Effects of slash managenment on soil property and productivity of the Acacia auriculiformis plantation 3-year-old, rotation 4, Phu Binh, Binh Duong

Abstract

Slash management is one of technical methods in site management to improve soil fertility and plantation productivity. Rotation four of the Acacia auriculiformis plantation established at Phu Binh, Binh Duong province with three treatments as follows: (i) FL: The whole tree was harvested and then all aboveground biomass, including litter and understory, was removed. This was repeated at every rotation; (ii) FM: Only merchantable stem wood (≥3 cm in diameter with bark) was harvested; all slash and litter retained. This treatment was reapplied at every rotation; (iii) FH: as FM plus each tree received superphosphate at 20 g tree −1 P (~30 kg ha −1 P) mixed with soil at the bottom of the planting holes before planting. Three years after planting, the results showed that: There was no significant difference between treatments in pH for both soil depths (0 - 10 cm and 10 - 20 cm), with pHH2O = 4.69 ± 0.03 and pHH20 = 4.63 ± 0.04, respectively. Slash retention plus applying 30 kg P ha-1 at planting (treatment FH) improved C, P, K, Ca and Mg in soil depths (0 - 10 cm and 10 - 20 cm) by 20%, 12.3%, 12.2%, 10.4%, 14.4% and 10%, 6.1%, 9.4%, 8.3%, 14.2%, respectively that compared to slash and litter removed (treatment FL). There was also no significant difference between treatments in survival rate and this rate decreased by time and was about 90% at 3 -year-old of the plantation. There were significant differences between treatments in diameter, height and productivity. Increment of diameter, height and productivity in treatments FH were greater than that in treatment FL by 7.3%, 3.2% and 16%, respectively. Overall results demonstrate that there is an opportunity to increase and sustain productivity of Acacia auriculiformis plantations over successive rotations by slash retention after harvesting and applying P fertilizer (30 kg/ha).