The dissertation gathers empirical evidence from several data sources in the United States and Nepal to provide a better understanding of the linkage between agriculture and the environment. The first essay examines the impact of fertilizer use on water quality using over 2.9 million pollution readings on nitrogen and phosphorus concentrations in water sites across the U.S. Findings show that a 10% increase in the use of nitrogen and phosphorus fertilizers leads to a 1.47% increase in the concentration of nitrogen and a 1.68% increase in the concentration of phosphorus, respectively. Results also indicate that there exists heterogeneity in nutrient pollution elasticity estimates across 18 water resource regions. The second essay presents empirical evidence that farmers adjust fertilizer application in response to variation in temperature and precipitation trends during the growing season in the corn belt of the United States. Estimates indicate that farmers increase nitrogen and phosphorus fertilizer use by 0.172% and 0.238% in response to moderate heat. However, farmers decrease nitrogen and phosphorus fertilizer application by 0.260% and 0.323% in response to temperature exceeding a threshold that leads to damaging effects on crop production. I further find that farmers will apply 37.41% more nitrogen fertilizers by mid-century when compared to a world without climate change, leading to deterioration of water quality. I show that the resulting nutrient runoff will increase nitrogen and phosphorus pollution by 9.72% and 12.91% under a business-as-usual scenario. The final essay studies the impact of a fertilizer subsidy program in the Hills region of Nepal that aims to enhance agricultural yields of smallholder farmers. Using data from household surveys conducted before and after the program, I apply difference-in-differences estimation to show that the subsidy, on average, leads to a 38.7% increase in fertilizer use among eligible households. However, compared to farmers with larger plot sizes, smallholder farmers experience a 12.1% decrease in the use of chemical fertilizers and a 21.2% decrease in agricultural yield after the subsidy program. I discuss how fertilizer supply shortages and varying access to the subsidy contribute to the negative impact of the subsidy program among smallholder farmers.