The counterclaim shall set forth the value of the land apart from the improvements, and the nature and value of the improvements apart from the land and the amount of said taxes and assessments so paid, and the date of payment. Issues shall be joined and tried as in other actions, and the value of the land and the amount of said taxes and assessments apart from the improvements, and the value of the improvements apart from the land must be specifically found by the verdict of the jury, report of the referee, or findings of the court as the case may be.