Proximal and distal control by pH of denitrification rate in a pasture soil

SUMMARYA field plot experiment of 271 days duration was conducted on New Zealand irrigated pastures, commencing in the summer (January) 1988, on a Templeton silt loam soil (Udic Ustochrept) by applying 35sulphur (35S)-labelled urine (250 μCi/g S with 1300 μg S/ml) to field plots (600 × 600 mm) at a rate equivalent to that normally occurring in sheep urine patches (150 ml/0·03 m2) to investigate the distribution, transformations and recovery of urinary S in pasture soil–plant systems and sources of plant-available soil S as influenced by the available soil moisture at the time of urine application and varying amounts of applied irrigation water. Results obtained showed that c. 55–90% of 35S-labelled urine was incorporated into soil sulphate (SO42−), ester SO42− and carbon (C)-bonded S fractions within the major plant rooting zone (0–300 mm), as early as 27 days after urine application. Hydriodic acid (Hl)-reducible and C-bonded soil S fractions showed no consistent trend of incorporation. On day 271, labelled-S was found in soil SO42−, Hl-reducible S and C-bonded S fractions to a soil depth of 500 mm, indicating that not only SO42− but also organic S fractions from soils and 35S-labelled urine were leached beyond the major rooting zone. A large proportion (c. 59–75%) of 35S-labelled urine was not recovered in pasture soil–plant systems over a 271-day period, presumably due to leaching losses beyond the 0–300 mm soil depth. This estimated leaching loss was comparable to that (75%) predicted using the S model developed by the New Zealand Ministry of Agriculture. The recovery of urinary S in soil–plant systems over a 271-day period was not affected by different amounts of irrigation water applied 7 days after urine application to soil at either 50 or 75% available water holding capacity (AWHC). However, significantly lower S recovery occurred when urinary S was applied to the soil at 25% AWHC than at field capacity, suggesting that urinary S applied at field capacity might not have sufficient time to be adsorbed by soil particles, enter soil micropores or be immobilized by soil micro-organisms. Both soil ester SO42− and calcium phosphate-extractable soil S in urine-treated soils were found to be major S sources for pasture S uptake. Labelled S from 35S-labelled urine accounted for c. 12–47% of total S in pasture herbage.

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Study on nitrified liquor recycling process operations using polyurethane foam sponge cubes as a biomass support medium

Water Science & Technology ◽

10.2166/wst.1994.0261 ◽

1994 ◽

Vol 30 (6) ◽

pp. 143-149 ◽

Cited By ~ 26

Author(s):

H. Deguchi ◽

M. Kashiwaya

Keyword(s):

Experimental Study ◽

Polyurethane Foam ◽

Type A ◽

Denitrification Rate ◽

Rate Coefficients ◽

Type B ◽

Recycling Process ◽

Support Medium ◽

Suspended Growth ◽

Nitrification And Denitrification

An experimental study was carried out to find a way of using sponge cubes as a biomass support medium to reaction tanks for nitrified liquor recycling process. Type-A, in which biomass fixed cubes are contacted with both anoxic and oxic stages and Type-B, where biomass fixed cubes are contacted with either anoxic or oxic stages, were selected as experimental cases. The results showed that the amount of CO2-C generated which was related to sludge production for Type-B exceeded the amount for Type-A by between 12 to 21%. The nitrification and denitrification rate coefficients at 20°C in Type-A were 1.5 and 1.6 times respectively higher than the coefficients for suspended growth. The rate coefficients in Type-B were 1.5 and 2.0 times respectively higher than the coefficients for Type-A.

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Screening and Characterization of a Bacterium Capable of Simultaneous Heterotrophic Nitrification and Aerobic Denitrification at High Concentrations of Ammonia-Nitrogen

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.665.487 ◽

2014 ◽

Vol 665 ◽

pp. 487-490

Author(s):

Te Wang ◽

Zhao Xia Liu ◽

Mei Juan Wu ◽

Fu Hui Kang ◽

Qing Chen ◽

...

Keyword(s):

16S Rdna ◽

Ammonia Nitrogen ◽

Heterotrophic Nitrification ◽

Denitrification Rate ◽

Aerobic Denitrification ◽

Optimal Conditions ◽

Carbon And Nitrogen ◽

Mass Ratios ◽

High Concentrations ◽

Denitrification Process

A bacterium capable of simultaneous heterotrophic nitrification and aerobic denitrification at high concentrations of ammonia-nitrogen was screened and identified and the denitrification property was investigated in this paper. The strain was isolated from aeration tank of wastewater disposed by activated sludge and analyzed and identified by 16S rDNA. The effects of different carbon sources and carbon and nitrogen mass ratios on denitrification rate were studied. The changes of various forms of ammonia-nitrogens during the simultaneous heterotrophic nitrification and aerobic denitrification process were characterized. A strain capable of simultaneous heterotrophic nitrification and aerobic denitrification at 600 mg/L nitrogen concentration has been isolated and screened. Comparison of its 16S rDNA sequence showed 100% similarity to Bacillus licheniformis strain Lr124/6. The strain was named as Bacillus sp. A22. The optimal conditions for degradation of ammonia-nitrogen by Bacillus sp. A22 were trisodium citrate as carbon source and carbon and nitrogen mass ratios of 10. The denitrification rate was 98.2% after 96 h of culture under the optimal conditions and there was hardly any intermediates accumulation in the denitrification process. It has practical applications that the denitrification can be performed efficiently at high concentrations of ammonia-nitrogen by method of simultaneous heterotrophic nitrification and aerobic denitrification by Bacillus sp. A22 in nitrogen purification treatment of wastewater with high concentrations of ammonia-nitrogen.

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Surface physical properties of a sandy loam soil under different tillage practices

Soil Research ◽

10.1071/sr9880549 ◽

1988 ◽

Vol 26 (3) ◽

pp. 549 ◽

Cited By ~ 35

Author(s):

KY Chan ◽

JA Mead

Keyword(s):

Organic Carbon ◽

Physical Properties ◽

Sandy Loam ◽

Sandy Loam Soil ◽

Organic Carbon Content ◽

Moisture Profile ◽

Tillage Practices ◽

Pasture Soil ◽

Cultivated Soil ◽

Loam Soil

The infiltration behaviour and physical properties of a hardsetting sandy loam soil at Cowra, N.S.W., following 2 years of different tillage treatments are reported. Soil that had not been cultivated for 25 years was also investigated at an adjacent pasture site. Infiltration of simulated rainfall at the end of the wheat-growing season gave moisture profiles that were quite different for cultivated, direct drilled and pasture soils. The moisture profile for the cultivated soil suggested the presence of an impeded layer which retarded the movement of infiltrated rain to the subsoil. Porosity measurements confirmed the presence of a layer with significantly fewer macropores (> 300 �m diameter) at the 50-100 mm depth in the cultivated soil, when compared with the direct drilled soil. The old pasture soil had significantly higher porosity (> 300 �m diameter) in the top 100 mm. Aggregate stabilities and organic carbon contents were measured in narrow increments to 150 mm depth for the three different soils, and revealed that a surface 25 mm layer of high organic carbon and highly stable macro-aggregates was present in the pasture and direct drilled soils but absent in the cultivated soil. The unstable surface layer in the conventionally cultivated soil was a consequence of the mixing and inverting action of cultivation and was not due to a net loss of organic carbon from the profile. The organic carbon content of the pasture soil was not significantly different from the direct drilled soil below 50 mm; however, it was significantly lower than the conventionally cultivated soil between 50 and 150 mm depth. These results indicate a need to adopt tillage practices that can preserve the top 25 mm layer of such fragile soils.

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