Many of the world's soils are experiencing degradation at an alarming rate. Climate change and some agricultural management practices, such as tillage and excessive use of chemicals, have all contributed to the degradation of soil fertility. Arbuscular Mycorrhizal Fungi (AMFs) contribute to the improvement of soil fertility. Here, a short review focusing on the role of AMF in improving soil fertility is presented. The aim of this review was to explore the role of AMF in improving the chemical, physical, and biological properties of the soil. We highlight some beneficial effects of AMF on soil carbon sequestration, nutrient contents, microbial activities, and soil structure. AMF has a positive impact on the soil by producing organic acids and glomalin, which protect from soil erosion, chelate heavy metals, improve carbon sequestration, and stabilize soil macro-aggregation. AMF also recruits bacteria that produce alkaline phosphatase, a mineralization soil enzyme associated with organic phosphorus availability. Moreover, AMFs influence the composition, diversity, and activity of microbial communities in the soil through mechanisms of antagonism or cooperation. All of these AMF activities contribute to improve soil fertility. Knowledge gaps are identified and discussed in the context of future research in this review. This will help us better understand AMF, stimulate further research, and help in sustaining the soil fertility.

Drought stress strongly affects soil biota and impairs crop production, which under climate change will be exacerbated in semi-arid cropping regions such as the Sahel. Hence soil management systems are needed that can buffer against drought. In West Africa, field studies have found intercropping of millet with the native shrub Piliostigma reticulatum improves soil-plant-water relations, microbial activity and diversity, and suppress parasitic nematodes, which can significantly increase crop yield. However, little information is available on its beneficial or negative effects on soils or crops during water stress. Therefore, the objective was to investigate the impact of P. reticulatum in moderating water stress effects on soil properties and pearl millet (Pennisetum glaucum [L.] R. Br.) productivity. In the greenhouse, soil chemical and microbial properties and millet growth were investigated with a factorial experiment of varying levels of soil moisture (favorable, moderately stressed, or severely stressed water conditions) that was imposed for 55 days on soils containing sole P. reticulatum or millet, or millet + P. reticulatum. The results showed that the presence of P. reticulatum did not buffer soils against water stress in relation to soil chemical and microbial properties measured at the end of the experiment. Severe water stress did significantly decrease the height, number of leaves, and aboveground biomass of millet plants. Additionally, respiration, nematofauna trophic structure and abundance decreased as water stress increased. Lastly, bacterial feeders and plant parasitic 190nematodes were the most sensitive to severe water stress while fungal feeding nematodes remained unaffected. The results suggested that the intensity of water stress had more negative effects on soil basal respiration rather than soil microbial biomass.

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The excessive application of mineral fertilizers in maize cultivation leads to progressive soil contamination in the long term and increases the cost of production. An alternative to reduce over-fertilization is to perform a partial replacement with microbes that promote nutrition and growth, such as Arbuscular Mycorrhizal Fungi (AMF). A pot experiment which was followed by two field experiments was performed with and without the application of indigenous AMF in combination with five nitrogen–phosphorus–potassium (NPK) fertilization rates (100% NPK = N120P60K60; 75% NPK = N90P45K45; 50% NPK = N60P30K30; 25% NPK = N30P15K15; control = N0P0K0). The objective was to investigate whether the soil application of indigenous mycorrhizal fungi inoculum combined with NPK fertilization can provide higher maize yields and soil-available N, P, and K than chemical fertilization can alone. The greenhouse results showed that the application of AMF with a 50% NPK treatment significantly increased the plant’s growth, root colonization, leaf chlorophyll content, and N, P, and K tissue content. The results from the field conditions showed that there was a highly significant yield after the treatment with AMF + 50% NPK. The study also revealed that mycorrhizal fungi inoculation increased the available soil N and P concentrations when it was combined with a 50% NPK dose. This suggests that the inoculation of fields with AM fungi can reduce the chemical fertilizer application by half, while improving soil chemistry. The results suggested that AMF inoculation can be used in integrated soil fertility management strategies.

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Piliostigma reticulatum is a native woody shrub found in cropped fields in the Sahel and has been shown to increase crop productivity and soil quality. Frequently occurring drying and rewetting cycles (DRW) may alter the soil quality beneath these shrubs. We investigated the effect of DRW cycles on microbial community in soil beneath and outside the P. reticulatum canopy and the roles of this shrub in the adaptation of the microbial community to abiotic stress. Soils were incubated in a climate controlled chamber for 45 days, after exposure to 10 consecutive days of DRW cycles at 75% of water holding capacity (WHC). Basal respiration, β-glucosidase activity, microbial biomass carbon (MB C ), and available nitrogen ( 4

A single paragraph Arbuscular mycorrhizal fungi (AMF) establish symbiotic relationships with many crops. These soil microbiotas improve the soil fertility through the soil physical, chemical and biological properties. extending the root absorbing area. In return, the symbiont receives plant carbohydrates for the completion of its life cycle. AMF also helps plants to cope with biotic and abiotic stresses such as extreme temperature, heavy metal, diseases, and pathogens. For soil physical properties, the mechanisms used by AMF are the production of a glycoprotein, glomalin, which creates a high quality of soil macro-aggregations. These macro-aggregations control soil erosion, nutrients and organic matter losses. For soil chemical properties, AMF produce acids and an enzyme called phosphatase. This enzyme hydrolyzes the inorganic phosphorus and the rock phosphate (RP) hence making P available in the soil for plant uptake. AMF also are involved in soil nitrogen, carbon and trace element cycling. Regarding the biological component of the soil, AMF influence the composition, diversity and activity of microbial communities in the hydrosphere. They also work in synergy with others soil microorganisms to improve soil fertility, plant growth and resistance against some diseases. In this review, we present the contribution of AMF on soil fertility and importance in polluted soils.

Piliostima reticulatum and Guiera senegalensis shrubs constitute “islands of soil fertility” in the rhizosphere, with better availability of water and more intense biological activity in the Sudano-Sahelian agro-ecosystems. There is, however, paucity of information on diversity of arbuscular mycorrhizal fungi (AMF) fungi, which have a wide ecological range of associations with a variety of vegetation. The purpose of this study was to identify the types of AMF in the rhizospheres of P. reticulatum and G. senegalensis shrubs in Senegal. Soil samples were collected from around the shrubs in Keur Matar Arame and Keur Ndary Ndiaye in 2019 after a rainy season. Arbuscular mycorrhizae fungi spores were isolated by the wet sieving method and identified based on their morphological characteristics (shape, size, colour, attached hyphae, and spore ornamentation). Four types of AMF were identified, namely Glomus aggregatum, Sclerocystis rubiformis, Gigaspora margarita and Scutellospora gregaria. In addition, the density of spores was more abundant in the soil outside the shrub canopy compare to the soil beneath the shrub.