Mycorrhizas and tropical soil fertility

• Published in: Agriculture, ecosystems & environment Vol. 116; no. 1; pp. 72 - 84
• Main Authors: Cardoso, Irene M., Kuyper, Thomas W.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-08-2006; Elsevier Science
• Subjects: Agronomy. Soil science and plant productions; Arbuscular mycorrhizal fungi; Bacteria; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; General agroecology; General agroecology. Agricultural and farming systems. Agricultural development. Rural area planning. Landscaping; General agronomy. Plant production; Generalities. Agricultural and farming systems. Agricultural development; literature reviews; mycorrhizal fungi; plant nutrition; soil biology; Soil fertility; Soil structure; sustainable agriculture; tropical agriculture; Tropical soils; Tropical soils; Soil structure; Arbuscular mycorrhizal fungi; Soil fertility; Symbiosis; Soils; Endomycorrhiza; Interspecific association; Mycorrhiza; Interspecific relation
• ISSN: 0167-8809; 1873-2305
• DOI: 10.1016/j.agee.2006.03.011

Major factors that constrain tropical soil fertility and sustainable agriculture are low nutrient capital, moisture stress, erosion, high P fixation, high acidity with aluminium toxicity, and low soil biodiversity. The fragility of many tropical soils limits food production in annual cropping systems. Because some tropical soils under natural conditions have high biological activity, an increased use of the biological potential of these soils to counter the challenges of food production problems is proposed. Most plant species (including the major crops in the tropics) form beneficial associations with arbuscular mycorrhizal (AM) fungi. These fungi could be the most important and poorly understood resource for nutrient acquisition and plant growth in agriculture. This review treats the role of AM fungi in enhancing physical, chemical, and biological soil quality. It focuses on the roles of AM in maintenance and improvement of soil structure, the uptake of relatively immobile elements, both macronutrients (phosphorus) and micronutrients (zinc), the alleviation of aluminium and manganese toxicity, the interactions with other beneficial soil organisms (nitrogen-fixing rhizobia), and improved protection against pathogens. Mycorrhizal associations enable a better use of sparingly soluble phosphorus pools, thereby increasing the efficiency of added phosphorus fertilizer and of the large relatively immobile phosphorus pools. Mycorrhizal management through agroforestry, reduced soil disturbance or crop rotation, is often a better option than mycorrhizal inoculation, considering the problems and costs of large-scale inoculum production. Research directions that are needed to increase understanding of mycorrhizal associations in tropical cropping systems and to increase mycorrhizal benefit are indicated.