Abstract
In recent years, soil addition with organic amendments, such as biochar and compost, has gained attention as an effective agronomic practice to sustain soil fertility, enhance plant growth and crop yield. Well known are the positive effects of compost on yield of a wide crop varieties, while both positive and negative responses are reported for biochar Therefore, the aim of the study was to verify the effect of biochar mixed with three types of compost on quanti-qualitative response of Swiss chard (Beta vulgaris L. cycla), a leafy green vegetable rich in dietary antioxidants, largely consumed worldwide. A factorial experiment in pots with two factors, including biochar (without biochar and with biochar from vine pruning residues) and compost (without compost, with compost from olive pomace, with vermicompost from cattle manure, and with compost from cattle anaerobic digestate), was setup. Two growth cycles were considered, and a set of quantitative (height of plants, number, area and fresh weight of leaves) and qualitative parameters (carotenoids, chlorophyll, total N, and NO3−content of leaves) were analyzed. Biochar decreased plant growth and NO3− leaf content; on the contrary, it increased total N leaf content, while compost improved all the considered parameters. The interactive effect of biochar and compost was evident only on total N and NO3− leaf content. In our experimental conditions, the compost showed to be the best option to improve Swiss chard growth and increase the content of phytopigments, while the biochar-compost mixtures did not produce the expected effect.
Highlights
Over the last half century, chemical-based fertilizers have played a significant role in increasing crop yield, but the over-application, especially N fertilizers, has caused soil quality degradation and other serious environmental impacts [1]
The plants were grown in pots and the experimental design included the following two factors: (1) biochar (B); (2) compost (C)
The findings of our study clearly showed a negative effect of biochar soil addition on plant height, leaf area, and leaf fresh weight of Swiss chard
Summary
Over the last half century, chemical-based fertilizers have played a significant role in increasing crop yield, but the over-application, especially N fertilizers, has caused soil quality degradation and other serious environmental impacts [1]. The application of organic residues to the soils, by ensuring the biological cycling of nutrients [2], could contribute to restore soil fertility. This is recognized as a sustainable strategy of soil management and agricultural productivity and is consistent with the “circular economy” principle of “closing the loop”. In this regard, there is a growing interest in the use of valuable and safe products deriving from technologies of organic wastes and residues recycling, such as biochar and compost. A number of environmental and agronomic benefits deriving from compost and biochar have been documented in several reviews and meta-analyses studies [7,8]
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