Partial Substitution of Urea with Biochar Induced Improvements in Soil Enzymes Activity, Ammonia-Nitrite Oxidizers, and Nitrogen Uptake in the Double-Cropping Rice System

Abstract

Biochar is an important soil amendment that can enhance the biological properties of soil, as well as nitrogen (N) uptake and utilization in N-fertilized crops. However, few studies have characterized the effects of urea and biochar application on soil biochemical traits and its effect on paddy rice. Therefore, a field trial was conducted in the early and late seasons of 2020 in a randomized complete block design with two N levels (135 and 180 kg ha−1) and four levels of biochar (0, 10, 20, and 30 t ha−1). The treatment combinations were as follows: 135 kg N ha−1 + 0 t B ha−1 (T1), 135 kg N ha−1 + 10 t B ha−1 (T2), 135 kg N ha−1 + 20 t B ha−1 (T3), 135 kg N ha−1 + 30 t B ha−1 (T4), 180 kg N ha−1 + 0 t B ha−1 (T5), 180 kg N ha−1 + 10 t B ha−1 (T6), 180 kg N ha−1 + 20 t B ha−1 (T7) and 180 kg N ha−1 + 30 t B ha−1 (T8). The results showed that soil amended with biochar had higher soil pH, soil organic carbon content, total nitrogen content, and mineral nitrogen (NH4+-N and NO3−-N) than soil that had not been amended with biochar. In both seasons, the 20 t ha−1 and 30 t ha−1 biochar treatments had the highest an average concentrations of NO3–-N (10.54 mg kg−1 and 10.25 mg kg−1, respectively). In comparison to soil that had not been treated with biochar, the average activity of the enzymes urease, polyphenol oxidase, dehydrogenase, and chitinase was, respectively, 25.28%, 14.13%, 67.76%, and 22.26% greater; however, the activity of the enzyme catalase was 15.06% lower in both seasons. Application of biochar considerably increased the abundance of ammonia-oxidizing bacteria (AOB), which was 48% greater on average in biochar-amended soil than in unamended soil. However, there were no significant variations in the abundances of ammonia-oxidizing archaea (AOA) or nitrite-oxidizing bacteria (NOB) across treatments. In comparison to soil that had not been treated with biochar, the average N content was 24.46%, 20.47%, and 19.08% higher in the stem, leaves, and panicles, respectively. In general, adding biochar at a rate of 20 to 30 t ha−1 with low-dose urea (135 kg N ha−1) is a beneficial technique for improving the nutrient balance and biological processes of soil, as well as the N uptake and grain yield of rice plants.

The interaction effect of superabsorbent and biochar on physiological properties of Satureja rechingeri under drought-stress

“…The main causes of the decrease in carotenoid and chlorophyll synthesis under drought stress have been attributed to the decrease in the efficiency of carbon use and the increase in ethanol and lactate production (Ahanger et al, 2021). Our findings are similar to those of Ullah et al (2023) who reported that by reducing nitrogen loss and increasing nitrogen absorption, biochar enhances the concentration of photosynthetic pigments. Drought stress decreased the amount of nitrogen in aerial parts (data not shown).…”

Chemical Fertilizer Reduction Combined with Biochar Application Ameliorates the Biological Property and Fertilizer Utilization of Pod Pepper

“…These findings imply that, in the specific setting of this investigation, decreasing the usage of chemical fertilizers and incorporating biochar can form a promising strategy to improve fertilizer utilization efficiency. Studies have shown that biochar utilization increases the soil C/N ratio and limits nitrogen conversion and denitrification by soil microorganisms, which facilitates the sequestration of more NH 4 + and NO 3 − in the soil [33,59,60]. In addition, biochar can be used as an alternative to traditional phosphorus fertilizers because of its inherently high content of effective phosphorus, and it can impact and alter the cycling and effectiveness of phosphorus in soils through the adsorption and desorption of phosphorus and the regulation of the soil microbial community structure [61][62][63].…”

Effects of biochar and vermicompost on growth and economic benefits of continuous cropping pepper at karst yellow soil region in Southwest China

“…In this study, the application of biochar and vermicompost alone or in combination not only significantly increased the accumulation of NPK ( Figure 3 ) but also significantly improved the fertilizer utilization efficiency ( Table 3 ). Studies have shown that biochar application increases the soil C/N ratio and limits nitrogen conversion and denitrification by soil microorganisms, facilitating the sequestration of NH 4 + and NO 3 - in the soil ( Zhao et al., 2022 ; Ullah et al., 2023 ). In addition, biochar can be used as an alternative to traditional phosphorus fertilizers because of its inherently high effective phosphorus content, which can also alter the cycling and effectiveness of phosphorus in soils through the adsorption and desorption of phosphorus and regulation of the soil microbial community structure ( Kong et al., 2023 ; Pokharel and Chang, 2023 ; Yan et al., 2023 ).…”