Fertilization Response, Light Use, and Growth Efficiency in Eucalyptus Plantations across Soil and Climate Gradients in Brazil

Abstract

Fertilization increases productivity in Eucalyptus plantations, but losses in productivity associated with soil fertility continue at operational scales. In this study, we evaluated the fertilization response (FR), light use efficiency (LUE) and growth efficiency (GE), i.e., the amount of wood biomass accumulated per unit of light absorbed (LUE) and per unit of leaf area index of Eucalyptus plantations. We used a "twin plot" approach, with 161 blocks representing 52,700 ha of planted forests that spanned a broad range of edaphoclimatic conditions in southeastern Brazil. The normal plots (NP) were part of a permanent inventory network, whereas the twin plots (TP) received extra high levels of fertilization and extra weed control after fertilization. The intensive management (twin plots) led to a large increase of 5.3 Mg¨ha´1¨year´1 of wood increment. The region without dry periods and with soils with high clay content was most responsive to fertilization, with a 15% increment in the LUE and 10% increase in the GE of the TPs compared with those of the NPs. Our results suggested that water availability was the primary element affecting productivity and potential response to fertilization. With this information, decisions can be made on which regions should receive priority fertilization investments. However, more research is required to determine the most limiting nutrient in each type of environment.

Fertilization of Eucalyptus Stands at Advanced Ages in Minas Gerais, Brazil

“…To demonstrate this effect, regions R2 and R3 were selected, since they possess all the age classes evaluated. A greater response to fertilization in regions with greater water availability is widely reported in the literature (Smethurst et al, 2003;Stape et al, 2010;Silva et al, 2016).…”

“…This marked reduction of the doses applied, associated with stress caused by the sprout thinning, eliminating between 50% and 70% of the biomass produced, is one of the factors that could explain the drop in productivity and the greater biological response to FA. Less productivity tends to present more significant responses to fertilizations in Eucalyptus stands (Ferreira & Stape, 2010;Silva et al, 2016). Studies in stands managed according to a coppice regime have shown lower productivity in relation to the tall shaft regime (Miranda et al, 1998a, b;Faria et al, 2002).…”

“…The lower response to FA at more advanced ages can be attributed to the establishment of nutrient cycling (Santana et al, 2008;Gonçalves et al, 2013) and of operational fertilization that adopted the nutritional balance model where one does not expect nutritional restrictions. Some authors report greater responses to FA at advanced ages in studies with twin-plots (Stape et al, 2006;Ferreira & Stape, 2010;Silva et al, 2016) where nutritional restrictions were observed using limited quantities of nutrients applied during operational fertilization.…”

“…Despite this, studies seeking to analyze the nutritional limitations and potential productivity of Eucalyptus have shown a response to fertilization at ages older than two years when very elevated doses of nutrients are applied (Stape et al, 2006;Ferreira & Stape, 2010;Silva et al, 2016). According to the cited authors, the increase in productivity due to fertilization at advanced ages is influenced, amongst other factors, by the stage of development of the forest, soil and climatic conditions, genetic material and type of forestry management adopted.…”

Evaluation of different silvicultural management techniques and water seasonality on yield of eucalyptus stands

“…Due to the predominance of eucalyptus plantations in soils with low fertility, the addition of mineral fertilizers has become essential to achieve high yields and reduce the rotation period in a sustainable way (Gonçalves et al, 2013;Carrero et al, 2018). Thus, studies have investigated the effects fertilization on forest plantations, which may vary according to edaphoclimatic conditions, genetic material, stage of forest development, uniformity level, and management regime adopted, such as first or second rotations (Melo et al, 2015;Silva et al, 2016).…”