Soil quality and constraints in global rice production

Abstract

We assessed soil quality in global rice production areas with the Fertility Capability Soil Classification (FCC) system adjusted to match the harmonized world soil database, established by the Food and Agriculture Organization and the International Institute for Applied Systems Analysis. We computed the distribution of 20 soil constraints, and used these to categorize soils as 'good', 'poor', 'very poor', or 'problem soil' for rice production. These data were then combined with data of global rice distribution to determine soil quality in the main rice production systems around the world. Most rice is grown in Asia (143.4. million. ha), followed by Africa (10.5. million. ha) and the Americas (7.2. million. ha). Globally, one-third of the total rice area is grown on very poor soils, which includes 25.6. million. ha of irrigated rice land, 18.5. million. ha in rainfed lowlands, and 7.5. million. ha of upland rice. At least 8.3. million. ha of rice is grown on problem soils, including saline, alkaline/sodic, acid-sulfate, and organic soils. Asia has the largest percentage of rice on good soils (47%) whereas rice production on good soils is much less common in the Americas (28%) and accounts for only 18% in Africa. The most common soil chemical problems in rice fields are very low inherent nutrient status (35.8. million. ha), very low pH (27.1. million. ha), and high P fixation (8.1. million. ha); widespread soil physical problems especially severe in rainfed environments are very shallow soils and low water-holding capacity. The results of the analysis can be used to better target crop improvement research, plant breeding, and the dissemination of stress-specific tolerant varieties and soil management technologies. © 2014 Elsevier B.V.