What Do We Need to Know about Crop Production to Feed Nine Billion Humans?.

“Realistic” crop scientists are somewhat to intensively daunted by the monumental task that lies ahead of them, their colleagues, and the next generation of crop scientists to meet the food demands of 9 billion people.   Yields of the major food crops are much higher now than 20 or 40 years ago, but simple extension of the current trajectory of crop yields will not achieve sufficient food crop production from existing cropland area to meet the expected demand from human population and income growth.  Too little is known about the scientific reasons for crop yield differentials between the maximum yields that have been recorded for specific cereal crops versus the much lower yield levels that routinely occur even on our so-called “productive” soils.  Although the present and future role of biotechnology in crop improvement is acknowledged, the fundamentals of crop yield improvements necessarily involve attaining a much expanded, and research driven, knowledge basis on how to achieve sustainable crop yield gains.  The fundamentals we need to know about each grain crop species to achieve sufficient intensification in crop yield gains include (a) a much more robust understanding of the key physiological factors at critical development stages limiting yields (particularly those less than half of record yields) in diverse soil and ecological regions, (b) intensive knowledge about the grain yield and harvest index impacts of the fundamental individual and interacting crop management factors (like plant density, fertilization, tillage, rotation, etc.) that vary within and among regions even when similar elite cultivars are seeded, (c)  the critical factors involved in improving plant resiliency to abiotic and biotic plant stresses (e.g. drought, temperature, pests), and (e) the simultaneous improvements in soil, water and air quality that can be achieved as knowledge-driven management inputs are judiciously applied at progressively higher yield levels over time.