm ruthenium-phosphorus film as a barrier to copper diffusion and analysis of the times-to-failure at accelerated temperature and field conditions implies that ruthenium-phosphorus performs acceptably as a diffusion barrier for temperatures above 165 °C. The future problems associated with the copper capping layer are primarily due to the poor adhesion between copper and the current Si-based capping layers. Cobalt, which adheres well to copper, has been widely proposed to replace the Si-based materials, but its ability to prevent copper diffusion must be improved if it is to be successfully implemented in the interconnect. Using a dual-source chemistry of dicobaltoctacarbonyl and trimethylphosphine at temperatures from 250-350 °C, amorphous cobalt-phosphorus can be deposited by chemical vapor deposition. The films contain elemental cobalt and phosphorus, plus some carbon impurity, which is incorporated in the film as both graphitic and carbidic (bonded to cobalt) carbon. When deposited on copper, the adhesion between the two materials remains strong despite the presence of phosphorus and carbon at the interface, but the selectivity for growth on copper compared to silicon dioxide is poor and must be improved prior to consideration for application in interconnect systems. A single molecule precursor containing both cobalt and phosphorus atoms, tetrakis(trimethylphosphine)cobalt(0), yields cobalt-phosphorus films without any co-reactant. However, the molecule does not contain sufficient amounts of amorphizing agents to fully eliminate grain boundaries, and the resulting film is nanocrystalline.Item Effects of Biochar Recycling on Switchgrass Growth and Soil and Water Quality in Bioenergy Production Systems(2012-07-16) Husmoen, Derek HowardIntensive biomass production in emerging bioenergy systems could increase nonpoint-source sediment and nutrient losses and impair surface and groundwater quality. Recycling biochar, a charcoal byproduct from pyrolysis of biomass, provides potential sources of mineral nutrients and organic carbon for sustaining biomass productivity and preserving soil and water. Yet, research is needed to verify that recycling of pyrolysis biochars will enhance crop growth and soil and environmental quality similar to black carbon or biochar derived from burning of biomass in tropical or Terra Preta soils. The experimental design of this study consisted of 3 replications and four biochar rates (0, 4, 16, and 64 Mg ha-1) incorporated in both a sandy loam and clay soil with and without fertilizer sources of N, P, and K. The sandy loam and clay soils were studied in separate experiments within a set of 24 box lysimeters seeded with switchgrass. Simulated rain was applied at 50 percent and 100 percent establishment of switchgrass for each soil type. Runoff and leachate were collected and analyzed for total and dissolved N, P, K and organic C. After the second rain event, each soil type and the accumulated switchgrass was sampled and analyzed. In the Boonville soil, biochar applied at 64 Mg ha-1 decreased switchgrass emergence from 42 percent to 14 percent when compared to soil alone. In the Burleson soil, 64 Mg ha-1 biochar had no effect (P > 0.05) on biomass production or leaf area index (LAI). Fertilizer N, P, and K had no effect (P > 0.05) on switchgrass emergence for either soil, but did increase (P < 0.001) N, P, and K uptake, biomass production, and LAI. Increasing rates of biochar increased (P < 0.001) runoff concentrations of DRP during each rain event for both the Boonville and Burleson soils. Four rates of biochar receiving supplemental N, P, and K fertilizer also resulted in greater runoff concentrations of DRP. Emergence tests under increased heat showed electrical conductivities of soil-water solutions to be as high as 600 microS cm-1, even after biochar was washed with acetone and water to remove residual oils and tars and soluble salts. Increasing biochar rates decreased soil bulk density and increased pH and SOC in the 0- to 5-cm depth of soil. As a result of high nutrient recovery during pyrolysis (58 percent of total N, 86 percent of total P and 101 percent of total K), high rates of biochar applied at 64 Mg ha-1 increased mass losses of TN, TP, and TK from both soils. Yet, the mass balance of nutrients showed a surplus of N, P, and K at 64 Mg ha-1 biochar, which suggests some nutrient inputs are not plant available and remain in soil. Careful management of biochar, especially at high rates with these high nutrient contents, is critical when trying to improve soil fertility while protecting water quality. ?Item Evaluation of selected new technologies for animal waste pollution control(Texas A&M University, 2006-10-30) Lazenby, Lynn AnneIn 1998, two upper North Bosque River segments were designated as impaired due to the nonpoint source (NPS) pollution of phosphorus (P) to these segments in the watershed. As a result, two Total Maximum Daily Loads (TMDLs) were applied which called for the reduction of annual loading and annual average soluble reactive P (Sol P) concentrations by 50 %. This study was conducted to evaluate the efficacy of two prospective new technologies, an Electrocoagulation (EC) system, and a Geotube???? dewatering system to potentially aid the dairy farmers in meeting the goals set by the TMDLs. The EC system analyzed in this study used chemical pretreatment to coagulate and separate solids in effluent pumped from the dairy lagoon; the liquid then flowed over charged iron electrodes giving off ions that cause coagulation and precipitation of P and other metals. Overall, the performance of the system was consistently highly effective in reducing total phosphorus (TP) and Sol P, on average, reducing these constituents by 96% and 99.6% respectively from the dairy lagoon effluent. However this consistency did not hold for the rest of the analytes. In the Geotube???? dewatering system geotextile tubes were utilized to dewater dairy lagoon effluent. Results showed this system performed very well in filtering solids from the dairy lagoon effluent, removing an average of 93.5 % of the total solids between the two pumping and dewatering events of March and April. It was effective in removing nutrients and metals as well. The average percent reduction of TP and Sol P for the two events were very high at 97% and 85 % respectively.Item Increased temperature effects on fish-mediated nutrient cycling in an East Texas stream(2017-11-07) McWilliams, Jessica Lynn; Hargrave, Chad W.The unprecedented rate of global warming is an inevitable outcome of anthropogenic CO2 release into the atmosphere and complex climatic feedbacks. In ectotherms, increasing temperature may increase metabolic rates, which could enhance the energy demands of individuals and should accelerate resource acquisition. Population size and fish biomass were measured seasonally in a small second order stream over a 10-year period to examine seasonal variation in these parameters. I examined effects of increased temperature on nitrogen and phosphorus excretion in the four most abundant fish in this stream system. These fishes represent three functional feeding guilds common to many temperate stream ecosystems and comprise approximately 80-90% of the fish community. I developed temperature dependent nitrogen and phosphorus excretion models for fishes and applied these models to daily average temperatures in the stream. I then simulated climate warming (+2, +4, & +6°C) to examine the potential effects of increased temperature on fish-mediated nutrient dynamics in a southern temperate stream ecosystem. I found that increased temperature does increase nutrient cycling and nutrient flux within aquatic ecosystems; however, these effects appear to be tied to population size, biomass in addition to seasonal temperature. With increased temperature effects in spring and autumn having the greatest effect, when temperatures are cool and fish abundance and biomass is also greatest.Item Locating turfgrass production sites for removal of phosphorus in Erath County, Texas(Texas A&M University, 2004-09-30) Hanzlik, Jeremy EdwardThe North Bosque River watershed of central Texas hosts a large portion of diary production in the state. In recent years, the Texas Commission on Environmental Quality (TCEQ), formerly known as the Texas Natural Resource Conservation Commission (TNRCC), has applied a Total Maximum Daily Load Program for soluble phosphorus to the watershed. Best management practices (BMPs) are now necessary to remedy the issue of excess phosphorus. This thesis explores the application of GIS as an agricultural planning tool in support of a BMP for the region. The suggested BMP calls for the production of turfgrass sod using composted dairy manure; this sod is then transported at a profit from the watershed and provides an economically sustainable means to reduce the nutrient loading in the watershed. Using GIS, a geospatial database was developed with available data from government and institutional sources. As part of the development process, these sites were verified by field technicians and the results were combined in the GIS to refine the database. This database demonstrates the suitability of GIS as a tool for large-scale planning in agriculture.Item Nitrogen and phosphorus nutrition for semi-dwarf castor (Ricinus communis L.) production in West Texas(2012-08) Wallace, Sean M.; Trostle, Calvin S.; Auld, Dick L.; Wheeler, Terry A.In general technical nitrogen and phosphorus requirements have not been established for castor in the United States. Brazil and India have each shown nutrient requirements for castor although the climate, soil types, cultivars, and cultivation techniques are vastly different than what would be used regionally in the United States. Our objective is to measure yield response to nitrogen fertilization on irrigated castor in West Texas. Field tests were conducted 2010-2011 at Lubbock, TX (Texas Tech University Quaker Research Farm, and Texas AgriLife Extension and Research Farm), and 2010 at Pecos, TX (Texas AgriLife Research Farm), using an RCDB layout with five replication of five treatments (0-40-80-120-160 lbs/A of N added in the form of UAN). Spring soil samples were collected from each plot (0-6”, 6-12”, 12-24”, 24-36”, and if possible 36-48”, 48-60” depths) and analyzed for nitrate and ammonium nitrogen, and additionally Melich III phosphorus for phosphorus test sites. The 2011 drought reduced the yields enough to likely overshadow possible significant differences. The 2010 TTU Quaker Research Farm Site showed significant increases in yield from the 80 and 120 lbs/A N vs. the 0 lbs/A N treatment (P = 0.05), with soil test to the 36” depth showing an accumulation that averaged around 45 lbs/A of nitrate nitrogen. The 2010 AgriLife Lubbock Research Farm site soil test results show large accumulations of soil nitrate nitrogen to the depth of 36” averaging near 150 lbs/A, with no significance differences between N treatments. The 2010 AgriLife Pecos Research Farm site soil test results also showed large accumulations of soil nitrate nitrogen to the depth of 36” averaging near 250 lbs/A. Yields for this site were low and differences were not meaningful, significant differences between treatments were found between the 0 and 40 lbs/A treatment vs. the 160 lbs/A treatment (P = 0.05). The sites with low levels of rainfall and irrigation showed N treatments ineffective at increasing yield. Test sites with higher levels of rainfall and irrigation show the treatments of 80-120 lbs/A of nitrogen to significantly increase the yield. High subsoil nitrate nitrogen levels masked any yield response to nitrogen fertilizers. Overall, the fields appear to have adequate P levels for most. Unlike typical recommended 0-6” soil tests for P, moderate levels of P were also measured at 6-12” for Quaker 2010 & Quaker 2011, and Lubbock 2011. For the Quaker 2010 & Quaker 2011, and Lubbock 2011 sites when subsoil P at 6-12” is added to 0-6” then the combined soil P became 25 to 39 ppm, or in the lower range of moderate P to a higher moderate range soil P. Only one test site showed any positive response to P fertilization Quaker 2010 testing 19 ppm P 0-6” or combining with the 6-12” sample of 10 ppm P totaling 29 ppm P. The recommendation for this 29 ppm P would be the addition of 20-40 lbs P2O5 fertilizer.Item Phophorus and nitrogen leaching losses during turf establishment(Texas A&M University, 2004-09-30) Hay, Francis JohnConcerns over water quality have led to required removal of 50 % of dairy manure phosphorus (P) from the impaired Bosque River Watershed. Application of composted dairy manure (CDM) to sod and moving P off the watershed with sod has prompted a study using box lysimeters to determine NO3--N and P leaching from transplanted sod grown with CDM and inorganic fertilizer as well as sprigs top-dressed with CDM. Treatments were applied to lysimeters filled with a silica sand medium. Three leaching events were imposed, leaching 0.07 to 0.09 % of the total P applied and 0.09 to 1.43 % of total N applied. Concentrations of P in leachate averaged 0.04 to 0.25 mg L-1. Top-dressed CDM on sprigs leached statistically greater amounts of NO3--N than both transplanted sod treatments and greater P than the fertilizer grown sod. After the third leaching event, all treatments received an additional application of P, 100 kg ha-1 as CDM for manure-grown sod and sprigs, 50 kg ha-1 as triple superphosphate for fertilizer-grown sod. An additional three leachings were imposed. Top-dressed sprigs and transplanted sod leached similar amounts of P following the additional P application. Applied nutrients appeared to stay mainly in the sod layer and in the sand medium just below the sod layer. Top-dressed CDM appears to exhibit greater leaching losses of NO3--N than transplanted manure-grown sod and greater N and P losses than transplanted fertilizer grown sod.Item Phosphorus and Other Nutrient Disappearance from Plants Containing Condensed Tannins Using In Situ and Mobile Nylon Bag Techniques(2011-02-22) Pagan Riestra, SuzikaPlants containing condensed tannins (CT) represent an alternative feed resource for ruminants. However, limited information regarding nutrient disappearance from these plants is available. Two experiments were conducted to evaluate phosphorus (P) and other nutrient disappearance from plants containing CT. In the first experiment, nutrient disappearance from three native Texas species (Acacia angustissima var. hirta, Desmodium paniculatum, Smilax bona-nox, and Medicago sativa as control) were evaluated using the mobile nylon bag technique. For the second experiment, ruminal degradation parameters, ruminal and post-ruminal disappearance of P and other nutrients from a browse containing CT (Quercus virginiana) were compared to species without CT (Cynodon dactylon cv. Tifton 85, and Medicago sativa). Results from the first experiment indicate that the proportion of nutrient that disappeared during rumen, pepsin/HCl, or intestinal incubation differed among plant species and nutrient evaluated (P<0.05) and did not appear to be directly related to relative CT concentrations. Dry matter (DM), inorganic matter (IM), and organic matter (OM) disappearance were greater (PItem Phosphorus speciation in municipal biosolids for efficient phosphorus recovery(2016-05) Gutierrez, Carlos Felipe; Katz, Lynn Ellen; Kinney, Kerry A.; Lawler, Desmond F; Kirisits, Mary Jo; Blackhurst, Michael FPhosphorus is a required element for industrialized crop production. Our ability to produce phosphorus fertilizers has allowed humanity to sustain its population. The current sources of phosphorus are apatite sedimentary deposits geographically concentrated in four countries (Vaccari 2009). Recent reports have suggested that these resources will be exhausted by the end of this century and that the limited geographical distribution of phosphorous deposits may prove to be a source of political conflict in the future (Smil 2000, Cordell et al. 2009, Vaccari 2009). To avoid these conflicts, the potential for spent phosphorus recovery and reuse must be explored. One promising source stream for phosphorus recovery is from municipal wastewater biosolids. Current methods of phosphorus recovery from these solids only target 10% of the total phosphorus in the biosolids. To recover greater quantities of phosphorus from biosolids, we must understand the phosphorus speciation within, and be able to predict the most effective recovery method for biosolids generated from conventional activated sludge, chemical phosphorus removal or enhanced biological phosphorus removal (EBPR). In order to understand the speciation of these three types of biosolids, nine municipal wastewater treatment plants were sampled. The results showed that in biosolids post-anaerobic digestion and gravity thickening a large portion of the phosphorus is present as particulate orthophosphate and polyphosphate and requires a process that targets these species. Comparison of the speciation of conventional biosolids to the speciation of biosolids from chemical phosphorus removal and EBPR showed that energy intensive technologies such as the Stuttgart process and KREPRO can recover significant quantities of phosphorus from all types of biosolids. Commercial technologies (AIRPREX) only recovered significant quantities of phosphorus when used only with EBPR biosolids. Finally, a life cycle impact assessment was performed to assess eutrophication and green-house gas potential under various scenarios of phosphorus recovery. The results showed that scenarios with chemical or biological phosphorus removal plants typically had a lower eutrophication potential than those with conventional activated sludge. Even though treatment plants with biological and chemical phosphorus removal require more energy and chemicals to operate, the global warming potentials were lower than for conventional activated sludge scenarios.Item Reactions of phosphorus (III) oxides(Texas Tech University, 1976-05) Walker, Michael L.Not availableItem Response of nitrogen and phosphorus leaching and soil properties to applications of biosolids during turfgrass establishment(Texas A&M University, 2005-02-17) Kerns, James PatrickRegulations for total maximum daily loads require management of phosphorus loading from farms and municipalities. This study evaluated environmental impacts of a system for using and exporting the phosphorus in composted dairy manure (CDM) and composted municipal biosolids (CMB) through turfgrass sod. Responses of soil physical, chemical, and biological properties within and below the sod layer were monitored during turfgrass establishment in two experiments under greenhouse conditions. During turf establishment in column lysimeters, phosphorus and nitrogen leaching from an amended surface layer through soil were evaluated. In addition, growth of turf was related to the observed changes in soil nutrients and properties. In the first experiment, four replications of a factorial design comprised three soil types (USGA greens sand, Windthorst fine sandy loam [fine, mixed, thermic Udic Paleustalf], Houston black clay [fine, smectitic, thermic, Udic Hapustert]), two dairy manure rates ( 200 kg P ha-1, 400kg P ha-1), and two turf species (St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze var. Raleigh) and Tifway 419 Bermudagrass (Cynodon dactylon [L.] Pers. x C. transvaaleensis Burtt-Davy). Columns received three separate leaching events in which a 9-cm depth of distilled water was applied. A similar experimental design was implemented for Experiment 2 in January 2004. Treatments consisted of the same three soils and three volume-based rates of CDM and CMB (0, 150, 250 cm3 L-1) during establishment of St. Augustinegrass turf. Columns received one pore volume of distilled water on three separate occasions. In both experiments, soil physical properties (bulk density, water infiltration rate, and water content) and microbial populations were unaffected by CDM or CMB. Applications of CDM at P-based rates utilized in the first experiment yielded no variation of leaching loss among rates of P or N. Most of the P applied was retained in the top 10 cm of soil. When large volume-based rates were used, leaching losses of P and N varied among CDM or CMB application rates. Leaching losses were only observed in the USGA sand and were highest for the 250 cm3 L-1 rate of CDM or CMB. Regardless of compost source, applications of organic amendments at volume-based rates can increase leaching loss of P and N on sandy soils. However, if P-based rates are used there is little risk for leaching loss of N and P during sod establishment.Item The fate of manure phosphorus during production and harvest of turfgrass sod(Texas A&M University, 2005-08-29) McDonald, Brandon TiemanRemoval of manure from dairies to sites less prone to point-source nutrient pollution is an option for dealing with dairy confined animal feeding operation wastes. Applications of dairy manure waste to turfgrass sod can be an environmentally sound approach because both plant matter and soil are removed during harvest (Vietor et al., 2002). Field scale research was conducted on a pair of adjacent, 1.42 ha Tifway bermudagrass fields on a fine-textured clay soil to investigate the fate of manure phosphorus (P) from composted dairy manure applications. Both fields received equal rates of supplemental nitrogen fertilizer but one was treated with composted dairy manure. The treated field received 75 kg ha-1 P during the first crop. After harvest, 127 kg ha-1 P was applied to the second crop. Once reestablished, this crop was harvested. Surface layer sod and subsurface soil were frequently sampled on a grid pattern from each field and analyzed to monitor soil P. Both plant extractable and total P analyses were used. It was determined that a sod harvest couldeffectively remove all of the applied manure P. Below the sod layer, there were no increases in soil P as a result of the composted dairy manure treatments, indicating that P leaching did not occur. Phosphorus runoff during rain events or irrigation was monitored by members of the Department of Biological and Agricultural Engineering. It was reported that more P was lost in runoff from the compost treated field than the untreated field. Cumulative water infiltration rate, soil bulk density, and plant available water holding capacity of the soil were tested to determine if the composted dairy manure treatments affected these soil physical properties. The only significant change was an increase in plant available water holding capacity on the surface layer of the treated field. An economic analysis was performed using actual financial data from the project. A scenario was created to investigate the feasibility of a dairy farm profitably adding a small turfgrass sod enterprise to its operation. It was determined that a sod field enterprise could be moderately to highly profitable for a dairy.Item Vegetative covers for sediment control and phosphorus sequestration from dairy waste application fields(Texas A&M University, 2008-10-10) Giri, SubhasisExcessive phosphorus (P) in runoff contributes to eutrophication of fresh water bodies. Studies have shown that manure and effluent applied from animal feeding operations to waste application fields (WAFs) have contributed to excess P in segments of the North Bosque River in east central Texas. There is a growing need for environmentally sound, economically viable, and easy to establish best management practices to control such pollution. Vegetative buffer strips offer a potential solution for reducing runoff P from WAFs by extracting it from soil and by reducing sediment P delivery (due to reduced runoff and soil erosion) to streams. In a field study, ten plots (5m x 5m) were assigned to five replicated treatments, namely control (bare, without having any plant cover), cool season grass, warm season forb, warm season grass, and warm season legume to assess their efficacy of runoff sediment control and P sequestration potential from soil. These plots were established on a coastal Bermuda grass WAF that received dairy lagoon effluent. A runoff collection system, a 1m x 1m sub-plot with a runoff conveyance and collection apparatus, was installed on the upstream and downstream margins of each plot. Natural rainfall runoff samples were collected and analyzed subsequently for total P, soluble P, and total suspended solids in the laboratory. Additionally, the total mass of runoff collected from each sub-plot was calculated. Results suggested that the warm season forb and warm season grass were the most effective vegetative covers for the reduction of runoff P, followed by coastal Bermuda and cool season grass, respectively. The lesser amount of runoff total P in these two treatments was due to lesser runoff mass and lesser sediments in the runoff due to initial interception of rain and less raindrop impact on soil because of denser vegetative cover in both treatments compared to all other treatments.