Productivity of Eucalyptus camaldulensis affected by rate and placement oftwo phosphorus fertilizers to a Brazilian Oxisol

This work evaluated the response of Eucalyptus camaldulensis to different s ources, rates and placement of phosphate fertilizers. The trial was install ed on an Oxisol in Brazil in the northwest of Minas Gerais State. Two sourc es were tested: rock phosphate (RP) from Araxa and single superphosphate (S SF) in rates equivalent to 100, 200 and 400 kg ha(-1) P2O5, applied in band s (1.2 m of width in the soil surface) or in furrows (0.2 m deep in the tre e rows). As additional treatments we tested a combination of RP (96 kg ha(- 1) P2O5), in furrows, or in bands, or broadcast (all the surface soil), wit h SSF (54 kg ha(-1) P2O5) placed in the planting holes. The effects of the treatments were evaluated 9.5 years after planting by assessing the biomass and nutrient contents in the tree shoots, and litter. Fertilizer applicati on increased tree stern volume and overall biomass compared to control plot s (no-phosphate fertilizer), The RP and SSF produced better results when th ey were applied in furrows due to enhanced absorption of P by the plants th at resulted in increased dry matter production. The placement in furrows al so resulted in highest plant recovery rate of the P fertilizers applied. Th e combination of SSF placed in the planting hole, with RP, applied in the f urrow, produced the highest stem volume and shoot dry matter, emphasizing t he influence of the initial fertilization on the final yield of the stand. The results showed that, considering the experiment period, the combined us e of low and high solubility forms of P fertilizer in a localized placement may attend the high initial demand of P by the seedlings and provide a lon g term P availability to allow high productivity. (C) 2000 Elsevier Science B.V. All rights reserved.