Biological oxidation of elemental sulphur added to three composts from different feedstocks to reduce their pH for horticultural purposes

“…At any rate, excessively high pH of an organic material can be easily improved by acidifying the material with elemental sulphur (García de la Fuente et al, 2007), and diluted sulphuric (Costello and Sullivan, 2014) or phosphoric acids (Mazuela et al, 2005). In addition, EC can be easily reduced by leaching the materials with good quality water (Fornes et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

Biochar versus hydrochar as growth media constituents for ornamental plant cultivation

Fornés

Belda

2018

Sci. agric. (Piracicaba, Braz.)

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Biochar and hydrochar have been proposed as novel materials for providing soilless growth media. However, much more knowledge is required before reliable advice can be given on the use of these materials for this purpose. Depending on the material and the technology applied (pyrolysis or hydrothermal carbonization), phytotoxicity and greenhouse gas emissions have been found for certain chars. In this study, our aim was to assess the feasibility of three chars as substrate constituents. We compared two biochars, one from forest waste and the other from olive mill waste, and a hydrochar from forest waste. We studied how chars affected substrate characteristics, plant performance, water economy and respiratory CO 2 emission. Substrates containing biochar from forest waste showed the best characteristics, with good air/water relationships and adequate electrical conductivity. Those with biochar from olive mill waste were highly saline and, consequently, low quality. The substrates with hydrochar retained too much water and were poorly aerated, presenting high CO 2 concentrations due to high respiratory activity. Plants performed well only when grown in substrates containing a maximum of 25 % biochar from forest waste or hydrochar. After analyzing the char characteristics, we concluded that biochar from forest waste could be safely used as a substrate constituent and is environmentally friendly when applied due to its low salinity and low CO 2 emission. However, biochar from olive mill waste and hydrochar need to be improved before they can be used as substrate constituents.

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“…Acidification with S may affect other characteristics besides the pH, i.e. a strong EC increase is expected, but nutrient availability and microbial biomass and activity may change as well ((Amberger-Ochsenbauer et al, 2017;Costello et al, 2019;García de la fuente et al, 2007).…”

Section: Physical Properties Nutrients and Saltsmentioning

confidence: 99%

Grow - Store - Steam - Re-peat: Reuse of spent growing media for circular cultivation of Chrysanthemum

Vandecasteele¹,

Blindeman²,

Amery³

et al. 2020

Journal of Cleaner Production

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Substantially extending the life span of peat-and perlite-based growing media is a measure to increase the sustainability of soilless cultivation. The extraction of peat from pristine peatlands threatens these sensitive ecosystems and carbon sinks, meanwhile resulting in increased emissions of greenhouse gasses. Each batch of peat that is reused, results in a clear reduction in CO 2 emissions and a lower impact on the climate. After using growing media for one cultivation, we aim at reusing the spent material as growing medium for another crop. Spent peat and perlite based growing media from strawberry and cucumber cultivation were upcycled after steam treatment. We tested the effectiveness of steaming to reduce phytosanitary risks. The hygienisation efficiency of the steam treatment was confirmed: plant pathogenic fungi, larvae of vine weevils and weed seeds added or already present before the process were killed by the steam treatment. As the upcycled spent growing medium already contained high nutrient levels, the fertilizer application in the reused growing medium should be reduced, especially for P and K. Five indicators for assessing stability of the materials were used: CO 2 flux measurements, oxygen uptake rate (OUR), biodegradation potential, mineral N content and risk for N immobilization. The spent growing media had a low decomposition rate and the release of nutrients in a leaching experiment was lower than for a fertilized peat-based growing medium, being a reference blend for open field cultivated Chrysanthemum. N mineralisation and P uptake were tested in an incubation and pot trial, respectively, and the upcycled spent growing medium was found to be an important source of plant-available K and P. Steam treatment did not severely affect the microbial biomass and diversity of the spent growing media. Blending the steam-treated spent media with other materials or inoculating by a commercially available biocontrol fungus also had a limited effect, indicating that newly introduced microorganisms do not easily establish in steamed-treated spent growing media (SSGM). Acidification of the SSGM was achieved by a low dose of elemental S. The steam-treated growing medium was tested for growing Chrysanthemum cuttings and plantlets. Spent growing media were not able to supply sufficient mineral N, but the stored amounts of P and K in the media were sufficiently plant available for optimal crop growth.

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Biological oxidation of elemental sulphur added to three composts from different feedstocks to reduce their pH for horticultural purposes

Cited by 34 publications

References 26 publications

Leaching composted lignocellulosic wastes to prepare container media: Feasibility and environmental concerns

Leaching composted lignocellulosic wastes to prepare container media: Feasibility and environmental concerns

Biochar versus hydrochar as growth media constituents for ornamental plant cultivation

Grow - Store - Steam - Re-peat: Reuse of spent growing media for circular cultivation of Chrysanthemum

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