Seasonal Runoff Losses of Carbon, Nitrogen and Phosphorus from warm-season turfgrass systems

Transcription

1 TREEE Funded Project FY Sesonl Runoff Losses of Crbon, Nitrogen nd Phosphorus from wrm-seson turfgrss systems Investigtors: Jcqueline. itkenhed-peterson nd en Wherley Funding: $1, Objectives: The objectives of our proposed reserch were to: 1) Quntify sesonl runoff losses of N, P, nd C from wrm-seson turfgrss systems. 2) Quntify irrigtion input nd output SR, dissolved orgnic crbon nd nitrogen nd orthophosphte-p weekly over one yer. 3) Clculte mss losses of C, N nd P per unit re nd 4) Develop empiricl models for predicting mss losses nd C, N nd P from soil over time. 5) Determine if fertiliztion reduces or enhnces C, N nd P losses. Summry: We exmined three replicte plots receiving zero fertilizer nd three replicte plots receiving 4.9 g m 2 ure fertilizer one week fter sod ws instlled nd 4.9 g m 2 of Scotts Compny Southern Turf uilder in My 213. Sod ws instlled on the plots in September 212. For the first six weeks we pplied irrigtion wter to force runoff to ssess losses of C, N nd P nd sodium retention nd ction relese from the soil. Therefter, rin event runoff only ws cptured nd nlyzed except for months where there ws no rin when we irrigted to produce runoff. Fertilizer nd Sesonl effects on mcro nd micro-nutrient export NO 3 -N (mg m -2 ) Fll Winter Spring b NH 4 -N (mg m -2 ) b DON (mg m -2 ) C Figure 1. Exports of nitrte-n, mmonium-n nd dissolved orgnic-n from fertilized nd unfertilized St. ugustine turfgrss plots by seson. Error brs re stndrd devition. Different lower-cse letters indicte significnt difference between unfertilized nd fertilized plots for ech seson. Different upper-cse letters indicte significnt difference in exports within unfertilized or within fertilized plots by seson. Nitrte-N Seson hd greter effect on nitrogen exports within tretments compred to fertiliztion type mong tretments. There ws significntly higher export of nitrte-n during the spring in the unfertilized tretments reltive to fll nd winter exports. There ws significntly lower export of nitrte-n during

2 the winter reltive to the fll in the fertilized tretments (Figure 1). Fertiliztion resulted in significntly higher exports of nitrte-n in the fll only just fter turf ws estblished (Figure 1). mmonium-n Seson hd significnt effect on mmonium-n exports in the fertilized plots only. Winter exports of mmonium were significntly lower thn in the fll for the fertilized plots (Figure 1). Fertiliztion significntly incresed export of mmonium-n in the spring only; there ws no effect of fertiliztion for the winter of spring sesons (Figure 1). Dissolved orgnic nitrogen Seson hd significnt effect on DON exports in both the unfertilized nd fertilized plots. DON export ws significntly lower in the winter compred to the fll nd spring in the unfertilized plots (Figure 1). DON export ws significntly higher in the spring compred to the winter nd fll, nd DON export ws significntly higher in the fll compred to the winter in the fertilized plots (Figure 1). Fertiliztion hd no significnt effect on DON exports in ny seson (Figure 1). Orthophosphte-P Seson lso hd greter effect on phosphte-p exports thn fertiliztion. There were significntly lower phosphte-p exports during the winter compred to the fll nd spring, but there ws no significnt difference in phosphte-p export when compring fll nd spring in both the unfertilized nd fertilized tretments (Figure 2). Fertiliztion hd no significnt effect on phosphte-p export (Figure 2). Phosphte- P (mg m - 2 ) DOC (mg m - 2 ) Figure 2. Exports of phosphte-p nd dissolved orgnic crbon (DOC) from fertilized nd unfertilized St. ugustine turfgrss plots by seson. Error brs re stndrd devition. Different lower-cse letters indicte significnt difference between unfertilized nd fertilized plots for ech seson. Different upper-cse letters indicte significnt difference in exports within unfertilized or within fertilized plots by seson. Dissolved orgnic crbon There ws no significnt effect of seson in the fertilized plots but in the unfertilized plots DOC exports were significntly lower in the winter compred to the fll (Figure 2). Fertiliztion hd no significnt effect on DOC export (Figure 2).

3 Sodium Fertiliztion hd no significnt effect on sodium exports but seson did. In the unfertilized plots there were significntly higher sodium exports in the fll compred to the winter nd spring sesons (Figure 3). In the fertilized plots sodium export ws significntly higher in the fll compred to the spring (Figure 3). Potssium Neither seson or fertiliztion hd significnt effect on potssium exports in the unfertilized plots (Figure 3). In the fertilized plots, fertiliztion hd no effect on potssium export but exports were significntly higher in the spring compred to the fll (Figure 3). Sodium (mg m - 2 ) Potssium (mg m - 2 ) Mgnesium (mg m - 2 ) C C Clcium (mg m - 2 ) Figure 3. Exports of sodium, potssium, mgnesium nd clcium from fertilized nd unfertilized St. ugustine turfgrss plots by seson. Error brs re stndrd devition. Different lower-cse letters indicte significnt difference between unfertilized nd fertilized plots for ech seson. Different upper-cse letters indicte significnt difference in exports within unfertilized or within fertilized plots by seson. Mgnesium Seson hd n effect on mgnesium exports but fertiliztion did not. Winter hd significntly higher mgnesium exports compred to fll nd spring nd spring hd significntly lower mgnesium exports compred to fll nd winter nd in both the unfertilized nd fertilized plots (Figure 3).

4 Clcium Seson hd n effect on clcium exports but fertiliztion did not. Winter hd significntly higher clcium exports compred to fll nd spring in both the unfertilized nd fertilized plots (Figure 3). Seson, Fertiliztion nd Irrigtion wter interctions Using multivrite nlysis with irrigtion wter (municipl tp wter or rin), fertiliztion (fertilized or unfertilized) nd seson (fll, winter or spring) s independent vribles nd run off chemistry s dependent vribles showed tht seson hd significnt effect on DOC, sodium, mgnesium nd clcium exports (p =.5-.1). Irrigtion wter type hd significnt effect on DON, phosphte-p, DOC, sodium, mgnesium nd clcium exports (p =.5-.1). Fertiliztion hd no significnt effect on ny nutrient exports mesured. There were some interctions; seson nd irrigtion hd significnt interction effect on DOC, mgnesium nd clcium (p =.2-.1). Retention nd relese of bse ctions To determine retention or relese of ctions from the plots we deducted runoff outputs (mg m -2 ) from rin nd irrigtion inputs (mg m -2 ) nd divided by inputs nd multiplied by 1 for percentge loss. Negtive vlues indicte tht ll input ction ws lost plus soil stored ctions. Sodium whether inputs were from rin or irrigtion wter ws retined in the plots during ll sesons (Figure 4). etween 77 nd 96% of ll input sodium ws retined during the course of the study. Potssium showed soil losses throughout the study; between 12 nd 115% of input potssium ws lost (Figure 4). Mgnesium nd clcium hd extremely high soil losses during the winter seson nd this ws likely cused by high rinfll nd gypsum ddition. Figure 4. Retention nd relese of ctions in unfertilized nd fertilized tretments by seson.

5 Modeling exports of C, N nd P Potssium export explined between 94 nd 96% of the vrince in nitrte-n exports in the unfertilized plots (Figure 5) nd between 77 nd 99% of the vrince in nitrte-n exports in the fertilized plots (Figure 6). Potssium lso explined between 82 nd 92% of the vrince in phosphte-p in the unfertilized plots nd between 56 nd 96% of the vrince in phosphte-p in the fertilized plots. Vrince in DOC nd DON exports ws lso well described by potssium exports (Figures 6 nd 6). etween 83 nd 84% of the vrince in DOC export in unfertilized plots ws explined by potssium (Figure 5) nd between 61 nd 92% of the vrince in DOC ws explined by potssium in the fertilized plots. Eighty-six to 98% of the vrince in DON ws explined by potssium in the unfertilized plots (Figure 5) nd between 77 nd 99% of the vrince in DON ws explined by potssium in the fertilized plots (Figure 6). Reltionships between nion exports nd potssium exports were stronger in both unfertilized nd fertilized plots irrigted with tp wter compred to rin wter inputs (Figures 5 nd 6).

6 NO 3 -N Export (mg m -2 ) Tp Wter y =.847e.98x R² =.96 Rin Wter y =.4x R² =.94 PO 4 -P Export (mg m -2 ) Rin Wter y =.1488x R² =.82 Tp Wter y = e.11x R² = Potssium Export (mg m -2 ) Potssium Export (mg m -2 ) DOC Export (mg m -2 ) Tp Wter y = 221.1e.65x R² =.83 Rin Wter y = x R² =.84 DON Export (mg m -2 ) Rin Wter y =.262x R² =.86 Tp Wter y = 3.771e.88x R² = Potssium Export (mg m -2 ) Potssium Export (mg m -2 ) Figure 5. Reltionship between nion (NO 3 -N, PO 4 -P, DOC nd DON) exports nd potssium exports in unfertilized plots. ll sesons re included. Open circles re municipl tp wter irrigtion nd grey circles re rin wter.

7 NO 3 -N Export (mg m -2 ) Tp Wter y = 1.947ln(x) R² =.99 Rin Wter y = e.21x R² =.77 PO 4 -P Export (mg m -2 ) Tp Wter y = ln(x) R² =.96 Rin Wter y = 62.42e.8x R² = Potssium Export (mg m -2 ) Potssium Export (mg m -2 ) DOC Export (mg m -2 ) Rin Wter y = 1.518x R² =.61 Tp Wter y = x.795 R² = Potssium Export (mg m -2 ) DON Export (mg m -2 ) Rin Wter y =.2588x R² =.77 Tp Wter y =.134x R² = Potssium Export (mg m -2 ) Figure 6. Reltionship between nions (NO 3 -N, PO 4 -P, DOC nd DON) nd potssium exports in fertilized plots. ll sesons re included. Open circles re municipl tp wter irrigtion nd grey circles re rin wter. Conclusion While runoff exports of N will increse slightly if runoff occurs just fter fertiliztion, overll these exports on sesonl bsis re not significntly different from plots tht hve received no fertiliztion. biotic functions in soil to mintin electroneutrlity of runoff wter must be considered when exmining nion nd ction losses nd exports from homeowner lwns. For exmple, consider the cid rin er when lrge exports of sulfte were ccompnied by exports of luminum nd iron nd then

8 when those were depleted by clcium. This study showed tht irrigtion with sodic municipl tp wter resulted in retention of sodium nd concomitnt relese of potssium, mgnesium nd clcium. This relese of bse ctions required n equivlent relese of nions to mintin the electroneutrlity of runoff wter. The mechnisms involved when irrigting vegettion with high sodium wter is the relese of protons nd replcement of potssium, then mgnesium nd clcium with sodium. The relese of protons will increse the ph of soil solution vilble to runoff. Fertiliztion ws rrely responsible for increses in C, N nd P export; insted seson hd greter effect on their exports.

9 Summry Progress Report for FY 213 TREEE wrds Title: Impct of Irrigtion Frequency nd Volume on Rinfll Cpture nd Runoff Losses from Turf Lwns PI: Richrd White Collbortors: Chrles Fontnier, en Wherley Objectives: 1) Quntify St. ugustinegrss cnopy density with diminishing soil moisture nd irrigtion tretment, 2) Mesure runoff volumes nd nutrient loding from St. ugustinegrss lwns s ffected by irrigtion level, 3) Evlute the significnce of soil wter content nd lwn cnopy sttus in predicting runoff volumes. Impct: Municipl wter suppliers in drought-stricken regions of Texs often implement restrictions on lndscpe irrigtion. The potentil for severe cnopy loss due to wter deficits could increse postdrought runoff volumes nd nutrient loding. Informtion gthered during the study will help municiplities nd strem mngement entities better understnd the hydrologicl implictions of locl wter restrictions. Summry: The study is being conducted t the Texs &M Surfce Runoff Fcility locted t the TMU Urbn Ecology Center. The site ws constructed with 3.5 to 4% slope nd ws plnted with St. ugustinegrss (Figure 1) to be mintined s residentil lwn. t the foot of ech plot, guttering systems route wter through clibrted flumes where meters monitor flow nd wter smples re collected. Tretments consist of three irrigtion levels (5%, 75%, nd 1% of ET c ) pplied on twody per week clendr-bsed intervls. Sttus: The bulk of the experiment remins ongoing. Sturted hydrulic conductivity, soil bulk density, horizon depths, nd slope hve been mesured for ech plot. Soil moisture monitoring devices were instlled (Figure 2) t multiple loctions nd soil depths nd wter infiltrtion ws mesured multiple times. iweekly rtings nd digitl imges hve been collected to monitor turf performnce. Cnopy prmeters such s lef re index, shoot density, nd bove ground biomss shll be collected t the onset of visible drought stress nd cnopy loss. When sesonl rins return, runoff volumes nd nutrient loding shll be compred mong irrigtion tretments. Figure 1. Newly sodded turf being irrigted with uto smplers in bckground.

10 Figure 2. Instlltion of soil moisture sensing probes t multiple depths. Figure 3. Mesurement of infiltrtion rtes using double-ring infiltrometers.

11 Summry Progress Report for FY 213 TREEE wrds Title: Cumultive Effects of Irrigting Turfgrss Lwns with Diminishing Wter Volumes sed Upon Historicl Evpotrnspirtion PI: Richrd White Collbortors: Chrles Fontnier, en Wherley Objectives: 1) quntify St. ugustinegrss turf performnce under deficit irrigtion using historicl verge ET o, 2) evlute interctions between deficit irrigtion nd fertility, nd 3) evlute the vribility in turf performnce between multiple yers of similr mngement. Impct: Results will offer science-bsed but prcticl recommendtions for mngement of St. ugustinegrss in Texs. Specificlly, mngers nd policy mkers cn better understnd the miniml irrigtion needs for vibility of St. ugustinegrss turfs becuse of this long-term irrigtion study. Summry: The study ws conducted t the Texs &M grilife Turfgrss Science fcility on F& Rod with Rleigh St. ugustinegrss mintined comprbly to residentil lwn. The experimentl design ws rndomized complete block split-plot rrngement. Whole min plots were sixteen individully irrigted zones hving four replictes of four irrigtion tretments. Split-plot tretments were fertilizer rtes. n udit reveled irrigtion ppliction rtes to be pproximtely 1.5 per hour. Irrigtion tretments were initited on July 1 in both 211 nd 212 to pply the following irrigtion mounts three dys per week (MWF): overwtering (1% ET o ), turf coefficient or Tc (.6 x ET o ), norml stress (6% Tc or.36 x ETo), severe stress (4% Tc or.24 x ET o ). seline ET o volumes were selected from historicl monthly verges for College Sttion. Irrigtion tretments continued through September. ny needed irrigtion fter October 1, 211 ws uniformly pplied to the study re (Photogrph 1). Three fertilizer rtes were evluted within ech irrigtion tretment:.,.4, nd.8 lb N 1 ft -2. Visul qulity, digitl imge nlysis (DI), nd volumetric wter content were mesured weekly through September. Clipping yield ws mesured monthly, nd soil chemistry ws nlyzed once t the conclusion of the growing seson. Photogrph 1. Irrigtion ws pplied s needed beginning October 1, 211 to llow recovery of St. ugustinegrss prior to the 212. Sttus: Tretment ppliction nd dt collection concluded during utumn 212 s described in the summry informtion. Results of the 212 growing seson experiment were compred to the previous yer, nd findings presented t the nnul S-CSS-SSS Meetings. Finl dt nlysis, report genertion, nd mnuscript preprtion re ongoing. Tretments will be continued in 213 in order to monitor cumultive effects of long-term irrigtion nd fertility mngement.

12 Preliminry Findings: verged over both yers, historicl ET o ws similr to ctul ET o, lthough from yer to yer ctul ET o differed by pproximtely ± 2%. During dry yer such s 211 (when conservtion is criticl), historicl ET o resulted in 2% wter svings compred to the wter tht would hve been pplied if ctul ET o hd been used for scheduling irrigtion. Where temporry turf density reductions cn be tolerted (Photogrph 2), irrigtion levels s low s.24 x ET o sustined sufficient survivl of crowns to llow full fll/spring recovery under the worst single-yer drought in Texs history. During 212, historicl ET-bsed irrigtion over irrigted by 22% compred to rel-time ET bsed Photogrph 2. Representtive res of severe stress tretment (.24 x ET o ) St. ugustinegrss in 211 (left) nd 212 (right). irrigtion estimtes. Turf density ws not reduced during 212 s substntilly s during 211 by deficit irrigtion (Photogrph 2 nd Figure 1) nd recovery ws much more rpid. In generl, recovery of turfgrss density incresed with incresing nitrogen fter irrigtion tretments were terminted. Figure 1. Mximum reduction in green cnopy cover of St. ugustinegrss in response to irrigtion tretments during 211 nd 212 t the Texs &M grilife Turfgrss Science fcility on F& Rod in College Sttion, Texs.