Reducing phosphorus release from paddy soils by a fly ash-gypsum mixture

Bioresource Technology 98 (2007) 1980–1984

Reducing phosphorus release from paddy soils by a Xy ash-gypsum mixture Chang Hoon Lee a, Yong Bok Lee b, Hyup Lee c, Pil Joo Kim

a,d,¤

a

Division of Applied Life Science, Gyeongsang National University, Kaswa-dong, Jinju, 660-701, South Korea School of Environment and Natural Resources, The Ohio State University, 2021 CoVey Road, Columbus, OH, USA c Department of Crops Biotechnology, Jinju National University, Jinju 660-758, South Korea d Institute of Agriculture and Life Sciences, Gyeongsang National University, Kaswa-dong, Jinju, 660-701, South Korea b

Received 12 April 2004; received in revised form 31 July 2006; accepted 31 July 2006 Available online 12 October 2006

Abstract A mixture of Xy ash and phospho-gypsum (50:50, wt wt¡1) was selected to study its potential to supply Ca and Si to rice while reducing B toxicity. We expected that the high Ca content in this mixture might convert water-soluble P to less soluble forms and thereby reduce the loss of soil P to surface runoV. The mixture was applied at rates of 0, 20, 40, and 60 Mg ha¡1 in two paddy soils of contrasting textures (silt loam in Yehari and loamy sand in Daegok). The mixture signiWcantly reduced water-soluble phosphate (W-P) in the surface soils by shifting from W-P and iron bound-P (Fe-P) to calcium bound-P (Ca-P) and aluminum bound-P (Al-P) during rice cultivation in both soils. Lancaster and Mehlich 3 extractable P increased signiWcantly with application rate due to high contents of P and Si in the mixture. Mixtures of Xy ash and phospho-gypsum should reduce P loss from rice paddy soils and increase soil fertility. © 2006 Elsevier Ltd. All rights reserved. Keywords: Paddy soil; Phosphorus; Gypsum; Fly ash

1. Introduction Increasing fertilizer use in Korea has resulted in excess P accumulations in some arable soils and may cause new environmental problems for Korean agriculture. The Penriched run-oV from agricultural soils can cause eutrophication of streams, lakes, freshwater portions of estuaries and other water bodies. A national soil survey in Korea has revealed that the P content of arable soils has increased greatly in recent years. In rice paddy soils, the content of available phosphate (P2O5) analyzed using the Lancaster method (RDA, 1988) was 60 mg kg¡1 in the 1960s and increased to about 130 mg kg¡1 by the 1990s, exceeding the limit of 100 mg kg¡1 recommended for rice (RDA, 1999). These high P levels have increased the amount of water* Corresponding author. Address: Division of Applied Life Science, Gyeongsang National University, Kaswa-dong, Jinju, 660-701, South Korea. Tel.: +82 55 751 5466; fax: +82 55 757 0178. E-mail address: [email protected] (P.J. Kim).

0960-8524/$ - see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2006.07.050

soluble P in the soil, thereby increasing the potential for P transport by surface runoV to streams (Sharpley, 1995; Sharpley et al., 1996). With standard management practices in Korea, about 35 kg ha¡1 yr¡1 of P2O5 was estimated to be lost from the surface layer through plant uptake in a long-term fertilized rice paddy soil (Lee et al., 2004). The average P2O5 over-fertilization has been estimated to be in excess of 20 kg ha¡1 for Korean rice paddy soils (RDA, 2001). In spite of net P accumulation, phosphate fertilizer has been applied to farm Welds with each cropping cycle because of the low plant-availability of phosphate. For example, a minimum of 30 kg ha¡1 of P2O5 is recommended for rice regardless of its content in the soil (RDA, 1999). One way of controlling soil P loss to surface runoV is to reduce its solubility by precipitation with Ca, Fe, or Al (Stout et al., 1998). Fly ash and phospho-gypsum are sources of elements and compounds that can form insoluble precipitates with P. In Korea, approximately 3.7 Tg of Xy ash was produced in 1997, and production is projected

C.H. Lee et al. / Bioresource Technology 98 (2007) 1980–1984

to rise to 6 Tg by the year 2010 (Cha et al., 1999). Gypsum resulting from the production of phosphate fertilizer has accumulated for over 35 years. In a previous study to satisfy the Si and Ca requirements of rice, we prepared a mixture of Xy ash and gypsum (50:50, wt wt¡1) and achieved positive eVects by improving soil fertility and stimulating rice growth (Lee et al., 2005). In this study, our research objective was to determine if this Xy ash-gypsum mixture would reduce the amount of water-soluble P in the soil, thereby reducing the potential for P export into streams and lakes. 2. Methods 2.1. Experimental site and treatment The same Xy ash and gypsum used in our previous research (Lee et al., 2002) were used for the Weld test. These samples were collected from the thermal power plant located at Hadong and from the phosphate fertilizer plant (Namhae Chemical Co. Ltd.) in Yeosu in southern Korea. To determine the eVects of a Xy ash-gypsum mixture (50:50, wt wt¡1) on rice production, two paddy soils were selected in Yehari (Pyeongtaeg series, a somewhat poorly drained silt loam soil) and Daegok (Nagdong series, a somewhat excessively drained loamy Wne sand soil) in Jinju (35°26⬘N and 128°20⬘E). The chemical properties of these paddy soils before the study are shown in Table 1. Four diVerent rates of the Xy ash-phosphogypsum mixture (0, 20, 40 and 60 Mg ha¡1) were selected as treatments. Uniform applications of N (120 kg ha¡1), P2O5 (48 kg ha¡1) and K2O (80 kg ha¡1) were incorporated in all treatments. The experimental plots (10 m £ 10 m in size) were arranged in a completely randomized design with triplicate replication. Dongjinbyeo and Hwayongbyeo rice cultivars were transplanted in the Yehari (silt loam) and Daegok (loamy sand) soils, respectively, on June 5, 1998 and were harvested on October 16 of the same year. Nitrogen and K were applied separately three and two times, respectively, during

Table 1 Physical and chemical properties of the soils used in the Weld tests before the experiments

pH (1:5 with H2O) OM (g kg¡1) Total N (g kg¡1) Available P2O5 (mg kg¡1) Available SiO2 (mg kg¡1) Ex. cations (cmolc kg¡1) Ca Mg K CEC (cmolc kg¡1)

Yehari (SiL)

Daegok (LS)

Mean

SD

Mean

SD

5.5 16.6 1.5 25 86

0.4 3.2 0.2 6 7.5

5.8 22.2 2.3 227 53

0.6 4.1 0.2 17 4.8

4.3 1.96 0.33 13.1

0.3 0.11 0.02 2.6

4.6 0.37 0.25 9.2

0.5 0.03 0.03 1.8

OM, organic matter; Ex. cations, exchangeable cations; CEC, cation exchange capacity; SD, standard deviation.

1981

the growing season and total phosphate was applied as a basal fertilizer on June 3. The Xy ash-phosphogypsum mixture was applied on May 8–9 and mixed with the soil to a depth of 15 cm. 2.2. Chemical properties and phosphorus fractionation Soil samples were collected for characterization from the 0–15 cm depth, air-dried and crushed to pass a 2 mm sieve. Sequential P fractionation from the soil samples involved extraction with H2O (water-soluble-P, W-P), 25 g L¡1 acetic acid and 1 M NH4Cl (calcium bound-P, Ca-P), 1 M NH4F (aluminum bound-P, Al-P), and 1 M NaOH (iron bound-P, Fe-P) (Sekiya, 1983; Watanabe and Kato, 1983). Available P content was also analyzed by the Melhich-3 (Wolf and Beegle, 1991) and Lancaster methods (RDA, 1988; 5 g soil were extracted with 20 ml of 0.33 M CH3CHOOH, 0.15 M lactic acid, 0.03 M NH4F, 0.05 M (NH4)2SO4 and 0.2 M NaOH at pH 4.25). 2.3. Statistical analyses A SAS statistical package was used to analyze the rice yield (Little and Hills, 1978). A one-way ANOVA was carried out to compare the means of the diVerent treatments. When signiWcant F-values were detected, the diVerences between individual means were tested using the least signiWcant diVerence (LSD) test (SAS, 1995). 3. Results and discussion The Xy ash-phosphogypsum (FG) mixture signiWcantly reduced W-P concentrations in the surface soils during rice cultivation (Fig. 1). This eVect increased with greater application rates regardless of the soil type. On July 20, the 45th day after rice transplanting, an average of 6.7 mg kg¡1, which was 1.5% of the total extractable P, was W-P at the Daegok (LS) location when no mixture was added. The WP concentration signiWcantly decreased to 5.0, 2.7 and 1.4 mg kg¡1 by applying 20, 40 and 60 Mg ha¡1 of the mixture, respectively. The same tendency was observed in Yehari (SiL). The eVect of the mixture application on reducing the water solubility of soil phosphorus continued during rice cultivation, irrespective of the soil type. The transfer of P in water draining from agricultural land to surface waters can contribute to eutrophication, toxic algal blooms, and a general deterioration of water quality (Foy and Withers, 1995). Concern over pollution by agricultural P has been heightened recently because of risks to aquatic organisms and human health, notably the potential for neurological damage from outbreaks of the dinoXagelatte PWeteria piscidia in the Chesapeake Bay area of eastern USA (Burkholder and Glasgow, 1997). Although the amounts of P transferred from the land are small in agronomic terms, typically <1 kg ha¡1 yr¡1, accumulations of P in excess of 35 g L¡1 can contribute to eutrophication (Vollenweider and Krekes, 1982).

1982

C.H. Lee et al. / Bioresource Technology 98 (2007) 1980–1984 4

Yehari (SiL)

FG 0 FG 20 FG 40 FG 60

3

a

a 2

a a

b

a

b bc

-1

Water soluble P (mg kg )

1

b

c

c

b b

b b

c

0

Daegok (LS) 8

a

a a

6

ab

b

a ab

c 2

b

ab

b

4

b d

c c

c

0

7/20

9/22 8/19 Sampling date (Month/day)

10/15

Fig. 1. Changes of water soluble phosphorus in surface soil during rice cultivation in 1998. Within each sampling date, bars with the same letters are not signiWcantly diVerent at P < 0.05 by LSD.

Using a quadratic response model, yields were related to the FG application rate as rice yield D 4754 + 50.9 £ FG ¡ 0.68 FG2 (model R2 D 0.676¤) in Yehari (SiL), and 6668 + 539 £ FG ¡ 0.81 FG2 (model R2 D 0.430¤) in Daegok (LS), where yield is expressed as kg ha¡1 and the mixture application rates as Mg ha¡1. Using this equation, the maximum grain yields in Yehari (SiL) and in Daegok (LS) were 5708 kg ha¡1 at the rate of 37 Mg FG ha¡1 in Yehari (SiL), which is 20% higher than that in the control (FG 0), and 7567 kg ha¡1 at 34 Mg FG ha¡1 in Daegok (LS), which is 14% higher than in the control, respectively. Water-soluble P was reduced by 75–80% at the application rate of 34–37 Mg ha¡1 FG at both sites on July 20. This tendency was persistent during the entire growing season, even though there was variation in the eYciency to reduce W-P depending on the rice growth stage. In contrast to decreasing W-P content, Ca-P content increased signiWcantly with the mixture application rate (Table 2). The gypsum (CaSO4 · 2H2O) in the mixture displaced hydrogen ion (H+) from weakly acidic organic groups and clay surfaces, or generated H+ by displacing Al and Fe from the soil exchange complex (Coleman and Thomas, 1967). The H+ reacts with W-P to form P compounds not readily extracted with water. Evidence for this is the eVect

of the mixture on soil extractable P fractions (Table 2). The distribution of the P fractions is dependent on, among other soil factors, the kinds of phosphate fertilizer applied, the soil mineralogy and the soil pH. Calcium bound-P is the predominant form of P in alkaline soils while Fe-P and Al-P predominate in acidic soils. In acid soils, the original, loosely bound phosphates are converted gradually via a reprecipitation process into Fe-P and Al-P compounds (Dean, 1949). In contrast to aerobic upland soils, rice paddy soils that are Xooded for more than 100 days become anaerobic. In the aerobic condition, ferric iron is of low solubility. When reduced to ferrous iron under anaerobic conditions, the mobility increases dramatically (Bohn et al., 1979). As a result, the high solubility of P and Fe in this paddy condition might explain the decrease in the Fe-P concentration during rice cultivation. Amendments with the mixture resulted in a shift from W-P and Fe-P fractions to Ca-P and Al-P under Xooded conditions. The amended soils showed a small increase in pH following increased applications of the mixture (Table 4). The soil pH increased from 5.2 with FG-0 to 6.0 with 60 Mg ha¡1 of the mixture (FG-60) at harvest in Yehari (SiL), and the pH changed from 5.7 to 6.2 in Daegok (LS). These increases indicate that the Ca2+ content of the mixture was the primary factor and the neutralizing capacity the secondary factor in shifting a sizable portion of the soil P to the Ca-P fraction. Mehlich-3 and Lancaster extractable P contents, which are used as plant available P indexes in arable soils, increased with increases in the mixture application rate during rice cultivation (Table 3), due to the high content of available P in the FG. Total P2O5 concentration of the selected Xy ash and gypsum was 3.81% and 0.58%, respectively, and available P2O5 concentration determined by Lancaster method (RDA, 1988) was 1323 and 73 mg kg¡1, respectively. As a result, the mixture contained about 700 mg kg¡1 of available P2O5. Thus, 14, 28 and 42 kg ha¡1 of available P2O5 were supplied by applications of 20, 40 and 60 Mg ha¡1 of the mixture, respectively. In addition, soil phosphate might be desorbed by the high content of Si in the FG. Silicate enhances the availability of soil phosphate by displacing phosphate from ligand exchange sites (Roy et al., 1971) and by inhibiting phosphate sorption for the same speciWc anion exchange sites (Hingston and Raupach, 1967; Hingston et al., 1972; Jepson et al., 1976). Evidence for this was the increase in available P2O5 contents, determined by Lancaster method (RDA, 1988), in the soils treated with Si fertilizer (87 mg kg¡1 in Yehari) compared with FG 0 (57 mg kg¡1 in Yehari) (Lee et al., 2002). The mixture contained about 556 mg kg¡1 of available SiO2, originating from 1100 and 12 mg kg¡1 of available SiO2 in Xy ash and gypsum (Lee et al., 2002), respectively. Thus, about 11, 22 and 33 kg ha¡1 of available SiO2 were applied with applications of 20, 40 and 60 Mg ha¡1 of the mixture, respectively. The available SiO2 content increased signiWcantly following the mixture appli-

C.H. Lee et al. / Bioresource Technology 98 (2007) 1980–1984

1983

Table 2 Changes of extractable phosphorus fraction in surface soil during rice cultivation (unit: mg P2O5 kg¡1) P fraction

Sampling date

Yehari (SiL)

Daegok (LS)

FG 0

FG 20

FG 40

FG 60

LSD0.05

FG 0

FG 20

FG 40

FG 60

LSD0.05

76 69 73 57 14

101 158 101 110 21

174 176 169 135 25

197 188 213 149 32

34 44 41 41

Ca-P

July 20 August 19 September 22 October 15 LSD0.05

9.8 8.2 8.2 4.4 3.9

11.9 9.2 8.9 6.4 4.4

18.5 13.5 11.9 8.2 6.2

39.6 31.1 13.3 12.4 10.8

8.0 13.5 ns 6.0

Al-P

July 20 August 19 September 22 October 15 LSD0.05

366 366 348 339 ns

382 396 389 392 ns

442 483 424 421 39

495 618 456 447 50

66 96 50 76

719 705 678 653 ns

845 834 799 703 ns

937 923 902 852 ns

1003 966 960 911 62

85 76 80 119

Fe-P

July 20 August 19 September 22 October 15 LSD0.05

373 389 373 401 ns

364 378 350 360 ns

355 371 341 344 ns

348 366 330 330 25

21 ns 41 44

527 282 316 332 66

373 279 309 275 57

277 268 286 268 ns

245 256 263 245 ns

94 ns ns 62

Ext.-P(1)

July 20 August 19 September 22 October 15 LSD0.05

756 7677 33 747 ns

765 783 753 763 ns

822 882 783 776 71

891 1024 806 792 78

82 112 69 ns

1337 1072 1081 1056 101

1337 1289 1227 1101 60

1406 1388 1376 1273 87

1470 1436 1456 1326 82

103 181 135 163

(1) Ext.-P means extractable phosphorus content which calculated by the sum of W-P, Ca-P, Al-P and Fe-P. (2) ns means not signiWcant within LSD0.05. Table 3 Changes of Mehlich 3 and Lancaster extractable phosphate contents in surface soil during rice cultivation (unit: mg P2O5 kg¡1) Analysis method

Sampling date

Yehari (SiL)

Daegok (LS)

FG 0

FG 20

FG 40

FG 60

LSD0.05

FG 0

FG 20

FG 40

FG 60

LSD0.05

Mehlich 3

July 20 August 19 September 22 October 15

82 63 71 56

101 80 78 88

116 106 106 115

147 140 110 126

21 18 23 31

182 172 175 164

207 185 188 219

280 262 216 238

342 296 276 293

43 35 26 39

Lancaster

July 20 August 19 September 22 October 15

51 48 48 57

53 53 55 78

59 58 59 98

70 61 68 119

12 9 8 15

151 159 171 161

215 202 182 202

244 229 220 239

302 250 250 293

42 33 29 34

Table 4 Chemical and physical properties of surface soils after rice harvest Location

Yehari (SiL)

Daegok (LS)

pH (1:5 H2O)

OM (g kg¡1)

T–N (g kg¡1)

Av. P2O5 (mg kg¡1)

Av. SiO2 (mg kg¡1)

Ex. cations (cmolc kg¡1) Ca

Mg

K

FG 0 FG 20 FG 40 FG 60

5.2 5.5 5.8 6.0

14.8 16.7 15.2 14.8

1.5 1.7 1.6 1.5

57 78 98 119

79 109 113 148

3.9 5.1 6.8 8.9

1.15 1.29 1.35 1.38

0.21 0.17 0.16 0.17

LSD0.05

0.3

ns

ns

15

21

1.1

ns

ns

FG 0 FG 20 FG 40 FG 60

5.7 5.8 5.8 6.2

14.5 14.5 17.2 19.5

1.5 1.6 1.7 1.8

161 202 239 293

38 70 83 117

2.8 4.6 6.0 8.5

0.44 0.50 0.54 0.62

0.14 0.14 0.18 0.19

LSD0.05

0.4

ns

ns

34

29

1.3

ns

ns

Treatment

cation (Table 4): it was 79 mg kg¡1 in FG-0 at Yehari (SiL) at the time of harvest and increased to 148 mg kg¡1 with 60 Mg ha¡1 of the mixture (FG-60). The same tendency

was observed in Daegok (LS). This increase might increase the plant available phosphate content of the soil during the investigation period.

1984

C.H. Lee et al. / Bioresource Technology 98 (2007) 1980–1984

4. Conclusions From an agronomic perspective, the Xy-ash and phosphogypsum mixture (50:50, wt wt¡1) should be useful for increasing plant-available phosphorus and rice productivity while reducing P export from Xooded paddy soils where P loss in surface runoV is a concern. The mixture should be a very good alternate soil amendment to improve rice productivity and fertility of Korean paddy soils and reduce P loss during rice cultivation. Acknowledgements This study was supported by Rural Development Administration, Republic of Korea (20040401033020). C. H. Lee is supported by scholarships from the BK21 Program, Ministry of Education and Human Resource Development, Korea. References Bohn, H., McNeal, G., O’connor, G., 1979. Soil Chemistry. A Wiley-Interscience Publication. Burkholder, J.M., Glasgow Jr., H.B., 1997. PWesteria piscicida and other PWesteria-like dinoXagellates: Behavior, impacts, and environmental controls. Limnol. Oceanogr. 42, 1052–1075. Cha, D.W., Lee, H.S., Jung, J.H., 1999. Production and composition of the power plant coal ash in Korea. In: Proceedings of Agricultural Utilization of Fly Ash Symposium. Gyeongsang National University, Chinju 1–23 (in Korean with English summary). Coleman, N.T., Thomas, G.W., 1967. In: Pearson, R.W., Adams, F. (Eds.), The basic chemistry of soil acidity. Madison (WI). American Society of Agronomy, pp. 1–42. Dean, L.A., 1949. Fixation of soil phosphorus. Adv Agron 1, 391–411. Foy, R.H., Withers, P.J.A. 1995. The Contribution of Agricultural Phosphorus to Euthrophication. Fertilizer Society, Proceedings No. 365. pp, 32. Hingston, F.J., Raupach, M., 1967. The reaction between monosilicic acid and aluminum hydroxide. I. Kinetics of adsorption of silicic acid by aluminum hydroxide. Aust. J. Soil Res. 5, 295–309. Hingston, F.J., Posner, A.M., Quirk, J.P., 1972. Anion adsorption by goethite and gibbsite. I. The role of the proton in determining adsorption envelops. J. Soil Sci. 23, 177–192. Jepson, W.B., JeVs, D.G., Ferris, A.P., 1976. The adsorption of silica on gibbsite and its relevance to the kaolinite surface. J. Colloid Interf. Sci. 5, 454–461.

Lee, Y.B., Ha, H.S., Park, B.K., Cho, J.S., Kim, P.J., 2002. EVect of a Xy ash and gypsum mixture on rice cultivation. Soil Sci. Plant Nutr. 48, 171– 178. Lee, C.H., Park, C.Y., Park, K.D., Jeon, W.T., Kim, P.J., 2004. Long-term eVects of fertilization on the forms and availability of soil phosphorus in rice paddy. Chemosphere 56, 299–304. Lee, Y.B., Ha, H.S., Lee, C.H., Lee, H., Ha, B.H., Kim, P.J., 2005. Improving rice productivity and soil quality by coal ash-phosphogypsum mixture application. J. Korea Soc. Soil Sci. Fert. 38, 45–50. Little, T.M., Hills, J.J., 1978. Agricultural experimentation, design and analysis. John Wiley, Chichester. RDA (Rural Development Administration, Korea). 1988. Methods of soil chemical analysis. National Institute of Agricultural Science and Technology, RDA, Suwon (in Korean). RDA. 1999. Fertilization standard of crop plants. National Institute of Agricultural Science and Technology, RDA, Suwon. P, 148 (in Korean). RDA. 2001. Survey report to fertilizer utilization situation in farming Welds. National Institute of Agricultural Science and Technology, RDA, Suwon, Korea. (in Korean). Roy, A.C., Ali, M.Y., Fox, R.L., Silva, J.A., 1971. InXuence of calcium silicate on phosphate solubility and availability in Hawaiian latosols. Proc. Int. Symp. On Soil Fertility Evaluation. New Delhi 1, 757–765. SAS, 1995. SAS System for WindowsTM, Release 6.11. SAS Institute, Cary, NC. Sekiya, K., 1983. Phosphorus. In: Methods of Soil Analysis (Dojou Youbu Bunsekihou) (ed. Min. Agric. Forest. Fish.) pp. 225–257. Youkendou, Tokyo (in Japanese). Sharpley, A.N., 1995. Dependence of runoV P on extractable soil phosphorus. J. Environ. Qual. 24, 920–926. Sharpley, A.N., Daniel, T.C., Sims, J.T., Pote, D.H., 1996. Determining environmentally sound soil phosphorus levels. J. Soil Water. Conserv. 51, 160–166. Stout, W.L., Sharpley, A.N., Pionke, H.B., 1998. Reducing soil phosphorus solubility with coal combustion by-products. J. Environ. Qual. 27, 111– 118. Vollenweider, R.A., Krekes, R.R., 1982. Eutrophication of waters : monitoring, assessment and control. Organization for Economic Co-operation and Development, Paris. Dean, L.A. 1949. Fixation of soil phosphorus. Adv. Agron. 1, pp. 391–411. Watanabe, M., Kato, N. 1983. Research on the behavior of applied phosphorus fertilizer in soil. (1) Fractionation method of soil inorganic phosphorus compounds in soil. (2) Changes in phosphorus compounds in soil with time. Miscellany Publication of Fertilizer Research. Division, National Institute of Agriculture Science Service. 1–31, pp. 251 (in Japanese). Wolf, A., Beegle, D.B. 1991. Recommended soil tests for macronutrients: phosphorus, potassium, calcium, and magnesium. In: Sims JT, Wolf A, editors. Recommended soil testing procedures for the northeastern United States. Northeast Regional Bulletin #493. Newark (DE): Agricultural Experiment Station, University of Delaware. pp. 25–34.