Evaluation of the root system of Vetiver grass (Chrysopogon zizanioides L. Roberty) using different sampling method

Abstract

Background: The objective of this work was to evaluate the root system of Vetiver grass through different methodologies. The trench method evaluated 50 images in 10 x 10 cm squares in its vertical face. The volumetric ring method uses a metallic ring with a volume of 50 cm³ (diameter ≅ 4.6 cm and height ≅ 3.0 cm) to collect samples in the same trench´s vertical face. A hand auger hole method worked with soil samples and roots removed from the surface up to 0.50 m depth. The monolith method comprises a 0.50 m wide, 0.50 m long, and 1 m deep monolith. A spatial correlation between root volume and root area was observed in the kriging maps by the volumetric ring method. Results: The root area values for both the volumetric ring method and the hand auger hole method were similar, up to 0.10 to 0.20 m. Among the analyzed variables, the root area showed the best correlation coefficient among the analyzed root methods, especially those that use the limited spatial distribution by its sampling collection, such as the volumetric ring method and the hand auger hole method (r = 0.526).Conclusions: The studied methods can be separated into two groups: those that provide more detailed information about the behavior and distribution of the root system, such as trench and monolith methods. The trench method requires turning the soil. Both require greater spatial coverage, and therefore have greater precision, and the methods that better describe the morphological characteristics of the features, such as the volumetric ring method.