Rhizosphere Processes and Management for Improving Nutrient Use Efficiency and Crop Productivity

Rhizosphere dynamics have been widely investigated since the beginning of last century but little attention has been paid to process-based rhizosphere management at an agroecosystem level. High inputs, high outputs, low nutrient use efficiency, and increasing environmental pressure are typical characteristics of intensive farming systems in China. Achievement of high nutrient use efficiency and high crop productivity together is a major challenge for sustainability of Chinese intensive agriculture. Over the last 20 years crop yield has not increased proportionately with increasing fertilizer inputs, leading to low nutrient use efficiency and increasing environmental risk. Traditional nutrient management is highly dependent on the external fertilizer inputs but ignores exploiting the intrinsic biological potential of rhizosphere processes for efficient mobilization and acquisition of soil nutrients by crops. Several successful case studies on rhizosphere processes and management have been summarized in this chapter, and the results demonstrate that rhizosphere management provides a unique opportunity to harmonize crop productivity, nutrient efficiency, and environmental impact. Rhizosphere management strategies emphasize maximizing the efficiency of root and rhizosphere processes in nutrient acquisition and use by crops rather than solely depending on excessive application of chemical fertilizers. The strategies mainly include manipulating root system, rhizosphere acidification, carboxylate exudation, microbial associations with plants, rhizosphere interactions in terms of intercropping and rotation, localized application of nutrients, use of efficient crop genotypes, and synchronizing rhizosphere nutrient supply with crop demands. Rhizosphere management has been proved to be an effective approach to increasing nutrient use efficiency and crop productivity for sustainable agricultural production.