Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

cartography --- Resource allocation --- Geographical information systems --- land suitability --- Sustainable development --- land use mapping --- Belgium

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

The predicted global population is set to reach 9.6 billion by 2050, which highlights the necessity to increase crop productivity to meet the growing demand for food and nutrition. Nevertheless, this is becoming increasingly challenging due to changing climatic conditions mainly under salinity stress. Soil phosphorus (P) availability and mobility are often limited in salt-affected soils mainly in arid and semi-arid regions. In Morocco, the soils are calcareous and deficient in available P. Hence, it is important to focus on a reasonable and more efficient use of P resources. In the present work, we conducted a series of experiments on durum wheat plants in controlled conditions (Petri dishes, pots, and hydroponic trials) during different stages of plant development. The objective is to evaluate above and belowground changes of wheat plants in response to contrasting P fertilizers doses (0, 30, 45 and 60 ppm of P) and forms: Orthophosphate (OrthoP) and Polyphosphate (PolyP) under salinity. Indeed, different physiological and agronomic traits have been used as key parameters in the enhancement of P fertilizer use efficiency, P acquisition, and crop quality. In the first experiment, we highlighted the effect of P supply on the germination characteristics, seedling growth and their mineral content under salt stress conditions. A second experiment was carried out in hydroponic conditions which focused on the wheat plant's growth using remote sensing technology to measure in vivo physiological parameters such as chlorophyll content index, stomatal conductance, chlorophyll a fluorescence, absorbance, and reflectance with some related parameters. In a pot experiment, we focused on the above-ground part where we assessed the photosynthetic performance and nutrient uptake of durum wheat grown under moderate salt stress. We also investigate if there are any differences between plants’ responses to Ortho-P and Poly-P application in the improvement of the enzymatic and non-enzymatic antioxidant systems to boost ROS detoxification. Similarly, we focused on the below-ground wheat plants’ responses with a special emphasis on how PolyP and P doses alter roots' morphology and their anatomy under salinity. In addition, we emphasized the significance of interconnections between below-ground and above-ground parts of wheat plants for improved P uptake under salt stress conditions. Another pot experiment focused on soil characteristics, major soil enzyme activities, soil nutrient availability and mobility of the rhizospheric and non-rhizospheric soil to improve both the P fertilizer’s use efficiency and soil quality under salinity. Our findings indicate that optimizing phosphorus fertilization management can achieve these goals. Using PolyP not only boosted wheat P acquisition but also coordinated above-below-ground traits, resulting in improved nutrient uptake and photosynthesis efficiency. The best results were observed with Poly-B at a low P concentration of 45 ppm, outperforming OrthoP which showed the best performances at a higher dose (60 ppm) only at moderate salt stress conditions. In conclusion, PolyP could be a favorable option as it gives positive significant responses at lower doses which reduces phosphorus losses over time in salt-affected soils while reducing the frequency of fertilizer application. Furthermore, the micronutrient chelation property enables PolyP fertilizers to enhance simultaneously the uptake of P and micronutrients under salinity where the P availability is reduced. All these findings could enhance the current understanding of durum wheat growth and promote the use of polyphosphates as a sustainable and effective source of phosphorus for crop growth in saline conditions where knowledge is still limited.

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Dans le monde, l'industrie minière génère de large quantité de déchets, qui sont accumulés dans des dépôts de résidus. Ces dépôts peuvent contenir des concentrations en éléments potentiellement toxiques plus élevées, qui peuvent s'accumuler dans la végétation et donc entrer dans la chaîne alimentaire. L'objectif principal de cette étude était d'évaluer le risque environnemental et l'état général des plantes poussant sur différents dépôts de résidus miniers composés de matériaux riches en sulfures et fermés avec différentes techniques conventionnelles. Un objectif secondaire du travail était de déterminer l'influence du système de fermeture sur différents paramètres. Pour cela, les concentrations pseudo totales et disponibles des éléments potentiellement toxiques (Al, As and Pb), macronutriments (Ca, K, Mg, N, P and S) et micronutriments (Cu, Fe, Mn, Ni and Zn) ont été mesurées dans la partie superficielle du sol ; ainsi que les concentrations de ces mêmes éléments dans la partie aérienne de la strate herbacée. Aussi, divers paramètres de la végétation ont été mesurés, et les espèces présentes ont été identifiées afin de calculer divers indices de biodiversité. Tous les paramètres cités précédemment ont également été mesurés dans une zone naturelle, à des fins de comparaison. Les résultats obtenus ont montré que les différents dépôts varient en terme de contamination du sol et présentaient tous des concentrations potentiellement toxiques pour les animaux dans leur strate herbacée. La plupart des indices de biodiversité n'étaient pas différents entre les secteurs miniers et la zone naturelle. Deux secteurs miniers ont présenté une similarité plus élevée que les autres en terme d'espèce par rapport à la zone naturelle. En général, l'influence de la technique de fermeture n'a pas été clairement détectée.

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Under the dual pressure of food demand growth and climate change intensification, how to promote soil organic carbon (SOC) sequestration and synergistically improve crop production via agricultural practice is not only a major strategic demand to ensure food security but also a key way to implement the "Four Per Mille Initiative" and "Carbon Neutrality". Fertilization, especially adding organic amendment, is the most effective practice to enhance SOC, but limited information is available on the underlying mechanism of SOC sequestration in intensive cropping systems. Moreover, in recent years, the application practices of both traditional (e.g., straw incorporation and organic substitution (substitution of chemical fertilizers by manure)) and emerging (e.g., biochar application) organic amendment have shown a great potential in enhancing crop yield and SOC. However, an understanding of how and to what extent organic substitution and straw incorporation impact SOC at different depths and crop yield remains limited. Moreover, previous results regarding the effects of biochar application on SOC and crop yield showed wide variation and high uncertainty. Therefore, it is essential to enhance the understanding of SOC sequestration mechanisms and crop yield response to those practices.In this thesis, firstly, we used a field experiment with double maize cropping to study the responses of OC in soil fractions to long-term fertilization and revealed the underlying mechanism of SOC sequestration in intensive cropping systems. Secondly, four organic substitution and one straw incorporation field experiments were conducted in China to quantify the effects of these practices on SOC at different depths and crop yield as well as their relationship. Finally, the effects of biochar application, as a new perspective of fertilization strategy evolution, on SOC and crop yield were evaluated via a global meta-analysis, and their key factors were determined using a boosted regression tree model.

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

This PhD research work is a contribution to the umbrella research project in Mindanao, Philippines entitled "Establishing strategic partnership in research to strengthen local governance in land and water management for greater human security in Mindanao (EPaM)" which was supportedby the Cooperation of Universities for Development - Inter University Program (CUD-PIC) of Belgium with the long term objective to capacitate local entities in managing land and water resources in their jurisdiction. As part of the CUD-PIC project, the research has two objectives: (1) the establishment of a Soil Reference System (SRS) to respond to the needs of soil information for scientific bases in land use planning and agricultural development at the local level, and (2) the use of this established SRS as a pertinent tool for agricultural extension services to local farmers on soil management and crop production. The specific study locations were Miarayon, Talakag and Bendum, Malaybalay City of the Bukidnon Province. The study had four sub components : (i) the geomorphopedological identification of potentialities and constraints, (ii) the soil fertility assessment with predominant crop yields to initiate a SRS as bases for monitoring in the future, (iii) the soil fertility assessment and calibrating using a test plant in a pot experiment, and (iv) the information integration of the SRS for highland areas in Mindanao, Bukidnon. Miarayon and Bendum soils are both derived from volcanic parent materials, but their development differs by duration and rock origin. Bendum soils are derived from ultramafic rocks in the periods of Upper Cretaceous and Paleogene and Oligocene Lower Miocene while Miarayon soils originated from pyroclastic rocks of the Pliocene-Quaternary period. Dominance of total elements in soils of both areas is due to either natural causes or anthropogenic activities. The dominance of Mg in Bendum rocks is effectively due to its ultramafic parent rock materials while in Miarayon the prevalence of Ca is due to the application of chicken dung in which chicken feed formulas have Ca additives. Moreover Miarayon soils have in general higher organic matter content and more available nutrients than Bendum soils. The encroachment of cultivation on the steep slopes in both areas indicates the high demand of lands for production in the highlands. Crops in Miarayon which are intended for the market are short term, such as vegetables, with agrowing season of three to four months. Bendum crops that are for the market are perennial ones such as rubber and coffee and therefore are long term crops, and abaca which are for fiber materials. Food crop in Miarayon is corn while in Bendum is corn and sweet potato. Crop yields are indicators of soil fertility and crop management in a given prevailing climate. In Miarayon soils, there is a good relationship between the yields of potato and TOC, TN, Ca and Mg. There is also a good relationship between yields of corn and Ca and Mg. The robustness of relationships is shown in spite of few observations. A pot experiment was carried out to test the response of a plant to different soil types. Results on plant nutrient analyses had shown the transfer of elements, from parent rock materials, to soil formation and until the nutrient absorption by the test plant. Results had corroborated the findings in literature researches about which nutrients are prevalently assimilated by test plants. The methodology used in this SRS shall serve as template for instruction and research on soils in Mindanao. The integrated information is good input for extension work on soil management and crop production at local level. To achieve a good data density, the Near Infrared Reflectance Spectroscopy (NIRS) is a promising technology in soil analysis. Findings in this research work had led to the following recommendations : (i) disseminate the developed SRS methodology and framework and replicate the work in other highland areas in Mindanao, Philippines, (ii) Disseminate the established SRS in the region, (iii) study the sustainability of highland agricultural production, (iv) make follow-up studies on soil nutrient dynamics, (v) study the hydropedology of highland areas, (vi) establish soil conservation programs, and (vii) conduct environmental toxicology studies in highland vegetable areas.