This paper presents data collected from 38 integrated crop-livestock farming systems in Ille-et-Vilaine, Brittany, France, during face-to-face surveys. Surveys were conducted using a quantitative questionnaire to collect information about farm management practices that affect nitrogen (N) inputs, N outputs, and internal N flows. The data were used to develop new indicators of N efficiency (SyNE, System N Efficiency) and of N balance (SyNB, System N Balance), as described in "SyNE: An improved indicator to assess nitrogen efficiency of farming systems" [1]. Also, the data were used to test an online tool developed to calculate these indicators, as described in "A free online tool to calculate three nitrogen-related indicators for farming systems" [2]. The data are provided with this article.