Fertilization of crops used as feed in the dairy industry represents up to 50% of greenhouse gases (GHG) and 30% of milk production costs. The environmental impacts raised from this activity are mainly associated with fertilizer manufacturing. Proper fertilizer selection for feed production is an alternative to improve the dairy industry's sustainability. This study proposes a strategy to mitigate the environmental and economic impacts in the dairy industry via optimization of crop fertilizer blends by using a parametric linear programming model. Individual fertilizers' environmental impacts and costs were evaluated through the ecoinvent database v. 3.3. and governmental information, respectively. The effect of the optimized fertilizer blends used in each crop on the life cycle of a dairy supply chain in the Mexican Bajio region was evaluated. Three analysis tiers were considered: livestock feed production, dairy cattle diet, and dairy farming system. The optimization results of fertilizer blends revealed an opposite behavior between the environmental and cost indicators for all crops; a reduction of 1% in the environmental impacts could increase the fertilization cost by 5.5%. In addition, the results indicated that with the use of optimized fertilizer blends, a reduction of GHG emissions up to 22 g CO2 eq kg−1 of milk could be achieved compared with those conventional ones. Focused on the Mexican Bajio region, this contribution implies up to 2.2% of Mexico's commitments in the COP21 agreement for the livestock sector. Our results show that potential savings in costs of 29.6 MUSD y−1 could be reached when the most economical fertilizer blends are used in the optimization. This work presents an alternative to improve the sustainability in the dairy sector, which could be easily implemented for the agricultural producers, especially in countries such as Mexico, where government budgets dedicated to mitigating environmental impacts are limited.