Please keep in mind that this is just an idea that I had. I want to see if there is any research supporting or refuting it. Feel free to expand upon/correct my thinking.
I recently was doing some thinking about how early cultures had developed from nomadic to agrarian and so forth. One common question that people come across in early history is the question of why there were not any large scale civilizations in the fashion of the Mesopotamians or the Maya that developed in the northern part of North America. Afterall, the region was by no means empty, but it seemed that the people had trouble developing the adequate agriculture necessary to support a large scale civilization. This is confounding, especially since much of North America is now very accessible as farmland. Then I had an idea. What if the introduction of earthworms in the 17th and 18th centuries led to the ability of the region to support agriculture.
Reports from early European colonies state that New England in particular had very poor soil for growing, and this seemed to be the case farther west into the Ohio country. In inland forests, there was a thick layer of decomposing plant matter upon the forest floor that allowed for the growth of many small ferns, but prevented suitable crops from growing. The introduction of earthworms changed that. Worms sped up the decomposition of dead plant matter and mixed the nutrient content of the soil throughout several layers of soil. Small plants such as ferns could not grow. The worms had effectively tilled the soil, and had eliminated the competition that may have been had between crops and other small plants. Was this a contributor to the increase in the agricultural capacity of these areas?
I would appreciate some help in researching this. It seems to make sense to me, but I want the opinions of some more informed than I. Also, if there are any articles concerning this, it would be great if you posted links to them. Thank you.
The only book I know of offhand to discuss the subject of New England agriculture is Changes in the Land, but I hesitate to recommend such a flawed book for further reading. Hopefully one of the New England experts can pop in with a better reference.
In any case, New England's soil is notoriously acidic, but it's not entirely unsuitable for crops. Agriculture had existed North of Mesoamerica for thousands of years prior to European contact and the natives had developed a number of techniques to deal with the issues of poor soil. For one, they were masters of site selection. The worst soils and bogs of New England were generally disregarded by Natives simply because they weren't idiots. Their livelihoods depending on being able to grow crops, so they learned what areas were and were not suitable for agriculture. Secondly, New England natives often used a technique called slash-and-burn to prepare fields for their crops. This has the benefit of depositing a layer of nutritious topsoil for crops to feed on in areas with poor subsoils. For acidic soils (like those of New England), the wood ash also helps to raise the pH of the subsoil to more manageable values.
However, I'm afraid the biggest issue is that Earthworms were already native to the Americas by the time Europeans arrived. There are well over a hundred described species in the literature. One example is Diplocardia mississippiensis, an earthworm native to Florida and the South. Invasive European earthworms are a major problem in the Americas today, but their American cousins did exist.
Reports from early European colonies state that New England in particular had very poor soil for growing, and this seemed to be the case farther west into the Ohio country.
Part of this perception was caused by importing European agricultural practices onto land that was poorly suited to those practices. You should definitely check out Cronon's Changes in the Land, particularly chapters 6 and 7, which discuss how differences in Native and European forestry and farming practices influenced the landscape, and soil quality, of New England. Unfortunately, I don't have my copy handle to give you detailed summary of those chapters.
Instead, let's look at other reports concerning the productivity of Native agriculture in eastern North America. They idea that there wasn't extensive and highly productive agriculture going on at the time of contact and later isn't accurate - at least not for significant portions of the region (we can discuss the exceptions later).
In the 1535, Cartier reported the area around Hochelaga (now Montreal) was covered in agricultural fields full of corn. While he doesn't give specific numbers, based on later Jesuit reports among the related Wendat (Huron), we'd expect a minimum of 60 acres under cultivation (which was average for Wendat villages). A few years later, when de Soto's men were marching through Coosa, the largest of the late Mississippian polities, they encountered several large towns and villages along the rivers of the southern Applachians, with cultivated fields stretching between them. In the late 1580s, shortly after the founding of Roanoke, Thomas Hariot explored mainland Carolina for the British and described the productive of local fields:
The planted ground, compared with an English acre of forty rods in length and four in breadth, yields at least two hundred London bushels of corn, beans, and peas, in addition to the crop of macocqtver [squash], melden [goosefoot / lamb's quarter], and sunflowers. In England we think it a large crop if an acre gives forty bushels of wheat.
In the summer of 1687, Denonville raided four Seneca villages and destroyed their crops. In his writings, Denonville described the productivity of these fields as a "vast abundance" (or a "great abundance" elsewhere). It took his forces, nearly 2000 men, 10 days to destroy these fields. In total, Denonville estimates that he and his men had destroyed 400,000 minots of corn (sometimes you'll see this as 1.2 million bushels, such as in Barbara Alice Mann's Iroquoian Women, but this seems to be result of confusion over conversion rates between minots, French bushels, and Imperial bushels. My understanding of the situation at the time is that, roughly speaking 1 Imperial bushel = 1 minot = 3 French bushels). In addition to destroying the crops in the field, Denonville also destroyed the great granary at Ganondagan, the Seneca capital, which held the nation's communal reserves. Despite this destruction, less than a month after after Denonville's raid, one of the men under his command reported that the Seneca had recovered their stores thanks to contributions pouring in from the other four nations of the Haudenosaunee (the Iroquois Confederacy).
In 1779, George Washington ordered several devastating sweeps through Haudenosaunee lands to destroy their crops during the American Revolution. The most famous of which was the Sullivan Campaign. In stretch of the campaign, 60,000 bushels of corn and 2-3,000 bushels of beans were destroyed; in another, conducted against the Cayuga 1,500 fruit trees, 160,000 bushels of corn, and an unspecified number of other crops were destroyed. This was all after Colonel Van Schiak had already attacked the Haudenosaunee earlier that year (though I don't know if specific numbers from his campaign are available).
Looking to the Ohio country, in 1781, a campaign against the Lenape in Ohio was ordered. Under the command of Colonel Brodhead, they spent three days destroying an estimated $30,000 dollars worth of corn in the vicinity of Coshocton, the Lenape capital. About a decade later, in the fall of 1790, General Harmar led a campaign against the Miami. Around Kekionga (now Fort Wayne, Indiana), the Miami capital, he described "vast fields of corn in almost every direction." His men spent three days burning "everything that could be of use" in Kekionga and five neighboring villages. In total, Harmar's men reported the destruction of 20,000 bushels of corn and an unspecified amount of "other vegetables."