# Root System and Its Relations with Soil Physical and Chemical Attributes in Orange Culture
## 2 Materials and Methods  
### Description of the Study Area and Experimental Design  
The experiment was carried out in areas of the company Fischer Citrosuco and partner companies, in the region of Aware, state of Sao Paulo, Brazil, with geographical coordinates of \"23'05'56'', 48'55'33\" W\". In the region, according to the Koppen climate classification, the site is located in a region of subtropical climate (Cfa), with a humid winter (Cwa) and annual precipitation index around 1200 mm [13].  
Soil and root collections were carried out in farms located in the municipalities of Pratania, Iaras and Santa Cruz do Rio Pardo, in which they presented soil of the type Argissolo Vermelho-Amarelo, and in the municipalities of Itai and Taquarituba where they presented soil classified as Latossolo Vermelho. The soils in the experimental areas were classified according to the Brazilian Soil Classification System [14] or Utisol and Oxisol, according to the soil taxonomy system [15].  
In the agricultural areas chosen for the experiment there are orchards with Valencia type oranges grafted with Swingle, with spacing of 7.0 m between lines and 3.0 m between plants, with grass of the _Brachiaria decumbens_ type planted between the rows.  
Planting was carried out between June 11 and 16, 2007, during which we applied a dose of 4 g of P\({}_{2}\)O\({}_{5}\), 12 g of N, and 24 g of K\({}_{2}\)O. Previously the area was exploited as an extensive grazing area. The experiment was carried out in June 2010, after about three years of planting, corresponding to the third year of orchard installation. During this period, a 120 hp, 4 \(\times\) 2 traction tractor (6740 kg) was driven between the lines five times a year applying insecticides, herbicides, fertilizers and also for clearing the land.  
The experimental areas cultivated with the orange crop had three tillage systems: minimum tillage, subsoiler tillage and soil tillage using triple tillage implement. Minimum tillage employed a plow with 18 disks measuring 34 inches each in total area, followed by planting row chiseling using 100 to 120 hp tractors (MF 292 and MF 297). The soil tillage us ing subsoilers reached 0.70 m in depth, with an Ast-Matic 550 implement. In addition, there was demarcation of the planting row with a tractor equipped with a global positioning system and the same operations performed in minimum tillage.  
In the tillage system using the triple tillage implement, the operations mentioned for minimum tillage were carried out, plus use of the implement developed by the Fisher Citrosuco group using a 180 hp tractor (MF 680), which simultaneously carried out the operations of planting, furrow fertilization, line subsoiling and patch construction in the planting row. The implement used has three mouldboard-shaped subsoilers with holes that allow fertilizer output. There is a set of hoses that conduct the fertilizers from the reservoir of these holes to different depths during passage in the planting row (Figure 1).  
The sequence of agricultural operations realized in each system of soil tillage can be observed in Table 1.