The best summary of this aspect of Roman history which I have read is that of Professor Simkhovitch, in an essay published in the Political Science Quarterly of the Columbia University, 1916, under the title of ‘Rome’s Fall Reconsidered’.
Simkhovitch began with quotations from Roman writers, Pliny, Horace, Varro, Columella and others, who were fully aware of Rome’s progressive degradation at the roots. The process was a slow, progressive exhaustion of soil fertility. It was not due to lack of knowledge of good farming, for, ‘nothing could be more startling than the Roman knowledge of rational and intensive agriculture’. Nor, I think, could it be said to be due to debt, for debt did not begin its devastating career until the fertility of the soil became impoverished. Debt was not necessary as long as the farming families were able to give their time to intensive cultivation.
The spread of the degradation of the soil was centrifugal from Latium itself outwards. Varro noted abandoned fields in Latium, and two centuries later Columella, about A.D. 60, referred to all Latium as a country where the people would have died of starvation, but for their share of Rome’s imported corn. The Roman armies moved outwards from Latium demanding land; victory gave more land to the farmers; excessive demands again brought exhaustion of fertility; again the armies moved outwards.
‘Province after province was turned by Rome into a desert,’ wrote Simkhovitch, ‘for Rome’s exactions naturally compelled greater exploitation of the conquered soil and its more rapid exhaustion. Province after province was conquered by Rome to feed the growing proletariat with its corn and to enrich the prosperous with its loot. The devastation of war abroad and at home helped the process along. The only exception to the rule of spoliation and exhaustion was Egypt, because of the overflow of the Nile. For this reason Egypt played a unique role in the empire. It was the emperor’s personal possession, and neither senators nor knights could visit it without special permission, for even a small force, as Tacitus stated, might “block up the plentiful corn country and reduce all Italy to submission”.’
Latium, Campania, Sardinia, Sicily, Spain, Northern Africa, as Roman granaries, were successively reduced to exhaustion. Abandoned land in Latium and Campania turned into swamps, in Northern Africa into desert. The forest-clad hills were denuded. ‘The decline of the Roman Empire is a story of deforestation, soil exhaustion and erosion,’ wrote Mr. G. V. Jacks in The Rape of the Earth. ‘From Spain to Palestine there are no forests left on the Mediterranean littoral, the region is pronouncedly arid instead of having the mild humid character of forest-clad land, and most of its former bounteously rich top-soil is lying at the bottom of the sea.’
The same fate at a later date fell upon Asia Minor, the decline of the Eastern repeating that of the Western Empire in its soil-aspects. Sir William Ramsay, in The National Geographical Magazine of November, 1922, wrote one of those articles which almost stagger one with the super-eminence of the treatment of the soil in the story of mankind. The Province of Asia ‘in Roman times was highly populated and therefore highly cultivated … It is difficult to give by statistics any conception of the great wealth and the numerous population of Asia Minor in the Roman period. In the single province of “Asia”, to use the Roman name for the western part of the peninsula, which was the richest and most highly educated of the whole country, there were 230 cities which each struck its own special coinage, under its own name and its own magistrates, each proud of its individuality and character as a self-governing unit in the great Empire.’
Sir William carried out a careful exploration of some of the areas of high cultivation, which he regarded as the necessary basis of this wealthy province. What he found was what is found elsewhere, namely, hills denuded of forest and swept by heavy seasonal rains, and what he further found was the relics of the extensive terraced engineering by which the nourishing water had once been conserved and distributed: ‘In older time’, he wrote, ‘the numerous terraces would have detained the water from point to point up the mountain side, preventing it from ever acquiring a sufficient volume to sweep down in a destroying flood.’ Against this fertile land came invaders. First came the least destructive, the Arabs, least destructive because they observed in war the sanctity of trees. The Arabs could under the rules of war destroy the crops and produce of the enemy, but only exceptionally the tree, which conserved the soil. ‘It was left to the Crusaders under the command of German, Norman and Frankish nobles and bishops, to inaugurate the era of total destruction of a country by cutting down the trees … These broke the strength of an organized society by reducing a great part of the country from the agricultural to the nomadic stage. The supply of food diminished accordingly, and with the waning of the food-supply the population necessarily decreased.
‘A decreasing population’, continued this masterly account, ‘in its turn was unable to supply the labour necessary to maintain the old standard of water engineering, on which prosperity rested. Gradually industries languished and died in the towns as well as the agriculture in the country. The Sultans did what they could. Neither the Seljuk Turks nor the Ottoman Turks were actuated by fanaticism. They wished to preserve the old social system so far as it was consistent with the dominance of a conquering caste; but they could not maintain the education which was necessary in the old Roman system … Thus the whole basis of prosperity was wrecked, not by intention, but by steady decay. A number of causes co-operated and each cause intensified the others. Can the prosperity of this derelict land be restored?’”