Nutrient exportation with the harvested biomass in a short rotation coppice plantation with willows (Salix spp.).

LUQUEZ VIRGINIA M.C.; DOFFO, GUILLERMO; ACHINELLI, FABIO

Simposio; VII IUFRO International Poplar Symposium; 2018

INTA

The production of biomass for energy through short rotation coppice(SRC) plantations implies the extensive use of fertilizers to compensate forthe nutrients exported with the harvest. It could be possible to reduce thisinput through management practices that increase the efficiency of use of theavailable nutrients. The aim of this work was to evaluate the effect ofgenotype, plantation density and irrigation on the exportation  of nutrients (N, P, Ca and K) with theharvest in a SRC system with willows (Salixspp.). A factorial field experiment was planted in an agricultural soil near LaPlata, Buenos Aires Province, Argentina, with a split-split plot design. Themain plots accommodated the rainfed and irrigated treatments, and were plantedwith clones S. matsudana x S. alba `Barrett 13-44 INTA´ (Barrett) andS. alba `Yaguareté INTA-CIEF´(Yaguareté). The clones were planted at 13,000 (low density) and 20,000 plants ha-1(high density). The trial was planted in 2012 and coppiced every year, the datain this work belongs to the 2015 harvest. For analysis, stools were separatedafter harvest in three diameter classes: small (0-10 mm), medium (10.1-20 mm)and big size (>20.1 mm). Irrigated plots had a significantly higher drybiomass yield than the rainfed plots (19.03 ± 1.48 Mg ha-1 vs. 11.99 ± 1.22 Mg ha-1). The average content of nutrients exported withthe harvested biomass were 89.17 ± 10.75 Kg N ha-1,86.80 ± 8.72 KgCa ha-1, 46.76 ± 5.17 Kg K ha-1 and 11.10 ± 1.39 Kg P ha-1. The amount of nutrientsexported with the harvested biomass was higher in the small stools; thisdiameter stool class was more abundant  inplots of clone Yaguareté and those of rainfed treatment. The exportation of N,Ca and K per hectare was significantly higher in the irrigated plots. Thegenotype had also an effect, since clone Barrett exported more N per harvestedbiomass than Yaguareté; while Yaguareté exported more K than Barrett. Therewere no significant effects of any of the analyzed factors on P exported withthe harvested biomass. Neither factor had a significant effect on the upperheating value of the wood (4705 ± 17.85 cal/g on average for all treatments). Ourresults indicate that it could be feasible to reduce the exportation ofnutrients with the harvested biomass in SRC plantations with adequatemanagement practices, without compromising the wood quality as biofuel.