Eucalyptus harvest residue management systems and their influence on soil properties and wood productivity

Author(s)

Karla Nascimento Sena

• Document type: Doctoral Thesis
• Press: Ilha Solteira. 2022-01-31.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Engenharia. Ilha Solteira
• Defense date: 2021-02-02
• Advisor: Engil Isadora Pujol Pereira Mikita; Kátia Luciene Maltoni

Abstract

Organic carbon (OC) introduced in soils, mainly through organic matter, has a relevant role in various soil properties and more in sandy soils. In these soils, the input of organic material is necessary to ensure the sustainability of production systems. This study aimed to investigate the changes in total organic carbon content and its effect on chemical, physical and microbial soil properties, of the residual phytomass of harvest and yield wood at 3 years, in commercial eucalyptus plantation areas after the harvest of eucalyptus. The study was performed in December 2017 in a Eucalyptus urograndis (clone E13) commercial plantation, in the municipality of Água Clara, Mato Grosso do Sul State, Brazil, classified as a sandy-textured Neossolo quartzarênico. The study was harvest occurred at the beginning of June 2017, according to the cut-to-length system. After 120 days (September, 2017) the plots were prepared to simulate the three different harvest management systems (HMS): CTL= cut-tolength – all phytomass maintained in the área; BA= bare – removal all of the residual phytomass, the installation of sombrite® protective netting to impede deposition of plant biomass and without supplementary fertilization; BL= bare litter– removal all of the residual phytomass; TL= tree-length– removal of the bark and maintaining the residual phytomass were maintained in the area; BLF= bare litter with fertilization – removal all of the residual phytomass, the installation of sombrite® protective netting to impede deposition of plant biomass and with supplementary fertilization. Field studies were conducted in a completely randomized experimental design, with four replications. After 90 days of HMS implantation and before plantation, in December of 2017, undisturbed oil samples were taken from the 0.00- 0.05, 0.05-0.10 and 0.10-0.20 m layers for determinations of aggregate stability, soil bulk density (BD), macroporosity (Macro), microporosity (Micro), total porosity (TP) and total organic carbon (TOC); and for calculation of carbon stock (CS). TOC and CS continued down into the 0.20-0.40, 0.40-0.60, 0.60-0.80, and 0.80-1.00 m layers. Soil mechanical penetration resistance (PR) was determined to the 0.40 m depth in 0.10 m intervals. Carbon content was evaluated in the aggregates of the 0.00-0.05 m layer after wet sieving in 2000, 1000, 250 and 53 μm diameter sieves. Soil samples were taken at depth 0.00-0.10, 0.10-0.20, 0.20-0.40, 0.40- 0.60, 0.60-0.80 e 0.80-1.00 m for chemical properties analysis (P, MO, pH, K, Ca, Mg, H+Al, Al and S). Litter bags were used to assess decomposition over a period of 36 months. Biological activities were assessed through microbial biomass carbon (MBC), basal respiration of soil (BRS); β-glycosidase (BGlu), acid phosphatase (P-ase), arylsulfatase (Aryl-S), total enzymatic activity (FDA) and calculation of metabolic (qCO2) and microbial (qMic) quotients were determined in the 0.00-0.10 m layer. Intact cores were obtained on each HMS and sieved to obtain large, macro and micro aggregates, 4000-2000, 2000-250 and 250-0.00 µm, respectively of the aggregates was performed considering three classes of aggregate diameter (large macroaggregates - MaG: 2000-4000 μm, medium macroaggregates - MaM: 250-2000 μm and microaggregates - MiP: 0-250 μm) to analyze MBC, BRS, qCO2 and qMic, TOC and NT, FDA, βGlu and active carbon. After 3 years of planting, chemical properties at 1m, microbiological and enzymatic properties in the 0.00-0.10 m layer were evaluated and wood yield was estimated. In the short term, the maintenance of residual phytomass on the soil surface can positively impact TOC and PR compared to others HMS; in the CTL HMS provides maintenance of TOC, with greater Macro (0.00-0.05 m); maintain the harvest residual phytomass on the surface became the microbial activity efficiently. Harvesting in CTL provides greater amount of phytomass and greater amount of N, P, K, Ca and C, with the greatest decomposition of residues occurring in the initial 6 months; removing the bark reduces the amount of Ca and N and increases the decomposition time. The eucalyptus HMS promoted changes in soil properties MBC, qCO2, qMic, COT, NT, βGlu and active carbon, with aggregates of diameter 2000 to 4000 µm being the most sensitive fraction to management systems, evidenced in greater microbiological, enzymatic and nutrient retention in the soil. HMS promoted changes in soil properties MBC, qCO2, qMic, COT, NT, β-gGlu and active carbon, where aggregates of diameter 2000 to 4000 µm were most sensitive fraction to management systems, pointed of higher microbiological, enzymatic and nutrient retention in the soil. The phytomass maintenance, partial and total, provided better soil conditions pointed in MBC, NT, TOC, enzymatic activity (β-Glu and FDA). After 3 years of eucalyptus planting, HMS promoted changes in the chemical, microbiological and enzymatic properties of the soil, with the 0.00-0.20 layer, where the most influenced by chemical properties; the maintenance of total residual phytomass from the harvest benefits and increases soil bases (Ca and V), reduces acidity (Al and m) and improves microbiological activity (RBS and qCO2). Keep just part of residual phytomass reduces the availability of soil nutrients and phosphatase enzyme activity. Avoid the currently litter from entering the current cycle increased βGlu activity; the residual phytomass and current litter are responsible for greater yield of eucalyptus wood at 3 years of age. The structural equation analysis showed adequate adjustment to comprehension the relationship between HMS, soil fertility at 1m and yield at 3 years, simultaneously. (AU)

• FAPESP's process: 17/14049-2 - Effects of eucalyptus cultivation on soil attributes and productivity on sandy soils
• Grantee: Karla Nascimento Sena
• Support Opportunities: Scholarships in Brazil - Doctorate