Effects of Rice Husk Biochar on Carbon Release and Nutrient Availability in Three Cultivation Age of Greenhouse Soils

Abstract

<jats:p>Greenhouse production can contribute to the accumulation of salt and heavy metals and nutrient imbalance, thus, increasingly degrading greenhouse soils. The potential of rice husk biochar to increase carbon sequestration, neutralize soil pH, increase nutrient retention, and change nutrient/heavy metal sorption/desorption in greenhouse soils is promising. Therefore, we investigated three greenhouse soils (red soil) with 3, 14, and 24 cultivation years (3S, 14S, and 24S) in northern Taiwan to test the effects of rice husk biochar (RHB) on carbon dynamics and nutrient availability. A 100-day incubation study was conducted in which poultry-livestock manure compost (2% by wt.) and six rice-husk-based, slow-pyrolysis biochars pyrolyzed at different temperatures were applied (0%, 0.5%, 1.0%, 4.0%, 10%, and 20% by wt.) to three red soils. The study results indicated that the RHB pyrolyzed at high temperatures, with relatively high pH and Ca content, could lead to a higher neutralizing effect when applied to the soil. In addition, the high temperatures pyrolyzed RHB had a higher capacity to reduce the concentration of Cu, Pb, and Zn in the three soils, especially for the younger cultivation soil, which contributed to the higher pH and relatively high surface area of these RHB, and the relative lower soil pH of the younger soil. Furthermore, only adding 0.5% RHB could result in an evident change in soil characteristics for 3S and 24S soil, including cumulative C release, pH, EC, TC, and available K increase, but 4% RHB addition was needed for 14S soil. In the condition of co-application with 2% compost (by wt.), 4% RHB addition was necessary for carbon sequestration, at least 10% RHB addition was needed for 3S and 14S soil, but 1.0 to 4.0% would be sufficient for 24S. In conclusion, the RHB and compost co-application in greenhouse soil resulted in improved chemical properties, and the effect of the pyrolysis temperature, application rate, and cultivation age had varying improvements.</jats:p>

Higher Biochar Rate Can Be Efficient in Reducing Nitrogen Mineralization and Nitrification in the Excessive Compost-Fertilized Soils

“…The jars were sealed and incubated at 25 • C. The soil moisture content was adjusted to 60% of field capacity before incubation, and this was maintained throughout the experiment via repeated weighing. The soils were destructively sampled at 1, 3,7,28,56,84,140,196,294 and 400 days after incubation, consistently with previous C mineralization processes [14].…”

“…However, at 57 weeks, a significant increase was observed only in the SAO soil, and an insignificant one in the MAI and SAI soils, indicating that the liming effect has been reduced (Table 4). Many reports have indicated that the inherent alkalinity of biochar could serve as a liming agent and leads to increased soil pH, especially for ameliorating the acidity of acidic soils [11,14,19,[24][25][26][27][28][29][30]. At the end of incubation, the soil pH increased by 0.01~0.24, 0.01~0.18, and 0.11~0.26 pH units for the SAO, MAI and SAI soils, respectively, and by 0.01~0.16, 0.03~0.13 and 0.06~0.26 pH units for the ash, bamboo, and lead tree biochars, respectively.…”

“…The soil's organic and mineral content and the soil's physical characteristics would affect soil buffering capacity [36]. Tsai and Change [28] indicated that major changes in soil pH have been prevented by the soil's buffering capacity, and the acidification and nitrification of 2% compost decomposition may offset the neutralizing effect of rice husk biochar. In the current study, a higher compost rate (5%) may have greater potential for offsetting the neutralizing effects of the studied biochars, as confirmed by the soil pH increasing by a maximum of 0.24, 0.18, and 0.26 pH units for the SAO, MAI, and SAI soils, respectively, and by a maximum of 0.16, 0.13, and 0.26 pH units for the A, B, and L biochars, respectively.…”

Quality Evaluation of Poultry Litter Biochar Produced at Different Pyrolysis Temperatures as a Sustainable Management Approach and Its Impact on Soil Carbon Mineralization

“…The studied soil characteristics, including soil pH, electrical conductivities (EC), the soils' particle sizes, total soil C contents (TC), exchangeable bases (K, Na, Ca, and Mg), cation exchangeable capacities (CEC), and base saturation percentages (BS%) were determined. The analysis methods used were the same as those described in previous studies [17,18]. The characterizations of the five studied PLBs, including the pH; EC; available N concentration; CEC; plant-available nutrients (P, K, Ca, and Mg); total contents of P, K, Ca, and Mg; elemental analyses (C, N, H, O, and S); and 13 C-Nuclear Magnetic Resonance (NMR) spectra, were determined, and the analysis method used was the same as that described in a previous study [17,18].…”

“…The land application of PL in open-field and greenhouse cultivation, due to bad odors and potential environmental and public health risks, has been gradually restricted since 2010 in Taiwan [17]. Thus, the production of stable PLBs from PL and its use in soil can play a vital role in solving the current problem in agriculture and could help mitigate rising greenhouse gas emissions, in addition to helping to partially achieve some SDGs.…”