The Oxyrhynchite estate of the Apion family is the most richly documented of the Byzantine period, and the pronoetes accounts associated with the estate shed light on its low-level functioning. Each records the target receipts and actual expenditures in both grain and money for subdivisions of the estate called prostasiai. Estimates of the number of prostasiai are difficult to come by: based on the entries in P.Oxy. 16.2032 (540/1 CE), an account of payments to the estate, Hardy (1931, 82) counted contributions from pronoetai for 20 prostasiai, which Ruffini (2008, 107) revised down to 16, the minimum possible number of prostasiai administered by the Apion estate in 540/1. In this paper I propose a new method of determining the number of prostasiai on the Apion estate for two dates in the sixth century separated by 45 years. This information can help to explain the increase in the collections made by the estate as a whole over that period as evidenced by P.Oxy. 16.1918.v and 18.2196.v (cf. Hickey 2008).
The method of determining the number of prostasiai is essentially to divide the total value of the collections from P.Oxy. 16.1918.v (542 CE) and 18.2196.v (586/7 CE), high-level accounts for the entire Oxyrhynchite estate, by the total value of a paradigmatic prostasia. This makes it necessary to establish the value of the paradigmatic prostasia. Because the ratio of collections in wheat to those in gold is not consistent across the accounts, it is difficult to make apples-to-apples comparisons between them to evaluate the consistency of collections across space and time. Using the rates of adaeratio (i.e., the practice of paying grain obligations in money), it is possible to determine the value of the entire collection, cash and wheat combined, of each pronoetes account. Applying the rate of adaeration from P.Oxy. 16.1909 (late 6th) to the wheat collections and adding this figure to the money collections yields very consistent results. Five of the six pronoetes accounts for which money and wheat collections are available, dating from the 550s to the 590s, have total values of between 750 and 830 solidi, with an average of just under 800 solidi. The remarkable consistency of these figures allows us to peg a pronoetes’ target collection from the paradigmatic prostasia at about 800 solidi per year. A total value figure can be similarly determined for the aggregate target collections in P.Oxy. 18.2196.v, yielding a value of just over 29,400 solidi. Dividing this total by the paradigmatic average of 800 gives a figure of about 37 prostasiai in 586/7. The same operation on P.Oxy. 16.1918.v gives a figure of about 18 prostasiai in 542 CE—more than a doubling in about 45 years.
Hickey (2008, 99) has laid out several possible explanations for the significant increase in the money collections over the 45 years between P.Oxy. 16.1918.v and P.Oxy. 18.2196.v: investment and increased productivity, the acquisition of more land, expansion of fiscal obligations (i.e., the number of people whose taxes the Apions collected), or increases in tax levels. The prostasiai numbers above now narrow the possibilities significantly. The stability of their overall value indicates that production levels were relatively uniform and remained consistent over the course of more than thirty years, thus arguing against increased productivity. It also militates against tax increases as an explanation, since that would cause the per prostasia collections to rise with the aggregate. Land acquisition and the expansion of fiscal obligations, then, are the likeliest explanations for the rise in the Apion estate’s collections between 540/1 and 586/7 CE.
 There are no grain lemmata in P.Oxy. 16.1918.v, so the total value is equal to the money lemmata. Even if an amount of grain proportional to that in P.Oxy. 18.2196.v were assumed, growth would still be on in the order of 30%. The significance of this issue is discussed further in the paper.
Culture and Society in Greek, Roman, and Byzantine Egypt