ASSESSMENT OF THE STRUCTURAL PROPERTIES OF AN ANDISOL UNDER DIFFERENT METHODS AND DEPTHS OF STUBBLE INCORPORATION INTO THE SOIL

Abstract

The objective of this research was to determine the changes in soil structural properties of an Andisol as a result of the incorporation of oat (Avena sativa) stubble between post-harvest and presowing, using three types of mechanical equipment. The following pieces of equipment were used for stubble incorporation: tines (P), discs (D), and alternating shanks and double discs (PD). The experimental unit in each treatment was 1 ha, while a control plot (C) of 0.25 ha (no stubble incorporation) was also included. For the evaluation of the treatments, soil samples were collected with cylinders before and after stubble incorporation. Treatments P, D and PD showed positive changes in air capacity (AC) and air conductivity 60 hPa (Kl) at a depth of 5-10 cm, with respect to values observed in the control plot (C). Only plant available water content (PAWC) was higher in C. Stubble incorporation had negative effects at a depth of 20-25 cm. The coefficient of linear extensibility (COLE) decreased in the treatments with stubble addition, while AC increased in all the treatments. It was concluded that, during the short period before the evaluation, the incorporation method did not produce significant changes, but some soil structural properties were improved.