《明史·志·卷五十三》
到宣德年问，原垦荒的田地永远不计亩收税以及低洼、盐碱不产粮食的田地，都核实纳入交纳赋税的数额中，田亩之数比过去更多。
至宣德间，垦荒田永不起科及洿下斥卤无粮者，皆核入赋额，数溢于旧。
In the Xuande years, the originally cultivated wasteland would no longer be exempted from taxation, and the low-lying saline-alkali land that did not produce any grains was also surveyed and included in the tax base, and the number of land and mu was much larger than before.