Rice-husk biochar effects on organic carbon, aggregate stability and nitrogen-fertility of coarse-textured Ultisols evaluated using Celosia argentea growth

Abstract

There are insufficient data supporting the enormous potential of biochar in highly weathered tropical soils. This glasshouse study assessed rice-husk biochar (RHB) effects on soil organic carbon, aggregate stability and nitrogen fertility of sandy-loam Ultisols which were evaluated using spinach (<em>Celosia argentea</em>) growth. Five RHB rates 0, 5, 10, 20, and 40 g per two-kg-soil (0, 7.5, 15, 30 and 60 t ha<sup>−1</sup>, respectively) were studied under 0, 4, 8, and 12 weeks of incubation (WOI). Batched potting of treatments enabled sowing on one date. Treatment effects on soil quality were assessed at sowing and spinach growth six weeks later. Soil organic carbon generally increased with RHB rate, with the greatest increments (37%) in maximum rate relative to no-biochar control for 8 WOI. Aggregate stability also generally increased with RHB rate, the range being 7.21%-17.21% for 8 WOI, beyond which it decreased in 10 and 20 but not 40 g pot<sup>–1</sup>. Total nitrogen was always highest in maximum rate, increasing with rate only for 8 WOI. Treatment affected plant height more clearly than leaf count. Optimum rates were 5 or 10 g pot<sup>–1</sup> for 8 and 4 WOI, respectively (plant height) and 10 g pot<sup>–1</sup> for 8 WOI (leaf count). Soil organic carbon influenced soil aggregate stability (R<sup>2</sup> = 0.505) which in turn was quadratically related to plant height (R<sup>2</sup> = 0.517), indicating stability threshold for spinach. Adding RHB at 40 g pot<sup>–1</sup> (≈ 60 t ha<sup>−1</sup>) to coarse-textured tropical soils is suggested to sustain its soil aggregating effect beyond the growth phase of short-cycle leafy vegetables which require a lower rate (10 g pot<sup>–1</sup>) 8 weeks before sowing. The observed role of soil aggregate stability in spinach growth rather than the overall effects of RHB should guide further search for edapho-agronomic optimum rate of RHB.

Soil physical health under different farming systems of rice fields and its effect on rice (Oryza sativa L.) productivity

“…Introducing biochar such as rice husks can increase the organic carbon content in the soil. Increasing the dose of biochar positively correlates with the organic carbon content (Ebido et al, 2021). Therefore, it is best to use biochar at the beginning and post-harvest of tillage.…”

Biochar Improves Soil Fertility and Crop Performance: A Case Study of Nigeria

“…In Enugu State, Nigeria, Ebido et al [186] conducted a study investigating the impacts of rice-husk BC pyrolyzed at 550-600 • C on organic carbon, aggregate stability, and the nitrogen fertility of coarse-textured Ultisols. They observed that as the rate of rice-husk BC increased, soil organic carbon and aggregate stability also increased.…”

“…As the rate of rice-husk-biochar (BC) application rose, there was a corresponding increase in soil organic carbon content and improvement in aggregate stability [186] ---Abia HF BC + poultry manure Significant improvement in soil chemical characteristics and the yield of fresh ginger rhizomes [187] Softwood prune branches -Nasarawa DS BC + supplemental micronutrient Okra vegetative-growth parameters increased with the application of both BC and micronutrients with no significant difference. Increased soil percentage of organic carbon, organic material, cation exchange capacity, nitrogen content, and pH levels [188] * SLS Sahel savanna, SS Sudan savanna, NGS Northern Guinea savanna, SGS Southern Guinea savanna, MA mid-altitude, DS derived savanna, HF humid forest.…”

“…These findings suggest that BC application benefits a wide range of crops, making it a versatile soil-amendment option. Studies like Remigius et al [181] and Ebido et al [186] highlighted the importance of optimized BC application rates. Higher application rates of BC led to increased soil organic carbon, aggregate stability, and nitrogen fertility, emphasizing the need for the careful consideration of BC dosage for optimal results.…”

Role of biochar amendments in improving the properties of acid sulphate soil

“…Previously, several studies on the effect of biochar singularly have been carried out, including on the P-availability (Zhang et al, 2022), improvement of soil physical properties (Aslam et al, 2014;Yin et al, 2018), chemical properties of the soil (Bista et al, 2019), some soil characteristics (Yadav et al, 2018), soil aggregate stability (Ebido et al, 2021) and to the development of rice roots (Kartika et al, 2021). However, no research has been found on how the role of biochar was given together with other organic amendments in acid sulphate soil.…”