Saïd Nouira

Bio: Saïd Nouira is an academic researcher from Tunis El Manar University. The author has contributed to research in topics: Dung beetle & Species richness. The author has an hindex of 6, co-authored 12 publications receiving 177 citations.

Comparative effects of conventional and no-tillage management on some soil properties under Mediterranean semi-arid conditions in northwestern Tunisia.

Abstract: No-tillage (NT) is becoming increasingly attractive to farmers worldwide because it clearly reduces production costs relative to conventional tillage (CT) and improves soil properties and crop yield. Currently, under semi-arid conditions in North Africa, modern no-tillage techniques are being practiced on several hectares of land. The effect of NT and CT management and crop rotation on soil properties under semi-arid Mediterranean conditions was studied, over a 4-year period at two locations in northern Tunisia. Data from a short-term (2000–2004) use of both no-tillage (NT) and conventional tillage (CT) at the ESAK (Tunisia) were used to evaluate the influence of the tillage systems on the physicochemical properties of soil at the 0–20 cm depth layers. Trial was set up in 2000, where the two tillage systems (CT and NT), and four crop types (durum wheat, barley, pea and oats) were implemented in two distinct sites close to two governorates: Kef (silt/clayey) and Siliana (sand/clay) in northwestern Tunisia. Four years after implementing the two different tillage systems, soil parameters (N, NO 3 2− , NH 4 + P, P 2 O 5 , K, K 2 O, SOC, SOM and CEC) were determined and comparison between the two tillage systems was made. Our results showed that after 4 years the contents of some parameters for most crop types were greater under NT than under CT at 0–20 cm depth layers, the results varied depending on crop type and site. NT significantly improved soil content especially for K, K 2 O, P 2 O 5 and N. Under NT system SOM and SOC were enhanced, but without significant results. These enhancements were accompanied by the enhancement of the CEC and the decrease of the C/N ratio. Thus the mineralization process was slightly quicker under NT. Our results also indicate that residue cover combined with no-tillage appears to improve some agronomic parameters and biomass production (grain yield). Multivariate analyses indicate that the improvement of soil properties was dependant on tillage management, sites (climate and soil type) and crop succession (species and cover residue). It must be pointed out that a 4-year period was not sufficient to clearly establish some parameters used in the effects of the NT system on soil properties under semi-arid conditions in northwestern Tunisia.

Soil invertebrates in durum wheat (Triticum durum L.) cropping system under Mediterranean semi arid conditions: A comparison between conventional and no-tillage management

Abstract: One of the challenges of research in soil ecology is to assess the impact of tillage managements on soil invertebrates. It is known that tillage practices change soil water content, temperature, the degree of mixing of crop residues within the soil matrix and the physico-chemical environment for soil organisms. The present study tested whether no-tillage (NT) or a conventional tillage (CT) of a cereal (durum wheat; Triticum durum ) field in a semi-arid zone of northwestern Tunisia could improve the biological activity and diversity of soil invertebrates, especially arthropod and earthworm communities. The experiment was conducted in January 2000 at two different sites (Mahasse/Kef Governorate and Krib/Siliana Governorate). Soils (Brunisols, isohumic or fersialitic soil) were silt/clay in Mahessen and sand/clay in Krib. After three and four years, soil fauna was sampled with two methods (quadrat and pitfall trap) over 7 months for the last two growing seasons (2002/2003 and 2003/2004). We hypothesized that: (i) soil fauna richness, abundance and diversity would be lower in CT soils than in NT soils and (ii) the move from CT to NT may improve the soil biological component under semi arid conditions. 380 invertebrates (37 species) and 309 invertebrates (24 species) were collected by quadrat and pitfall trap methods, respectively. NT greatly enhanced the species richness (from 26 species in CT to 34 species in NT) and abundance (from 61 individuals in CT to 319 individuals in NT) of soil invertebrates with quadrat method. Only abundance was significantly enhanced with pitfall trap method (from 78 individuals in CT to 235 individuals in NT). So, abundance, species richness and diversity of soil arthropods were significantly higher ( P Predators (mostly Carabidae ), detritivore (especially: Formicidae , Dolicoderidae , Lumbricidae ) and herbivore (represented here by Julidae , Pyrrhochridae and some Scarabaeidae ) were significantly ( P V (index which compares the relative increase or decrease of the population density between the two tillage modes) showed that all major taxonomic groups were extremely inhibited by CT, confirming our second hypothesis. So, NT seems to be beneficial to biological soil component where it favoured the establishment of diverse soil communities than did CT in durum wheat cropped field. Furthermore, soil fauna may enhance crop-residues decay processes.

Seasonal occurrence and local coexistence within scarabaeid dung beetle guilds (Coleoptera: Scarabaeoidea) in Tunisian pasture

Abstract: Dung beetle assemblages were monitored using baited pitfall traps from January to December 2006 in Northern Tunisia. 4,965 beetles belonging to 37 species were trapped. Aphodius lineolatus and Onthophagus taurus dominated the assemblages. Results showed a significant seasonal variation in assemblage composition, and diversity. There were four periods of activity during the course of the year. Temporal turnover was highest in October and in February. Temporal distribution of species shows seasonal segregation and opposite patterns in the two dominant guilds (Aphodiinae-dwellers and Scarabaeidae-tunnelers). Aphodiidae- dwellers were active from autumn to spring, although they were affected by summer drought. The Aphodius-dweller showed high temporal plasticity and phenological segregation. In contrast, Scarabaeidae-tunnelers were active all year round but mainly in the spring-summer period and less so in winter. Species in this guild showed a high degree of phenological overlap and a short eco- logical length. Our results suggest that coexistence in dung beetle guilds is facilitated by their phenological patterns, which reflect distinct ecological requirements and biogeographical origin of species. Geotrupidae-tunnelers and Scarabaeidae-rollers were rare and occurred mainly in the summer-autumn period, when individuals of the two other guilds were rare.

Spatial and Temporal Variation in Species Composition, Diversity, and Structure of Mediterranean Dung Beetle Assemblages (Coleoptera: Scarabaeidae) Across a Bioclimatic Gradient

Abstract: Both spatial (bioclimatic stages) and temporal (seasons) analyses were contemplated to estimate the influence of Mediterranean bioclimate on dung beetle assemblage's distribution. Insects were pitfall trapped once per season from 2008 to 2009 at eight bioclimatic sites from north to south of Tunisia. In total, 3,278 specimens and 39 species (18 Aphodiinae and 21 Scarabaeinae) were collected and the completeness of sampling was of 76.81%. Along the bioclimatic gradient species richness of these two families were of the same order (Scarabaeinae/Aphodiinae ratio 1.16). The highest value of species richness occurs in subhumid site (27 species) and the lowest in the arid sites (5 species). More beetles were captured in spring and few beetles in autumn. However, more Scarabaeinae were captured in summer and more Aphodiinae in winter. Humid and subhumid sites were more diverse with high temporal turnover and, 80% of species occur in this area of the north-west of Tunisia. Conversely, the arid sites have the lowest values of α- and β-diversity. The highest spatial turnover occurs between semiarid middle and semiarid inferior. Several factors could explain these results such as the soil nature, the geographical position, and latitude. Multivariate analyses showed that: 1) latitude greatly influenced the assemblage organization than bioclimate; 2) spatial factors (soil, bioclimate, latitude, altitude, marine influence) have greater effect than temporal factors (season); and 3) the Tunisian Dorsale is a stronger determinant where it act as a barrier or a filter that limit the colonization of arid sites by dung beetles and species occurred in these sites were those locally abundant an largely distributed. Results indicate that there were no spatio-temporal patterns according to bioclimate, but the influence of local and regional factors predominates on the dung beetle assemblages distribution.

Food habits of the aoudad Ammotragus lervia in the Bou Hedma mountains, Tunisia

Abstract: A micro-histological analysis of composite faecal samples was used to determine the food plants consumed by the aoudad Ammotragus lervia (Barbary sheep) in the mountains of Bou Hedma National Park, as well as to study food preferences and seasonal variation of the diet of this ungulate. A total of 19 plant species was identified in the faecal samples: 8 grasses, 6 browse types and 5 forbs. The annual diet of this ungulate is composed of approximately 67% grasses, 17% browse and 16% forbs. Two grass species, Stipa parviflora and Stipa tenacissima, comprised 97% of grasses consumed and 63% of the annual diet, and were eaten in the year with considerably greater frequency than any other plant species. The diet of the aoudad at Bou Hedma National Park showed a seasonal variation. For example, grasses were consumed the entire year with a preference in spring (72.57%) and summer (78.31%), but their occurrence in the diet dropped in winter (38.7%). Browse was eaten preferentially in autumn (21.86%) and forbs were utilised most during winter (43.22%) and least during summer (7.53%). Our results show the plasticity of the Tunisian aoudad’s diet and identify it predominantly as a grazer.

No-till in northern, western and south-western Europe: A review of problems and opportunities for crop production and the environment

Abstract: Recent literature on no-till is reviewed with particular emphasis on research results and commercial uptake in northern, western and southwestern Europe. Increased interest in no-till, as well as minimum or reduced tillage, is the result of changes in the economic circumstances of crop production, the opportunity to increase the area of more profitable autumn-sown crops and increased concern about environmental damage associated with soil inversion by ploughing. Highly contrasting soil and climate types within and between these regions exert a strong influence on the success of no-till. While no-till may often result in crop yields which equal or exceed those obtained after ploughing, modest reductions in yield may be tolerated if production costs are appreciably lower than with ploughing. The relative costs of fuel and herbicides have changed appreciably in recent years making no-till more attractive commercially. While effective weed control is an essential aspect of no-till, current herbicide technology may not yet fully achieve this. No-till soils will usually have lower temperature and higher moisture content at the time of drilling, delaying drilling of spring-sown crops in northern regions. Their bulk density and bearing capacity are greater than for ploughed soils but the pronounced vertical orientation of macroporosity will allow encourage penetration of roots and water, especially in view of the increased population of deep-burrowing earthworms. Particular care must be taken to minimise soil damage at harvest and to ensure the even distribution of crop residues prior to drilling. Reduced erosion and runoff under no-till are widely observed and are of particular importance in southwestern Europe. No-till reduces losses of phosphorus in runoff and the loss of nitrate through leaching. Emissions of greenhouse gases CO2 and N2O from no-till soils are highly variable and depend on complex interactions of soil properties. Emission of CO2 from fuel during machinery usage is always appreciably reduced with no-till. Increased soil organic carbon in surface layers of no-till soils may not be associated with increased carbon sequestration throughout the profile. All relevant factors must be included in the evaluation of the relative overall climate forcing effects of no-till and ploughing. Adoption of no-till could be encouraged by government financial assistance in recognition of environmental benefits, although future restrictions on the use of herbicides may be a deterrent. Opportunities for further research on no-till are outlined.

Effect of long term no-till and conventional tillage practices on soil quality

Abstract: Management systems influence soil quality over time. A randomized block design in 2 (tillage system) × 3 (crop rotation) factorial arrangement was laid-out to evaluate the impact of tillage and crop rotation (2002–2007) on soil quality. Conventional tillage and No-till were factored into continuous corn, corn–soybean, and corn–soybean–wheat–Cowpea systems. Ten soil cores were collected at 0–7.5, 7.5–15, 15–22.5 and 22.5–30 cm depths and analyzed for biological, chemical and physical parameters. The inductive additive approach was used to calculate biological, chemical, physical and composite soil quality indices. A significant impact of no tillage on different physical chemical and biological parameters was observed. The estimated soil quality index was significantly higher in soil under No-till than conventional tillage. Soil biological quality is a sensitive and consistent indicator of soil quality in response to management practices.

Conventional tillage decreases the abundance and biomass of earthworms and alters their community structure in a global meta-analysis.

Abstract: The adoption of less intensive soil cultivation practices is expected to increase earthworm populations and their contributions to ecosystem functioning. However, conflicting results have been reported on the effects of tillage intensity on earthworm populations, attributed in narrative reviews to site-dependent differences in soil properties, climatic conditions and agronomic operations (e.g. fertilization, residue management and chemical crop protection). We present a quantitative review based on a global meta-analysis, using paired observations from 165 publications performed over 65 years (1950–2016) across 40 countries on five continents, to elucidate this long-standing unresolved issue. Results showed that disturbing the soil less (e.g. no-tillage and conservation agriculture [CA]) significantly increased earthworm abundance (mean increase of 137% and 127%, respectively) and biomass (196% and 101%, respectively) compared to when the soil is inverted by conventional ploughing. Earthworm population responses were more pronounced when the soil had been under reduced tillage (RT) for a long time (>10 years), in warm temperate zones with fine-textured soils, and in soils with higher clay contents (>35%) and low pH (<5.5). Furthermore, retaining organic harvest residues amplified this positive response to RT, whereas the use of the herbicide glyphosate did not significantly affect earthworm population responses to RT. Additional meta-analyses confirmed that epigeic and, more importantly, the bigger-sized anecic earthworms were the most sensitive ecological groups to conventional tillage. In particular, the deep burrower Lumbricus terrestris exhibited the strongest positive response to RT, increasing in abundance by 124% more than the overall mean of all 13 species analysed individually. The restoration of these two important ecological groups of earthworms and their burrowing, feeding and casting activities under various forms of RT will ensure the provision of ecosystem functions such as soil structure maintenance and nutrient cycling by “nature's plough.”