Production of Cricotopus ornatus (Meigen) (Diptera: Chironomidae) in Waldsea Lake,Saskatchewan

Cricotopus ornatus was the predominant chironomid in meromictic, saline Waldsea Lake. Annual production of C. ornatus larvae in the mixolimnion was estimated to be 107 mg m^-2 (dry weight) in 1974, 66.5 mg m^-2 in 1975 and 69.5 mg m^-2 in 1976. These estimates are similar to those for chironomids in Canadian arctic lakes and deep-water areas of the Great Lakes. Annual P/B ratios were 5.4 in 1974, 6.8 in 1975 and 6.8 in 1976. These ratios are in the middle of the range reported for chironomids. The major factors limiting chironomid production in Waldsea Lake appear to be: (1) restriction of the habitable zone because of meromixis with accompanying loss of mobile first and second instars that are swept out of the mixolimnion (2) the relatively narrow zone of good C. ornatus habitat, i.e. areas of dense macrophyte or benthic algal growth and (3) predation by nine-spine stickleback and damselfly naiads.     

A quantitative study of seasonal foraging by the grass harvesting termite,Trinervitermes geminatus (Wasmann), (Isoptera,Nasutitermitinae) in Southern Guinea savanna,Mokwa, Nigeria

Summary Trinervitermes geminatus (Wasmann) harvests standing grass tussocks which are cut into pieces and carried back to the nest. During this activity a certain proportion is left on the soil surface as litter whilst some is ingested. Foraging is mainly accomplished during the dry season (mid-October to the end of April) for periods of 2–4 h daily, either early in the morning, in the evening, or occasionally during both morning and evening. The duration and daily pattern of foraging is partly dependent on temperature, with a lower temperature threshold of 20° C and an upper threshold of 35° C below or above which foraging is restricted.The quantity of grass cut down and carried back to the nest by a population of 737 m^-2 (3.08 g m^-2) was estimated at 60.3 kg ha^-1a^-1 with approximately 18 kg ha^-1a^-1 cut and left as litter. Estimated consumption whilst foraging was approximately 20.4 kg ha^-1a^-1, giving a total consumption of about 81 kg ha^-1a^-1. Compared with a total estimated grass production of 3157 kg ha^-1a^-1 and consumption by cattle of 1404 kg ha^-1a^-1, the quantity of grass removed by T. geminatus, amounting to only 3.1% of the net primary production, did not appear to be economically significant in this locality.     

Chemical aids to drying seeds of beans (Phaseolus vulgaris) before harvest

The effects on seed moisture content of seven different chemical formulations applied to bean (Phaseolus vulgaris) crops in two successive years were observed. Those containing bipyridyl herbicides caused the biggest effects. In 1974, diquat (0–59 kg a.i. ha^-1), applied to a French bean crop cv. Processor 26 days before harvest, decreased seed moisture content by 98 mg g^_1 dry weight below a control value of 438 mg g^_1. In 1975, diquat applied at the same rate to a navy bean crop cv. Seafarer 16 days before harvest, decreased seed moisture content by 123 mg g^_1 below a control value of 364 mg g^_1. Diquat applied at a lower rate (0–3 kg a.i. ha^-J) caused a decrease of 79 mg g^_1 and paraquat decreased seed moisture by 147 mg g^_1. In both years smaller effects were observed for dimexan (15 kg a.i. ha^-1) which decreased seed moisture content by 32 mg g^-1 in 1974 and 72 mg g^_1 in 1975 and for ethephon (1-0 kg a.i. ha^-1) which caused decreases of 78 mg g^_1 in 1974 and 31 mg g^_1 in 1975. In 1975, metham-sodium (70 kg a.i. ha^-1) a soil sterilant, proved almost as effective as the bipyridyls, decreasing moisture content by 105 mg g^_1. Trimming the roots mechanically reduced seed moisture by 67 mg g^_1. Other chemical treatments, tried in 1975 only, were less effective and decreased seed moisture content by 31–60 mg g^_1. These were Wiltz-65 (pentanoic and hexanoic acids, 14-6 kg a.i. ha^-1), N252 (dihydro-dimethyl-dithiin tetroxide, 0–56 kg a.i. ha^-1) and an application of diquat (0–3 kg a.i. ha^-1) to plants treated 10 days before with ethephon (1-0 kg a.i. ha^-1)- In addition to the effects on seed moisture content, all treatments decreased seed yield. The largest decreases were caused by diquat and were attributable mainly to effects on mean seed weight. The paper concludes with an economic analysis which shows that at present prices chemical drying of beans in the field is not worthwhile because the yield loss nullifies any savings in drying costs.     

Estimated Impact of feral house mice on sub-Antarctic invertebrates at Marion Island

Summary The energy metabolism of feral house mice Mus musculus was established on sub-Antarctic Marion Island, using the doubly-labelled water turnover technique. Mean water influx was 565 ml kg^-1 day^-1 and mean CO₂ production was 5.41 ml g^-1 h^-1, i.e. 3375 kJ kg^-1 day^-1. From the energy content of the main items (Lepidoptera larvae, Curculionidae) in the diet of the mice it was estimated that the dry mass of food consumed was 3.5 g mouse^-1 day^-1. The overall impact of mice on invertebrates, based on mean mouse density and the mean percentage invertebrates in the diet, was estimated at 108 g ha^-1 day^-1 or 39.4 kg ha^-1 y^-1 (dry mass). Greatest predation pressure was on larvae of the flightless moth Pringleophaga marioni: 65 g ha^-1 day^-1 or 23.7 kg ha^-1 y^-1. Insect biomass is lower on Marion Island than on nearby Prince Edward Island, which is mouse-free. It is suggested that populations of certain insects on Marion Island are depressed by the alien mice.     

The ecology of Lake Nakuru (Kenya)

Summary The Cichlid fish Tilapia grahami (-Sarotherodon alcalicum grahami) was introduced into Lake Nakuru (Kenya) in about 1960 and is now one of the main herbivores. Spatial distribution and biomass changes were estimated from lift net catches from 1972–1974 which were partly continued until 1976. The length/weight relationship is represented by the equation W=0.008·l ^2.98 (W=dry weight=24% of fresh-weight; l=standard length=85.1% of total length). The fish distribution is very patchy (aggregation coefficient 5.2–12.2). The density decreased and the mean fish size increased from in-shore to off-shore regions. At noon the fish concentrate near the shore and at hight they move off-shore, a migration pattern probably reflecting a preferance for higher temperatures. 70% of Tilapia concentrate in the top 50 cm and 80% in the top 100 cm. The total ichthyomass of the lake had a mean of 90 t dry weight (=2.1 g/m²) in 1972 and it increased to a mean of 400 t dry weight (=10.2 g/m²) during 1973. Possible causes for the spatial distribution and the biomass variations are discussed. The high density of Spirulina platensis makes nutritional competition among the herbivores unlikely. The main impact of Tilapia grahami on the lake's ecosystem is a substantial increase in diversity by extending the food chains to fish eating birds, of which the Great White Pelican is dominating. The breeding of Pelicans at a neighbouring lake causes a considerable nutrient export (13 t phosphorus/year).     

Production and ecology of eelgrass (Zostera marinal L.) in the Grevelingen estuary,the Netherlands,before and after the closure

The Grevelingen estuary was cut off from the North Sea and from the influences of the river Rhine by a dam in 1971, and became a stagnant salt-water lake. Production and ecology ofZostera marina L. were studied in 1968 and in 1973–1975, both through standing stock estimations, biomass increases in permanent quadrats, and correlation of distribution patterns with ecological factors. After the closure of the estuary the intertidal eelgrass population extended downwards to 5 m below lake level, probably owing to the increased transparency of the water; the area occupied, and the density of the eelgrass beds increased strongly. Eelgrass annual overground production, based on doubled maximum standing crop values in July–August, was estimated at 50 g C/m² in 1968, 121 g C/m² in 1973 and 91 g C/m² in 1975 inZostera beds, and 4 g C/m² in 1968, 18 g C/m² in 1973 and 23 g C/m² in 1975 for the entire Grevelingen area. A minimum estimate of net production inZostera beds at a depth of 0.50–0.75 m, based on short term changes in biomass in 2 permanent quadrats in 1974 and 1975, was 40.5 g C/m²/yr for overground parts and 12.7 g C/m²/yr for underground parts. Horizontal distribution of celgrass is not primarily limited by grainsize distribution, but more by exposure to wave action and currents. On account of irradiance reduction light is a limiting factor in the vertical distribution of the eelgrass population in Lake Grevelingen. Communication no. 146 of the Delta Institute for Hydrobiological Research, Yerseke, The Netherlands.     

Secondary productivity and energy flow in a tropical pond

Monthly changes in density and biomass of a Pila globosa population were estimated in the littoral area of the pond Idumban. Mean density of active snail was 10.4, equivalent to 76 g dry weight/m² during 1973 and 6.5, equivalent to 45 g/m² during 1974. Total population size of the snail decreased from 9.2 × 10⁶ individuals, equivalent to 6.5 ton during 1973 to 6.3 × 10⁶ snails, equivalent to 4.4 ton during 1974. The period from December to May represented the time of abundance and active growth. Mortality assessed from marking and recapture as well as from monthly changes in population density, averaged to 2.7 snails/m²/month or 20% of the density. Growth estimated by marking and recapture suggested that the snail required a period of over 4 years to attain a body (wet) weight of 35 g. Laboratory experiments revealed that young (<4 g), intermediate (4 g><24 g) and old (>24 g) P. globosa grew at the rate of 4.0, 1.5 and 0.3 mg dry weight/g live weight/day. Using these values and the size-wise population density data, net productivity of the snail was estimated as 74 and 40 g/m²/year in 1973 and 74, respectively. The snail exhibited an efficiency of 70% for absorption and 10% for conversion. Using these values, it was further possible to estimate rates of feeding and absorption for the population. Consumption amounted to 1039 g/m² in 1973 and 560 g/m² in 1974. The efficiencies of exploitation, gross and net productions were 21, 7 and 10%, respectively; ecological efficiency amounted to 1.4% only.     

Anatomy and histology of the alimentary tract of the desert millipede Orthoporus ornatus (Girard) (Diplopoda: Spirostreptidae)

The alimentary tract of the desert millipede Orthoporus ornatus is essentially a straight tube consisting of a histologically distinct foregut, midgut, pylorus, hindgut, and rectum. Common to each region, but often different in regional appearance, are an outer sheath layer, longitudinal and circular muscle layers, a basement membrane, and an inner epithelial layer. Foregut and midgut lumina are lined by a cuticular intima, while a peritrophic membrane occurs in the midgut lumen. Gut structure is considered in the context of the known feeding habits and digestive efficiency of this long-lived, seasonally restricted detritivore.     

Population dynamics and energy budget of Marionina southerni (Cernosvitov) (Enchytraeidae,Oligochaeta) in the shallow littoral of Lake Esrom,Denmark

Marionina southerni (Cernosvitov) was numerically the dominant oligochaete in a shallow, strongly exposed surf zone locality (0–1 m depth) in the mesotrophic Lake Esrom. It comprised 21,500 ind m^–2 or nearly 50% of the total oligochaete community, which otherwise was dominated by Nais spp. and the lumbriculid Stylodrilus heringianus Claparède. M. southerni appears to have a 1-y life cycle. Individual biomass ranged from 3 to 48 µg ash free dry weight. Annual net production at the site was 5.1 kcal m^–2 (size-frequency method) with a P/B ratio of 2.5. This is about 0.5% of the estimated mean zoobenthic production in the littoral zone from 0 to 2 m depth in Lake Esrom. At 5° C M. southerni showed a constant oxygen uptake down to 25% oxygen saturation, but practically no regulatory respiration was found at 20 °C. In the field M. southerni was never found in sediment with less than 60% oxygen saturation. The annual community respiration of M. southerni was 14.2 kcal m^–2, and annual assimilation thus made up 19.3 kcal m^–2 with a net production efficiency of 26.5%.     

Energy loss in an aestivating population of the tropical snail pila globosa

The dried peripheral area of pond Idumban (62 ha) increased from 3.2 ha in January to 3 1.9 ha in April. Pila globosa, which were abundant in the littoral area, did not commence aestivation during this period, perhaps due to low temperature and/or high dissolved oxygen content. The number of aestivating snails averaged 0.5/m² in May, 1973 (3.6% of the total population) and it increased to 1.1/M² in September (26.2%). Biomass of the snail increased from 3.5 to 19.9 g dry weight (including shell)/M². Number of aestivating snails increased from 0.4/m² (5.2% of the total population) in May 1974 to 0.8/m² (11.1%) in July and the biomass from 4.1 g/m² to 10.7 g/m². Availability of dried area for aestivation increased from 5.3 to 23.7 ha in 1973 and from 13.5 to 30.2 ha in 1974.Monthly observations made on the marked snails forced to aestivate at 7.5, 15.0, 22.5 and 30.0 cm depth in the pond during May, revealed that temperature above 35°C and moisture below 5% were critical. Mortality and weight loss decreased in the snails forced to aestivate at increasing depth. Random observations indicated that 83% of the aestivating snails buried themselves at 15 cm depth in the pond. On the whole, 98,480 snails (592 Kg) and 115,270 (758 Kg) died during aestivation in 1973 and 1974 respectively. Of the total weight loss, the energy lost via metabolism contributed only a small fraction of 2.2% (12 Kg) and 2.1% (15 Kg) during these years. Considering the total aestivation area, the snails which succumbed averaged only 0.4/m²/year (2.5 g/m²/year). On an average, dry substance equivalent to about 2.6 mg dry weight/ g dry weight of snail/ day (3.7 gcal/ g live snail/ day) was lost on metabolism by the aestivating snails, i.e. the metabolic level of the aestivating snail was about 1 / 18th of that of the actively feeding snail.     

Nutrient cycling by the subterranean termite Gnathamitermes tubiformans in a Chihuahuan desert ecosystem

Summary We estimated the density of subterranean termites Gnathamitermes tubiformans at 800,000 · ha^-1 for a standing crop biomass of 2 kg · ha^-1 Predation losses were estimated to be 5,73 kg · ha^-1 · yr^-1 representing the major release of nutrients from termites to surficial soil layers. Nutrient fluxes from termites to predators amounted to 410g N·ha^-1·yr^-1, 33 g S · ha^-1 · yr^-1 and 19 g P · ha^-1 · yr^-1. These fluxes account for 8% of the litter N, 1.5% of the litter P and 2.9% of the litter S. The termites fixed an estimated 66 g · ha^-1 · yr^-1 atmospheric N and returned an estimated 100 g · ha^-1 · yr^-1 in the surface gallery carton. Since losses of elements from subterannean termites were greater than standing crops, we estimated an annual turnover of N at 3.5 times per year, P of 2.5 times per year, and S of 2.5 per times per year.Since surface foraging, predation and alate flights are pulse regulated by rainfall, nutrient flows through subterranean termites are episodic and releases of nutrients accumulated in termite biomass preceeds or is coincident with productivity pulses of some shallow rooted plants. We propose that subterranean termites are important as regulators in desert nutrient cycles.     

Durations of development and production estimates by two crustacean zooplankton species Thermocyclops oblongatus Sars (Copepoda) and Diaphanosoma excisum Sars (Cladocera), in Lake Naivasha,Kenya

Durations of embryonic and post-embryonic development of the two dominant zooplankton crustaceans Thermocyclops oblongatus (Copepoda) and Diaphanosoma excisum in Lake Naivasha were determined at various lake water temperatures to provide the time element for the calculation of their production. Developmental times were temperature dependent in as much as food resource was not limiting. Production estimates were calculated. The turnover times of their biomass was 11.4 and 13.7 days, with production rates of 11.0 and 6.0 µg dw m^-3 d^-1 for T. oblongatus and D. excisum, respectively. Annual production was estimated as 3302 mg m^-3 yr^-1 for T. oblongatus and 2176 mg m^-3 yr^-1 for D. excisum. Production was continuous but with several irregular peaks particularly during the wet seasons when plankton biomass was high.     

Effects of the herbicide trifluralin in the initial development of Piptadenia gonoacantha (Fabales: Fabaceae)

Abstract

Trifluralin, a pre-emergent herbicide, is widely used in Brazil in the weed grass management in restoration areas. The objective was to evaluate the tolerance of Piptadenia gonoacantha to trifluralin. The treatments had three trifluralin doses (445, 890, and 1335?g a.i. ha^?1), applied in pre-sowing, as well as the control, without herbicide. Visual intoxication, seed germination, survival rate, emergence speed index (EMI), mean germination period, seedling height, and diameter, micromorphometric parameters of plant roots collected at 60 d after sowing, root length (RL) and volume, leaf area (LA), leaf numbers, root and shoot dry matter, and fluorescence of chlorophyll a at 30, 45, and 60 d after sowing were analyzed. Visual intoxication values above 50% were observed only with 1335?g a.i. ha^?1. The herbicide did not affect seed germination, EMI, average germination period, seedling height, and diameter, root micromorphometric parameters, length, dry matter or root volume, and chlorophyll a fluorescence. The dose 1335?g a.i. ha^?1 caused a reduction of 41.5% in survival, 50.3% in the LA, 36.7% in the number of leaves (LN), and 59.8% in the aerial dry mass of seedlings. The trifluralin presents potential for restoration programs of degraded areas with this forest species.     

Long- and short-term effects of crop residues on aluminum toxicity,phosphorus availability and growth of pearl millet in an acid sandy soil

Pasture swards containing perennial ryegrass (Lolium perenne L.) alone or with one of five different white clover (Trifolium repens L.) cultivars were examined for production and transfer of fixed nitrogen (N) to grass under dairy cow grazing. Grass-only swards produced 21% less than mixed clover-grass swards during the second year after sowing. Production from grass-only plots under a mowing and clipping removal regime was 44% less than from grass-only plots under grazing. Much of this difference could be attributed to N transfer. In swards without clover, the ryegrass component also decreased in favour of other grasses.The average amount of fixed N in herbage from all clover cultivars was 269 kg N ha^–1 yr^–1. Above-ground transfer of fixed N to grasses (via cow excreta) was estimated at 60 kg N ha^–1 yr^–1. Below-ground transfer of fixed N to grasses was estimated at 70 kg N ha^–1 yr^–1 by ¹⁵N dilution and was similar for all clover cultivars. Thus, about 50% of grass N was met by transfer of fixed N from white clover during the measurement year. Short-term measurements using a ¹⁵N foliar-labelling method indicated that below-ground N transfer was largest during dry summer conditions.     

Production of the predaceous midge tribes Sphaeromiini and Palpomyiini (Diptera: Ceratopogonidae) in Lake Norman,North Carolina

Production and P/B ratios of predaceous midges of the tribes Sphaeromiini and Palpomyiini (Diptera: Ceratopogonidae) collected from sublittoral and littoral depths in Lake Norman, North Carolina, were estimated by the size-frequency method. Production estimates in g dry wt/m²/yr at eight sampling locations ranged from 0.002 to 0.022. The littoral zone as a whole was more productive (0.015 g/m²/yr) than the sublittoral zone (0.006 g/m²/yr). The P/B ratios ranged from 2.37 to 3.78 among all stations and depths.     

Nest and soil populations of Trinervitermes spp. with particular reference to T. geminatus (Wasmann), (Isoptera), in Southern Guinea savanna near Mokwa,Nigeria

Summary Nest and soil populations of Trinervitermes spp. were estimated on grazed secondary savanna woodland near Mokwa cattle ranch and on primary savanna woodland, 6 km from the ranch. Nest populations were estimated by obtaining a relationship between size of nest and the number of termites in the nest and using the relationship to estimate populations in measured nests within the study area.Mound populations of T. geminatus, by far the most abundant species, were 222 m^-2 at a mound density of 232 ha^-1 at the ranch, and 225 m^-2 at a mound density of 175 ha^-1 on primary savanna woodland. The mound population at the ranch represented a fresh weight biomass of 1.089 g m^-2. Changes in abundance of the mound population of T. geminatus were correlated with breeding and foraging cycles. Maximum numbers (388 m^-2, 2.03 g m^-2) in August/September were reduced by the flight of alates and loss of foragers to predators; thereafter, the population continued to decrease (126 m^-2, 0.57 g m^-2) until the cessation of foraging in April/May and numbers of larvae and nymphs began to increase. Soil and mound sampling in primary and secondary savanna showed that although T. geminatus is a mound inhabiting species, two thirds of the mound plus soil population was outside the mounds giving a total population of 737 m^-2 (3.08 g m^-2). Alate production was estimated at 15.5 m^-2 (0.19 g m^-2) and neuter production at 367 m^-2 (1.66 g m^-2); production/biomass ratio was 1.0 T. togoensis (total population of 21 m^-2) and T. occidentalis (200 m^-2) had 90–96% of the total numbers outside the mounds, indicating that these two species were primarily subterranean.     

Burrowing,feeding, egestion and energy budgets of Allolobophora rosea (Savigny) (Lumbricidae)

Summary Allolobophora rosea (Savigny) was found to be common in mull type soils beneath bramble (Rubus fruticosus L.). Burrow construction in this soil type in the laboratory at 4.4, 10.0 and 14.8°C ranged between 133 and 516 mm g^-1 fresh wt of worm day^-1. Burrowing was affected by both body size and temperature. Rates of soil displacement during burrowing were estimated from burrowing rates, burrow dimensions and soil density; depending on body size and temperature they were in the range 809–1,928 mg dry wt of soil g^-1 fresh wt of worm day^-1. These values were in reasonable agreement with measured egestion rates (range: 1,000–2,000 mg dry wt of egesta g^-1 fresh wt of worm day^-1). It was concluded that A. rosea eats its way through the soil and is adapted to its rapid turnover. Gut turnover times were calculated to be between 1 and 2.5 h.Direct observation indicated that feeding was by a grazing procedure and it was shown that A. rosea preferentially selects the more organic fractions of the soil for ingestion.The evaluation of energy budgets for individual small immature, large immature and adult worms at 10°C revealed respiration to production ratios (R/P) of 1.0, 1.8 and 4.1, respectively. Assimilation efficiencies (A/C) were always less than 2.5%.     

Vegetation and litter production in Southern Guinea savanna,Nigeria

Summary This study examines the woody vegetation, annual leaf-fall and annual wood-fall in Southern Guinea savanna near Mokwa, Nigeria. There were 1425±402 (95% limits) trees ha^-1 of which Caesalpiniaceous legumes made up 53%. Annual leaf-fall was 2.387 t ha^-1 a^-1 equivalent to 11,238,932 kcal ha^-1 a^-1 and was highly seasonal, peaking from November to February, with a maximum in January after the annual bush fires. Annual wood-fall was 1.391 t ha^-1 a^-1 equivalent to 7,598,256 kcal ha^-1 a^-1 and was less seasonal but with two peaks, one from January to March after the fires and another from May to July in the rainy season.The litter-fall data currently available from West Africa are reviewed and indicate a negative correlation between litterfall and latitude (P<0.001). Litter production is found to be positively correlated with rainfall (P<0.001) and it is suggested that seasonal distribution of rainfall may also be a factor contributing to the limits of litter production.     

Characterization of transgenic sulfonylurea-resistant flax (Linum usitatissimum)

Summary Fourteen transgenic flax (Linum usitatissimum) lines, carrying a mutant Arabidopsis acetolactate synthase (ALS) gene selected for resistance to chlorsulfuron, were characterized for resistance to two sulfonylurea herbicides. Progeny of 10 of the 14 lines segregated in a ratio of 3 resistant to 1 susceptible, indicating a single insertion. Progeny of 1 line segregated in a 151 ratio, indicating two insertions of the ALS gene at independent loci. Progeny from 3 lines did not segregate in a Mendelian fashion and were likely the products of chimeric shoots. Resistance to chlorsulfuron was stably inherited in all lines. At the enzyme level, the transgenic lines were 2.5 to more than 60 times more resistant to chlorsulfuron than the parental lines. The transgenic lines were 25–260 times more resistant to chlorsulfuron than the parental lines in root growth experiments and demonstrated resistance when grown in soil treated with 20 g ha^-1 chlorsulfuron. The lines demonstrated less resistance to metsulfuron methyl; in root growth experiments, the transgenic lines were only 1.6–4.8 times more resistant to metsulfuron methyl than the parental lines. Resistance was demonstrated in the field at half (2.25 g ha^-1) and full (4.5 g ha^-1) rates of metsulfuron methyl.     

Nitric oxide flux from soil during the growing season of wheat by continuous measurements of the NO soil–atmosphere concentration gradient: A process study

The surface flux of nitric oxide from a wheat field was investigated from 23 March to 29 May 1997 in the Kerzersmoos, Switzerland. A plot fertilised with 19 kg N ha^-1 in cattle slurry and 40 kg N ha^-1 in mineral NH₄NO₃ fertiliser and a plot receiving no nitrogen containing fertiliser were compared. The flux was calculated based on hourly measurements of the NO soil–atmosphere concentration gradient using the one-dimensional soil diffusion model of Galbally and Johansson (1989). The soil bulk diffusion coefficient was determined from measurements of the ²²²Rn surface flux and the activity gradient between 10 cm depth and the surface. It ranged between 79% and 0.3% of the NO diffusion coefficient in air and was parameterised by air filled soil pore space. The indirectly determined NO flux agreed well with standard flux measurements using dynamic chambers. The largest NO emission was found following fertiliser application and irrigation. The emission occurred in pulses, which lasted for 4 days up to 3 weeks coinciding with elevated soil ammonium concentrations. Nitric oxide emission in 5 days following application of cattle slurry were 31 g NO-N ha^-1 and 5 g NO-N ha^-1 from the non-fertilised plot, respectively. Nitric oxide emission in 15 days following application of NH₄NO₃ was 95 g NO-N ha^-1 and 10 g NO-N ha^-1 from the non-fertilised plot, respectively. NO emission in 4 days following irrigation on 21 April were 36 g N ha^-1 from the fertilised and 39 g N ha^-1 from the non-fertilised plot. The daily NO emission before and after fertiliser and irrigation pulses was between 0.3 and 0.7 g NO-N ha^-1 d^-1. NO production and NO uptake of the soil was measured regularly. No systematic influence of management or climate on NO uptake was found. NO production was strongly stimulated by fertiliser input and soil moisture content. The simulation of NO production could be reproduced using a nitrification algorithm (Riedo et al., 1998) driven by soil temperature, moisture and ammonium concentration. A NO production rate constant of 1.1ċ10^-3 h^-1 at 15 °C was derived from a linear regression between nitrification and NO production. Introducing the parameterisation of NO production into the model of Galbally and Johansson (1989) the duration and the strength of the NO emission pulses could be reproduced and the total NO emission during the experiment was approximated within a factor of two. This revised version was published online in June 2006 with corrections to the Cover Date.