Dynamics of Plant Nutrients, Utilization and Uptake, and Soil Microbial Community in Crops Under Ambient and Elevated Carbon Dioxide

Abstract

In natural settings such as under field conditions, the plant-available soil nutrients in conjunction with other environmental factors such as solar radiation, temperature, precipitation, and atmospheric carbon dioxide (CO2) concentration determine crop adaptation and productivity. Therefore, crop success depends on the intricate balance among these multiple environmental factors. Plant nutrients are the major constraint for crop productivity worldwide because it must be supplied externally to achieve maximum production. The depleting natural resources of mineral nutrients in addition to the global changes in climate caused by the emission of green house gases including CO2 are among the major concerns of crop production and food security. Moreover, crop demand for nutrients has been increased due to use of modern cultivars and improved irrigation facilities and is expected to be even higher under elevated CO2. Soil microorganisms including arbuscular mycorrhizal (AM) fungi partly enhance crop nutrient availability and acquisition in many soil types through symbiotic or non-symbiotic relationships. Atmospheric CO2 concentration is expected to be doubled from its current level of 400 μmol mol−1 at the end of this twenty-first century. Elevated CO2 increases growth and yield of many crops upon which humans depend for food and clothing. However, plant nutrient availability exerts major control on the degree of stimulation by elevated CO2 on crop growth and yield. One of the objectives of this chapter is to provide a summary of crop responses to plant nutrients mainly nitrogen, phosphorus, and potassium and underline in part the dynamics of soil microorganisms including AM fungi in the nutrient accessibility under current and elevated CO2 concentrations. Regardless of the CO2 levels, nutrient deficiencies negatively affect crop photosynthesis, growth and biomass production, yield, and yield quality. Elevated CO2 tends to compensate, at least partly, for the losses caused by nutrient deficiency especially by increasing plant growth due to improved efficiency of nutrient acquisition and utilization. However, crop species, deficiency of the specific nutrient, and its severity greatly influence the nutrient efficiency in crop plants. The critical tissue nutrient concentration required to achieve 90 % of maximum productivity of some plant nutrients is likely to be higher at elevated CO2. Another objective of this chapter is to discuss the influence of crop species, soil nutrient status, and elevated CO2 on the dynamics of nutrient uptake and utilization efficiency and resultant tissue nutrient concentration. Future research methods utilizing the combined effect of plant nutrient status and elevated CO2 on crops will improve our understanding of the complex relationships among various plant processes leading to efficient use of nutrient under field conditions.