{'fraction_non_alphanumeric': 0.015100671140939598, 'fraction_numerical': 0.002348993288590604, 'mean_word_length': 5.113846153846154, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Influence on Soil Structure Supports Agricultural Role for Prairies, Prairie Restoration

Do prairie restoration efforts offer more to society than mere museum pieces put on stage like a buffalo behind a fence? Or are they nothing more than the work of romantics and conservation fanatics, as some people would have us believe? As we are finding out from our research at Argonne National Laboratory, where we are investigating the effects on soil processes of the prairie restoration effort at the Fermi National Accelerator Laboratory, prairie restoration can be much more. Through the process of putting these ecosystems together again we are gaining insights into how prairie soils were formed, which in turn may help us better manage our soil resources. Specifically, we are finding that the crumb structure of soils degraded by rowcrop agricultural practices may recover more rapidly under restored prairie than under pasture. This could have important implications for agriculture in the Midwest. It suggests a way of getting prairies back into the landscape on a large scale by making them an agricultural ally and hence, integrating them into the human economy. To understand the importance of this concept, it is necessary to realize that the success of agriculture in the Midwest is based on past soil forming processes in which the interactions of biota and climate over time were constrained mainly by parent material and topography. Prairie soils owe their tilth to the quantity and quality of their organic matter, and this in turn, is a consequence of how they were formed. The buildup of organic matter in these soils was due in part to the dominance of grasses in association with herbivores that grazed on them but was also a response to the ever-present drought cycles characteristic of the prairie region. With the advent of the moldboard plow, the prairie sod could be broken. Agriculture quickly moved from forest soils onto the prairies, and farmers began to utilize the past inputs of nature. After 10,000 years of accumulated assets, human beings were cashing in on both the interest and the capital. In other words, the prairie farmer is essentially a miner, depleting soil reserves associated with rich supplies of organic matter by the practice of steadily working the soil and removing its crop year after year. To maintain the productivity of these soils the farmer has been required to replace the depleted nutrients through applications of fertilizers and other amendments, and also through the use of improved crop varieties. In many ways soils today are little more than a physical medium to support plants. And yet even that physical medium is in danger, since continued cultivation and depletion of organic matter reserves will eventually destroy the favorable crumb (aggregate) structure of prairie soils that presently allows for high production as long as chemical amendments are used. It has been estimated that 400 million acres of American farmland are currently losing at least 9 tons of soil per acre each year. Much of the loss has resulted from the expansion of production from prime croplands onto marginal sites. However, similar losses are also occurring on the deeper soils of prime croplands where soil tilth has been taken for granted simply because of the inherent nature, apparent resiliency, and seemingly unlimited quantity of these soils. As we are finding out, though, erosion shows no bias. As soil structure is broken down, both prime croplands and marginal lands are susceptible; the only difference may be the length of time that the process takes. One thing is clear: the forms of agriculture most extensively used in the Midwest create conditions that favor the breakdown rather than the buildup of soil aggregates, and that this inevitably results in increased soil erosion. Our interests in the Fermilab prairie restoration effort have been an outgrowth of our past research in the reclamation of drastically disturbed lands (see, for example, R&MN 3, p. 14). This work focused on disturbances associated with energy extraction, where we were primarily concerned with identifying the consequences of different reclamation procedures on revegetation success as measured by the condition of the belowground community. These studies, as well as more basic studies of others, have clearly demonstrated the value of integrated research centered around the soil/root interface. Past research in our laboratory has emphasized the mycorrhizal association as a means of studying this region, which is often referred to as the rhizosphere. One of the more interesting finds in rhizosphere research has been the role and importance of plant roots and mycorrhizal fungal hyphae in the binding of soil particles into stable aggregates that are relatively resistant to breakdown. We now know that the presence of physical conditions favorable for plant growth is largely dependent upon the size distribution of these soil aggregates. Yet it also appears that plants play an intimate role in the development of water-stable aggregates. Previous studies have suggested that microaggregates --that is, aggregates that are less than 0.2 mm in diameter-are held together by relatively permanent inorganic means and by persistent organic binding agents. The larger macroaggregates, however, are bound together largely by fine roots and fungal hyphae, especially the hyphae of vesicular-arbuscular mycorrhizae. In soils in which organic matter is a major binding agent, the waterstability of macroaggregates is affected by agricultural practices or other disturbances; cropping systems that result in reduced rooting density and hyphal lengths or that allow roots and hyphae to decompose without replacement can also result in a decrease in the numbers of water-stable aggregates. In contrast, microaggregates are generally not disrupted by management practices, although in cropping systems where organic matter is