Add to ORKGSome little-known and essential chains for agriculture are inputs related to agricultural activities. Regarding natural gas corresponds to a different market than anhydrous ammonia, the overall objective of this investigation was to analyze the link between natural gas and anhydrous ammonia prices, it is as liquid fertilizer for direct application in agriculture sector as well as the impact that may exist in these markets by the existence of a state monopoly. Using a dummy variable regression is concluded that the nominal price of ammonia to the farmer who buys a unit asymmetric with respect to the nominal price of natural gas with two-month delay that sell Pemex Petrochemicals, which guides the mexican State if applicable agricultural poli...