Rachid Mrabet

Total, particulate organic matter and structural stability of a Calcixeroll soil under different wheat rotations and tillage systems in a semiarid area of Morocco

Wheat production in Morocco is constrained by both scarce climate and degraded soil quality. There is an urgent need to revert production decline while restoring country’s soils. Among conservation tillage systems known for their improvement in yield, no-till technology was found to influence soil quality as well. Soil quality indices are also affected by wheat rotations at medium and long-terms. This paper discusses changes in selected properties of a Calcixeroll soil, including total and particulate soil organic matter (SOM), pH, total N and aggregation, subjected, for 11 consecutive years, to various conservation and conventional agricultural systems. Tillage systems included no-tillage (NT) and conventional tillage (CT). Crop rotations were continuous wheat, fallow‐wheat, fallow‐wheat‐corn, fallow‐wheat‐forage and fallow‐wheat‐lentils. Higher aggregation, carbon sequestration, pH decline and particulate organic matter (POM) buildup are major changes associated with shift from conventional- to NT system. Better stability of aggregates was demonstrated by a significantly greater mean weight diameter under NT (3.8 mm) than CT system (3.2 mm) at the soil surface. There was 13.6% SOC increase in (0‐200 mm) over the 11-year period under NT, while CT did not affect much this soil quality indicator. Another valuable funding is the stratification of SOC and total nitrogen in NT surface horizon (0‐25 mm) without their depletion at deeper horizon compared to tillage treatments. Fallow‐wheat system resulted in reduction of SOC compared to WW, but 3year wheat rotation tended to improve overall soil quality. Benefits from crop rotation in terms of organic carbon varied between 2.6 and 11.7%, with fallow‐wheat‐forage exhibiting the maximum. Combined use of NT and 3-year fallow rotation helped to improve soil quality in this experiment. # 2001 Elsevier Science B.V. All rights reserved.

Stratification of soil aggregation and organic matter under conservation tillage systems in Africa

Abstract Soil degradation due to tillage has been reported Africa-wide. Other main causes of soil degradation are overgrazing, extensive cultivation of marginal lands, widespread clearing of vegetation for agriculture, deforestation, exploitation of unsuitable agricultural technologies, mis-management of arable lands, and frequent drought. Hence, declining soil fertility and increasing population pressure on lands are fragile bases on which to build expectations for improved crop production. This paper recognizes conservation tillage systems as one means for preventing food shortages and natural resources degradation throughout the continent. Conservation tillage has the potential for increasing soil organic matter content and enhancing soil aggregation. Conservation tillage systems can create an aggregated, fertile surface layer that is important from a soil erosion reduction perspective and thus for a sustainable agriculture in Africa. Some indigenous tillage systems in Africa can be adapted to meet objectives of conservation tillage systems. Further, recent technological developments in tillage and seeding machinery will certainly enhance the rate of farmer’s acceptance and adoption of conservation tillage.

Effect of Thymus vulgaris and Origanum compactum essential oils on the shelf life of fresh goat cheese

We have carried out our study on the chemical composition and antimicrobial activity of Thymus vulgaris and Origanum compactum essential oils that were harvested in the northeast of Morocco. Carvacrol was the major component in the two investigated essential oils. A high antimicrobial activity has been shown on all tested bacterial strains. The effect of the incorporation of these two essential oils at concentrations of 0.05% and 0.1% on physicochemical, microbiological and sensorial characteristics of goat fresh cheese stored at 8°C has also been studied. No significant differences have been showed between control and aromatized cheeses with respect to pH, titrable acidity, dry matter, lactic acid bacteria and aerobic mesophylic flora. However, coliforms were completely inhibited by the presence of both essential oils from the first storage day. Shelf life estimation has been determined by the reparameterized Gompertz equation by monitoring the growth of molds and yeasts. Origanum compactum essential oil was more effective on extending the shelf life of fresh goat cheese than Thymus vulgaris essential oil. Nevertheless, the aromatized cheese with Thymus vulgaris essential oil was the most appreciated by the tasting panel.

No-Tillage Agriculture in West Asia and North Africa

Agriculture in West Asia and North Africa (WANA) is losing momentum. Serious problems of land degradation, desertification, declining soil quality, reduced soil fertility and low agricultural production levels may be irreversible if appropriate measures are not taken soon. Past research in agriculture focused on testing cropping systems under conventional soil management which may no longer be relevant to the WANA region. Most of WANA’s soils need skilled management practices such as no-tillage and stubble retention to ensure sustainable agricultural production. This chapter reviews research on no-till (NT) and conservation agriculture (CA) and their application in rainfed regions of WANA. In WANA countries where water scarcity is becoming endemic, NT could rehabilitate productivity of soils and farmers’ returns, although it can result in lower yields where weeds are not controlled. Institutions need to disseminate the principles and practices of no-till in order to improve productivity and profitability and benefit both the environment and society.

Managing Mediterranean soil resources under global change : expected trends and mitigation strategies

The soils of the Mediterranean Basin are the products of soil processes that have been governed by a unique convergence of highly differentiated natural and anthropogenic drivers. These soils are expected to be dramatically affected by future climate and societal changes. These changes imply that suitable adaptive management strategies for these resources cannot simply be transposed from experiments that are performed in other regions of the world. Following a framework that considers the chain of “drivers-soil process-soil capital-ecosystem services/disservices,” the paper review the research undertaken in the Mediterranean area on three types of Mediterranean soil degradation than can be expected under global change: (i) soil losses due to the increase of drought and torrential rainfall; (ii) soil salinization due the increase of droughts, irrigation, and sea level; and (iii) soil carbon stock depletion with the increase of temperature and droughts. The possible strategies for mitigating each of these degradations have been largely addressed and are still studied in current research projects. They should include changes in agricultural practices, soil water management, and vegetal material. As a pre-requisite for the site-specific adaptations of such mitigation strategies within viable Mediterranean agrosystems, it is highlighted that methodological advances are necessary in integrated assessment of agricultural systems and in finer resolution soil mapping.

Long and Midterm Effect of Conservation Agriculture on Soil Properties in Dry Areas of Morocco

In Morocco, conservation agriculture, particularly no tillage systems, has become an alternative strategy to mitigate land degradation caused by conventional tillage in semiarid to arid regions. This paper is based on behaviour to tillage treatments of two Vertisols in Morocco. After 11 years of testing, soil organic matter content results showed a significant difference () only at soil surface (0–10 cm) in favour of no tillage and a variation of 30% at this depth. The results obtained after 32 years of testing showed a significant soil profile difference (), up to 40 cm under no tillage compared to conventional tillage, and a variation of 54% at 5–10 cm. For total nitrogen, there was no significant effect between no tillage and conventional tillage at the soil surface after 11 years unlike the result obtained after 32 years. There are no significant differences in bulk density between tillage treatments at soil surface for both sites. The measurement of soil structural stability showed a significant effect () for all three tests and for both sites. This means that no tillage helped Vertisols to resist different climatic constraints, preserving environmental soil quality.

Diversity of fungal assemblages in roots of Ericaceae in two Mediterranean contrasting ecosystems

The plants belonging to the Ericaceae family are morphologically diverse and widely distributed groups of plants. They are typically found in soil with naturally poor nutrient status. The objective of the current study was to identify cultivable mycobionts from roots of nine species of Ericaceae (Calluna vulgaris, Erica arborea, Erica australis, Erica umbellate, Erica scoparia, Erica multiflora, Arbutus unedo, Vaccinium myrtillus, and Vaccinium corymbosum). The sequencing approach was used to amplify the Internal Transcribed Spacer (ITS) region. Results from the phylogenetic analysis of ITS sequences stored in the Genbank confirmed that most of strains (78) were ascomycetes, 16 of these were closely related to Phialocephala spp, 12 were closely related to Helotiales spp and 6 belonged to various unidentified ericoid mycorrhizal fungal endophytes. Although the isolation frequencies differ sharply according to regions and ericaceous species, Helotiales was the most frequently encountered order from the diverse assemblage of associated fungi (46.15%), especially associated with C. vulgaris (19.23%) and V. myrtillus (6.41%), mostly present in the Loge (L) and Mellousa region (M). Moreover, multiple correspondence analysis (MCA) showed three distinct groups connecting fungal order to ericaceous species in different regions.