Wood ash as a vegetative-growth promoter in soils with subsurface compaction

Edna M Bonfim-Silva,Thiago F Duarte,Tulio Martinez-Santos,Everton A R Pinheiro,Rackel D De S Alves,Tonny J A Da Silva

doi:10.1590/1807-1929/agriambi.v26n4p258-265

Abstract

ABSTRACT Subsurface soil compaction and nutritional stress are among the main factors that limit the yield of crops. Using forest residues, such as wood ash, is a viable option in the chemical recovery of soils and can promote vigorous root development in soils with subsurface compaction. The objective of this study was to indicate the most adequate dose of wood ash for efficient management of this residue applied in rotational crops cultivated in soils with subsurface compaction. Safflower plants (Carthamus tinctorius), a rotational crop with a deep taproot system, were grown in clay soil fertilized with different doses of ash and with induced levels of compaction in the subsurface layer. The experiment was conducted in a randomized block design, under a 4 × 5 factorial scheme, composed of four doses of wood ash (8.0, 16.0, 24.0, and 32.0 g dm-3) and five levels of soil bulk density (1.0, 1.2, 1.4, 1.6, and 1.8 kg dm-3), with four replicates. Crop growth variables (plant height, number of leaves, stem diameter, and SPAD chlorophyll index) were evaluated at 15, 45, and 75 days after emergence. The results indicated that soil compaction was the most limiting factor to the vegetative development of safflower, regardless of the ash dose. The interaction between the wood ash dose and bulk density, when present, showed that the best growth response occurred for ash dose of 25 g dm-3 for a soil bulk density of 1.2 kg dm-3.

Highlights

The use of soil conditioners obtained from residues rich in nutrients that are essential to plants, such as wood ash, can accelerate the soil recovery process while preventing environmental impacts caused by the diffuse disposal of these residues by industries (Qin et al, 2017; Johansen et al, 2021)
The types and amounts of nutrients and organic matter present in wood ash depend on the source material, as well as on the conditions in the burning process, such as temperature, oxygen concentration in the system, and type of boiler used by the industry (Merino et al, 2017)
Given the naturally low pH of soils from the Brazilian Cerrado (Table 1) and the wood ash capacity of neutralizing H+ ions, it was verified that the safflower plants could not survive the early stages of development under the wood ash dose of 0 g dm‐3; for this reason, the safflower vegetative growth was not analyzed for this specific treatment

Summary

Introduction

Factors that limit agricultural production include soil compaction, which in addition to causing a physical impediment to root penetration, reduces soil macroporosity, affecting dynamic processes related to water availability, water infiltration, and gas flow in the soil profile (Shah et al, 2017a; Stoessel et al, 2018; Correa et al, 2019).The adoption of crop rotation, associated with the use of plant species with the potential to promote soil biological scarification, is a more sustainable option of decompaction when compared to mechanical methods for the recovery of compacted soils (Martinez-Santos et al, 2019).The use of soil conditioners obtained from residues rich in nutrients that are essential to plants, such as wood ash, can accelerate the soil recovery process while preventing environmental impacts caused by the diffuse disposal of these residues by industries (Qin et al, 2017; Johansen et al, 2021).The types and amounts of nutrients and organic matter present in wood ash depend on the source material, as well as on the conditions in the burning process, such as temperature, oxygen concentration in the system, and type of boiler used by the industry (Merino et al, 2017). The use of soil conditioners obtained from residues rich in nutrients that are essential to plants, such as wood ash, can accelerate the soil recovery process while preventing environmental impacts caused by the diffuse disposal of these residues by industries (Qin et al, 2017; Johansen et al, 2021). Studies with wood ash have verified, to some degree, positive alterations in chemical, physical, and biological properties of agricultural and forested soils (Bonfim-Silva et al, 2015; Symanowicz et al, 2018; BangAndreasen et al, 2021). Studies investigating wood ash effects on compacted and acidic soils, as is the case of many degraded areas in the Brazilian Cerrado, are still scarce (Bonfim-Silva et al, 2018; Martinez-Santos et al, 2019)

Objectives

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Results