Variabilidade espacial da resistência à penetração em neossolo litólico degradado

Abstract

Resistance to penetration allows evaluation of soil behavior in relation to the management practices adopted. The aim of the present study was to analyze the behavior of resistance to penetration in the dry and rainy season by spatial variability in a degraded area in Gilbués, PI, Brazil. The study was conducted in a 4-ha experimental area, belonging to Embrapa Meio Norte, in 2010/2011. Soil in the area is a Neossolo Litólico Eutrófico (Udorthent) with exposure of the C horizon. We built an irregular grid and a transect near the central part of the area, and undisturbed soil samples were taken from three depths (0.00-0.10, 0.10-0.20, and 0.20-0.30 m) at the following spacing: points numbered from 1-21 have a 30 × 30 m spacing; from 22-52 are spaced every 5 m; 52 and 53 have a 15 m spacing; and 54-79 are spaced every 30 m, for a total of 79 points. At each point, resistance to penetration was verified, and undisturbed soil samples were collected in order to quantify soil moisture for three depths (0.00-0.10, 0.10-0.20, and 0.20-0.30 m) in the dry and rainy season. In general, soil resistance to penetration showed moderate spatial dependence in the dry and rainy seasons. Moisture strongly influenced the values of penetration resistance in the rainy season.