Preparo do solo no estabelecimento inicial da nogueira-pecã carya iIlinoinensis (Wangenh.) K. Koch em argissolo vermelho no Rio Grande do Sul

Abstract

Soil structure is defined by its physical condition, expressed by the size, shape and arrangement of solid particles and the pores are concerned. With the use and soil management in pecan orchards, soil structure is modified by soil tillage, growth and root development during cultivation. The objective of this study was to evaluate the effect of soil tillage in the growth of pecan seedlings at different times of development and, through physical-hydric soil parameters define the conditions that may favor better root and aerial plant growth. The study was conducted at FEPAGRO Forests, located in Santa Maria, Rio Grande do Sul. Soil tillage systems were: T1-Planting with small pit 0,20 x 0,60 m (PCP); T2-Subsoiler plus disking and small pit (SG); T3-Rotary hoe and small pit (ER) T4-Planting with a large pit 0,40 x 0,60 m (PCG). The experimental design was a randomized block design with 5 replications. Soil samples with preserved structure were collected in layers 0,00 to 0,10; 0,10 to .20; 0,20 to 0,40; and 0,40 to 0,60 m, to determine the bulk density (Ds), pore size distribution, air permeability (Ka), saturated hydraulic conductivity (Ksat) and the water retention curve. The soil penetration resistance (Rp) was determined in three distances around the four quadrants of pecan trees. The walnut crop growth was evaluated through the high and stem diameter at different times, the shoot dry mass, density and root length at 24 months. The planting in small pit tillage of pecan reduced root growth and vegetative growth. The soil tillage in large pit provided the highest growth in height, diameter and length of roots after 21 months to 24 months of evaluation. Subsoiler plus disking favored the retention and water availability in soil at depth between 0,40 and 0,60 m, but showed no significant difference in the results on the survival rate, root growth and vegetative pecan growth.