Metasurfaces are artificial materials composed of sub-wavelength building blocks whose size, shape, periodicity, and composition are tailored to achieve arbitrary control of their interactions with light and engineer their optical response. Their phase discontinuities or resonances are critically dependent upon the local dielectric or refractive index environment, thus making metasurfaces excellent candidates as refractive index sensors. A unique application of such passive metasurface refractive index sensors is in agricultural and environmental sensing to conduct in-situ measurements of crop health conditions with high spatiotemporal resolution, thus maximizing crop yield. This application necessitates compact, low-cost, biocompatible metasurface sensors that can be distributed en-masse. In this thesis, we investigate low-cost, scalable metasurface fabrication techniques that combine top-down nanoimprint lithography (NIL) with bottom-up assembly of solution-processable metallic and dielectric nanocrystals (NCs) to realize low-cost, large numbers of biodegradable and biocompatible optical metasurface based refractive index sensors. We demonstrate that multiple metasurface geometries can be fabricated from a single NIL master template, offering flexibility and scalability in manufacturing, and by exploiting NC assembly different from physical deposition of materials, achieve fabricated structures with critical dimensions of ~20 nm that are desirably smaller than the lithographically-defined template dimensions. To enable real-world deployment of these refractive index sensors, we explore sensor interrogation techniques using conventional RGB and hyperspectral imaging, and establish a complete imaging pipeline capable of identifying metasurfaces and tracking their resonant behavior in outdoor agricultural settings. We also introduce a novel monochromatic, state-of-polarization (SOP)-based sensing modality/interrogation and, experimentally and through simulations, demonstrate its operation and its advantages through the example of humidity sensing, eliminating the need for broadband illumination and monitoring. Together, these contributions aim to validate the real-world feasibility of metasurface-based refractive index sensors and lay the groundwork for their quantitative performance evaluation in distributed environmental sensing applications.