Physiological integration improves nitrogen use efficiency of moso bamboo: An isotopic (15N) assessment

Rational application of N fertilizer is essential for maintaining the long-term productivity of Moso bamboo forests. Microbial activity is a crucial indicator of soil quality. Changes in soil nutrient resources due to N addition can lead to microbial nutrient limitations, thereby impeding the maintenance of soil quality. Currently, there is limited research on the effects of N application on microbial nutrient limitations in Moso bamboo forest soils. To examine the changes in extracellular enzyme activity and microbial nutrient limitations in Moso bamboo forest soils following N application, we conducted an N application experiment in northern Guizhou. The findings revealed that the N3 treatment (726 kg·N·hm−2·yr−1) significantly reduced β-glucosidase (BG) activity by 27.61% compared to the control group (no fertilization). The N1 (242 kg·N·hm−2·yr−1), N2 (484 kg·N·hm−2·yr−1), and N3 treatments notably increased the activities of leucine aminopeptidase (LAP) and N-acetyl-β-D-glucosidase (NAG) by 11.45% to 15.79%. Acid phosphatase (ACP) activity remained unaffected by fertilization. N application treatments significantly decreased the C:Ne and C:Pe ratios, while the N:Pe ratio was less influenced by N fertilizer application. Scatter plots and vector characteristics of enzyme activity stoichiometry suggested that microorganisms in the study area were limited by C and N, and N fertilizer application reduced the vector length and increased the vector angle, indicating that N application alleviated the C and N limitation of microorganisms in Moso bamboo forests. Redundancy Analysis (RDA) demonstrated that microbial biomass phosphorus (MBP) was the most critical factor affecting extracellular enzyme activity and stoichiometry. Furthermore, Random Forest Regression analysis identified MBP and the N:Pm ratio as the most significant factors influencing microbial C and N limitation, respectively. The study demonstrated that N application modulates the microbial nutrient acquisition strategy by altering soil nutrient resources in Moso bamboo forests. Formulating fertilizer application strategies based on microbial nutrient requirements is more beneficial for maintaining soil quality and sustainably managing Moso bamboo forests. Additionally, our study offers a theoretical reference for understanding carbon cycling in bamboo forest ecosystems in the context of substantial N inputs.

Section: Introductionmentioning

confidence: 99%

Enzyme Activity Stoichiometry Suggests That Fertilization, Especially Nitrogen Fertilization, Alleviates Nutrient Limitation of Soil Microorganisms in Moso Bamboo Forests

Chu,

Su,

Zhou

et al. 2024

“…The history of bamboo production and utilization in China is long, and it is one of the countries with the most abundant bamboo resources and the widest grove area in the world [1]. Bamboo plays a pivotal role in mitigating the greenhouse effect and fostering rural development [2]. Moso bamboo (Phyllostachys edulis (Carrière) J. Houz) is renowned for its rapid growth, robust regeneration capabilities, and significant potential for carbon Forests 2023, 14, 2460 2 of 14 sequestration [3,4].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Nitrogen Fertilizer Input Alters Soil Carbon Dynamics in Moso Bamboo Forests, Impacting Particulate Organic and Mineral-Associated Carbon Pools

Chu,

Ni,

et al. 2023

The application of nitrogen fertilizer is crucial in the cultivation of bamboo forests, and comprehending the alterations in soil organic carbon (SOC) due to nitrogen application is essential for monitoring soil quality. Predicting the dynamics of soil carbon stock involves analyzing two components: particulate organic carbon (POC) and mineral-associated organic carbon (MAOC). This study aimed to investigate the impact of high nitrogen inputs on SOC stock in Moso bamboo forests located in southwestern China. The research focused on analyzing changes in soil chemical properties, SOC content, and its components (POC and MAOC), as well as microbial biomass in the surface layer (0–10 cm) under different nitrogen applications (0, 242, 484, and 726 kg N ha−1 yr−1). The results indicate that nitrogen application significantly reduced the SOC content, while concurrently causing a significant increase in POC content and a decrease in MAOC content within the Moso bamboo forest (p < 0.05). The HM treatment notably increased the NO3−-N content to 2.15 mg/kg and decreased the NH4+-N content to 11.29 mg/kg, although it did not significantly influence the microbial biomass carbon (MBC) and nitrogen (MBN). The LN and MN treatments significantly reduced the MBC and MBN contents (71.6% and 70.8%, 62.5% and 56.8%). Nitrogen application significantly increased the Na+ concentration, with a peak observed under the LN treatment (135.94 mg/kg, p < 0.05). The MN treatment significantly increased the concentrations of Fe3+ and Al3+ (p < 0.05), whereas nitrogen application did not significantly affect Ca2+, Mg2+ concentration, and cation exchange capacity (p > 0.05). Correlation and redundancy analyses (RDAs) revealed that the increase in annual litterfall did not significantly correlate with the rise in POC, and changes in extractable cations were not significantly correlated with the decrease in MAOC. Soil nitrogen availability, MBC, and MBN were identified as the primary factors affecting POC and MAOC content. In conclusion, the application of nitrogen has a detrimental impact on the soil organic carbon (SOC) of Moso bamboo forests. Consequently, it is imperative to regulate fertilization levels in order to preserve soil quality when managing these forests. Our research offers a theoretical foundation for comprehending and forecasting alterations in soil carbon stocks within bamboo forest ecosystems, thereby bolstering the sustainable management of Moso bamboo forests.

Impact of Nitrogen Fertilizer Application on Soil Organic Carbon and Its Active Fractions in Moso Bamboo Forests

Chu,

Su,

Fan

et al. 2024

Soil organic carbon (SOC) is a crucial indicator of soil quality and fertility. However, excessive nitrogen (N) application, while increasing Moso bamboo yield, may reduce SOC content, potentially leading to soil quality issues. The impact of N on SOC and its active fraction in Moso bamboo forests remains underexplored. Investigating these effects will elucidate the causes of soil quality decline and inform effective N management strategies. Four N application gradients were set: no nitrogen (0 kg·hm−2·yr−1, N0), low nitrogen (242 kg·hm−2·yr−1, N1), medium nitrogen (484 kg·hm−2·yr−1, N2), and high nitrogen (726 kg·hm−2·yr−1, N3), with no fertilizer application as the control (CK). We analyzed the changes in SOC, active organic carbon components, and the Carbon Pool Management Index (CPMI) under different N treatments. The results showed that SOC and its active organic carbon components in the 0~10 cm soil layer were more susceptible to N treatments. The N0 treatment significantly increased microbial biomass carbon (MBC) content but had no significant effect on SOC, particulate organic carbon (POC), dissolved organic carbon (DOC), and readily oxidizable organic carbon (ROC) contents. The N1, N2, and N3 treatments reduced SOC content by 29.36%, 21.85%, and 8.67%, respectively. Except for POC, N1,N2 and N3 treatments reduced MBC, DOC, and ROC contents by 46.29% to 71.69%, 13.98% to 40.4%, and 18.64% to 48.55%, respectively. The MBC/SOC ratio can reflect the turnover rate of SOC, and N treatments lowered the MBC/SOC ratio, with N1 < N2 < N3, indicating the slowest SOC turnover under the N1 treatment. Changes in the Carbon Pool Management Index (CPMI) illustrate the impact of N treatments on soil quality and SOC sequestration capacity. The N1 treatment increased the CPMI, indicating an improvement in soil quality and SOC sequestration capacity. The comprehensive evaluation index of carbon sequestration capacity showed N3 (−0.69) < N0 (−0.13) < CK (−0.05) < N2 (0.24) < N1 (0.63), with the highest carbon sequestration capacity under the N1 treatment and a gradual decrease with increasing N fertilizer concentration. In summary, although the N1 treatment reduced the SOC content, it increased the soil CPMI and decreased the SOC turnover rate, benefiting soil quality and SOC sequestration capacity. Therefore, the reasonable control of N fertilizer application is key to improving soil quality and organic carbon storage in Moso bamboo forests.