Northern states had well-cultivated and productive land, but southern states had tremendous labor resources in the form of slavery. Southern states also held immense tracts of land, but they did not have the same productivity value of northern states because they were not as densely populated or cultivated. In order to protect its own best interests, states supported the means of taxation that required them to pay the least taxes.
Northern states argued that taxation should be based on the number of laborers in each state, including slaves, because only through labor is land turned into economic value. Southern states countered this argument by stating slaves were property, and unless Northern states agreed to count their horses and cows for the taxation purposes, slaves could not be fairly counted. Aside from this obviously derogatory statement about the nature of slavery, the southern point of view clearly demonstrates that they would count slaves if it was to their advantage for representation purposes, but not when it would take a large chunk out of their profit from slavery.
Southern states strongly argued that it was the value of property that determined the potential wealth of a state, because property was more permanent than laborers. The land argument put the burden of taxation on the Northerners, who obviously resented that they would have to shoulder the burden of debt while the lucrative southern industry of cash crops would continuously prosper. Congress retained the power to determine the value of land, and therefore determine the relative contribution of taxes from each state. However, without the power to enforce the collection of taxes, which was a sole power of the state, Congressional finances became a large and problematic issue under the Articles of Confederation.