Fertilising Eucalypt Plantations on the Brazilian Savannah Soils

SYNOPSIS Eucalypt plantations have been the main source of wood for pulp and charcoal in Minas Gerais State, Brazil. A considerable part of these plantations is located in the savannah area where soil fertility is low and fertiliser application is necessary to increase forest productivity. Initially, eucalypt fertilisation consisted of applying 100–150g of a NPK mixture (10–28-6) per plant regardless of soil type, species or time of planting. Later, field trials on fertilisation indicated that further growth increase could be obtained if rock phosphate was broadcasted (at about 1,0 t/ha) or banded (at about 0,5 t/ha) in addition to the NPK mixture. The amount of K-fertiliser needed depended on soil K level and site quality and could be as high as 200 kg of K2O/ha. Eucalypt response to N is restricted to sandy soils with low (less than 1,5%) levels of organic matter. In most cases, S application increased eucalypt yield by more than 50%. Species such as Eucalyptus camaldulensis and E. citriodora, when planted in sites with severe water deficit (more than four months of drought), are very sensitive to B deficiency and application of 1,0-1,5 g of B/plant reduced dieback and increased volume growth up to 32%. Phosphate rock proved to be a good Ca source. Based on experimental results, a software program to prepare a nutrient balance and recommend eucalypt fertilisation according to soil fertility level and site productivity classes was developed.