Result of supplemental studies on planting techniques for eucalyptus in some main ecological areas

Abstract

Supplemental studies on silvicultural techniques were implemented including application of fertilizers and planting densities for afforestation with eucalypts using advanced technical varieties PN10, PN46, PN47, PN3D, PN21 and PN108 in Yen Bai, Hoa Binh, Thanh Hoa, Dak Nong, Lam Dong and Kien Giang provinces, with other varieties SM16, SM23, EF24, EF39, CU91 and U6 in Ca Mau province. The silvicultural experiments comprised two treatments of fertilizer: (1) 200gram of NPK (5 - 10 - 3) + 200gram of Song Gianh organic microbial fertilizer per tree and (2) 200gram of NPK (5 - 10 - 3) + 14gram of microbial inoculum (named MF1) per tree and two treatments of planting densities (1660 trees/ha and 1110 trees/ha). After three years, the average productivity ( m3/ha/yr) of the eucalypt varieties treated with MF1 increased 18 - 41% more when compared to trees treated Song Gianh organic microbial fertilizer in Yen Bai, Hoa Binh and Thanh Hoa provinces. Average productivity did not differ significantly between the two fertilizer treatments in Dak Nong, Lam Dong, Ca Mau and Kien Giang provinces. There were significant differences in growth (diameter and height) of the eucalypt clones in the two planting density treatments in Yen Bai, Hoa Binh and Thanh Hoa two years after planting, but three years after planting, there were no significant differences between the two treatments in all experiment locations. In Yen Bai, Hoa Binh and Thanh Hoa provinces the best eucalypt clones growth volumes were obtained by applying 200gram NPK + 14 gram of MF1 per tree, with a planting density of 1660 trees/ha. Productivity levels reached 38.6 m3/ha/yr, 36.2 m3/ha/yr and 23.6 m3 /ha/yr respectively, three years after planting.