Effects of biochar compared to organic and inorganic fertilizers on soil quality and plant growth in a greenhouse experiment

Abstract

Our contemporary society is struggling with soil degradation due to overuse and climate change. Pre‐Columbian people left behind sustainably fertile soils rich in organic matter and nutrients well known as terra preta (de Indio) by adding charred residues (biochar) together with organic and inorganic wastes such as excrements and household garbage being a model for sustainable agriculture today. This is the reason why new studies on biochar effects on ecosystem services rapidly emerge. Beneficial effects of biochar amendment on plant growth, soil nutrient content, and C storage were repeatedly observed although a number of negative effects were reported, too. In addition, there is no consensus on benefits of biochar when combined with fertilizers. Therefore, the objective of this study was to test whether biochar effects on soil quality and plant growth could be improved by addition of mineral and organic fertilizers. For this purpose, two growth periods of oat (Avena sativa L.) were studied under tropical conditions (26°C and 2600 mm annual rainfall) on an infertile sandy soil in the greenhouse in fivefold replication. Treatments comprised control (only water), mineral fertilizer (111.5 kg N ha–1, 111.5 kg P ha–1, and 82.9 kg K ha–1), compost (5% by weight), biochar (5% by weight), and combinations of biochar (5% by weight) plus mineral fertilizer (111.5 kg N ha–1, 111.5 kg P ha–1, and 82.9 kg K ha–1), and biochar (2.5% by weight) plus compost (2.5% by weight). Pure compost application showed highest yield during the two growth periods, followed by the biochar + compost mixture. biochar addition to mineral fertilizer significantly increased plant growth compared to mineral fertilizer alone. During the second growth period, plant yields were significantly smaller compared to the first growth period. biochar and compost additions significantly increased total organic C content during the two growth periods. Cation‐exchange capacity (CEC) could not be increased upon biochar addition while base saturation (BS) was significantly increased due to ash addition with biochar. On the other hand, compost addition significantly increased CEC. Biochar addition significantly increased soil pH but pH value was generally lower during the second growth period probably due to leaching of base cations. Biochar addition did not reduce ammonium, nitrate, and phosphate leaching during the experiment but it reduced nitrification. The overall plant growth and soil fertility decreased in the order compost > biochar + compost > mineral fertilizer + biochar > mineral fertilizer > control. Further experiments should optimize biochar–organic fertilizer systems.

Effect of Biochar and Inorganic Fertilizer in Yam (Dioscorea rotundata Poir) Production in a Forest Agroecological Zone

“…The non-significant effect of the treatments on yields observed in this study however contrasts the findings of (Yamato, Okimori, Wibowo, Anshori, & Ogawa, 2006;Schulz & Glaser, 2012) which found significant increase in crop yield as a result of biochar and fertilizer addition. They attributed it to biochar's ability to efficiently utilize nutrients by holding ammonium ions in soils and inhibiting nitrogen fertilizer nitrification.…”

Impact of Biochar Addition on Productivity and Tubers Quality of Some Potato Cultivars Under Sandy Soil Conditions

“…Carter et al (2013) confirmed that the biochar treatments were increased the final biomass, root biomass, plant height and leaf number of lettuce and cabbage in all the cropping cycles. Also, biochar addition to mineral fertilizers significantly increased plant growth (Schulz andGlaser, 2012, Biederman andHarpole, 2013).…”

“…Graber et al (2010) mentioned that treating tomato plants by biochar positively enhanced plant height and leaf size. Also, biochar addition to mineral fertilizers significantly increased plant growth (Schulz andGlaser, 2012, Biederman andHarpole, 2013). The biochar treatments were found to increase the final vegetative biomass, root biomass, plant height and leaf number of lettuce and cabbage in all the cropping cycles compared to no biochar treatments (Carter et al, 2013).…”

A Review of Biochar and Soil Nitrogen Dynamics

“…For example, Jones et al [26] found no effects of biochar (50 t ha , respectively. In sandy soils this biochar input may be significant in terms of CEC, but may also be insignificant [27], while for many soils that already contain higher levels of organic matter and clay the impact of biochar may be inconsequential. Further studies need to report on the change in freshly incorporated biochar CEC values over time for biochars that have been placed in situ.…”