Influence of calcium chloride and ammonium ...

Communications in Soil Science and Plant Analysis

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Influence of calcium chloride and ammonium thiosulfate on bermudagrass uptake of urea nitrogen J. J. Sloan & W. B. Anderson To cite this article: J. J. Sloan & W. B. Anderson (1998) Influence of calcium chloride and ammonium thiosulfate on bermudagrass uptake of urea nitrogen, Communications in Soil Science and Plant Analysis, 29:3-4, 435-446, DOI: 10.1080/00103629809369956 To link to this article: http://dx.doi.org/10.1080/00103629809369956

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COMMUN. SOIL SCI. PLANT ANAL., 29(3&4), 435-446 (1998)

Influence of Calcium Chloride and Ammonium Thiosulfate on Bermudagrass Uptake of Urea Nitrogen J. J. Sloana and W. B. Andersonb a

U.S. Department of Agriculture, Agricultural Research Service, Soil Science Department, University of Minnesota, 439 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108 b Department of Soil and Crop Sciences, Texas A&M University, College Station, TX 77843

ABSTRACT Calcium chloride (CaCl 2 ) and ammonium thiosulfate (ATS) have demonstrated an ability to inhibit urea hydrolysis and NH3 volatilization. The objective of this experiment was to determine the effect of rainfall and soil drying on the ability of CaCl2 and ATS to increase bermudagrass nitrogen (N) uptake from surface-applied urea. Urea fertilizer, labeled with 15N and amended with CaCl2 or ATS, was surface-applied to bermudagrass sod-cores from Ships clay (C) and a Lufkin fine sandy loam (fsl) soils. Bermudagrass sod-cores were subjected to either low or high rainfall regimes beginning seven days after fertilizer applications. After one month, bermudagrass was harvested and analyzed for total N and 15N content. Calcium chloride significantly increased bermudagrass N use efficiency (NUE) of surface applied urea by 33 to 47% on the Lufkin fsl, but had little effect on the Ships c. Apparently, CaCl2 is most effective on coarse textured soil with low cation exchange capacity (CEC). Simulated rainfall had no effect on yield or NUE

435 Copyright © 1998 by Marcel Dekker, Inc.

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for the Lufkin fsl, but for the Ships c, bermudagrass yield and NUE generally increased with rainfall. The absence of differences among N treatments on the Ships c suggests that urea hydrolysis and N loss were limited due the combined effects of high soil CEC and rapid daily drying of the sod-core surfaces. Ammonium thiosulfate did not affect bermudagrass yield or NUE for either soil or rainfall regime. INTRODUCTION When urea is surface-applied to the soil, as is common in reduced tillage operations and pasture fertilization, N can be lost through NH3 volatilization. Fertilizer researchers have searched for methods to retard the ammonia volatilization process. Most efforts have concentrated on ways to inhibit the activity of urease, the soil enzyme responsible for the hydrolysis of urea. Calcium chloride (CaCl2) and ammonium thiosulfate (ATS, 12-0-0-26S) are two readily available and economically feasible materials that have been investigated as possible urease and NH3 volatilization inhibitors. Fenn et al. (1981a, 1981b, 1981c, 1982) conducted extensive laboratory studies to determine that soluble Ca inhibited the NH3 volatilization process. The inhibitory effects of ATS on urea hydrolysis and NH3 volatilization have been studied in the laboratory and field (Goos, 1985a, 1985b; Goos andFairlie, 1988; Goos etal., 1986; Fairlie and Goos, 1986; McCarty etal., 1990; Sullivan and Havlin, 1992a, 1992b). Soil moisture influences dissolution of urea granules and urea hydrolysis (Volk, 1966; Fenn and Escarzaga, 1976; Vlek and Carter, 1983; Reynolds and Wolf, 1987). Urease activity increases with soil moisture to a maximum at 50% of the soil water holding capacity, but above that level begins to decrease (Roberge and Knowles, 1968; Dalai, 1975). Soil moisture and drying also influence the effectiveness of the volatilization inhibitors, CaCl2 and ATS. Sloan and Anderson (1995) found that rapid soil drying following fertilizer application increased the ability of CaCl2 to reduce ammonia volatilization from surface-applied urea, but had no effect on the ability of ATS to reduce ammonia volatilization from surface applied UAN. Other researchers reported that the efficacy of ATS to inhibit urea hydrolysis was greatest at high temperatures and low soil moisture contents (Sullivan and Havlin, 1992a). The objective of this experiment was to determine the effect of rainfall and soil drying on the ability of CaCl2 and ATS to increase bermudagrass N uptake from surface-applied urea. MATERIALS AND METHODS Experimental Design and Nitrogen Fertilizer Treatments Urea fertilizer labeled with 15N was used to determine the fraction of surface-applied urea-N taken up by Coastal bermudagrass grown on sod-cores in a greenhouse. A 4 by 2 factorial design consisted of 4 N-treatments and 2 rainfall

INFLUENCE OF CaCl2 AND ATS

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regimes with 3 replications. The four N-treatments were 1) control, 2) urea, 3) urea + CaCl2 (0.25, Ca/N eq. wt. ratio), and 4) urea + 10% ATS (w/w). Fertilizer treatments were applied to sod-cores from Ships clay (c) and Lufkin fine sandy loam (fsl) soil at an equivalent rate of 200 kg N ha 1 .


Collection of Coastal Bermudagrass Sod-Cores Coastal bermudagrass sod-cores (10 cm diam. by 10 cm depth) were collected from established field plots on calcareous Ships c (mixed, thermic, udic, chromoustert) and acid Lufkin fsl (montmorillonitic, vertic, thermic, albaqualf) soils. Additional soil properties were reported in a previous publication (Sloan and Anderson, 1995). The sod-cores were placed in plastic pots on top of 6 cm of sand. The purpose of the sand was to support the sod core within the pot and to provide a reservoir for subsurface irrigation. Pots were placed in the greenhouse and the existing bermudagrass was cut to a height of 5 cm. A single application of N, phosphorus (P), and potassium (K) (24-50-50 kg ha 1 ) was applied to each sod-core and soil moisture was maintained near field capacity in order to promote growth of grass and establishment of a uniform bermudagrass stand on each core. After one month, bermudagrass was cut to a height of 5 cm. The harvested bermudagrass was dried and weighed. An analysis of variance was performed on the bermudagrass yield data to ensure that all sod-cores exhibited uniform growth (SAS, 1988). Fertilizer and Rainfall Application Soil moisture was established near field capacity by applying 5-cm water to the sod-core surface and allowing the excess water to drain into the sand below the sod-core for 24 h. Fertilizer treatments were applied as a 1 cm liquid band across the center of the sod-core surface using a uniform drop size of 0.1 mL and a rate equivalent to 200 kg N ha"1. The N rate was based on the surface area of the bermudagrass sod-core. After application of the fertilizer treatments, sod-cores were left undisturbed for 7 days to allow potential ammonia volatilization. Following the initial potential volatilization period, low and high rainfall regimes were imposed on the sod cores (Table 1). The number of days between rainfall occurrences was shorter for the Lufkin fsl since it retained less water and dried out more quickly than the Ships c. Rainfall was simulated by slowly wetting the surface of the sod-core with droplets of water from a squirt bottle. Water was applied in 2.5 mm increments. Following the final simulated rainfall (Table 1), soil moisture in the root zone of all sod-cores was maintained near field capacity using subsurface irrigation. Subsurface irrigation eliminated the risk of washing 15 N down the sides of the pot into the sand. Bermudagrass Harvest and Analysis Bermudagrass sod-cores were allowed to grow for 1 month beyond the first simulated rainfall. Grass from each core was cut at the sod-core surface, rinsed in

438

SLOAN AND ANDERSON TABLE 1. Amount of water applied to bermudagrass sodcores in the greenhouse. Rainfall regime

Low

High

DAFAt


ein-' ShinsLfi

7 14 19

0.75

1.50 1.50 1.50

1.00 1.50 Lufkin fsl

7 11 15

1.50 1.50 1.50

0.75 1.00 1.50

fDays after fertilizer application.

o Q. O>

O" LU

V) V) O

! cu

LOW

HIGH

RAINFALL REGIME

FIGURE 1. Bermudagrass dry matter yield from greenhouse sod-cores. Bars within a soil and rainfall regime with the same letter are not statistically different (DMRT, p=0.10).



439

deionized water, placed in individual paper bags, dried at 70°C for 24 hours and weighed. Dry matter yields were statistically analyzed using Duncan s Multiple Range Test (DMRT) (SAS, 1988). Bermudagrass samples were ground to pass a 40 mesh screen and digested at 350°C on an aluminum block using concentrated H2SO4 and a K2SO4-CuSO4-SeO2 catalyst mixture (Nelson and Sommers, 1973). Total N was then measured by micro-Kjeldahl distillation of the plant digest and titration of the distillate with standard HC1 (Bremner and Mulvaney, 1982). Following titration and calculation of total N, each titrated distillate was acidified with 0.05M H2SO4, dried to 2 to 3 mL volume on a hot plate, transferred to a 10 mL culture tube and taken to complete dryness in a forced-air, heated, oven. The dried sample was analyzed for 15N atom excess by mass spectrometry (Hauck, 1982). The 15N-tagged urea fertilizer solution which was applied to the bermudagrass sod-cores was also analyzed by mass spectrometry for 15N atom excess. Results of the 15N analyses were used to calculate the fraction of N derived from fertilizer (fNdfF) in plant material, fertilizer-N uptake (FNU) and N use efficiency (NUE) (Hauck and Bremner, 1976). RESULTS AND DISCUSSION Coastal Bermudagrass Yield Bermudagrass yield is shown in Figure 1 for both soils. Bermudagrass yields for the three N fertilizer treatments were significantly higher than the controls for both soils and both rainfall regimes. There was no significant difference in yield among the three N treatments for the low rainfall regime on both soils. For both soils under the high rainfall regime, yield for the +10% ATS treatment was significantly lower than the urea and +CaCl2 treatments (p=0.10). In general, addition of CaCl2 or ATS to surface-applied urea did not result in increased bermudagrass yields relative to unamended urea fertilizer. Nitrogen Content All N fertilizer treatments increased bermudagrass N concentration relative to the control on the Ships c, regardless of rainfall regime, but there were no significant • differences among the three fertilizer treatments (Figure 2). On the Lufkin fsl, the urea treatment failed to increase N concentration for either rainfall regime. This is surprising for the high rainfall regime because water infiltration should have moved urea into the soil, protecting it from volatilization. However, Ferguson and Kissel (1986) found that urea moved upward in the soil profile with soil water as the soil dried. High temperatures in the greenhouse promoted rapid soil drying of sod-core surfaces, so even though the rainfall moved the urea into the soil, subsequent soil drying probably brought it back to the surface where it was susceptible to NH3 volatilization.

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SLOAN AND ANDERSON


Q

i n -

ll]

o o o

I

ce. LU

m

LOW

HIGH

RAINFALL REGIME

FIGURE 2. Nitrogen content of bermudagrass grown on sod-cores. Bars within a soil and rainfall regime with the same letter are not statistically different (DMRT, p=0.10).

Source of Coastal Bermudagrass Nitrogen Uptake Fertilizer N uptake (FNU) and soil N uptake (SNU) are shown in Figure 3 for both soils. The 162 mg pot"1 N rate is equivalent to 200 kg N ha"1. The FNU corresponds to that part of total plant N derived from the fertilizer, as measured by 15N. The upper part of each bar is soil N uptake (SNU) and corresponds to that part of total plant N derived from the soil. The sum of FNU and SNU equals total N uptake (TNU) by the bermudagrass. The SNU values for both soils and rainfall regimes were approximately equal for all three fertilizer treatments and only slightly greater than SNU for the control. The addition of fertilizer N apparently stimulated mineralization of soil organic N which lead to greater uptake of soil N by fertilizer treatments relative to the control. A small but significant increase in SNU for the +10% ATS treatment under the low rainfall regime is possibly due to the added stimulation of soil microorganisms by ATS-supplied sulfur. The increase in SNU induced by added S and N was not observed under the high rainfall regime, possibly due to leaching of the thiosulfate


441


N rate = 162 mg pot

LOW

HIGH

RAINFALL REGIME

FIGURE 3. Fertilizer N uptake (FNU) and soil N uptake (SNU) by bermudagrass grown on sod-cores. Bars within a soil, rainfall regime, and N uptake source with the same letter are not statistically significant (DMRT, p=0.10).

ion to a depth where its influence on soil microorganisms near the soil surface horizon was lessened. Goos (1985a) reported that the thiosulfate anion is very mobile in the soil and quickly separates from the NH4+ component of ATS. Since SNU is approximately equal for all fertilizer treatments (Figure 3), differences in TNU are attributed primarily to FNU. On the Ships c, under a high rainfall regime, Coastal bermudagrass FNU, and consequently TNU, was greatest from urea, followed by urea+CaCl2 and then urea+10%ATS (Figure 3). High rainfall probably moved urea into the soil where it was protected from NH3 volatilization. Thus, urea performed as well as or better than the other urea treatments that contained N-loss inhibitors. Generally, FNU values for the Ships c were lower for the low rainfall regime than the high

SLOAN AND ANDERSON


442

LOW

HIGH

RAINFALL REGIME

FIGURE 4. Bermudagrass N use efficiency (NUE) from greenhouse sod-cores. Bars within a soil and rainfall regime with the same letter are not statistically different (DMRT, p=0.10).

rainfall regime. Under the high rainfall regime, urea fertilizer treatments were probably moved by water into the soil to a depth where NH3 volatilization was reduced. Fenn and Kissel (1976) observed reduced NH3 volatilization from urea as it was incorporated into the soil to increasing depths. Apparently, the low rainfall regime in the present study was not as effective as the high rainfall regime at moving urea into the soil to a depth where it was protected from NH3 volatilization. Differences among FNU treatment means were much greater on the Lufkin fsl than the Ships c (Figure 3). The +CaCl2 treatment significantly increased FNU under both rainfall regimes (p=0.10). There was no significant difference between the urea and +10% ATS treatments under either rainfall regime. FNU values for the urea and +10% ATS treatments were much larger on the Ships c than the Lufkin fsl under both rainfall regimes (Figure 3). Lower FNU from the Lufkin fsl was probably due to its low CEC. Fenn and Kissel (1976)



443

demonstrated that NH3 volatilization losses from urea increased as soil CEC decreased. Similar effects of soil texture and CEC on NH3 volatilization have been reported by other researchers (Gasser, 1964; Verma et al., 1974). The ineffectiveness of ATS is evident by its inability to increase uptake of urea-N from the Lufkin fsl soil. This is supported by an earlier laboratory study that found no difference between cumulative NH3 volatilization losses for urea and urea+10% ATS treatments on Ships c and Lufkin fsl soils (Sloan and Anderson, 1995). Nitrogen Use Efficiency Nitrogen use efficiency (NUE) denotes the fraction of applied fertilizer N utilized by bermudagrass. Figure 4 shows NUE values for both soil types. The values reported here are lower than those reported by Fenn et al. (1981a, 1982) in a similar greenhouse experiment using sudangrass (Sorghum bicolor) as the test crop. However, Fenn et al. (1981a, 1982) used 3 sudangrass harvests to calculate NUE while the present study used only one bermudagrass harvest. Trends in NUE among the fertilizer treatments and soils are essentially identical to the trends in FNU observed in Figure 3. For the Ships c, NUE of urea-N was not increased by the addition of CaCl2 or ATS (Figure 4). For the Lufkin fsl, addition of CaCl2 to urea increased NUE, but there was little difference in NUE between the low and high rainfall regimes. Different soil responses to fertilizer treatments and rainfall regimes were most likely attributable to differences in soil properties. The high CEC of the Ships c (29 cmol kg 1 ) protected hydrolyzed urea from volatilizing (Fenn and Kissel, 1976; Gasser, 1964) and thus, very few differences in NUE were observed among fertilizer treatments. The relatively high field capacity moisture content (0.433 kg kg 1 ) of the Ships c prevented significant soil drying and movement of urea back to the soil surface after rainfall additions. Additional rainfall kept urea in the subsoil where it was protected from NH3 volatilization. Thus, NUE values for the Ships c were slightly greater for the high rainfall regime (Figure 4). The presence of significant differences among treatments on the Lufkin fsl for both the low and high rainfall regimes suggests that most NH3 volatilization occurred during the seven days after fertilizer application and before the first simulated rainfall. This possibility is supported by a laboratory study that showed NH3 volatilization following urea application began more quickly and proceeded at a much faster rate from the Lufkin fsl than from the Ships c (Sloan and Anderson, 1995). The first rainfall application (Table 1) probably leached urea and its amendments into the soil to a depth where NH3 volatilization was mostly inhibited. Researchers have reported almost complete inhibition of NH3 volatilization with the addition of 10 mm of rainfall (Fox and Hoffman, 1981). However, the Lufkin fsl was susceptible to rapid soil drying and NH3 volatilization losses due to a sandy texture (74% sand) and low CEC (1.5 cmol kg 1 ). Even after rainfall was

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applied, rapid drying of the Lufkin fsl probably brought urea back to the surface where it was susceptible to NH3 volatilization (Ferguson and Kissel, 1986). Therefore, CaCl2 was able to effectively reduce N loss from the Lufkin fsl and increase the NUE of urea-N. CONCLUSIONS The effectiveness of CaCl2 and ATS as NH3 volatilization inhibitors was evaluated in the greenhouse under both high and low simulated rainfall regimes. For Ships c soil, addition of CaCI2 to urea did not increase bermudagrass yield, N concentration, total N uptake, or N use efficiency under either rainfall regime. The lack of significant differences among treatments was primarily due to the high CEC of the Ships c. Rapid drying of the sod-core surface promoted by high, daily greenhouse temperatures probably prevented significant urea hydrolysis. For the Lufkin fsl, CaCl2 increased bermudagrass urea-N uptake, N concentration, and NUE for both rainfall regimes, but not dry-matter yield. High soil moisture at the time of fertilizer application led to rapid urea hydrolysis and the low CEC of the Lufkin fsl provided little protection against NH3 volatilization. Rapid drying of the sod-core surface following fertilizer application probably prevented dilution the CaCl2 amendment and consequently increased its effectiveness. For the most part, ATS had no effect on bermudagrass dry-matter yield, N concentration, or urea-N uptake for either soil type under either simulated rainfall. ACKNOWLEDGMENTS Research was conducted with support of the Texas Agricultural Experiment Station. REFERENCES Bremner, J.M. and C.S. Mulvaney. 1982. Nitrogen—Total, pp. 595-618. In: A.L. Page, R.H. Miller, and D.R. Keeney (eds.), Methods of Soil Analysis. Part 2. 2nd ed. Agronomy 9. American Society of Agronomy, Madison, WI. Dalai, R.C. 1975. Urease activity in some Trinidad soils. Soil Biol. Biochem. 7:5-8. Fairlie, T.E. and R.J. Goos. 1986. Urea hydrolysis and NH3 volatilization characteristics of liquid fertilizer mixtures. II. Studies under modified field conditions. J. Fert. Issues 3:86-90. Fenn, L.B. and R. Escarzaga. 1976. Ammonia volatilization from surface applications of ammonium compounds on calcareous soils: V. Soil water content and method of N application. Soil Sci. Soc Am. J. 40:537-540.


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Fenn, L.B. and D.E. Kissel. 1976. The influence of cation exchange capacity and depth of incorporation on NH3 volatilization from ammonium compounds applied to calcareous soils. Soil Sci. Soc. Am. J. 40:394-398. Fenn, L.B., J.E. Matocha, and E. Wu. 1981a. Ammonia losses from surface applied urea and ammonium fertilizers as influenced by rates of soluble calcium. Soil Sci. Soc. Am. J. 45:883-886. Fenn, L.B., J.E. Matocha, and E. Wu. 1981b. A comparison of calcium carbonate precipitation and pH depression on calcium reduced NH3 loss from surface-applied urea. Soil Sci. Soc. Am. J. 45:1128-1131. Fenn, L.B., J.E. Matocha, and E. Wu. 1982. Soil cation exchange capacity effects on NH3 loss from surface-applied urea in the presence of soluble calcium. Soil Sci. Soc. Am. J. 46:78-81. Fenn, L.B., R.M. Taylor, and J.E. Matocha. 1981c. Ammonia losses from surface applied N fertilizer as controlled by soluble calcium and magnesium: General theory. Soil Sci. Soc. Am. J. 45:777-781. Ferguson, R.B. and D.E. Kissel. 1986. Effects of soil drying on NH3 volatilization from surface-applied urea. Soil Sci. Soc. Am. J. 50:485-490. Fox, R.H. and L.D. Hoffman. 1981. The effect of N fertilizer source on grain yield, N uptake, soil pH, and lime requirement in no-till corn. Agron. J. 73:891-895. Gasser, J.K.R. 1964. Some factors affecting losses of NH3 from urea and ammonium sulfate applied to soil. J. Soil Sci. 15:258-272. Goos, R.J. 1985a. Identification of ammonium thiosulfate as a nitrification and urease inhibitor. Soil Sci. Soc. Am. J. 49:232-235. Goos, R.J. 1985b. Urea hydrolysis and NH3 volatilization characteristics of liquid fertilizer mixtures. I. Laboratory studies. J. Fert. Issues 2:38-41. Goos, R.J. and T.E. Fairlie. 1988. Effect of ammonium thiosulfate and liquid fertilizer droplet size on urea hydrolysis. Soil Sci. Soc. Am. J. 52:522-524. Goos, R.J., R.P. Voss, T.E. Fairlie, and B.E. Johnson. 1986. Containing N loss. Solutions, January:40-43. Hauck, R.D. 1982. Nitrogen—Isotope ratio analysis. pp. 735-779. In: A.L. Page, R.H. Miller, and D.R. Keeney (eds.), Methods of Soil Analysis. Part 2. 2nd ed. Agronomy 9. American Society of Agronomy, Madison, WI. Hauck, R.D. and J.M. Bremner. 1976. Use of tracers for soil and fertilizer nitrogen research. Adv. Agron. 28:219-266.

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McCarty, G.W., J.M. Bremner, and M.J. Krogmeier. 1990. Evaluation of ammonium thiosulfate as a soil urease inhibitor. Fert. Res. 24:135-139.


Nelson, D.W. and L.E. Sommers. 1973. Determination of total nitrogen in plant material. Agron. J. 65:109:112. Reynolds, C.M. and D.C. Wolf. 1987. Effect of soil moisture and air relative humidity on NH3 volatilization from surface-applied urea. Soil Sci. 143:144-152. Roberge, M.R. and R. Knowles. 1968. Factors affecting urease activity in a black spruce humus sterilized by gamma radiation. Can. J. Soil Sci. 48:355-361. SAS. 1988. SAS/STAT User's Guide, Release 6.03 Edition. Statistical Analysis System, Cary, NC. Sloan, J.J. and W.B. Anderson. 1995. Calcium chloride and ammonium thiosulfate as ammonia volatilization inhibitors for urea fertilizers. Commun. Soil Sci. Plant. Anal. 26:2425-2447. Sullivan, D.M. and J.L. Havlin. 1992a. Soil and Environmental effects on urease inhibition by ammonium thiosulfate. Soil Sci. Soc. Am. J. 56:950-956. Sullivan, D.M. and J.L. Havlin. 1992b. Thiosulfate inhibition of urea hydrolysis in soils: Tetrathionate as a urease inhibitor. Soil Sci. Soc. Am. J. 56:957-960. Verma, R., N. Singh, and M.C. Sarkar. 1974. Some soil properties affecting loss of N from urea due to NH3 volatilization. J. Ind. Soc. Soil Sci. 22:80-83. Vlek, P.L.G. and M.F. Carter. 1983. The effect of soil environment and fertilizer modification on the rate of urea hydrolysis. Soil Sci. 136:56-63. Volk, G.M. 1966. Efficiency of fertilizer urea as affected by method of application, soil moisture, and lime. Agron. J. 58:249-253.