This soldier is from the 29th Alabama regiment, which served in the Army of Tennessee in the later stages of the war. Here's a quick history of the 29th Alabama to the timeframe of this photo, edited from the Alabama State Archives page:
This regiment was organized at Pensacola in February, 1862. The regiment remained at Pensacola till it was evacuated, suffering much from diseases that usually afflict raw troops. It then lay between Pollard and Pensacola for over a year, when it was ordered to Mobile, and there remained from July 1863 to April 1864.
The regiment then joined the Army of Tennessee at Resaca, in time to initiate the Atlanta-Dalton campaign, and was brigaded with the First, Seventeenth, and Twenty-sixth of Alabama, and Thirty-seventh of Mississippi regiments, commanded at different intervals by Col. Murphey of Montgomery, Gen. O'Neal of Lauderdale, and Gen. Shelley of Talladega.
The Twenty-ninth was engaged at the battle of Resaca with a loss of about 100 killed and wounded, out of 1100 men engaged. At New Hope the loss was very heavy, and at Peach-tree Creek the regiment was cut to pieces. Again, July 28, near Atlanta, half of the regiment was killed and wounded in the fierce and protracted assault on the enemy's line.
The most notable feature on this soldier is the frock coat, which by 1864 were probably quickly becoming non-existent in the Confederate army as a whole. Looking at the regimental history, it would make sense that the 29th Alabama soldiers would have frock coats this late in the war, being that this was the first campaign the regiment was involved in. The frock coat shown is modeled after the "Peachtree Creek" frock coat that belonged to John E. Johnson the time he died at the Battle of Peachtree Creek. Although it's a frock, like many uniforms manufactured in the Confederacy, it shows signs that material was becoming scarce. One sleeve shows that left-over scraps of material were used to fill out construction.
Another notable feature is what looks to be a bedroll and backpack combination. In fact, the "bedroll" is a light cotton fabric that was a common item with AoT soldiers. Rather for sleeping, this cotton sheet was used to create shade and shield soldiers from the sun during the hot summers in the Deep South. The roll made it handy for the soldier to quickly set up a lean-to or place over a trench.
The soldier is geared up with items typical of a soldier on the march, including a tin drum canteen, Mexican War pattern haversack, and Confederate-made accoutrements. The haversack would have been light-colored at one time, but by the time the soldier had gone on the march, it would be stained with meat grease and dirt - putrid would probably be a good term for it. The common reenactor practice of putting personal gear in a haversack would have been a bad idea in a historical context. Also, captured Federal items would be uncommon with AoT troops in 1864, since they were in a constant state of retreat and did not have the opportunity to collect Federal equipment from the field.