Studies developed by students and teachers can guide future occupation of land acquired in 2014 by Unicamp
Research carried out within the scope of an undergraduate course and scientific initiation projects at the Geosciences Institute (IG) at Unicamp resulted in the first Detailed Pedological Map of the Argentine Farm. The map, which was delivered to those responsible for the Campus City Hall, characterizes the different types of soil present on the land and warns of precautions that must be taken when planning the occupation. More and less fertile areas were demarcated, and problems such as soil compaction and erosion were highlighted. According to Professor Francisco Ladeira, responsible for the discipline and research advisor, there are still studies to be carried out at the site.
“This map was produced from the analysis of material collected in several holes, made on the ground with equipment called Auger. We drilled the holes, collected soil samples, analyzed them and sent them to the laboratory; the data reveals physical and chemical information to us. Then, for each of these units, we made trenches at least one meter deep. In them, we carried out the entire soil description procedure. Based on these descriptions and laboratory information, we were able to make classifications and separations”, reported Ladeira.
The 1,4 million square meter plot of land, acquired by Unicamp in 2014, is adjacent to the Barão Geraldo campus and presented itself as the perfect field for the discipline taught by the professor. “The undergraduate elective course in pedological mapping consisted exactly of taking the students, going into the field, creating a mapping system and generating a soil map. As the work was intense and required many days, we always needed an area relatively close by, where students could easily stay all day and return several times”, said the teacher.
According to Ladeira, this first study of the area revealed a series of interesting conditions that required more detailed investigations. Such demands gave rise to two scientific initiation projects, the results of which are beginning to be presented. O Detailed Pedological Map of the Argentine Farm is the result of research by Taciana A. Alvarenga, a Geography student. In addition to the traditional chemical composition of the soil, the research revealed a series of degradations associated with the soil, related to the intensive use of machinery during the long time in which the area was used for sugarcane planting. “In the entire area the soil is completely compacted. To be able to drill the first 40 or 50 centimeters of soil, it took a lot of effort”, reported Ladeira.
In part of the terrain, a light yellow area on the map (Red Latosol), the soil found immediately below this compacted band has an extremely porous characteristic. “We have soil with a pore space of almost 70%. This means that one meter of soil has 70 centimeters of void. It is a natural characteristic of the soil. The construction of a building in this area will need a specific foundation, much wider because it will have to rest on a much larger area”, reported Ladeira.
On the other hand, much of the land was identified as Red Nitisol (reddish-brown area on the map below) and has significantly greater consistency, strength and hardness. “These soils were the apple of coffee's eye, it's the 'structured purple earth'”, she said.
Another point that caught the researchers' attention was the discovery of buried and decapitated soil. According to Ladeira, in the regions around the two rivers present on the land, around 50 centimeters of surrounding soil were found above the original soil. “There was an erosion process in the surrounding area. Erosion brought the soil to this area, which is lowland, and buried the soil there. We therefore have buried soil resulting from inadequate management”, explained the professor. In addition to being partially buried, this area had another important characteristic: it is a Gleisol (light blue area on the map below) land that remains flooded for much of the year. “This means that it is not suitable for any type of building. In other words, it is an area that should be used for plant recovery”, revealed Ladeira.
The map produced by student Taciana Alvarenga under the guidance of professor Francisco Ladeira
In addition to the interest of engineers and landscapers involved in a possible occupation of the land, the map serves as a historical record of the region. “In the future, we will have a picture of what the soils in this area of Unicamp were originally like,” Ladeira pointed out. According to the professor, in the current area of Unicamp, the soils are completely modified by earthmoving processes, in which land is cut and other land is buried. “They no longer have the natural characteristics that we can still observe at Fazenda Argentina.”
Another important fact, highlighted by the professor, is that the map was created with the Geographic Information System (GIS), which guarantees its georeferencing, thus allowing the future overlay of other maps. “GIS is a program that allows you to carry out various types of mapping with georeferenced information. What we did is one of them. In the future, when the road plan, or sewage plan, or any other survey is made, all maps can be superimposed”, he illustrated.
In progress
The other scientific initiation project, which is ongoing, is by student Gabriel Todaka and aims to generate a new map showing other characteristics of the terrain. “The classification we have made so far is valid for the first two meters. We have the soil types, but this map does not represent where the rock appears. What we are doing now is manual probing. We go down every 10 centimeters. The objective is to drill until you finish the soil, until you hit the hard rock, where the Auger can't go anymore. The objective is to generate another map, the Soil Thickness Map, or if you prefer, Depth of the Rock”, reported the advisor.
According to him, soil depth information is essential for planning land occupation, considering that some buildings need to be “anchored” in hard rock. “At the top, we hit the rock at 9,60 meters. In other sections, the rock is much closer to the surface. In these, the foundation, theoretically, would be much shallower. We are generating a series of information that can be used in the future”, he highlighted.