Search Results (2)

Peatlands have been irreversibly destroyed by draining and mining for horticulture, in the course of which tremendous amounts of greenhouse gasses were released into the atmosphere. To avoid this in the future, sustainable alternatives are urgently needed to substitute peat as growing media. An appropriate alternative could be biochar, because it has beneficial effects on nutrient availability and retention, water holding capacity, and organic matter stability. In this study, we compared three different commercially available biochar-containing growing media (Palaterra, Sonnenerde, Terra Magica) with three commercially available peat-based growing media (CompoSana, Dehner die leichte, Dehner mit Vorratsdünger), in a randomized greenhouse pot experiment. Pure sand was used as a control and, to test a potential amount effect, we mixed the used growing media with increasing amounts of pure sand (0, 25, 50, 75, and 100 volume % of individual growing media). The consecutive yields of several agronomically relevant cereals (barley, wheat, and maize) were measured in the mixtures mentioned previously. Additionally, the contents of biochar, amino sugar, and polycyclic aromatic hydrocarbons were measured in each pure growing media before and after the growth experiments. Only Sonnenerde exhibited an increased plant yield of 30–40% compared with peat-based growing media. The growing media exhibited no significant differences of chemical soil properties during the experiment. Only slight tendencies are recognizable towards higher fungal community in biochar- and peat-based growing media. A clear fungi contribution was observed in Palaterra, most probably due to the fact that fungi was a production ingredient. Surprisingly, peat-based growing media also contained about 30 g kg⁻¹ black carbon, a polycondensed aromatic carbon typical for biochar. Overall, our results indicated that biochar-containing growing media, especially Sonnenerde, is a potential alternative for peat-based growing media in horticulture and can enhance degraded soils. Full article

Biochar has the potential to be used as a growing media component, and therefore plays a role in reducing peat usage. It has unique properties apart from the ability to sequester carbon. Here we investigated the nutrient contents of four commercial biochars and their fractions. The biochars’ feedstock was wood waste, except for one with paper fibres and husk. The fine or finer fractions in wood waste biochars contained higher levels of nutrients that were available to plants. The coarse fraction of the biochar derived from husk and paper fibre feedstock had a higher level of total N, P and K in contrast to the other three biochars. The pH of the finer fraction (pH of 9.08) was also higher compared with coarse fraction (pH of 8.71). It is important that when biochar a is used as a component of a peat based growing media, particle size information should be provided, as fractions from the same biochar can have different levels of total extractable nutrients and pH levels. If biochar is used to replace or reduce lime application rates of a peat-biochar mixtures, one must take into account the levels of total and extractable Ca and Mg levels, as these can vary. The variation of these elements was not only between biochars’ feedstocks, even at similar pH-values, but within different fractions in the same biochar. We concluded that biochars should be characterized from the feedstock as well as from the particle size aspect, as it could have a profound effect on nutrient availability of Ca and Mg. This could lead to nutrient imbalances in cultivating plants on substrate mixtures. In addition to nutrient ratios, the suitable pH-level for a given grown species should be adjusted. Full article