I also discovered that the grain offerings for the Levites had not been provided, and that as a result the Levites and the singers who performed this work had all gone off to their fields.

On that day men were appointed over the storerooms for the contributions, first fruits, and tithes, to gather into them from ¹  the fields of the cities the portions prescribed by the law for the priests and the Levites, for the people of Judah ²  took delight in the priests and Levites who were ministering. ³ 

So in the days of Zerubbabel and in the days of Nehemiah, all Israel was contributing the portions for the singers and gatekeepers, according to the daily need. ¹  They also set aside ²  the portion for the Levites, and the Levites set aside the portion for the descendants of Aaron.