Many travelers and observers, from Millau in the 1770s to Martin de Moussy in the 1850s, described the organization of production on the Buenos Aires estancias. The operations required for cattle raising, since cattle was their main business, were roundups, aquerenciamiento, branding, sorting, dehorning, and gelding. All that is known. But the economic result of those and other operations on one particular estancia for a number of years is much harder to uncover.

Sources for a precise analysis of the estancia operations are not plentiful, and those that have survived usually relate to the rural properties of religious institutions that came under state control following the expulsion of the Jesuits in 1767 or the 1822 ecclesiastical reform. The organization of production on those estancias, however, was not necessarily the same as that of the more numerous non-ecclesiastical rural establishments. Other sources are necessary to study those non-ecclesiastical, privately owned estancias. Probate records are the best source of information on them. When a landowner died, inventories were taken, so the land, barns and sheds, farming tools, livestock, and slaves were described and evaluated. In cases where the heirs disputed the division of the estate – particularly when children were involved, there being legal provisions protecting their interests – it is possible to find income and expenditure accounts covering the period of litigation. Clemente Lopez Osornio's was one of such cases.

This chapter studies the Clemente Lopez Osornio estancia from 1785 to 1796, for which both income and expenditure accounts as well as inventories are available.