Printer Friendly

Estimating nitrous oxide emissions from flood-irrigated alkaline grey clays.

Introduction

Concern is mounting regarding the quantities of nitrous oxide ([N.sub.2]O) entering the earth's atmosphere, as agriculture is a major contributor to the atmospheric [N.sub.2]O pool. Carbon dioxide, methane, and [N.sub.2]O combined represent 80% of emissions contributing to the global greenhouse effect (Russell 1991). Emissions of [N.sub.2]O are critical, as the greenhouse warming potential of [N.sub.2]O is estimated as 295 times greater than of C[O.sub.2] (IPPC 2001). Although agriculture may be a small contributor to the total [N.sub.2]O emission on a global scale (Weier 1998), it dominates anthropogenic [N.sub.2]O emissions and it is possible that such emissions can be reduced with improved irrigation and N fertiliser management.

Recent field studies have indicated that substantial quantities of [sup.15]N-labelled fertiliser can be lost from flood-irrigated grey clays used for cotton cropping (Freney et al. 1993; Rochester et al. 1994, 1996). Denitrification is believed to be the dominant process contributing to these losses, which commonly exceed 50% of applied N (Freney et al. 1993). High rates of N fertiliser (up to 200 kg N/ha) may be required to optimise lint yield. Hence, N fertiliser losses may exceed 100 kg N/ha during a growing season. Soils of high clay content can rapidly become anaerobic when flood irrigated, providing ideal conditions for denitrification.

However, little is known of the proportions of the various N gases emitted following denitrification. Published research reveals that high [N.sub.2]O/[N.sub.2] mole ratios are commonly associated with soils of low pH. Several authors indicate that where several soils of varying pH are compared, those with higher pH commonly emit less [N.sub.2]O (Gilliam et al. 1978; Koskinen and Keeney 1982). [N.sub.2]O/[N.sub.2] mole ratios reported from investigations of alkaline soils are commonly low or negligible (Simpson et al. 1984; Avalakki et al. 1995b). Hauck and Melsted (1956) showed that liming an acid soil reduced emission of [N.sub.2]O relative to unlimed soil. Moraghan and Buresh (1977) reported that [N.sub.2]O remained the dominant gaseous N form evolved at pH 6, but 84% of the [N.sub.2]O was reduced to [N.sub.2] at pH 8.

[N.sub.2]O emissions may be reduced by managing, reducing, or avoiding denitrification. The use of nitrification inhibitors can maintain fertiliser N as ammonium, thereby avoiding loss of nitrate-N (Eriksen and Holtan-Hartwig 1993). Alternatively, legume cropping can substantially reduce the need for the high rates of fertiliser N commonly used in commercial cotton production (Rochester et al. 2001). Although it was shown that N loss was reduced under this system, significant denitrification may still occur when leguminous residues of high N content decompose. By improving drainage through better field design and irrigation management, waterlogging and denitrification can be reduced.

Because of the difficulties in quantifying [N.sub.2]O emissions in the field, most studies have been conducted in the laboratory. Therefore, identification of surrogate measures of [N.sub.2]O emissions determined under laboratory conditions is one means of estimating [N.sub.2]O losses in the field. This paper develops a correlation between soil pH and [N.sub.2]O emissions that is then used to estimate [N.sub.2]O loss from field experiments where N loss has been determined in [sup.15]N balance studies.

Methods

Research published in relation to [N.sub.2] and [N.sub.2]O emissions from soil is collated in Table 1. Where the time course of [N.sub.2]O and [N.sub.2] emissions was published, the [N.sub.2]O/[N.sub.2] mole ratios were calculated for the highest level of [N.sub.2]O emission. It is recognised that [N.sub.2]O/[N.sub.2] mole ratios vary with time and soil moisture content (Hauck and Melsted 1956; Aulakh et al. 1984). Where the method of determining soil pH was not specified, it was assumed that 1: 5 soil: water was used for the determination, as used for the cotton-growing soils reported here. A relationship between the [N.sub.2]O/[N.sub.2] mole ratio and the pH of each soil was determined using the Sigma Plot program (Anon. 2000). A negative exponential function most closely fitted the data.

In order to estimate the quantities of [N.sub.2]O emanating from alkaline soils, the following procedures were followed. The [N.sub.2]O/[N.sub.2] mole ratio was estimated using the relationships with soil pH described above. The proportion of the total N lost as [N.sub.2]O-N [i,e. [N.sub.2]O/([N.sub.2]O + [N.sub.2])] was then calculated. This fraction was then multiplied by the apparent N fertiliser loss, as published in [sup.15]N balance studies (Freney et al. 1993; Rochester et al. 1994, 1996, 2001). The apparent N fertiliser loss reported in Tables 2, 3, and 4 includes ammonia volatilisation loss, but this is a very minor source of N loss from fertilisers placed below the soil surface in this cropping system (~1% of N applied; Denmead et al. 1977).

Results and discussion

pH effect on the [N.sub.2]O/[N.sub.2] mole ratio

The [N.sub.2]O/[N.sub.2] mole ratio (Table 1) was related to soil pH (Fig. 1) using a negative exponential function. This relationship indicated that equivalent amounts of [N.sub.2]O and [N.sub.2] would be produced from soil of pH 6.04. Acidic soils were prone to produce more [N.sub.2]O relative to [N.sub.2]; alkaline soils produced relatively less [N.sub.2]O than [N.sub.2] during denitrification.

Koskinen and Keeney (1982) reported that soil pH may have a strong effect upon the composition of the N gases evolved, with a higher proportion of [N.sub.2]O to [N.sub.2] in soil of pH <6.0, whereas [N.sub.2] was the dominant N gas emitted from soil of pH > 6.9. Christensen et al. (1990) reported that [N.sub.2]O was the sole denitrification product from an acid soil (pH 3.8). Substantial amounts of [N.sub.2]O are emitted from acid soils but [N.sub.2] is the major gas emitted following denitrification in alkaline soils (Cooper and Smith 1963). The model of Focht (1974) predicts enhanced denitrification rates with higher soil pH, but with a decreased proportion of [N.sub.2]O. Soil pH of 7.7 produces the optimum conditions for reduction of [N.sub.2]O (Wicht 1996), whereby a small decrease in pH produces a substantial increase in nitrous oxide evolution. Hauck and Melsted (1956) indicated that soil pH influences the [N.sub.2]O/[N.sub.2] mole fraction, where abundant [N.sub.2]O production was observed below pH 6; liming this soil to pH 7.2 more than doubled the rate of denitrification, although less [N.sub.2]O was produced. Koskinen and Keeney (1982) concluded that the sequence of denitrification products follows the exhaustion of the more readily reducible N compounds and the final or dominant product of denitrification is affected by soil pH. Weier and Gilliam (1986) found that almost no [N.sub.2]O was emitted during incubation of flooded soil of pH >5.8, with [N.sub.2]O being the sole product of denitrification at pH <5. These results concur with the data in Fig. 1.

[FIGURE 1 OMITTED]

Other edaphic factors may also affect the [N.sub.2]O/[N.sub.2] mole fraction. Weier et al. (1993) observed a wide range of [N.sub.2]O/[N.sub.2] mole fractions that normally decreased over time. The lowest ratios were observed in soils high in soluble C and with high water-filled pore space. The highest ratios were associated with higher nitrate concentration. The [N.sub.2]O/[N.sub.2] mole fraction normally declines as soil moisture increases and aeration decreases (Eriksen and Holtan-Hartwig 1993).

The [N.sub.2]O/[N.sub.2] mole fraction also increases with nitrate, and particularly nitrite, concentrations (Firestone et al. 1979; Smith and Tiedje 1979). Galsworthy and Burford (1978) showed that nitrous oxide was the dominant gas evolved from soils amended with 400 mg N[O.sub.3]-N/kg and the [N.sub.2]O/[N.sub.2] mole fraction changed little with time.

The rate of denitrification may also be affected by soil pH. Bollag et al. (1970) indicated that denitrifying microorganisms grow slowly and rates of denitrification are depressed below pH 6; the optimum pH range for the isolates they examined was neutral to slightly alkaline. Cooper and Smith (1963) suggested that in acid soils, nitrate reduction may be the rate-limiting step, whereas nitrite reduction may limit denitrification in alkaline soils. Koskinen and Keeney (1982) considered that C availability, rather than soil pH, limited denitrification in most situations, whereas pH may have a stronger effect upon the composition of the gases evolved.

Importantly, the 2 reports that relate to field observations (Table 1, Fig. 1) indicate extremely low [N.sub.2]O emissions, but both relate to flooded fields where [N.sub.2] would normally be the sole product of denitrification. Simpson et al. (1984) found only negligible amounts of [N.sub.2]O in flooded alkaline grey clay, and Denmead et al. (1979) found similarly low [N.sub.2]O emissions from flooded acidic red clay.

Soil profile characteristics can play an important part in the reduction of [N.sub.2]O. In the field [N.sub.2]O is largely evolved from banded fertiliser placed at depth in the soil and this [N.sub.2]O may then be reduced as it diffuses through the soil (Gilliam et al. 1978). Where shallow samples of soil are used in laboratory studies, there may be little opportunity for further reduction of [N.sub.2]O. Possibly, the laboratory studies may overestimate emission of [N.sub.2]O from soil and may not be indicative of [N.sub.2]O emissions in the field; the high [N.sub.2]O/[N.sub.2] ratios described in Table 1 and Fig. 1 may be a consequence of the experimental conditions. Gilliam et al. (1978) indicated that low [N.sub.2]O/[N.sub.2] mole fractions result from [N.sub.2]O formation at depth and this [N.sub.2]O is reduced as it moves to the soil surface and this complicates the prediction of the [N.sub.2]O/[N.sub.2] mole fraction in agricultural soils. Nitrate and soluble organic compounds may be leached through the soil to more anaerobic regions where denitrification prevails, although the production of N gases generally decreases with depth (Khan and Moore 1968).

Estimation of [N.sub.2]O emission

Based on the relationship depicted in Fig. 1, emission of about 5 kg [N.sub.2]O-N was predicted from several alkaline grey clay soils during a cotton season, according to the calculations reported in Table 2. A mean loss of 2.0 kg [N.sub.2]O-N/ha (range 1.6-2.6) was calculated using the N fertiliser recovery data from the 3 soil types reported by Rochester and Constable (2000). [N.sub.2]O was estimated to comprise about 2.4% of the N gases evolved, based on the fitted curve in Fig. 1. The higher values of [N.sub.2]O emission calculated were associated with finer textured soils, where poorer aeration and drainage produced higher rates of denitrification. Currently, it is assumed that because of the high soil pH, fine soil texture, and waterlogging through imperfect drainage, virtually all [N.sub.2]O is reduced to [N.sub.2] and only traces of [N.sub.2]O are emitted.

Low rates of [N.sub.2]O emission have been reported by Avalakki et al. (1995a), who observed that [N.sub.2]O comprised only 0.5% of the N emissions from a Vertosol, even when straw was added. Also, Mosier et al. (1986) observed in irrigated maize that <3% of applied N fertiliser was denitrified, although about 70% of this N was evolved as [N.sub.2]O, and concluded that the importance of denitrification may have been overemphasised in some agricultural systems.

More significant [N.sub.2]O emissions have been reported. Murakami and Kumazawa (1987) reported that [N.sub.2]O comprised 92% of the evolved N gases, but when this soil was kept at 90% of water-holding capacity, [N.sub.2]O emission was reduced to 24% of the N gases evolved. Ryden and Lund (1980) measured [N.sub.2]O fluxes of up to 1 kg N/ha.day from vegetable-cropped fields, with the highest emission occurring at the first irrigation post-fertilisation and emissions declining during the cropping cycle. [N.sub.2]O emission accounted for the loss of 4.2 kg N/ha (8% of total N emission from this system). Of the 250 kg ammonia-N/ha applied by Bremner et al. (1981), 16 kg/ha was lost as [N.sub.2]O, mostly in the first 6 weeks of the 20-week experiment; the unfertilised control lost only 2 kg N/ha over the same period. N losses from the control and fertilised soil were similar after 14 weeks. Colbourn et al. (1984) estimated that 0.3 kg N/ha.day was denitrified over a 23-day period; 93% of this loss was as [N.sub.2] but 30% of the 100 kg N/ha applied was denitrified over 2 months.

Because [N.sub.2]O is one gas in a sequence of gases formed during denitrification, it is possible that [N.sub.2]O not reduced to [N.sub.2] will be emitted from the soil as [N.sub.2]O. Mosier et al. (1995) proposed that a figure of 1.25([+ or -]1)% of the N applied be used to estimate [N.sub.2]O emission from fertiliser. This is close to the values estimated from alkaline cotton-growing soils in Table 2 where losses averaged 1.1% (range 0.9-1.4%) of N fertiliser applied.

Alkaline cotton-growing soils in Pakistan (Mahmood et al. 2000; Table 3) may lose similar amounts of N and [N.sub.2]O as in Australia due to the similar N fertiliser losses and soil pH. However, wheat grown in an acidic soil in Australia may lose substantially larger quantities of [N.sub.2]O (Freney et al. 1992; Table 3).

In comparison, Weier (1998) estimated that losses of [N.sub.2]O from Australian sugarcane fields were of the order of 4400 t [N.sub.2]O-N/year (1994). The area under sugarcane was quoted at 365000 ha, indicating that more than 12 kg [N.sub.2]O-N/ha was emitted from the soil via denitrification in that year. The proportion of N gases emitted as [N.sub.2]O was between 0.45 and 0.78, which reflects the more acidic soils on which sugarcane is grown in Australia. Weier (1998) estimates that a further 28 kg [N.sub.2]O-N/ha was emitted from the area where cane trash was burnt following harvest.

Possible strategies to reduce [N.sub.2]O emissions

Nitrification inhibitors

Alternatively, the use of nitrification inhibitors has not only reduced the total quantity of N denitrified, but the [N.sub.2]O component of N gases emitted may be altered. Rochester et al. (1994) reported that total [sup.15]N recovery in the plant/soil system was significantly increased (by 43% in one instance) with the use of etridiazole; N and estimated [N.sub.2]O loss would be reduced by 24% (Table 3). Mikkelsen et al. (1986) reported that the application of etridiazole substantially reduced denitrification loss (by 64%); leaching was also reduced through delayed nitrification in the free-draining soil. Further, Somda et al. (1990, 1991) reported that etridiazole significantly suppressed microbial reduction of nitrate and nitrite under anaerobic laboratory conditions and production of [N.sub.2]O was almost eliminated, and [N.sub.2] production was reduced by 19%. Mills and McElhannon (1984) demonstrated in the laboratory that etridiazole substantially reduced the evolution of [N.sub.2] and [N.sub.2]O, and a lower proportion of [N.sub.2]O relative to [N.sub.2] was evolved from soil treated with etridiazole. Importantly, the addition of a nitrification inhibitor (wax-coated calcium carbide) reduced N loss (and estimated [N.sub.2]O emission) by almost 50% in a wheat cropping system in Australia (Freney et al. 1992; Table 3).

Legume cropping

Another means of overcoming the loss of N fertiliser and thus emission of [N.sub.2]O is to include legume cropping in agricultural systems as a means of reducing N fertiliser inputs. Rochester et al. (2001) indicated in [sup.15]N balance studies that loss of legume N was substantially less than of fertiliser N applied at the time of incorporation of legume stubble. A reduced input of N fertiliser would be expected to result in a commensurate reduction in [N.sub.2]O loss, as estimated in Table 4. Loss of N and estimated [N.sub.2]O emission from green-manured legumes (field peas and lablab) were smaller than with legume stubble following grain harvest (fababean and soybean), but considerably more N was recovered from legume residues than from fertiliser N (Table 4). It is possible that N is lost from the crop or stubble before it is incorporated into the soil; hence soil pH may have little bearing on the composition of nitrogen gases derived from this source at this time. However, losses of N or [N.sub.2]O may not be substantial even where legume stubble of high N content is incorporated, although Aulakh et al. (1991) observed higher rates of [N.sub.2]O emission from organic residues of low C/N (legumes) compared with high C/N (maize or wheat) residues in the short term. Previously, Aulakh et al. (1983) had concluded that incorporation of clover residues substantially reduced gaseous N loss compared with fallowing.

Further in-field experimentation is required to measure the emission of [N.sub.2]O from alkaline soils, particularly those that support cotton crops that require substantial inputs of N fertiliser or where legume crops have been included in the cropping system.

Conclusions

Although measurements of the [N.sub.2]O/[N.sub.2] mole fraction from alkaline soils are low, the evolution of [N.sub.2]O from these soils may be significant. Because of the large quantities of fertiliser N applied to these cropping soils, estimates indicate that a small proportion of the denitrified fertiliser N is emitted as [N.sub.2]O, but this may amount to about 2 kg [N.sub.2]O-N/ha or 1% of the N fertiliser normally applied to alkaline grey clays for cotton cropping.
Table 1. Description of soils and [N.sub.2]O/[N.sub.2] mole ratios
reported in various studies

It was assumed that 1:5 soil: water was used for all pH
determinations where not specified

 [N.sub.2]O/
Reference Conditions Soil type Soil pH [N.sub.2]

Eriksen and Holtan- Laboratory Clay loam 5.5 2.9
 Hartwig 1993 5.9 0.2
Koskinen and Laboratory Silt loam 4.6 6.0
 Keeney 1982 5.4 5.2
 6.0 1.2
 6.9 0.4
Gilliam et al. 1978 Laboratory Loam 6.2 4.0
 Fine silt 6.3 0.01
 Silty clay 7.4 0.01
 Loam 7.9 0.00
Firestone et Laboratory Loamy sand 6.4 1.20
 al. 1979 Loam 7.0 0.44
Avalakki et al. Laboratory Black earth 8.0 0.05
 1995a, 1995b Laboratory Red-brown
 earth 6.3 0.266
 Black earth 8.0 0.064
Keeney et al. 1979 Laboratory Silt loam 6.8 0.50
Hauck and Melsted Laboratory Silt loam 5.9 6.77
 1956 7.2 0.45
Bronson and Laboratory Clay loam 7.9 <0.01
 Mosier 1991
Yeomans and Laboratory Clay loam 7.5 0.23
 Bremner 1988 Silty clay 7.7 0.22
 Silty clay
 loam 8.1 0.18
Weier and Laboratory Histosol 4.2 13.0
 Gilliam 1986 Histosol 4.6 3.3
 Histosol 4.7 >20
 Histosol 4.7 >20
 Histosol 5.0 9.5
 Histosol 5.4 1.94
 Histosol 5.6 0.2
 Histosol 5.6 2.0
 Histosol 5.7 0.3
 Histosol 5.8 0.1
Denmead et al. 1979 Flooded Red clay 5.8 0.01
 field
Simpson et al. 1984 Flooded Grey clay 8.2 <0.01
 field

Table 2. Estimated loss of fertiliser-derived [N.sub.2]O-N
during a cotton season from an application of 180 kg N/ha

Soil and nitrogen fertiliser recovery (NFR)
data are from Rochester and Constable (2000)

Soil series Soil Clay NFRB N
 pH (A) content (%of N fertiliser
 (%) applied) lost
 (kg/ha)

Gommel
 medium clay 8.3 53 68 57.6
Gommel
 medium clay 8.5 59 52 86.4
Gommel
 heavy clay 8.4 69 40 108.0
Mean 8.4 60 53 84.0

Soil series [N.sub.2]O/ [N.sub.2]O/ [N.sub.2]O-N [N.sub.2]O-N
 [N.sub.2]C ([N.sub.2]O+ emitted emitted
 [N.sub.2]) (kg/ha) (% of N
 applied)

Gommel
 medium clay 0.0283 0.0275 1.58 0.9
Gommel
 medium clay 0.0207 0.0203 1.75 1.0
Gommel
 heavy clay 0.0242 0.0236 2.55 1.4
Mean 0.0242 0.0236 1.98 1.1

(A) Soil pH (1:5 soil:water).

(B) Nitrogen fertiliser recovery.

(C) Ratio derived from the fitted curve in Fig. 1.

Table 3. Estimated emission of fertiliser-derived [N.sub.2]O-N
during the growth of cotton and wheat crops

The application of nitrification inhibitors reduced
N fertiliser loss and estimated [N.sub.2]O emission

Reference Soil NFR (A) N
 (% of N fertiliser
 applied) lost
 (kg/ha)

Mahmood et al. (2000), Sandy clay loam, 58 (C) 71.8
 cotton, Pakistan pH 7.9
Rochester et al. (1994), Gommel heavy 35 52
 cotton, Australia clay, pH 8.4 50 (D) 40
Freney et al. (1992), Red-brown 50 50
 wheat, Australia earth, pH 6.2 73 (E) 27

Reference [N.sub.2]O/ [N.sub.2]O/
 [N.sub.2] (B) ([N.sub.2]O+
 [N.sub.2])

Mahmood et al. (2000), 0.0532 0.0505
 cotton, Pakistan
Rochester et al. (1994), 0.0242 0.0236
 cotton, Australia 0.0242 0.0236
Freney et al. (1992), 0.773 0.436
 wheat, Australia 0.773 0.436

Reference [N.sub.2]O-N [N.sub.2]O-N
 emitted emitted
 (kg/ha) (% of N
 applied)

Mahmood et al. (2000), 3.63 2.1
 cotton, Pakistan
Rochester et al. (1994), 1.23 1.5
 cotton, Australia 0.94 1.2
Freney et al. (1992), 21.8 21.8
 wheat, Australia 11.8 11.81

(A) Nitrogen fertiliser recovery.

(B) Ratio derived from the fitted curve in Fig. 1.

(C) 173 kg urea-N applied/ha.

(D) Nitrification inhibitor (Terrazole) applied; 80 kg N/ha applied.

(D) Nitrification inhibitor (wax-coated calcium carbide) applied;
100 kg N/ha applied.

Table 4. Estimated emission of [N.sub.2]O from [sup.15]N-labelled
fertiliser or legume stubble as described by Rochester et al. (2001)

The soil was a Gommel medium clay, pH 8.3 and 53% clay. The
summer and winter crop stubbles were incorporated 5 and 11 months,
respectively, before the microplots were destructively sampled
in October 1996; fertiliser was applied at the same time that
the crop stubbles were incorporated

Previous Source N NFR (A) N
crop of applied (% of N fertiliser
 [sup.15] N (kg/ha) applied) lost
 (kg/ha)

Wheat Fertiliser 100 18 82
Cotton Fertiliser 100 11 89
Fababean Stubble 80 60 32
Field pea Stubble 107 78 24
Soybean Stubble 220 72 62
Lablab Stubble 247 91 23

Previous [N.sub.2]O/ [N.sub.2]O/ [N.sub.2]O-N [N.sub.2]O-N
crop [N.sub.2] ([N.sub.2]O+ emitted emitted
 (B) [N.sub.2]) (kg/ha) (% of N
 applied)

Wheat 0.0283 0.0275 2.26 2.26
Cotton 0.0283 0.0275 2.45 2.45
Fababean 0.0283 0.0275 0.88 1.10
Field pea 0.0283 0.0275 0.66 0.62
Soybean 0.0283 0.0275 1.71 0.78
Lablab 0.0283 0.0275 0.63 0.26

(A) Nitrogen fertiliser recovery.

(B) Ratio derived from the fitted curve in Fig. 1.


Acknowledgments

Drs P. Grace, K. Weier, D. Barrett, M. Peoples, G. Constable, and S. Milroy provided helpful comments on the manuscript.

References

Anon. (2000) 'Sigma Plot 2000 for Windows version 6.00.' (SPSS Inc.: Chicago)

Aulakh MS, Doran JW, Walters DT, Mosier AR, Francis DD (1991) Crop residue type and placement effects on denitrification and mineralization. Soil Science Society of America Journal 55, 1020-1025.

Aulakh MS, Rennie DA, Paul EA (1983) The effect of various clover management practices on gaseous N losses and mineral N accumulation. Canadian Journal of Soil Science 63, 593-605.

Aulakh MS, Rennie DA, Paul EA (1984) Gaseous nitrogen losses from soils under zero-till as compared with conventional-till management systems. Journal of Environmental Quality 13, 130-136.

Avalakki UK, Strong WM, Saffigna PG (1995a) Measurements of gaseous emissions from denitrification of applied [sup.15]N. II Effects of cover duration. Australian Journal of Soil Research 33, 77-87.

Avalakki UK, Strong WM, Saffigna PG (1995b) Measurements of gaseous emissions from denitrification of applied [sup.15]N. II Effects of temperature and added straw. Australian Journal of Soil Research 33, 89-99.

Bollag JM, Orcutt ML, Bollag B (1970) Denitrification by isolated soil bacteria under various environmental conditions. Soil Science Society of America Proceedings 34, 875-879.

Bremner JM, Breitenbeck GA, Blackmer AM (1981) Effect of anhydrous ammonia fertilization on emission of nitrous oxide from soils. Journal of Environmental Quality 10, 77-80.

Bronson KF, Mosier AR (1991) Effect of encapsulated calcium carbide on dinitrogen, nitrous oxide, methane and carbon dioxide emissions from flooded rice. Biology and Fertility of Soils 11, 116-120.

Christensen S, Simkins S, Tiedje JM (1990) Spatial variation in denitrification: dependency of activity centres on the soil environment. Soil Science Society of America Journal 54, 1608-1613.

Colbourn P, Harper IW, Iqbal MM (1984) Denitrification losses from [sup.15]N-labelled calcium nitrate fertilizer in a clay soil in the field. Journal of Soil Science 35, 539-547.

Cooper GS, Smith RL (1963) Sequence of products formed during denitrification in some diverse western soils. Soil Science Society of America Proceedings 27, 659-662.

Denmead OT, Freney JR, Simpson JR (1979) Nitrous oxide emission during denitrification in a flooded field. Soil Science Society of America Journal 43, 716-718.

Denmead OT, Simpson JR, Freney JR (1977) A direct field measurement of ammonia emission after injection of anhydrous ammonia. Soil Science Society of America Journal 41, 1001-1004.

Eriksen AB, Holtan-Hartwig L (1993) Emission spectrometry for direct measurement of nitrous oxide and dinitrogen from soil. Soil Science Society of America Journal 57, 738-742.

Firestone MK, Smith MS, Firestone RB, Tiedje JM (1979) The influence of nitrate, nitrite and oxygen on the composition of the gaseous products of denitrification in soil. Soil Science Society of America Journal 43, 1140-1144.

Focht DD (1974) The effect of temperature, pH and aeration on the production of nitrous oxide and gaseous nitrogen--a zero-order kinetic model. Soil Science 118, 173-179.

Freney JR, Chen DL, Mosier AR, Rochester IJ, Constable GA, Chalk PM (1993) Use of nitrification inhibitors to increase fertilizer N recovery and lint yield in irrigated cotton. Fertilizer Research 34, 37-44.

Freney JR, Smith C J, Mosier AR (1992) Effect of a new nitrification inhibitor (wax-coated calcium carbide) on transformations and recovery of fertilizer nitrogen by irrigated wheat. Fertilizer Research 32, 1-11.

Galsworthy AM, Burford JR (1978) A system for measuring the rates of evolution of nitrous oxide and nitrogen from incubated soils during denitrification. Journal of Soil Science 29, 537-550.

Gilliam JM, Dasberg S, Lund LJ, Focht DD (1978) Denitrification in four California soils: effect of soil profile characteristics. Soil Science Society of America Journal 42, 61-66.

Hauck RD, Melsted SW (1956) Some aspects of the problem of evaluating denitrification in soils. Soil Science Society of America Proceedings 20, 361-364.

IPPC (2001) 'Climate change 2001: a scientific basis.' Intergovernmental Panel on Climate Change. (Eds JT Houghton, Y Ding, DJ Griggs, M Noguer, PJ van der Linden, X Dai, CA Johnson, K Maskell) (Cambridge University Press: Cambridge, UK)

Keeney DR, Fillery IR, Marx GP (1979) Effect of temperature on the gaseous nitrogen products of denitrification in a silt loam soil. Soil Science Society of America Journal 43, 1124-1128.

Khan MFA, Moore AW (1968) Denitrification capacity of some Alberta soils. Canadian Journal of Soil Science 48, 89-91.

Koskinen WC, Keeney DR (1982) Effect of pH on the rate of gaseous products of denitrification in a silt loam soil. Soil Science Society of America Journal 46, 1165-1167.

Mahmood T, Ali R, Sajjad MI, Chaudhri MB, Tahir GR, Azam F (2000) Denitrification and total fertilizer-N losses from an irrigated cotton field. Biology and Fertility of Soils 31, 270-278.

Mikkelsen RL, Jarrell W M, Letey J, Whaley S (1986) Effect of Terrazole on nitrogen transformations and movement in irrigated corn. Soil Science Society of America Journal 50, 1471-1478.

Mills HA, McElhannon WS (1984) Terrazole suppression of denitrification. HortScience 19, 54-55.

Moraghan JT, Buresh RJ (1977) Chemical reduction of nitrite and nitrous oxide. Soil Science Society of America Journal 41, 47-50.

Mosier AR, Duxbury JM, Freney JR, Heinemeyer O, Minami K (1995) Nitrous oxide emission from agricultural fields: assessment, measurements and mitigation. Plant and Soil 181, 95-108.

Mosier AR, Guenzi WD, Schweizer EE (1986) Soil losses of dinitrogen and nitrous oxide from irrigated crops in north-eastern Colorado. Soil Science Society of America Journal 50, 344-348.

Murakami T, Kumazawa K (1987) Measurement of denitrification products in soil by the acetylene inhibition method. Soil Science and Plant Nutrition 33,225-234.

Rochester IJ, Constable GA (2000) Denitrification and immobilization in flood-irrigated alkaline grey clays as affected by nitrification inhibitors, wheat straw and soil texture. Australian Journal of Soil Research 38, 633-642.

Rochester IJ, Constable GA, Saffigna PG (1996) Effective nitrification inhibitors may improve fertilizer recovery in irrigated cotton. Biology and Fertility of Soils 23, 1-6.

Rochester IJ, Gaynor H, Constable GA, Saffigna PG (1994) Etridiazole may conserve fertilizer N and increase lint yield of irrigated cotton. Australian Journal of Soil Research 32, 1287-1300.

Rochester IJ, Peoples MB, Hulugalle NR, Gault RR, Constable GA (2001) Using legumes to enhance nitrogen fertility and improve soil condition in cotton cropping systems. Field Crops Research 70, 27-41.

Russell JS (1991) Land sources and sinks of carbon dioxide. In 'The global greenhouse effect and the impact of emission policies on rural industry'. (Eds JN Tullberg, J Pulsford, JS Russell) pp. 15-18. AIAS Occasional Publication No. 66. (AIAS: Melbourne)

Ryden JC, Lund LJ (1980) Nitrous oxide evolution from irrigated land. Journal of Environmental Quality 9, 387-393.

Simpson JR, Freney JR, Wetsellaar W, Muirhead WA, Leuning R, Denmead OT (1984) Transformations and losses of urea nitrogen after application to flooded rice. Australian Journal of Agricultural Research 35, 189-200.

Smith MS, Tiedje JM (1979) The effect of roots on soil denitrification. Soil Science Society of America Journal 43, 951-955.

Somda ZC, Phatak SC, Mills HA (1990) Nitrapyrin, Terrazole, Atrazine and Simazine influence on denitrification and corn growth. Journal of Plant Nutrition 13, 1195-1208.

Somda ZC, Phatak SC, Mills HA (1991) Influence of biocides on tomato nitrogen uptake and soil nitrification and denitrification. Journal of Plant Nutrition 14, 1187-1199.

Weier KL (1998) Sugarcane fields: sources or sinks for greenhouse gas emissions? Australian Journal of Agricultural Research 49, 1-9.

Weier KL, Doran JW, Power JF, Walters DT (1993) Denitrification and the dinitrogen/nitrous oxide ratio as affected by soil water, available carbon and nitrate. Soil Science Society of America Journal 57, 66-72.

Weier KL, Gilliam JW (1986) Effect of acidity on denitrification and nitrous oxide evolution from Atlantic Coastal Plain soils. Soil Science Society of America Journal 50, 1202-1205.

Wicht H (1996) A model for predicting nitrous oxide production during denitrification in activated sludge. Water Science and Technology 34, 99-106.

Yeomans JC, Bremner JM (1988) Denitrification in soil: effect of herbicides. Soil Biology and Biochemistry 17, 447-452.

Manuscript received 11 June 2002, accepted 11 November 2002

Ian J. Rochester

Australian Cotton Cooperative Research Centre, CSIRO Plant Industry, Cotton Research Unit, LB 59, Narrabri, NSW 2390, Australia 2390; email: ian.rochester@csiro.au
COPYRIGHT 2003 CSIRO Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2003 Gale, Cengage Learning. All rights reserved.

 
Article Details
Printer friendly Cite/link Email Feedback
Author:Rochester, Ian J.
Publication:Australian Journal of Soil Research
Geographic Code:8AUST
Date:Mar 1, 2003
Words:5455
Previous Article:Nitrous oxide emission from Australian agricultural lands and mitigation options: a review.
Next Article:Using quantity/intensity relationships to assess the potential for ammonium leaching in a Vertosol.
Topics:


Related Articles
Fresh smoke lowers nitrous oxide estimate.
Nitrous oxide emission from Australian agricultural lands and mitigation options: a review.
Estimating a nitrous oxide emission factor for animal urine from some New Zealand pastoral soils.
Can soil amendments (zeolite or lime) shift the balance between nitrous oxide and dinitrogen emissions from pasture and wetland soils receiving urine...
'Laughing gas' leaves ozone layer in splits.
Humane Society wants EPA to cut emissions from feedlots.
Urban green spaces may actually contribute to global warming.

Terms of use | Privacy policy | Copyright © 2018 Farlex, Inc. | Feedback | For webmasters