ORIGINAL ARTICLE
Agronomic and environmental impacts of phosphorus fertilization of low input bahiagrass systems in Florida
Augustine K.Obour ?Maria L.Silveira ?
Joao M.B.Vendramini ?Lynn E.Sollenberger ?
George A.O’Connor ?James W.Jawitz
Received:11May 2010/Accepted:30July 2010/Published online:19August 2010óSpringer Science+Business Media B.V.2010
Abstract Phosphorus management in low input bahiagrass (Paspalum notatum Flugge)systems rep-resents a major challenge of agronomic and environ-mental importance.Concerns over agricultural P transport to surface waters have prompted several revisions in the P fertilizer recommendations for bahiagrass in Florida.This study evaluated the effects of revised P fertilizer recommendations on forage dry matter yield (DMY)and nutritive value and the potential impacts on water quality in bahiagrass pastures growing on a Spodosol.Treatments con-sisted of the factorial combination of three N rates (0,56,and 112kg N ha -1)and four P rates (0,5,10,and 20kg P ha -1),replicated three times and applied annually in May of 2007and 2008.Forage was harvested at 28-d intervals and DMY,tissue P and crude protein concentration,and P uptake were measured.To monitor P leaching potential,suction cup lysimeters were installed at 15-,30-,60-,90-,and
150-cm depths.In 2007,bahiagrass DMY was not affected by P;however,in 2008there was a linear increase in DMY from 6.9to 8.2Mg ha -1as P rate increased.In both years,tissue P increased linearly from 2.1to 2.5g kg -1as P rates increased from 0to 20kg P ha -1.Similarly,P uptake increased from 14kg P ha -1for the control to 19kg P ha -1for the treatment receiving 20kg P ha -1.During the 2-year study,P fertilization had no impact on soil Mehlich-1,water-extractable P,and leachate P concentrations.Leachate P concentrations at the 15-and 30-cm depths varied seasonally (from 0.05to 0.85mg P l -1),with greater spikes occurring during periods of high water table conditions.Current P fertilization recommenda-tion can increase bahiagrass DMY with no adverse impacts on water quality.
Keywords Leaching áPasture fertilization áSpodosol áWater quality
Introduction
Bahiagrass is the most widely planted perennial forage grass in Florida,occupying about 2million ha in the state (Muchovej and Mullahey 2000).Bahiagrass pastures are predominantly grown on Spodosols and are well adapted to the sandy soils of Florida.The grass tolerates low soil fertility conditions,low pH,and intermittent wet conditions and produces reasonable
A.K.Obour áM.L.Silveira (&)áJ.M.
B.Vendramini Range Cattle Research and Education Center,University of Florida,3401Experiment Station,Ona,FL 33865,USA e-mail:mlas@u?.edu
L.E.Sollenberger
Agronomy Department,University of Florida,2185McCarty,Gainesville,FL 32611,USA
G.A.O’Connor áJ.W.Jawitz
Soil and Water Science Department,University
of Florida,106Newell Hall,Gainesville,FL 32611,USA
Nutr Cycl Agroecosyst (2011)89:281–290DOI 10.1007/s10705-010-9393-1
forage yields in droughty conditions.Most forage-based cow-calf(Bos sp.)systems in Florida rely on bahiagrass pasture as the major source of energy and protein for most of the growing season,therefore adequate production of bahiagrass forage is critical for the success of the cow-calf industry in the state.
Approximately80%of cow-calf production in Florida is concentrated in environmentally sensitive areas in Central and South Florida(FDCAS1998), where P transport from agricultural activities repre-sents a serious threat to water quality(Reddy et al. 1999).The primary cow-calf production region in the state,the Lake Okeechobee watershed,faces signif-icant problems associated with nonpoint-source pol-lution of surface waters by agricultural P.Although dairy and beef operations have been suggested as the major contributors of P to Lake Okeechobee watershed(Burgoa et al.1991),potential P losses from low-input cow-calf systems are smaller than other intensive agricultural operations such as con-?ned animal feeding operations and intensive row-crop farming.However,because of the extensive acreage occupied by grazinglands in Florida,P transport from beef ranching operations can poten-tially have major impacts on water quality(Allen 1988).Therefore,effective P-management strategies that balance productivity and environmental protec-tion are required to support the continued success of the cow-calf industry and water quality programs in the state.
In recent years,concerns about the environmental impacts of P fertilization on bahiagrass pastures have prompted several revisions in the University of Florida bahiagrass fertilization recommendations (Hanlon et al.2008).The current P fertilizer recom-mendation for established bahiagrass in Florida is based on both soil and plant tissue P testing (Mylavarapu et al.2007).Phosphorus is recom-mended only when tissue P concentrations are below1.5g kg-1and soil test P levels are very low or low(\15mg kg-1Mehlich-1P).However,there are limited?eld data to validate the revised P fertilization recommendations for established bahia-grass pastures.
The emphasis of most previous studies on bahia-grass P fertilization has been maximizing bahiagrass yield at relatively high levels of fertilizer P.Thus, despite signi?cant literature on bahiagrass response to P fertilization,there is limited information on strategies that balance productivity with environmen-tal implications.Field research is necessary to determine the minimum amount of P required to sustain bahiagrass yield and pasture persistence without adversely affecting water quality.This is particularly important in Florida where the hydrology in combination with environmental conditions and soil characteristics accelerate nutrient transport of agricultural P to surface water.The objectives of the study were to(i)investigate bahiagrass response to reduced P fertilization rates and(ii)evaluate the potential effects of bahiagrass P fertilization on soil-test P concentrations and water quality.
Materials and methods
The experiment was conducted on an established bahiagrass?eld(27°230N,81°560W)on Smyrna sand (sandy,siliceous,hyperthermic Aeric Alaquods). Initial soil characterization of the Ap horizon(to a depth of15cm)showed an average soil pH of5and Mehlich-1extractable P,K,Mg,and Ca of5,40,74, and579mg kg-1,respectively.Bahiagrass was established in1990and had no history of N and P fertilization during the past15years.Plot size was 12.2912.2m,with a3.1-m alley between plots. Treatments were a factorial combination of three N application rates(0,56and112kg N ha-1year-1) and four P rates(0,5,10,and20kg P ha-1year-1) arranged in a completely randomized design with three replications,for a total of36plots.The56and 112kg N ha-1rates correspond to the recommended University of Florida Institute of Food and Agricul-tural Sciences(UF-IFAS)low and medium bahia-grass N options,respectively(Mylavarapu et al. 2007).Phosphorus application rates correspond to0, 0.5-,1-,and2-times the UF-IFAS P fertilizer application rate of10kg P ha-1.Nitrogen was applied as ammonium nitrate and P as potassium phosphate.Each plot also received a basal annual application of47kg K ha-1(as KCl)and5kg ha-1 of micronutrient mix(F503G micromix)containing 24g kg-1of B and Cu,144g kg-1of Fe,60g kg-1 of Mn,0.6g kg-1of Mo,and56g kg-1of Zn.Plots received lime prior to the initiation of the study to raise the soil pH to 5.5.The experiment was conducted for2years(2007and2008),and treat-ments were applied in May of each year.
Forage dry matter yield,crude protein and tissue
P analysis
The plots were harvested at28-d intervals from June to October each year to determine DMY,tissue N and P concentrations,and N and P uptake.During each harvest,two0.9-96.1-m forage strips were har-vested from each plot to a7.5-cm stubble height using a forage harvester.The remaining herbage was mowed with a?ail harvester at the same stubble height and removed from the experimental site. Samples were weighed fresh,and sub-samples weighed and oven dried at60°C for48h for DMY determination.Dried samples were ground to pass a 1-mm mesh screen in a Wiley mill.Cumulative DMY was calculated as the sum of individual harvests for each year.
Tissue N and P were determined using the Kjeldahl digestion procedure(McKenzie and Wallace1954). Brie?y,0.2g of plant material and2g Kjeldahl digestion mixture were digested in5ml concentrated sulfuric acid at365°C for3–4h.Digested samples were diluted to100ml and analyzed on a Seal AQ2 discrete auto analyzer using the Kjeldahl N and P procedures(USEPA1993).Crude protein(CP)con-centration was calculated as percent N multiplied by 6.25(Stewart et al.2007).Nitrogen and P uptake were calculated as the product of tissue N and P concen-tration and DMY for each plot and harvest.
Soil analysis
Prior to treatment application,and at the end of each growing season,?ve composite soil core samples were taken from the Ap(0–15cm),E(16–30cm)and Bh (31–60cm)horizons of each plot.Soil samples were air dried,crushed,and sieved through a2-mm stainless steel screen and analyzed for Mehlich-1P(Mehlich 1953)and WEP(Page et al.1982).Mehlich-1extract-able P concentrations was determined by equilibrating 5g of soil and20ml of Mehlich-1solution (0.0125M H2SO4and0.05M HCl)for5min on a reciprocating shaker and then?ltering through a Whatman#42?lter paper.Phosphorus concentrations were measured colorimetrically on a Seal AQ2discrete analyzer(USEPA1993).Water-extractable P was determined by equilibrating2g of air-dried soil and 20ml of DDI water.The suspension was shaken on an orbital shaker at a rate of200strikes min-1at room temperature for1h.After shaking,the samples were centrifuged at3,2009g for10min,and the superna-tant was?ltered(0.45l m).Phosphorus analysis was performed as described for Mehlich-1P.
Water quality monitoring
Water quality was monitored on plots receiving annual application of56kg N ha-1and0,5,or 10kg P ha-1.The N rate of56kg ha-1represents the UF/IFAS low N option and is use most commonly in cow-calf systems in Florida.The plots were isolated hydrologically by berms and ditches.Due to the?at topography of the landscape,coupled with the sandy nature of the soil,leaching and sub-surface runoff are expected to be the predominant pathways of nutrient losses.The berms and dense ground cover are expected to further reduce the risks of nutrient transport via surface runoff.
Five suction cup lysimeters(referred to as lysime-ters herein)were installed in the center of each plot at 15-,30-,60-,90-,and150-cm depths.The15-and 30-cm lysimeters were located above the spodic horizon,whereas lysimeters at60-,90-,and150-cm were below the spodic horizon.Leachate samples were collected after rainfall events[10mm.A total of12leachate samples were collected per year in 2007and2008.Samples were collected within 2–24h(depending on the soil moisture conditions) using a hand vacuum pump(*60kPa)and stored at 4°C until analysis.Lechate samples were?ltered through a0.45-l m pore size?lter and analyzed for ortho-P concentration using a Seal AQ2discrete auto analyzer(USEPA1993).
Statistical analysis
Statistical analyses were performed using Proc Mixed (SAS1999).Nitrogen and P rates and year were considered?xed effects,with replicates and their interactions considered as random effects.Year was considered a?xed effect because of the potential for carryover effects of treatments from Year1to2.Year was included in the model as a subplot treatment in a split-plot arrangement,with the treatment combina-tions being the main plots.The PDIFF test of the LSMEANS procedure and single degree of freedom orthogonal contrasts were used to compare means. Treatments and their interactions were considered
signi?cant when F -test P values were \0.05.Inter-actions not discussed in the results and discussion section were not signi?cant (P [0.05).The means reported are least squares means.
Results and discussion Climatological data
Total rainfall recorded in 2007and 2008was below the 67-year average (Table 1).Rainfall in 2008was greater than 2007,especially during the months of May through August,which correspond to the peak of forage production in South Florida.Minimum and maximum temperatures were similar during the 2-year study.
Cumulative bahiagrass dry matter yield
There was signi?cant (P =0.03)interaction between P application and year for cumulative bahiagrass DMY (Table 2).Although P application showed no effects on forage DMY in 2007,bahiagrass increased linearly to increasing P application in https://www.doczj.com/doc/fb8509237.html,-pared to the zero P control,in 2008bahiagrass DMY
increased *4,10,and 19%when P was applied at rates of 5,10,and 20kg P ha -1,respectively.Results observed in 2008are consistent with those reported by Rechcigl et al.(1992)who observed a 25%yield
Table 1Monthly average maximum and minimum temperatures and total monthly rainfall at the range cattle research and education center,Ona,FL in 2007and 2008Month
Temperature Rainfall
20072008
Min (°C)
Max (°C)Min (°C)Max (°C)2007(mm)2008(mm)67-year
average a (mm)Jan.13231422382355Feb.12221623163967Mar.17251724515780Apr.1828202741863May 22302231107096June 23302531203249221July 26322431152195213Aug.26322631208250210Sept.25312530169141187Oct.24291828524279Nov.1926162521950Dec.15241422523151Total
–
–
–
–
992
1,124
1,372
a
Source :Sellers 2006
Table 2Cumulative bahiagrass dry matter yield (DMY),tis-sue P concentration,and P uptake as affected by P application rates and on bahiagrass swards P rate (kg ha -1)
Cumulative DMY a Tissue P b (g kg -1)
P uptake b (kg ha -1)
2007(Mg ha -1
)2008(Mg ha -1)0 6.5 6.9 2.113.957.07.2 2.315.710 6.67.6 2.417.320 6.88.2 2.518.9SE 0.30.30.060.7Polynomial contrast
NS c
L**
L***
L***
**P B 0.01;***P B 0.0001
a
Cumulative DMY was calculated as the sum of individual harvests for each year.Data are means across three N rates and three replicates (n =9)
b
Data are means across three N rates,2years,and three replicates (n =18)
c
NS not signi?cant,L linear
increase in bahiagrass plots grown on a Spodosol and receiving24kg P ha-1compared to control(zero P) treatments.In that study,N application rates were similar to our study(120kg N ha-1),and the bahi-agrass yield response was linear for P rates up to 24kg ha-1.However,Rhoads et al.(1997)showed that bahiagrass grown on an Ultisol in North Florida receiving336kg N ha-1can respond to P applica-tion rates as high as84kg P ha-1.
There was a linear response of bahiagrass DMY to N application rates in both years;however,the interaction‘N9P’was not signi?cant.Cumulative DMY in2007ranged from4.9to8.4Mg ha-1for the 0and112kg N ha-1treatments,respectively, whereas in2008DMY was 5.1and9.9Mg ha-1 for the same treatments.More rainfall in2008likely caused greater DMY in that year,and it also may have increased response to P fertilizer,resulting in a linear DMY response to P applications.
Our results showed that bahiagrass response to P application can be variable depending on year and environmental conditions.This trend may also explain the apparent discrepancies in the literature relative to the effects of P fertilization on bahiagrass pastures in South Florida.For instance,whereas Rechcigl et al.(1995)showed that P application had no effect on bahiagrass DMY,other studies by the same researchers(Rechcigl et al.1992;Rechcigl and Bottcher1995)using similar P application rates, showed that bahiagrass DMY increased quadratically to P application with maximum yield obtained at 24kg P ha-1.Ibrikci et al.(1992)showed that bahiagrass response to P may also depend on the application rate.Bahiagrass responded to P rates of 17kg P ha-1,beyond which there was no response to additional P(up to68kg P ha-1).The poor correla-tion between P application rates and bahiagrass DMY (R2=0.13–0.23)observed by Rechcigl and Bottcher (1995),indicates that other factors such as climate conditions may have affected bahiagrass response to fertilizer application.As in our study,Ibrikci et al. (1999)observed no response to P in Year1of a 2-year study,but P application increased bahiagrass DMY in Year2.Although the authors did not explain the lack of response in Year1,they showed that P application increased root length density which may have enhanced P uptake over time and,consequently, increased DMY in Year2.Tissue P concentration and P uptake
Tissue P concentration was affected by P application rate(P=0.002)and year(P\0.0001).Tissue P concentration increased linearly in response to P application rates from0to20kg P ha-1(Table2). Tissue P varied from2.1(no P added)to2.5g kg-1 (20kg P ha-1).These values were well above the proposed critical limit of1.5g kg-1(Silveira et al. 2007),which explains the lack of DMY response to P in2007and the relatively small response observed in 2008.The linear increase in tissue P concentration as a function of P application rate suggests luxury P consumption by bahiagrass.These tissue P concen-trations,despite low Mehlich-I soil P in the Ap horizon,support the suggestion that bahiagrass growing on Spodosols accesses P from below the Ap(Ibrikci et al.1994).
Tissue P was greater in2007(2.5g kg-1)than in 2008(2.2g kg-1).The interaction between P rates and year was not signi?cant(P=0.3).Tissue P concentration in2007were2.3,2.4,and2.6g kg-1 for the treatments receiving0,5,10,and 20kg P ha-1,respectively;whereas the same treat-ments showed tissue P concentrations of1.9,2.1,2.3, and2.4g kg-1in2008.Greater tissue P concentration in2007was likely due to the greater yields obtained in 2008which resulted in greater dilution of tissue P. Similar results were also reported by Vendramini et al. (1999)who observed a linear decrease in tissue P concentration as a function of bahiagrass yield.Unlike results reported by Silveira et al.(2010)from a greenhouse study,N rates had no effect(P=0.07)on tissue P concentrations.Differences were likely due to the much smaller N application rates used in our study (0to112kg N ha-1)than by Silveira et al.(2010)(up to300kg N ha-1).
Tissue P concentrations observed in this study are consistent with previous research conducted on sim-ilar soils in South Florida.Adjei et al.(2006)observed tissue P concentrations ranging from1.5to3.0g kg-1 in bahiagrass plots receiving0to20kg P ha-1 harvest-1.Rechcigl et al.(1992)reported tissue P concentrations ranging from1.6g kg-1for control unfertilized plots to3.3g kg-1for treatments receiv-ing48kg P ha-1.
Bahiagrass P uptake responded linearly to P appli-cation rates(Table2).Increasing P application rates
from0to20kg ha-1increased bahiagrass P uptake by *36%.Similarly,N application increased bahiagrass P uptake linearly(P\0.0001).On average,N appli-cations of0,56,and112kg ha-1resulted in P uptakes of12,17,and20kg P ha-1.Newman et al.(2009a,b) studying bahiagrass P uptake growing on a Spodosol also reported that N fertilization enhanced bahiagrass P uptake.These authors reported bahiagrass P uptake of 13–32kg P ha-1in plots receiving N application rates of*250to600kg N ha-1year-1.Since DMY reported by Newman et al.(2009a,b)were similar to ours,greater P uptake in those studies compared to our study was likely due to the differences in initial soil P concentrations(Mehlich-1P concentrations in the Ap horizon=29mg kg-1)and N fertilization regimens. Crude protein concentration and N uptake
Crude protein concentration increased linearly with increasing N application but was unaffected by P application(P=0.9).Adjei et al.(2000)and Obour et al.(2009)reported similar lack of response of CP to P application.Averaged across P rates and year,CP concentration varied from92g kg-1for the control to 99for the56N ha-1treatment,and105g kg-1for the treatment that received112kg N ha-1.These CP values are consistent with values reported by others for warm-season grasses in Florida(Adjei et al.2000; Muchovej and Mullahey2000;Obour et al.2009).
There was a year effect on bahiagrass CP concen-tration(P\0.0001),with greater average CP in2007 (106g kg-1)than in2008(87g kg-1).Differences were likely due to variation in environmental condi-tions and the lower bahiagrass DMY in2007.Similar results were also observed by Johnson et al.(2001), who reported a7%reduction in bahiagrass CP concentrations during the months of greater forage production.Sumner et al.(1991)observed a14% decrease in bahiagrass CP concentration in response to greater forage mass production.
Bahiagrass N uptake was affected by N rate (P\0.0001)and year(P=0.008).Bahiagrass N uptake varied from74kg N ha-1(control)to151kg N ha-1for the treatments receiving112kg N ha-1. Nitrogen uptake was greater in2007(116kg N ha-1) than in2008(108kg N ha-1).This was due to the greater tissue N concentrations in2007.Phosphorus addition had no effect on bahiagrass N uptake (P=0.2).Soil phosphorus concentrations
Phosphorus applications to bahiagrass showed no effect on Mehlich-1soil P concentrations in the Ap, E,and Bh horizons.Mehlich-1soil P concentrations in the Ap horizon ranged from4.2mg kg-1(zero P control)to 5.5mg kg-1P for the20kg P ha-1 treatment.Similarly,Mehlich-1P in the Bh horizons was40mg kg-1for the zero P control and46mg kg-1 for the20kg P ha-1treatment.Although soil-test P was not affected by P application rate,there was a year effect on soil-test P concentrations(Table3). After2years of P application,Mehlich-1soil P concentration in the Ap horizon were lower than the initial conditions and were considered very low (\10mg kg-1),according to the current soil test P interpretations for agronomic crops in Florida(My-lavarapu et al.2007).Therefore,based on soil test results alone,it was expected that bahiagrass would respond to P application.Similarly,Mehlich-1P concentrations in the E and Bh horizons found at the end of2007and2008growing season were either smaller or similar to the initial conditions(Table3). This result suggests that P application at rates similar to P removal will likely have no impacts on soil-test P concentrations.
Regardless of treatment,P concentration in the Bh horizon was always greater than in the Ap and E horizons(Table3).The substantial amount of P held in the Bh horizon may be plant available(Ibrikci et al.1994)and likely contributed to bahiagrass P uptake,masking treatment effects.
There was no effect of P application on WEP concentration(P=0.75).Water-extractable P con-centration averaged across treatments after2-year of P fertilization was3.6,0.4,and2.8mg kg-1for the Ap,E,and Bh horizons,respectively.Numerous studies have shown that WEP is a reliable indicator of P loss potential(Kleinman et al.2002;Ehlert et al. 2003).Results from the current study indicate that addition of relatively low rates of P fertilizer for 2years did not increase the risks associated with P transport,even when P was applied up to twofold the recommended rate(20kg P ha-1).Extensive bahi-agass roots,adequate ground cover,and removal of harvested forage(i.e.,no grazing and associated P return in excreta)likely increased fertilizer utilization ef?ciency and removal from the sward and mini-mized the potential for soil P accumulation.
Leachate phosphorus concentration
There was a year 9P rate 9sampling depth inter-action for leachate P concentration (Table 4).In 2007,leachate P concentration measured in the lysimeters placed at 15cm were not different between the control and the 10kg P ha -1treatments,but concentration for the 10kg P ha -1rate was greater than the treatments receiving 5kg P ha -1(Table 4).For the lysimeters at 30-cm depth,the greatest P concentration of 0.9mg l -1was recorded for the control treatments.In 2008,increased leachate P concentrations at 15-cm depth were observed in the treatments receiving 10kg P ha -1.However,leach-ate P at the 30-cm depth was similar for the control and the treatments receiving 10kg P ha -1,which suggests that limited P leaching from the upper soil layers occurred.Regardless of the P application rate,leachate P concentrations found in lysimeters at 60-,90-,and 150-cm depths were similar in both years.Thus,P application had no effect on leachate P concentration below the spodic horizon.In general,leachate P concentrations in the lysimeters below the spodic horizon ([60cm)were less than in the lysimeters installed at upper depths.This trend suggests there was limited P movement below the Bh horizon during the 2-year study.These results are also consistent with the Mehlich-1and WEP soil data that showed no effect of P fertilization on soil P concentration in the Bh horizon (Table 3).The high variability associated with leachate P in both years (Table 4)re?ects the seasonal ?uctuation in P losses by leaching.It is likely that high water table conditions experienced during the summer months increased P release from the Bh horizon and promoted subsequent transport of P to the surface horizons.Toor et al.(2004)also observed signi?cant variations in leachate P as a function of the season.There was seasonal variation in leachate P during the 2-year study (Fig.1)but the interaction ‘sea-son 9treatment’was not signi?cant (P =0.3).In 2007,leachate P concentrations in all ?ve lysimeters were similar during the ?rst four sampling events (Fig.1a).However,after 4July,there was a gradual increase in leachate P concentration measured in the upper two lysimeters (15and 30cm)than in the lysimeters below the spodic horizon.In 2007,there was a large spike in leachate P concentration in the 15-and 30-cm lysimeters in September and October
T a b l e 3M e h l i c h -1s o i l P c o n c e n t r a t i o n s a t t h e v a r i o u s d e p t h s a s a f f e c t e d b y y e a r
A p h o r i z o n (0–15c m )
E h o r i z o n (16–30c m )
B h h o r i z o n (31–60c m )
I n i t i a l a
(m g k g -1)
2007(m g k g -1)
2008(m g k g -1)S E P v a l u e b I n i t i a l (m g k g -1)2007(m g k g -1)2008(m g k g -1)S E P v a l u e I n i t i a l (m g k g -1)
2007(m g k g -1)2008(m g k g -1)S E P v a l u e
4.0b
6.3a 3.0c 0.4\0.00012.3a 0.9b 1.0b 0.30.000546a
32b 51a
4.20.0001
D a t a a r e m e a n s a c r o s s t h r e e N r a t e s ,f o u r P r a t e s ,a n d t h r e e r e p l i c a t e s (n =36)
a
I n i t i a l s o i l t e s t P r e f e r s t o s o i l P c o n c e n t r a t i o n s i n s a m p l e s c o l l e c t e d p r i o r t o P a p p l i c a t i o n .2007a n d 2008r e f e r t o s a m p l e s c o l l e c t e d a t t h e e n d o f e a c h g r o w i n g s e a s o n (N o v e m b e r o f e a c h y e a r )
b
M e a n s w i t h i n a s o i l d e p t h f o l l o w e d b y t h e s a m e l e t t e r a r e n o t d i f f e r e n t u s i n g t h e L S M E A N S /P D I F F p r o c e d u r e (P [0.05)
Table4Leachate P concentration at the various depths as affected by year and P application rate to bahiagrass swards
20072008
P rate(kg ha-1)
Depth(cm)05100510 Leachate P(mg L-1)
150.4ab a0.07b0.5a0.2b0.09b0.5a 300.9a0.05c0.3b0.3a0.10b0.4a 600.01a0.07a0.009a0.005a0.03a0.03a 900.1a0.02a0.01a0.009a0.03a0.11a 1500.03a0.008a0.006a0.009a0.01a0.02a SE0.20.1
Data are means across12sampling events for each year
a Means within a soil depth and year followed by the same letter are not different using the LSMEANS/PDIFF procedure(P[0.05)
(Fig.1a).For instance,leachate P concentration in the15-cm lysimeter increased from0.03mg l-1on4 June to0.76mg l-1in September,representing a 25-fold increase in P concentration compared to the initial sampling period.A similar trend was observed in2008,with the greatest spike in leachate P concentrations in the upper lysimeters occurring in August and September(Fig.1b).
In both years,the period of large spikes in soil solution P concentration in the15-and30-cm lysimeters coincided with periods of high rainfall and high water table conditions at the experimental site. The high water table might have contributed to P ?uxes from the spodic horizon into the surface layers, thus increasing P concentration in the lysimeters above the spodic layer.The?uctuating water table conditions experienced in Florida may affect the redox conditions in the soil and P release from the spodic,hence contributing signi?cantly to P?uxes from the spodic layer(Pant et al.2002).Further studies are needed to evaluate the in?uence of ?uctuating water table on P bioavailability to bahi-agrass pastures growing on Spodosols in Florida and potential losses of P to the environment. Summary and conclusions
Treatments spanning a range of low levels of P fertilization were targeted in this study because of the critical need to minimize P loss to surface water while maintaining vigorous bahiagrass stands.Across the range of N rates most often used on bahiagrass swards in Florida,increasing P application from0to 20kg ha-1had no effect on DMY in1year and increased DMY by19%in the second year.There was no effect of P application on any soil P response. Leachate P was generally not affected by P applica-tion.The only exception occurred in2008where leachate P concentration at15-cm depth was greater for the10kg P ha-1compared to the other treat-ments.However,leachate P at the30-cm depth was either lower or similar for the10kg P ha-1com-pared to the control in2007and2008,respectively. Results suggested that limited P leaching occurred at depths[30cm.
Additional work with low rates of P is warranted because this study covered a relatively short time scale and because these data are from harvested bahiagrass swards instead of grazed pastures.Results also suggest that further studies are needed to investigate the impact of?uctuating water table on P availability and loss potential.
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企业各职位英文缩写： GM(General Manager)总经理 VP(Vice President)副总裁 FVP(First Vice President)第一副总裁 AVP(Assistant Vice President)副总裁助理 CEO(Chief Executive Officer)首席执行官，类似总经理、总裁，是企业的法人代表。 COO(Chief Operations Officer)首席运营官，类似常务总经理 CFO(Chief Financial Officer)首席财务官，类似财务总经理 CIO(Chief Information Officer)首席信息官，主管企业信息的收集和发布CTO(Chief technology officer)首席技术官类似总工程师 HRD(Human Resource Director)人力资源总监 OD(Operations Director)运营总监 MD(Marketing Director)市场总监 OM(Operations Manager)运作经理 PM(Production Manager)生产经理 (Product Manager)产品经理 其他： CAO: Art 艺术总监 CBO: Business 商务总监 CCO: Content 内容总监 CDO: Development 开发总监 CGO: Gonverment 政府关系 CHO: Human resource 人事总监 CJO: Jet 把营运指标都加一个或多个零使公司市值像火箭般上升的人 CKO: Knowledge 知识总监 CLO: Labour 工会主席 CMO: Marketing 市场总监 CNO: Negotiation 首席谈判代表CPO: Public relation 公关总监 CQO: Quality control 质控总监 CRO: Research 研究总监 CSO: Sales 销售总监 CUO: User 客户总监 CVO: Valuation 评估总监 CWO: Women 妇联主席 CXO: 什么都可以管的不管部部长 CYO: Yes 什么都点头的老好人 CZO: 现在排最后，等待接班的太子 常用聊天英语缩写
雅思大作文环境保护集团文件发布号：（9816-UATWW-MWUB-WUNN-INNUL-DQQTY-
环境保护类 一．环境问题 1.气候变化、全球变暖：climate change global warming 2.空气污染、垃圾增多：air pollution increase of rubbish / garbage 3.能源危机、缺水、森林砍伐：energy crisis water shortage deforestation 4.自然灾害、酸雨、沙尘暴、干旱、水灾： natural disasters acid rain stand storm drought flood 二．原因（根本） 人口增长工业发展人类活动Population growth industrial development long-term human activities 三．方法 1.世界方面: 全球合作达成共识制定环境保护国际准 Global cooperation reach agreement set international standard s for 2.政府方面： 环保政策鼓励低碳经济发展
Work out / make / enact environmental policy encourage low carbon economy 3.企业方面： 推出环保产品引领大众绿色消费习惯 Promote environmental products / production lead green consuming habits Environmental-friendly 4.个人: 提升环保意识倡导低碳生活方式Improve public’s green awareness encourage / advocate low carbon life style Raise Arouse Increase 5．科技： 开发可再生清洁能源投资开发节能科技 Exploit renewable clean energy invest in energy-saving technologies 你认为环保一定是政府或企业的责任吗? 范文
雅思7分大作文范文批改和解析 距离雅思写作7分你大概还有3个步骤要走，是的，不是谁都可以轻轻松松活动雅思高分的。今天给大家带来了雅思7分大作范文批改和解析,希望能够帮助到大家，一起来学习吧。 雅思7分大作范文批改和解析 雅思写作提高第一步：结构(5.0 - 5.5) 问题：出国留学的优点(the advantages of disadvantages of study abroad) 同学：One reason for those who decide to go overseas to get a higher degree is that they believe they can get better education in certain fields. That is to say, different universities in different countries have their specialized courses and rich resources can be provided according to their needs and requirements. Another reason is that they can learn a foreign language in a more efficient way. There is no denying that living in an all-round English environment and being affected by local culture make people quick learners. 解析：出国留学和高学历完全是两回事(出去读初中和高中都算出国);出国就是better education，在国内就不是better? 出
DARPA ：国防高级研究计划局 ARPARNET(Internet) ：阿帕网 ICCC ：国际计算机通信会议 CCITT ：国际电报电话咨询委员会 SNA ：系统网络体系结构(IBM) DNA ：数字网络体系结构(DEC) CSMA/CD ：载波监听多路访问/冲突检测(Xerox) NGI ：下一代INTERNET Internet2 ：第二代INTERNET TCP/IP SNA SPX/IPX AppleT alk ：网络协议 NII ：国家信息基础设施(信息高速公路) GII ：全球信息基础设施 MIPS ：PC的处理能力 Petabit ：10^15BIT/S Cu芯片: ：铜 OC48 ：光缆通信 SDH ：同步数字复用 WDH ：波分复用 ADSL ：不对称数字用户服务线 HFE/HFC：结构和Cable-modem 机顶盒 PCS ：便携式智能终端 CODEC ：编码解码器 ASK(amplitude shift keying) ：幅移键控法 FSK(frequency shift keying) ：频移键控法 PSK(phase shift keying) ：相移键控法 NRZ (Non return to zero) ：不归零制 PCM(pulse code modulation) ：脉冲代码调制nonlinear encoding ：非线性编程 FDM ：频分多路复用 TDM ：时分多路复用 STDM ：统计时分多路复用 DS0 ：64kb/s DS1 ：24DS0 DS1C ：48DS0 DS2 ：96DS0 DS3 ：762DS0 DS4 ：4032DS0 CSU(channel service unit) ：信道服务部件SONET/SDH ：同步光纤网络接口 LRC ：纵向冗余校验 CRC ：循环冗余校验 ARQ ：自动重发请求 ACK ：确认 NAK ：不确认
环境保护类 一．环境问题 1.气候变化、全球变暖：climate change global warming 2.空气污染、垃圾增多：air pollution increase of rubbish / garbage 3.能源危机、缺水、森林砍伐：energy crisis water shortage deforestation 4.自然灾害、酸雨、沙尘暴、干旱、水灾： natural disasters acid rain stand storm drought flood 二．原因（根本） 人口增长工业发展人类活动 Population growth industrial development long-term human activities 三．方法 1.世界方面: 全球合作达成共识制定环境保护国际准Global cooperation reach agreement set international standard s for 2.政府方面： 环保政策鼓励低碳经济发展 Work out / make / enact environmental policy encourage low carbon economy 3.企业方面： 推出环保产品引领大众绿色 消费习惯 Promote environmental products / production lead green consuming habits Environmental-friendly 4.个人: 提升环保意识倡导低碳生活方式 Improve public’s green awareness encourage / advocate low carbon life style Raise Arouse Increase 5．科技： 开发可再生清洁能源投资开发节能科技 Exploit renewable clean energy invest in energy-saving technologies 你认为环保一定是政府或企业的责任吗? 范文 第一段：（背景句）environmental protection is one of the most important challenges almost every countries is facing . (复合句) 六种：宾从、定从..... however ，whether only government and big firms have resources and powers to preserve our environment is a controversial issue .
Some experts believe that it is better for children to begin learning a foreign language at primary school rather than secondary school. Do the advantages of this outweigh the disadvantages? Foreign languages have increasingly gained popularity among students these years, given that the world is shrinking and each country now has a more frequent contact with the outside world. Many people[c1]argue that children should begin learning a foreign language at elementary school, instead of waiting until [c2] they enter secondary school. There are several reasons for this. Firstly, despite the fact that parents do not want to put too much pressure on their children, they also do not want them to lose at the starting line. This means, if the kids start to learn a foreign language early, their parents are relieved from the thought that their kids will have to catch up later on, which is true to some extent. On the other hand, it is scientifically proved that children tend to learn a language faster before the age of 12. As far as I know, my friends who started to learn English when they were six or seven now have a much more satisfactory English level than those who started at12 or 13. So it is wise to have foreign language course in primary school curriculum. Additionally, learning a foreign language at an earlier age can lay children a solid foundation for future studying.Rather than just learning a language itself, children learn a lot more about the learning methods. As a result, when they enter secondary school, they can explore more languages and enrich their knowledge by extensive readings.
招呼篇 GTSY：Glad To See You高兴认识你 PMJI：Pardon My Jumping In ＝PMFJI：Pardon Me For Jumping In 败势，加入你们的谈话 WB：Welcome Back 欢迎回来 LTNS：Long Time No See 好久不见 笑篇 BEG：Big Evil Grin （非常）邪恶的笑 C＆G：Chuckle And Grin 喀喀笑 GMBO：Giggling My Butt Off 笑掉我的屁屁 BWL：Bursting With Laughter 笑掉不行 CSG：Chuckle Snicker Grin 嘿嘿窃笑 KMA：Kiss My A$$ ＝MKB：Kiss My Butt 亲我的屁屁 LMAO：Laughing My A$$ Of ＝LMBO：Laughing My Butt Off ＝LMHO：Laughing My Head Off 笑死我了 LOL：Laughing Out Loud 放声笑 LSHMBB：Laughing So Hard My Belly Is Bouncing ＝LSHMBH：Laughing So Hard My Belly Hurts 笑到我肚子痛 告知篇 AFK：Away From Keyboard 离开键盘 BBL：Be Back Later ＝BBS：Be Back Soon ＝BRB：Be Right Back 稍待回来 CNP：Continue In Next Post 请看下一个留言 FYI：For Your Information 只给你知道 OIC：Oh，I See 喔，瞭 PS：Post Script 附注 QSL：Reply 回答 RTF：Read The FAQ 请看常见问题 AKA：Also Known As 又名为 FAQ：Frequently Asked Question 最常被问的问题 IC：I See 瞭 IGP：I Gotta Pee 我要去尿尿 POOF：I Have Left Chat 我已经离开聊天室啰 PM：Private Massage 私下寄消息。在聊天室常见的功能，你可以单独对有兴趣的人私下聊
《保护环境的英语作文》 保护环境的英语作文（一）： Now， our side of the car constant more up， the environment also increasingly worse! That the air around us there are many harmful substances。 Therefore， we want to Sue around things start to do。 For example， we can go to school by bike or walk， it can exercise。 If you have time can use less elevator， many climb stairs。 We can not only physical exercise， but also to protect our environment。 此刻，我们身边的汽车不断的多了起来，环境也越来越糟糕！以至于我们周围的空气有很多有害物质。所以，我们要苏身边的小事做起。比如，我们能够骑自行车上学或者步行，这样还能够锻炼身体。有时光的话能够少用电梯，多爬楼梯。我们不仅仅能锻炼身体，也能保护我们的环境。 保护环境的英语作文（二）： There are still many problems of environmental protection in recent years。 One of the most serious problems is the serious pollution of air，water and soil。 the polluted air does great harm to peoples health。 The polluted water causes diseases and death。 What is more， vegetation had been greatly reduced with the rapid growth of modern cities。 To protect the environment， governments of many countries have done a lot。 Legislative steps have been introduced to control air pollution，to protect the forest and sea resources and to stop any environmental pollution。 Therefore， governments are playing the most important role in the environmental protection today。 In my opinion， to protect environment， the government must take even more concrete measures。 First， it should let people fully realize the importance of environmental protection through education。 Second， much more efforts should be made to put the population planning policy into practice， because more people means more people means more pollution。Finally，those who destroy the environment intentionally should be severely punished。 We should let them know that destroying environment means destroying mankind themselves。 保护环境 目前环保还存在着许多问题。最严重的问题就是空气、水和土壤的严重污染。污染的空气对人类的健康十分有害。污染的水引起疼病，造成死亡。更有甚者，随着现代社会的迅速扩建，植被大大的减少。
duno=don't know u=you ur=your kinda=kind of sorta=sort of 2=two或to 4=for shoulda=should have congrat=congratulation thx=thanks X'mas=Christmas wat=what biz=business ad=advertisement ft.=featuring abt=about pls=please rgds=regards ---问好--- 1,hiho=hola=yo=hi=hey=hellow=你好，大家好 2,wuz up=sup=what's up=(原意：怎么样你？/有什么事儿嘛？)也可作为问好用(当然是比较熟的两个人之间的问候)，回答时有事说事，没事用"nothing/nothin much/not much/nm等回答就可以。 ---再见--- 1,cya=cu=see ya=see you=再见 2,laterz=later=cya later=see ya later=see you later=再见 3,gn=gn8=gnight=good night=晚安 4,nn=nite=晚安 说明：一般第一个人常说gnight/gn8,然后第二个人用nite,后面的用nn什么的都可以了。不要问我为什么，约定俗成而已。 ---惊叹赞扬--- 1,OMG=oh my god=我的天；**！ 2,OMFG=oh my f ucking god=我的老天；**靠； 3,wtf=what the f uck=怎么会事！？；*！； 4,n1=nice 1=nice one=漂亮 5, pwnz=ownz=牛比！(例句：pwnz demo!;lefuzee ownz all the others!) 6,rullz=强！(例句：lefuzee rullz!;you guyz rull!!!) 7,you rock!=你牛比！(口语中常用，irc中偶尔能看到。) ---笑--- 1,lol=laughing out loud /laugh out loud=大笑 2,lmao=laughing my ass off=笑的屁股尿流 3,rofl=roll on floor laughing=笑翻天了 排序:hehe 环境类--雅思范文 1. Environmental problems are too big for individual countries and individual people to address. We have reached the stage where the only way to protect the environment is to address it at an international level. To what extent do you agree or disagree? Nowadays, environmental problem has been the focus of a debate. Among these related problems, the issue of international efforts in combating environmental pollution is an extremely acute one. It is firmly believed that the benefits of large scale groups have remarkable impact on our society, especially on environment and animals aspects. First and foremost, environmental pollution is a problem that beyond national borders. This is because the destructive effects that it brought cannot be solved without the co-operation of all the countries in the world. A case in point is the occurrence of extreme weather condition, like La Nina in terms of heavy flood and drought; in addition to, global warming, acid rain that happen in many parts of the world. Due to its chronic and perpetual environment effect, it is necessary for the countries on the earth to form an association and join hands to protect our land from further environment deterioration. Another reason is that it is urgent to set up international alliance to prevent the shrinking space of animals' habitat. It is due to the fact that, local ecosystem has gradually been destroyed all over the world. For instance, Mountain Gorilla has loss its natural habitat to human beings, for being continually developing housing estate deep into the forest. Thus, the breaking down of ecosystem has pushed species closer to the brink of extinction. Hence, it is cleared that the prevention of declining the numbers of rare animals need the joint efforts from many administrative agencies in the world. In conclusion, I totally agree with the idea that international collaboration and cooperation in tackling environmental pollution is positively affects the sustainable development on earth. It is expected that environmental preservation can be greatly enhanced through cultivating environmental awareness around the people in every countries in the foreseeable future. Task：Some people think getting old is entirely bad. However, others think that life of the elderly in modern world is much easier than in the past. Discuss both views and give your own opinion. 思路解析： 2016年雅思收官之战的作文来了一道新题，问当今社会老年人的生活是不是很 糟糕?说是新题，因为本题以前从未原题出现过，但关于年龄的话题却不缺少。 比如2010年7月10日“年轻人是否适合担任政府要职”，2012年3月10日“老 龄化现象的原因及解决方法”，2012年3月31日“年轻人和老年人谁的价值更 高?”，2013年6月8日“政府是否应该对老年人养老提供财政支持?”，2015 年1月1日“年轻人当领导，行不行?”，2015年4月11日“老年人与年轻人 争夺工作职位，怎么办?”等等。 本题需要论证的对立观点是：年老很糟糕 vs. 当今社会年老没有那么糟糕。那 么，变老有哪些坏处呢?首先，当然是身体条件没有以前好了，甚至可能出现多 种疾病(物质层面);其次，不工作了，与人的联系少了，心里可能会感觉孤单， 甚至感觉没有价值了(精神层面);最后，变老后对社会的依赖程度更高，给社会 增加了压力(社会层面)。那么，这些问题在当今社会是不是得到了解决呢?首先， 医疗条件的改善有助于保持老年人的身体状况;互联网的出现有助于缓解老年人 的心理孤单问题;物质水平的提高也降低了老年人给社会造成的压力。如此观之， 现代社会老年人的生活的确容易多了，但我的观点是：外部条件只是改善老年人 生活的一个方面，最重要的还是老年人自己要积极调整心态，努力适应退休后的 生活，从而过一个更幸福更祥和的晚年。 Sample answer： Getting old is a natural process that nobody really likes. When you reach a certain age, your physical conditions will inevitably deteriorate, and you may suffer from various kinds of diseases. When you retire, you will feel isolated because your previous work contacts may be all gone, then you may feel useless to the world. Furthermore, when you get too old, you’ ll have to rely heavily on the support from others, either physically or emotionally, and your life will become a great pressure to your family and the whole society as well. For all these bad things about getting old, many people argue that the life of the elderly today is much easier than in the past. In the first place, medical advances nowadays have made it possible for the old people to stay sound and healthy for quite a long while even after they retire. Diseases such as diabetes, hypertension and heart attack which might have 与外国人聊天常用缩略词 刚上线时一般的使用:----------------------------- 1. Hi 嗨 2. Hey 嘿 3. Yo 喂 4. WOW 哇 5. ICQ 我找你. I seek you. 6. TNS 好久不见. Long time no see. 7. VG 很好 Very good. 8. yep 是 <俚> yes. 9. yup 是 <俚> yes. 10. yeah 是 = yes. 11. RYOK 你好吧? Are you ok? 12. YR 对,是的. yeah,right. 中间有事离开一会儿:----------------------------- 13. bbiam 我很快回来 Be back in a minuta. 14. hang on 等一下. 15. bll 过一会儿回来. Be back late. 16. BRB 很快回来. Be right back. 17. RSN 马上 Real soon now. 19. afk 暂时离开(键盘) away from keyboard. 20. bak 回(键盘前)来了. back at keyboard. 21. BBIAB 马上回来. be back in a bit. 告诉对方欲下线:---------------------------- 22. TAFN 到此为止. That's all for now. 23. GTGB 得走了.再见. Got to go,Bye. 24. SRI 对不起. Sorry. 25. Gotta go 我得走了. Gotta go=have to go=I have to go. 告别:---------------------------------------------- 26. Bye 再见. 27. CU 再见. See you. 28. CU2 再见. See you too. 29. CUL 下次再会. See you later. 30. CUA 再会. See you again. 31. HTH 睡觉去了. Hit the hay (hay <俚> 床) 33. See ya. 再见. See ya = See you (ya 表示 you 或 young adult) 34. AMF 再会,我的朋友. Adios my friend. 英语作文范文 雅思写作高分范文：环境保护 Environmental hazards are often too great for particular countries or individuals to tackle. We have arrived at a point in time where the only way to lessen environmental problems is at an international level. Environmental problems have reached such proportions that people feel international organizations must be set up to intervene in world affairs to resolve these problems. Whether this will resolve the problem is very unlikely as international organizations are just an extension of human behavior. That is, if human conflicts cannot be resolved at home, then they are unlikely to be resolved at the international level. Nevertheless, international organizations do attract attention to the growing problem of aims of the international community to resolve the issue of environmental pollution and support their cause, I do not believe it is the best or only way to protect the environment; in fact, it is only a small part of what is needed in a global initiative. 雅思小作文7分万能模板整合 在这一雅思备考阶段，不知道雅思小作文如何观察图表，如何对比构思，尤其是一些涉及数据表达句式，可以借用雅思小作文万能模板进行练习仿写。。下面就和大家分享，来欣赏一下吧。 雅思小作文7分万能模板 1go up and down/ wave/ fluctuate/ beunstable/ be in flexible 起伏不定 2 The first point tonote is the huge increase in the number of 需要注意的第一点就是…的急剧增长 3 The statistics show that这些数据表明 4Form/comprise/make up/constitute/ account for….percent占百分之几 5 This cure graph describes the trendof该曲线图描述了…的 趋势 6 The statistics lead us to theconclusion that由这些数据，我们可以做出如下结论 7 As can be seen from the line graph, 由线状图我们可以看出 8增加：Increase / raise / rise / go up/ soar/ascend/ mount/ climb 9减少：Decrease / grow down / drop / fall/ reduce/descend/ shrink to/decline 10稳定：Remain stable / stabilize / level off/ remainunchanged 雅思小作文7分万能模板 1 It can be seen from the table that 由表格我们可以看出 2 The table shows the changes in thenumber of… over theperiod from…to… 该表格展示了从…到…数据的变化 3 The table provides some data of 该表格提供了有关…的数据 4 As can be seen clearly from thetable, 从表格中我们可以清楚地看出， 5 As can be seen from the table,great changes have taken place in... 网络聊天中常见英语缩写词 下面列举一些典型的网络英文潮语。 btw(by the way)：这个大多数人都会用，就是“顺便再说一句”的意思。 g2g(got to go)：要走了。原句是I've got to go。 ttyl(talk to you later)：下次再说。 brb(be right back)：很快回来。也就是I'll be right back 或I'm gonna be right back的简写。 jk(just kidding)：开玩笑，别当真。 omg(oh my god)：我的天啊！有时为了表达更强烈的情感，有人会打：OMGGGGGGG! lol(laugh out loud)：大声地笑。这个缩写已经快被用烂了。 Imao(laughing my arse/ass off)：笑死我了。遇到真正搞笑的事，可以这么说，不过有点粗俗。 rofl(rolling on the floor laughing)：笑到摔到地上。 roflmao(rolling on the floor laughing my ass of)：前两个的结合版，也就是超级搞笑的意思。 sth(something)：某事某物。 nth(nothing)：什么也没有。 plz(please)：请。please 字尾是z 音，所以按照读音缩写为plz。 thx(thanks)：谢谢。按照发音来看，thanks字尾的ks可以用字母X代替。 idk(I don't know)：我不知道。 imho, imo(in my humble opinion, in my opinion)：在我看来，常见于论坛。 以上这些网络潮语当然不是叫大家不顾场合，不看对象地乱用。写信给校长，总不能以"Yo! Wassup?" 开头问好吧。运用你的智慧，尽情享用这些最流行的英文潮语吧。 ASAP：As soon as possible尽快 BF：Boyfriend男朋友 BTW：By the way随便说一下 BBL：Be back later稍后回来 保护环境的英语作文10篇 保护环境的英语作文保护环境的英语作文（一）： Now , oursideofthecarconstantmoreup , theenvironmentalsoincreasinglyworse!Thattheairaroun dustherearemanyharmfulsubstances 。Therefore , wewanttoSuearoundthingsstarttodo。Forexa mple, weca n gotoscho ol bybikeo rwa lk, itc anex ercis e。Ify ouha vetime can useless el evator, m a nyclimbst airs we can noton lyphy sicalexer c ise, buta Is otoprot ect ourenv iron ment o 此刻，我们身边的汽车不断的多了起来，环境也越来越糟糕！以至于我们周围的空气有很多有害物质。所以，我们要苏身边的小事做起。比如，我们能够骑自行车上学或者步行，这样还能够锻炼身体。有时光的话能够少用电梯，多爬楼梯。我们不仅仅能锻炼身体，也能保护我们的环境。 保护环境的英语作文（二）： Th erearesti 1 lmanypro bl emsofen vir onment alpr otect o neofthe mo stseriou s problemsi stheseriou ionin rece ntyear s o spollution ofair, wat e randsoil。t hepollu ted airdoe sgre athar mtope ople，sheal th。Thepoll ut edwaterc a usesdisea sesanddeat h。whatismo re, vegeta, t ionhadbe en greatly red ucedwi thth erapi dgrow thof modern cit ies。 T o protectth eenvironme nt, governm entsofman y countrie环境类--雅思范文Environmental-problems
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