A method and apparatus for treating a cellulosic feedstock, such as for subsequent ethanol production, are disclosed. The method comprises determining an initial moisture content of the cellulosic feedstock and adding an amount of moisture to the cellulosic feedstock to obtain a predetermined moisture content of the cellulosic feedstock, wherein the cellulosic feedstock may subsequently be subjected to hydrolysis. The apparatus comprises a moisture sensor that provides an initial moisture content reading of the cellulosic feedstock, and a weight sensor providing the weight of the cellulosic feedstock. A processor is configured to determine an amount of moisture to be added to the cellulosic feedstock based on the weight and the initial moisture content of the cellulosic feedstock to obtain treated cellulosic feedstock having a predetermined moisture content.