Fertilization and agroforestry in Eucalyptplantations in Guanxi southern China

Abstract: Eucalyptus spp. has got good properties in both pulp and timber production, and is very suitable for plantations due to its fast growing abilities; which can be approved by adding nutrients. The trees in a plantation are often strictly planted in rows with an un-used spacing between the rows. This spacing could be utilized by using agroforestry and give an increased socioeconomic welfare, more revenue, and a better ecological situation. The purpose with this study is to investigate how fertilizers may affect Eucalyptus urophylla (S.T Blake.), and if agroforestry practice is possible in E. urophylla plantations. Biomass estimations were made through randomized plot samples, and nutrients analysis through leave samples. The site and the area around were also evaluated on the basis of agroforestry possibilities through interviews and literature. The results showed high standing volumes in treatment NPK-150-B (81, 3 m3 ha-1) and NPK-300-B (82, 4 m3 ha-1), and a high volume increment over the past year in treatment NPK-100 (43, 6 m3 ha-1 yr-1). The best revenue in veneer was achieved in treatment NPK- 150-B (47 318 RMB/ha) and treatment NPK-300-B (46 665 RMB/ha), and the best revenue in pulp was achieved in treatment NPK-150-B (35 123 RMB/ha) and treatment NPK-300-B (34 305 RMB/ha) The agroforestry survey showed possibilities of conducting agroforestry with Eucalyptus spp. and peanuts or cassava. The revenue in roughly numbers were 7500 RMB/ha for cassava and 1275-1530 RMB for peanuts. Nutrient analysis showed high Mn/N and Mg/N-ratios, and a decreased B/N-ratio compared to the readings done last year. Almost every N-ratio level was higher than the recommended value besides from the P/N-ratio which had a lower value. The recommended nutrient compound should be between NPK-100 and NPK-100-B Agroforestry can be cooperated into E. urophylla plantations. Preferably using cassava or peanuts as intercrop species: depending on the commodity interest of the user.