The success of Linum usitatissimum as a commercial crop depends on its value for seed/oil (linseed) and/or fibre/straw production (flax). In the present study we evaluated nine linseed × linseed and two linseed × flax crosses for their potential to produce recombinant inbred lines (RILs) that give higher yields for dual-purpose (high seed–high fibre) traits. Analysis of the early generations indicated that while all crosses segregated for seed weight, straw weight, capsule weight and total plant weight, some crosses lacked the necessary genetic diversity to produce superior RILs. The performance of F3 families supported this conclusion as only two crosses were identified which had adequate potential to produce improved RILs with high seed and straw/fibre yields. The four most heterotic crosses identified in a previous experiment showed little potential for transgressive recombinants, although the best of these RILs would make better dual-purpose varieties compared to existing cultivars. Genotypic correlations were generally positive and should increase the chances of extracting RILs producing both high seed/oil and straw/fibre yields.

Fourteen field trials were conducted on farmers' fields in five villages of the Union Territory of Delhi, India during 1995–96 and 1996–97 to study the effect of introducing a crop of summer mungbean on the productivity of a rice–wheat cropping system. Timely sown summer mungbean yielded 0·4–1·3 t/ha protein-rich grain and, on average, increased rice yields by 0·5–0·9 t/ha and the yields of the succeeding wheat by 0·4–0·7 t/ha. The yield response of rice to the summer mungbean crop was greater when less urea-N fertilizer was applied, and N applied to the rice did not decrease the residual effect of the summer mungbean on the succeeding wheat. The increase in total productivity of rice–wheat cropping system due to summer mungbean ranged from 0·3 to 2·6 t/ha with an average of 1·6 t/ha.

Field investigations were conducted during the winter seasons of 1992/93 and 1993/94 to find the optimum sowing time and time of last fodder cut for the fodder and seed production of Egyptian clover (Trifolium alexandrinum L.). The delay in sowing from 1 October to 15 November decreased the green and dry fodder yields but increased the seed yields. Total green and dry fodder yields (of all cuttings) for 1 or 15 October sowings were significantly higher than the 15 November sowing in both years and 1 November sowing in 1992/93. Increase in seed yield from the 15 November sowing was greater than from the 1 and 15 October sowings. Straw yields followed similar trends. Delay in the last cut for fodder, however, increased green and dry fodder yields but decreased the seed yield. The percentage increase in dry fodder yield with each successive delay in last cut for fodder was higher than that of green fodder yield. The 11 April cutting date of fodder produced the highest green and dry fodder yields but the lowest seed yield. Two years mean data showed that the 2 March cutting date of last fodder gave the highest seed yield. It is concluded that higher seed yield of Egyptian clover can be produced by sowing on 15 November and giving the last fodder cutting on 2 March.

The late-season period in the humid tropics is characterized by drought and the production of crops such as tomato (Lycopersicon esculentum L.), okra (Abelmoschus esculentum), pepper (Capsicum spp.) and leafy vegetables depends upon the utilization of stored soil water. The efficient use of stored soil moisture ensures maximum plant adaptation and yield stability. The growth, development and yield of tomato grown on mulched and unmulched hand-hoed, raised beds and ridged sandy loam soil during the late cropping seasons of 1994, 1995 and 1996 in Akure, Nigeria was investigated. Hand-hoeing reduced soil temperature and conserved more soil moisture than ridging or the raised bed while grass mulch improved soil temperature and soil moisture regime compared with bare ground. Root biomass and root/shoot ratio increased in the order ridging, raised bed and hand-hoeing while shoot biomass, leaf area/plant and percentage fruit set decreased in the order raised bed, ridging and hand-hoeing. Number of fruit and fruit yield/plant produced by raised beds were significantly higher than those produced by ridging and hand-hoeing. Mulch ameliorated the hydrothermal regime of the soil, improved the vegetative and flowering performance and significantly increased the fruit yield of tomato over bare ground.

Controlled release (CR) formulations can significantly influence the fate of carbofuran in the environment. The influence of three alginate-encapsulated CR formulations compared with the granular formulation (G10%) on the mobility of carbofuran in sandy clay loam soil and sandy loam soil was investigated. In flooded soil the leaching potential of the three alginate controlled release formulations tested was decreased more than nine times (not more than 3%) compared with the G10% (28%). Most of the released carbofuran was confined to the top 0–5 cm of the soil column followed by the second 5–10 cm layer and the least was found in the fourth section (15–20 cm). The data obtained for a sandy loam soil irrigated by drip irrigation showed that the greatest proportion of carbofuran leached through the columns was from the G10% (52%) compared with 3–4% from CR formulations over a 30-day period. The carbofuran concentrations found in different soil depths showed similar trends to those for the flooded soil. Based on the residue levels recorded within the 20 cm depth, the relative retention ratio of carbofuran in sandy clay loam versus sandy loam soil was 1·2[ratio ]1 for the controlled release formulations and 1·9[ratio ]1 for the G10%.

In the last two decades, crop production models have been developed or modified for use in the semi-arid tropics. Although potential uses of crop models have been discussed in detail in the literature, examples of successful uptake and impact of those models is lacking. Four models developed specifically for the semi-arid tropics were used as a basis for evaluating uptake and impact of models in the semi-arid tropics. PARCH accounts for differences in water availability when predicting yield. PARCHED-THIRST covers water-harvesting, run-off and run-on. EMERGE identifies opportunities for successful crop establishment, and SWEAT calculates evapo-transpiration and estimates temperature and moisture throughout the soil profile. The models are dynamic, deterministic and mechanistic in nature. The equations and notations comprising them are generally well structured, meaningful and concise. The uptake and impact of these models on crop production in the semi-arid tropics was assessed using questionnaires and semi-structured interviews with the model developers. There was limited uptake. Low uptake resulted from lack of efficient dissemination and discontinuity in information transfer: from model developers to scientists in the national research institutions; and thereon to extension agents and so to farmers. Although this paper is based on a study of only four models, there are important lessons to be drawn in order to avoid similar mistakes being repeated. Guidelines for improving impact for future crop production modelling projects are proposed.

A collection of 64 accessions of the South American pasture legume Aeschynomene histrix Poiret was characterized in 1995 at Ibadan in south-west Nigeria in order to test the potential of the accessions as forage plants in subhumid areas and as a trap crop for the parasitic plant Striga hermonthica (Del.) Benth. All accessions had a low biomass production during the first 8 weeks after sowing but soon variations in the collection became apparent. Morphologically, accessions could be classified as having prostrate, decumbent, semi-erect and erect growth habit. The semi-erect to erect accessions grew vigorously and had high dry matter yields. The most frequent disease was Rhizoctonia foliar blight, for which, in general, prostrate accessions had a higher severity. In contrast, plants with semi- erect to erect growth habit were more susceptible to a wilting disease probably caused by Fusarium spp. With an average crude protein content of 16% and 48-h in sacco dry matter and protein digestibilities of c. 50%, fodder quality of 13-week-old plants was similar to that of other tropical forage legumes. As a result of a laboratory experiment to test the potential of A. histrix to act as a trap crop for Striga hermonthica, 13 accessions showing a significant influence on in vitro Striga hermonthica seed germination were identified. Twenty promising accessions were selected for further evaluation. These accessions showed good biomass production and/or high tolerance to diseases and/or significant influence on Striga hermonthica seed germination. Such material has the potential to contribute to both livestock-forage and improved fallow systems with the aim of increasing the sustainability of agricultural production in West Africa.

Liriomyza huidobrensis, the pea leafminer, is a recently identified pest on vegetables in Lebanon. The objectives of this study were to survey the leafminer infestation, to study its dispersion and its development on cucumber, swisschard and bean. In general, the infestation level was found to be higher in the middle coastal sites than in the other sites during the period of the study 1994–95. In the former sites, the pest was found to thrive on swisschard in October and November, in presence of cucumber under greenhouses, while it was encountered in significantly higher numbers on cucumber during the spring season, in absence of swisschard. Pairwise comparisons of Taylor's and Iwao's regression slope for L. huidobrensis larval mines indicated a contagious dispersion on leaves of cucumber and bean, while the pattern was random to slightly aggregated on swisschard. There was a significantly higher number of larval mines on the lower plant stratum compared to the middle and upper strata of cucumber through the cropping season. There was a significant difference in the overall development duration (19·6–22·3 days) of the insect among the three hosts. The larval development duration was significantly shorter on bean compared to swisschard and cucumber consecutively. However, there was no significant difference in egg or pupa duration among the three hosts. Results of this study provide bases for appropriate management of the pest, taking into consideration its infestation level, spatial pattern, and development duration on the mentioned hosts.

Four near-isogenic lines of wheat were employed to compare the effects of endosperm texture (hard v. soft) and the presence or absence of the 1B/1R translocation on amino acid digestion as determined with young broilers. Wheat samples were incorporated into diets at rates of inclusion of 250, 500 and 750 g/kg, with wheat as the only protein source. Diets included a mineral/vitamin mixture (50 g), oil (50 g) and were made up to 1000 g with a 50[ratio ]50 starch[ratio ]glucose mixture. Titanium dioxide was included at 5 g/kg as an inert marker. Each of the 12 diets was fed to 6 pairs of growing male (Ross) chickens for 3 days. Samples of ileal digesta were obtained from the birds following slaughter at 21 or 22 days of age and analysed for amino acid and titanium dioxide content. True and apparent digestibility coefficients were determined by regressing the amount of dietary apparently digestible amino acid in the diet against the rate of wheat inclusion and extrapolating the response to 1000 g and 0 g wheat/kg. The ordinate intercept was assumed to represent endogenous losses. Both the presence of the translocation and hard endosperm texture were associated with decreases in the apparent digestibility of amino acids, although the latter characteristic was not as important. As examples, for methionine the translocation was associated with a decrease in the coefficient of digestibility from 0·872 to 0·802 and a change in endosperm texture from soft to hard was associated with a decrease from 0·845 to 0·829.

In situ and in vitro rumen incubations were used to determine the effect of condensed tannins (CT) on the solubilization and degradation of the plant protein from white clover (Trifolium repens) and Lotus corniculatus. These forages contained, respectively 0·3 and 22·1 g CT/kg dry matter (DM). The sheep used for the experiments were also fed either white clover or L. corniculatus. Effects of CT were determined by making measurements in the presence and absence of polyethylene glycol (PEG; molecular weight 3500), which binds and inactivates CT. The loss of DM, neutral detergent fibre (NDF), total nitrogen (N) and Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase; EC 4.1.1.39; fraction I leaf protein) from polyester bags suspended in the rumen of sheep was measured. The loss of these constituents from polyester bags suspended in the rumen was used as a measurement of their solubilization. Degradation was defined as the disappearance of Rubisco from white clover and L. corniculatus added to in vitro incubations with rumen fluid obtained from the same fistulated sheep fed either white clover or L. corniculatus.

In the absence of PEG, the in situ loss of Rubisco from L. corniculatus was less rapid than the loss of this protein from white clover when each forage was incubated in the rumen of sheep fed the same diet. Addition of PEG tended to increase the loss of Rubisco from L. corniculatus, suggesting that CT slowed the rates of solubilization of Rubisco from this forage. Effects of rumen fluid were small, but there was some evidence that the rumen fluid in sheep fed L. corniculatus reduced the solubilization of Rubisco from white clover. The action of CT did not inhibit the in situ loss of NDF from either white clover or L. corniculatus.

In the absence of PEG, the in vitro degradation of Rubisco from L. corniculatus was slower when compared to the degradation of this protein from white clover; PEG addition increased the degradation of Rubisco from L. corniculatus, but not from white clover, showing that CT was the causal agent. The addition of CT extracted from L. corniculatus markedly depressed the degradation of Rubisco from white clover, with the effect being completely reversible by PEG. The large subunit (LSU) of Rubisco was consistently degraded at a faster rate than the small subunit (SSU) and added CT had a greater effect in slowing the degradation of the LSU compared to the SSU. There was little difference in the degradation of Rubisco when rumen fluid from sheep fed either white clover or L. corniculatus was used for in vitro incubations.

It was concluded that the action of CT from L. corniculatus reduces the digestion of protein in the rumen of sheep. This effect is predominantly due to the action of CT reducing the degradation of plant protein, although CT also reduced the solubilization of plant protein. The main effects of CT on protein solubilization and degradation seemed to be produced locally by CT present in plant tissue; transfer of these effects through rumen fluid was small in magnitude.

Pearl millet (Pennisetum glaucum (L.) R. Br.) is commonly grown at a wide range of plant population densities, both by design and as a consequence of stand establishment problems. High tillering genotypes are known to compensate effectively for lower plant population densities through their tillering capacity; less is known about the ability of naturally low tillering genotypes to adjust to low plant population densities. This is a particular concern in the case of the Iniadi landrace materials which are currently widely used in breeding programmes in both India and Africa. This research was done to determine how effectively the low tillering Iniadi types adjust to low plant population densities and how their mechanism(s) of adjustment compares to those of higher tillering materials. Two high and two low tillering genotypes were grown over a period of 5 years at plant population densities ranging from 12 to 2 plants/m2, under both high and low fertility regimes at the ICRISAT Centre, India. Both the high and low tillering types adjusted equally well to the reduced plant population densities, as judged by grain yield, but differed in their mechanism of adjustment. The high tillering genotypes adjusted, as expected, primarily by increasing productive tiller numbers, with only small changes in individual tiller productivity. The Iniadi genotypes increased productive tiller numbers in response to decreasing plant population densities to a limited degree, but increased panicle productivity to a much greater degree than the high tillering types. There was no differential effect on adjustment ability between the two types as a consequence of increased fertility, despite the stimulating effect of fertility on productive tiller numbers. The results are discussed in terms of generalized mechanisms of response to changing individual plant environmental resources (fertility and space), and in terms of the use of Iniadi germplasm in pearl millet breeding programmes.

Aqueous extracts of fruits and leaves of the Chinaberry tree, Melia azedarach L. were tested for their efficacy versus other biotic and synthetic insecticides against the pea leafminer, Liriomyza huidobrensis (Blanchard). The study included field experiments on naturally infested swiss chard, Beta vulgaris var. Cicla L., and greenhouse experiments on artificially infested cucumber, Cucumis sativus L. that were conducted in 1995–96. The other treatments included azadirachtin (0·25%), ultrafine mineral oil, abamectin, cyromazine, imidacloprid, pyrazophos and control. Results of field experiments indicated that Melia fruit extract and the other insecticides significantly lowered the number of larvae per swiss chard plant as compared to the control, at 5 days sampling after second spray or 15 days after first spray, when two consecutive sprays were performed. However, at 10 days after second spray, the fruit extract did not differ significantly from the control, but it was comparable in its effect to the insecticides, except abamectin and cyromazine. In greenhouse experiments, the pea leafminer larvae were found at higher densities on cucumber leaves located at the lower plant part (10–60 cm) compared to other leaf positions. The Melia fruit extract and the other pesticides significantly decreased the number of live larvae per cucumber leaf compared to the control, 10 days after each spray. The fruit extract, abamectin, cyromazine, imidacloprid and pyrazophos lowered the leafminer population significantly compared to the control, throughout the period of the experiments. However, the fruit extract was significantly less effective than these insecticides at the final count, 20 days after second spray. Abamectin and cyromazine consistently showed a significant decrease in number of larvae, in both field and greenhouse experiments. At certain periods of the experiments, Melia extracts were comparable in their efficacy to the tested commercial biorational and synthetic pesticides. Thus, they have a good potential to be used in the management of the pea leafminer. This is the first report for use of M. azedarach against L. huidobrensis.

An isotope dilution method using [U-13C]glucose and a glucose clamp approach were applied to determine the effects of supplemental chromium (Cr) and heat exposure on blood glucose metabolism and tissue responsiveness and sensitivity to insulin in sheep. The sheep consumed diets with either 0 or 1 mg of Cr/kg (Control and +Cr diet, respectively) from high-Cr-yeast, and were exposed from a thermoneutral environment (20 °C) to a hot environment (30 °C) for 5 days. Blood glucose turnover rate did not differ between the diets, and was lower (P < 0·05) during heat exposure than in the thermoneutral environment. The maximal glucose infusion rate (tissue responsiveness to insulin) tended to be lower (P = 0·06) for the +Cr diet than for the Control diet, but did not change with heat exposure. The plasma insulin concentration at half maximal glucose infusion rate (tissue sensitivity to insulin) did not differ between the diets, and was greater (P < 0·05) during heat exposure than in the thermoneutral environment. No significant diet × environment interactions were observed. There was no significant evidence that Cr supplementation moderated heat stress in sheep from the measures of blood glucose metabolism and insulin action.

The influence of an additional supply of ammonium to a nitrate containing hydroponic solution on the mineral nutrition of greenhouse rose plants (Rosa hybrida cv. ‘Lambada’) has been investigated. The effect on NPK uptake, mineral contents in roots and leaves as well as nitrate reductase (NR) and glutamine synthetase (GS) activities were examined. The addition of ammonium in a nutrient solution containing nitrate produced a total nitrogen uptake increase during shoot elongation, while in the absence of ammonium, nitrate uptake was lower during shoot elongation. Adding ammonium to the hydroponics solution caused an increase of potassium uptake while ammonium absorption was constant. Phosphate uptake was always higher in combined nitrate plus ammonium treatment, likewise in this treatment the most relevant effect on plant mineral content was the increase of P concentration in the roots. In both treatments with or without NH+4, free nitrate was notably higher in the roots than in leaves, indicating that nitrate reduction in rose plants takes place mainly in the leaves. NR activity in the leaves was higher when ammonium was present, whereas the root GS activity was similar in both treatments. The influence of ammonium on phosphate uptake and the subsequent effects on transport of other ions and enzymatic activities are discussed.

Total DNA was extracted and purified from luminal digesta samples (1 g) of 14-week-old (c. 43 kg bodyweight) pigs. Digoxigenin (DIG) labelled PCR products of the beta toxin gene of Clostridium perfringens type C were generated with DIG-11-UTP and chemoluminescent signals of DIG-labelled PCR products were detected on slot blots and recorded with a sensitive charge coupled densitometric camera. Detection limit and correlation of chemoluminescent signals to initial target DNA concentration were evaluated. Detection of the beta toxin gene could be achieved with 100 ag C. perfringens DNA in the presence of 1 μg unspecific DNA. The semiquantitative DIG-PCR assay was used to evaluate the relative abundance of the beta toxin gene of C. perfringens type C in purified DNA extracts from intestinal samples of pigs, which were fed a wheat/barley diet (controls), supplemented with the antibiotic avilamycin (40 mg/kg feed), a xylanase (4000 U/kg feed) or a combination of both feed additives. The antibiotic treatment significantly reduced the amount of PCR product in ileal and colon DNA extracts. Xylanase supplementation significantly reduced the amount of PCR product in colon samples, but led to an increase in jejunal samples. From the results it is concluded, that the antibiotic inhibited growth of C. perfringens type C in the ileum and colon of pigs. The semiquantitative DIG-PCR assay can be used to sensitively monitor the relative abundance of specific pathogens in the intestinal tract.

Starting with the F2 generation of the single-cross commercial hybrid Lorena (PR3183), recombinant lines were developed combining half-sib/S1 evaluation on widely spaced plants in the direction of high yielding per se. Combining ability tests consisted of crosses between: (a) recombinant lines of common pedigree and (b) recombinant lines and freely available inbred lines. The highest-yielding crosses between recombinant lines reached 100% of the original F1 hybrid in a percentage of 14·2. Low heterosis was estimated owing to additive gene action of recombinant lines. Crosses between recombinant lines and freely available inbred lines outyielded significantly the commercial F1 hybrid in a percentage of 33·3. Heterosis was greater and the original F1 hybrid was outyielded significantly because of non-additive gene action. When the applied breeding procedure on a source population with high yield adaptability is adopted and where effects of intergenotypic competition masking the inherent genotypic value are controlled, population improvement may be substituted by combined half-sib/S1 selection for productivity of lines per se in low stress conditions during the very early stages.

The aim of this study was to determine whether the inclusion of a condensed tannin (quebracho tannin, QT) and/or the elevation of dietary protein could reduce Trichostrongylus colubriformis establishment and existence in the small intestine of lambs. Thirty-six lambs (mean liveweight 32·6±3·9 kg) were randomly allocated to one of six experimental groups, groups 1–5 were parasitized with a trickle infection of 3000 infective Trichostrongylus colubriformis larvae daily, whilst group 6 remained as uninfected controls. Experimental diets were formulated to contain 222 g CP/kg (high protein) or 97 g CP/kg (low protein) with or without the inclusion of 50 g QT/kg. All six animal groups were fed the low protein diet, group 2 fed low protein diet+QT, for one month prior to infection (groups 1–5). Once nematode eggs were observed in the faeces, diets were abruptly changed in three experimental groups. Group 1 remained on the low protein diet, group 2 remained on the low protein+QT diet, group 3 changed to the high protein diet, group 4 changed to the high protein+QT diet, group 5 changed to the low protein+QT diet and group 6 remained uninfected and fed the low protein diet. Production, haematological and parasitological parameters were monitored at regular intervals. Results show that parasitized animals fed the high protein diet achieved growth rates similar to those of uninfected low protein-fed lambs. Inclusion of dietary QT did not depress liveweight gain. Total daily faecal egg counts declined after feeding the high protein diet. Inclusion of QT into the low protein diet also reduced faecal egg counts to similar levels observed in the high protein-fed lambs. The inclusion of QT into the high protein diet did not further reduce faecal egg counts. No significant differences in the haematological parameters measured were observed between infected animals (groups 1–5), suggesting that the beneficial effect of dietary QT in the low protein diet is unlikely to be mediated through an immune response. These data suggest that the inclusion of QT in low protein diets may be an alternative to feeding high protein diets to reduce nematode burden in lambs.

Available pasture, liveweight gain, milk yield and supplementary feeding of Awassi sheep were monitored for four seasons (1991/92 to 1994/95) on pasture fertilized with superphosphate between 1984 and 1990. The experimental plots received three rates of phosphate (0, 25 and 60 kg P2O5/ha) annually, but no application after September 1990. The experiment was grazed at low (1·1 sheep/ha per year) and high (2·3 sheep/ha per year) stocking rates. The experimental site was typical of communally owned grasslands within the cereal zone of west Asia, where cropping is not possible because of shallow, stony soil and steep slopes. Plots with residual phosphate contained significantly more herbage and supported heavier animal liveweights, especially in the first two seasons. Milk yield and lamb production were greater and the need for supplementary feeding was reduced due to increased herbage. The results suggest that benefits of residual phosphate on pasture and livestock production can be considerable and should be included when assessing the value of applying fertilizer to degraded marginal lands in west Asia. Provided that the stocking rates remain within the range tested in the study, the pasture would suffer no harm. However, the higher stocking rates now practiced in the spring under communal grazing might severely limit flowering and seed-set. The property right to own or use the grazing land is seen as a key factor, deserving attention from governments in west Asia in order to apply new technologies to improve degraded marginal lands.

The study was undertaken at Punjab Agricultural University, Ludhiana, in 1991–1992 to investigate the behaviour of the pollen tubes of four wild Pennisetum species in the stigmatic tract of P. typhoides and to identify stages of pre-fertilization impediments to interspecific hybridization. Pollen germination was normal in crosses with P. violaceum, P. squamulatum and P. orientale and slightly inhibited in a cross with P. setaceum. Fertilization was accomplished within 3 h of pollination in a control cross within P. typhoides. P. typhoides × P. violaceum was a compatible cross and the pollen tubes of P. violaceum reached the ovary within 4 h of pollination. The presence of P. squamulatum and P. orientale pollen tubes in the ovary 10–15 h after pollination indicated the possibility of normal fertilization, while in crosses with P. setaceum, pollen tubes did not penetrate the ovary even 15 h after pollination. The study indicated that there is no impediment at the pollen germination stage or in the stigmatic hairy region. Delayed/restricted growth of pollen tubes indicated that the barrier operates in the styllar hairless region for the crosses with P. squamulatum and P. orientale, and at the ovarian level for the P. typhoides × P. setaceum cross.

Of the anthropogenic greenhouse gas emission in Denmark animal manure contributes an estimated 40% of methane (CH4) and 20% of nitrous oxide (N2O). Livestock production systems undergo changes for the purpose of increasing animal welfare, and such changes often include increasing the amounts of bedding manure. Emission of greenhouse gases from composting pig deep litter was studied during a 4-month period. Effects of increasing the amount of straw used in deep litter (reducing litter density) were included in the study. Methane was produced at a high rate in the centre of the heap at high density during the thermophilic phase of composting, and CH4 emission was only measured during this phase. In this treatment N2O was also produced in the centre both initially and after the temperature of the compost had dropped to below 45 °C. Emissions of N2O were only significant in the low temperature phases. Production of N2O was probably restricted to the surface layers during the thermophilic phase of composting. Total carbon dioxide (CO2) emissions were 7·37 and 0·09 kg C/t fresh weight from the heaps with bulk densities of 0·44 and 0·23 kg/l, respectively. Methane emission from the high density compost heap was 191 g C/t and N2O emission was 58 g N/t. Emissions of CH4 and N2O from the low density heap were not detected. The greenhouse effect of gas emission from the high density compost heap was calculated by multiplying the climate force efficiencies and the cumulated gas emission. This calculation showed that CH4 contributes almost as much to the global warming potential as CO2, and N2O contributed twice as much as CO2.