南臺灣著名熟番部落鳳山八社之一的下淡水社，在康熙六十年(1721)二月立下的一份合約（簡稱「下淡水社文書」），因可詮釋歷史發展之轉折關鍵，而特別受到了研究者的青睞。邵式伯(John R. Shepherd)以下淡水社文書明確記載熟番每年從漢佃手中收取接近於漢人大租的租額，而視之為清代「番大租」的起源。柯志明批評邵式伯的見解而主張：清朝官員介入頓物莊的租佃關係，排除漢墾戶何周王的權利，要求漢佃依據田土面積繳納高額大租給番社，主要是因為地方官有徵足稅額的壓力，必須確保當時作為稅收主體的熟番部落有充分的租穀得以繳稅。本文則認為：下淡水社文書傳達的社會訊息，其實很接近康熙五十年代縣級方志所要表達的社會圖像。當時的社會裡，佃農因在鄉村地區投入工本改良土地，逐漸強化土地和地域社會的控制，他們甚至擁有業主無法干涉、可以獨立買賣和繼承的田底權。業主的權勢則相對退化，成為僅擁有固定租額的收租權。儘管官府和法律批評這樣的趨勢和現象，但田底卻逐漸成為民間社會的慣習。我們也可以瞭解，即使佃農們一開始沒有從官府手中獲得墾照，業主也無法隨意撤換他們。他們可以長期控制土地、定居，並投入土地的改良和經營。

The 1721 contract, drawn up by the aboriginal heads of the Xiadanshui she 下淡水社, was significant in that it illustrates a turning point in the early history of Qing Taiwan. John R. Shepherd cites this document as signifying the beginning of the collection of large-rent by aboriginals, due to the amount recorded in the contract being close to the average collected by Han proprietors of nearby land. Ka Chih-ming 柯志明, on the contrary, rejects this point and asserts that it was the local magistrate who, being more concerned with bureaucratic obligations, made the decision to exclude the Han cultivating household (kenhu 墾戶) from the land-tenure system and deliberately require the Han tenants to pay a higher rate of large-rent to the aborigines directly. The magistrate did so because he wanted to secure the income of the aborigines, so that aboriginal taxpayers would not avoid paying the majority of their taxes. In other words, the magistrate’s chief concern was to avoid failing in his duties. This paper finds that the contract and the local gazetteers of the 1710s reveal very similar social pictures. By providing their own labor and capital, the Han tenants not only turned wasteland into paddy fields, but through the process of land development also strengthened their control over the land and society. As a result, their rights to the land evolved into a partial right commonly called tiandi 田底, the subsoil land right. Such a right was tradable, inheritable, and immune from any interference by the proprietors of the land. By contrast, the rights of the proprietors dwindled to the right to collect rent at a fixed rate. The local officials were aware of such a tendency, but nevertheless the subsoil land rights held by the Han tenants gradually matured and became a common land tenure practice. It is not difficult to imagine how their influence gradually solidified and grew stronger as, over the generations that followed, they continued to settle the region, and invest in working and improving the land.