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

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.

摘要：土壤下层压实与营养胁迫是限制作物产量的核心因素之一。利用木灰等森林残留物开展土壤化学修复是切实可行的方案，可在下层压实土壤中促进作物根系旺盛生长。本研究旨在确定适用于下层压实土壤轮作作物的最优木灰施用量，以实现该残留物的高效管理。本试验选取具有深主根系统的轮作作物红花（Carthamus tinctorius），在施加不同剂量木灰且下层设置不同压实程度的黏土中种植。试验采用随机区组设计（randomized block design），设置4×5因子试验方案，包含4个木灰施用量梯度（8.0、16.0、24.0和32.0 g dm⁻³）与5个土壤容重（soil bulk density）水平（1.0、1.2、1.4、1.6和1.8 kg dm⁻³），每组设置4次重复。分别于出苗后15、45、75天测定作物生长指标，包括株高、叶片数、茎粗及SPAD叶绿素指数（SPAD）。研究结果表明：无论木灰施用量如何，土壤下层压实均是限制作物红花营养生长的最主要因素；当木灰施用量与土壤容重存在交互效应时，最优生长响应出现在木灰施用量25 g dm⁻³、土壤容重1.2 kg dm⁻³的组合条件下。