Link to the dissertationExcellent synopsis of that Ph.D. dissertation. It would be fun to read the entire work, but I don't know if our library can get it from the University library. It's worth a try.
However, we can learn something from the extract: They wanted only American cotton. I know that there are several species of cotton, but did not know that there was any substantial difference in the cellulose fibers to make a difference in cloth manufacture. Now I know that there was. The mill spinning and weaving machinery was set up for the American species. Buying it from other countries with different species would have required a lot of changeovers and maybe even different machinery altogether.
Although cotton is a perennial, it is grown as an annual to reduce disease penetration and it grows fast, so I surmise that mill owners were planning to promptly distribute the American seeds to areas where there was plenty of sunlight and long, warm growing seasons. If they were successful, then that is why, after an initial dip, the imports remained high when American exports were almost nil. That success would have reduced the leverage that the Conf. gov't had over European mills about recognizing the Confederacy as an independent nation - or else.
Also, do the stats tell us something about the success of the blockade runners? I thought that from the literature the blockade was only moderately successful. If true, then why the precipitous decline in exports? Wouldn't the runners have loaded their outgoing vessels with cotton to pay for the weapons, ammo, and food on the return voyage? There's a lot of story behind these stats, but where to find it?