Agricultural intensification and global environmental change

Abstract

Intensification of agricultural management has allowed substantial increases in food production on existing agricultural lands, but with major global environmental costs. This dissertation explores the global-scale possibilities and tradeoffs associated with agricultural intensification using spatial data analysis and modeling. In Chapter 2, we analyze intensification opportunities from closing yield gaps, and find that large production increases (45% to 70% for most crops) are possible. We also examine what changes to management practices may be necessary to close these yield gaps, and find these vary considerably by region and current management intensity. A sub-national, crop-specific dataset of cropland nutrient use was developed to support this analysis. Chapter 3 focuses on intensification potential in the context of climate change. We find that a moderate yield gap closure scenario could result in net yield increases across much of the globe, even in the context of circa 2050 climate change. However, the capacity for intensification to overcome climate impacts erodes considerably under uniform global temperature increases of 4-5°C. Chapter 4 examines the opportunity space for improved nitrogen (N) management. We find that a reallocation of spatial N use intensity could achieve current cereal production with ~50% less N application and ~60% less excess N. We quantify a tradeoff frontier for nitrogen use and cereal production, and discuss the potential for efficiency improvements to push the frontier forward. This dissertation highlights the importance of improving agricultural management across the globe to meet food security and environmental goals.