In this paper we analyse, as a whole and for the period 1970-95, the outstanding factors that explain the behaviour of total productivity in the Spanish agrarian sector. In the study, two main methods of modeling had been used: those we consider like "traditional" econometric methodology and the methodology of cointegration. We accepted the influence on the productivity, with the same results that the majority of authors which obtain equal results about this subject, and about variables like, human capital, or the expenditures in agrarian research and development; but in adition we stick out the big influence of others variables like weather conditions, the change in the own structure of productivity by the sector and the public capital.