Modeling Agricultural Systems- from Fields to Regions to the Network.

Laj Ahuja is among those from a generation who devoted their career to understanding processes and mechanisms within the complex web of agricultural systems. With the emergence of computers readily accessible by agricultural researchers and breakthroughs in the development of sensors and devices brought about by an emerging digital revolution initiated more than 50 years ago, a wave of interest to characterize, in a quantitative manner, the response of vegetation to the soil, atmospheric, and biotic environment resulted in the establishment of biophysical and physiological principles and mathematical algorithms to describe vegetation responses to the environment. As significant and illuminating this period was, we are now at the verge of a rapid change of the environment under which this knowledge is put to work. Most of this quantitative descriptions have been encapsulated in crop models and linked to hydrological, nutrient cycling, and other models to describe agricultural systems, and applications have moved from field to regional/global scales. However, there is a large diversity in the implementation of quantitative knowledge in models, which could be conceptually positive except that has led to a large disparity of projected responses that we have not yet resolved. Whether we see it or not, the clock is ticking. In the next decade, there will be a mounting need to include components of agricultural system models into complex tools and products for the network, which will connect to applications we do not necessarily visualize today. This is the highly connected playing field where the global society will play for better or worse. Our community will need to develop the black boxes to be incorporated into these tools and products using the knowledge that Laj and many others have and will continue to develop. Doing so is imperative for relevance.