Substituting Food for Cotton

One of the arguments made by Southerners opposed to secession was that the South was not ready to fight the war that would likely follow secession. They pointed out that the South could not even feed itself, much less provide the armaments for war.
Shortly after the war began, the Confederate government tried to remedy this food production problem by advocating shifting from the growing of cotton to the growing of various foods. While certainly the right thing to do for the country, such a move made life much more difficult for the railroads.
The South's railroads had been conceived to move the inland cotton production to nearby seaports for shipment to the North or England. This movement was a large surge of traffic to the ports over a few months each year. Many of the railroads carried guano, plaster and other fertilizers from the ports to the plantations during another part of the year. Both sets of traffic required only box cars, did not required connection with or sharing cars with other roads, and allowed much construction and repairing of the road during the low traffic periods.
The shipment of the new food crops produced serious problems. First, the food was mostly required in a dozen major cities and where the armies were, not at seaports. Efficient movement to the armies required that the gaps between the roads be filled (see Confederate City Rail Gaps) and cars be through loaded (i.e. loaded once at the source and unloaded once at the destination -- not as each new railroad company was encountered). Though forced to use through loading to some extent, the railroads hated it because they lost control of their cars and, if they ever returned, they were usually in very poor shape.
Second, the food was not as easy to move as the cotton. The following is quoted from the Superintendent's Report of the Savannah, Albany & Gulf Railroad on April 30, 1863:
"If you will but consider the disparity in the weight of Grain and Cotton, together with the inconvenience and labor of transporting the former, you will readily perceive the disadvantages under which we have labored. Rail Road Cars are estimated to carry but a given weight with safety, it matters not whether they are loaded with Grain, Cotton or other produce. Eight tons, or 16,000 lbs., is considered one full car load, and is all that a car is expected to carry with safety. Allowing then, that Grain is cultivated in the place of Cotton, and that one acre of ordinary good land will produce one half bale or 200 lbs. of cotton, the same land, when planted in corn will produce twelve bushels or 672 lbs. of corn, about 250 lbs. fodder and about 300 lbs. of peas, making 1,222 lbs. when planted in grain, against 200 lbs when planted in Cotton. The grain weighing six times as much as the Cotton, requires a great deal more labor and a much larger number of cars to remove it..."
The Superintendent neglected to mention that the movement of food required huge numbers of barrels and sacks that cotton did not require. In a country with a serious manpower shortage, the requirement to make these additional barrels and sacks was asking for the impossible.
Finally, the shipment of food in place of cotton was made even more difficult by the requirement to ship via railroad the goods that had previously been transported by ships and coastal shipping, now unavailable because of the blockade.
Many of these issues are visible in the table Savannah, Albany & Gulf Railroad Freight 1861 - 1863.