Biochar Amendment Alters the Nutrient-Use Strategy of Moso Bamboo Under N Additions.

Jinpei Gao,Man Shi,Xinzhang Song,Zhizhuang Wu,Junbo Zhang,Kunkai Cui,Quan Li

doi:10.3389/fpls.2021.667964

Abstract

Nutrient resorption can affect plant growth, litter decomposition, and nutrient cycling. Although the effects of nitrogen (N) and biochar fertilizers on soil nutrient concentrations and plant nutrient uptake have been studied, an understanding of how combined applications of N and biochar affect plant nutrient resorption in plantations is lacking. In this study, we applied N (0, 30, 60, and 90 kg N ha−1 yr−1 defined as N0, N30, N60, and N90, respectively) and biochar (0, 20, and 40 t biochar ha−1 defined as BC0, BC20, and BC40, respectively) to the soil of a Moso bamboo plantation. We investigated the effects of these treatments on N and phosphorus (P) resorption by young and mature bamboo plants, as well as the relationships between nutrient resorption and leaf and soil nutrient concentrations. Young bamboo showed significantly greater foliar N resorption efficiency (NRE) and P resorption efficiency (PRE) than mature bamboo. N addition alone significantly increased the N resorption proficiency (NRP) and P resorption proficiency (PRP) but significantly decreased the NRE and PRE of both young and mature bamboo. In both the N-free and N-addition treatments, biochar amendments significantly reduced the foliar NRE and PRE of young bamboo but had the opposite effect on mature bamboo. Foliar NRE and PRE were significantly negatively correlated with fresh leaf N and P concentrations and soil total P concentration but significantly positively correlated with soil pH. Our findings suggest that N addition inhibits plant nutrient resorption and alters the nutrient-use strategy of young and mature bamboo from “conservative consumption” to “resource spending.” Furthermore, biochar amendment enhanced the negative effect of N addition on nutrient resorption in young bamboo but reduced the negative effect on that of mature bamboo under N-addition treatments. This study provides new insights into the combined effects of N and biochar on the nutrient resorption of Moso bamboo and may assist in improving fertilization strategies in Moso bamboo plantations.

Highlights

Our study found that fresh leaf N and P concentrations were significantly higher in the N-addition treatments (Figure 1) and were negatively correlated with foliar N resorption efficiency (NRE) and P resorption efficiency (PRE), which supports the above argument that N addition decreases nutritional resorption by increasing foliar nutrient concentrations
Our findings show that N addition alone significantly decreased leaf nutrient resorption (NRE and PRE) in both young and mature bamboo, indicating that N deposition reduced internal nutrient cycling and altered the nutrient-use strategy of Moso bamboo from “conservative consumption” to “resource spending.”
Biochar amendment alone significantly decreased the leaf NRE and PRE of young bamboo but increased that of mature bamboo, suggesting that the effect of biochar amendment on nutrition resorption depends on the age of the bamboo

Summary

Introduction

Nutrient resorption – a physiological process by which plants reallocate nutrients from senescent structures to other living tissues for later use (Clark, 1977; Turner, 1977; Yuan and Chen, 2015) – can improve nutrient utilization (Chapin, 1980; Vitousek, 1984; Wu et al, 2020) and reduce plant nutrient uptake from the environment (Brant and Chen, 2015; Yuan and Chen, 2015; Lü et al, 2020). Nutrient resorption is an important strategy employed by plants to overcome nutrient limitations and meet their nutritional demands (Killingbeck, 1996; Vergutz et al, 2012), and is most commonly quantified using nutrient resorption efficiency (RE) and resorption proficiency (RP; Lü et al, 2020; Wu et al, 2020). Changes in nutrient (N and P) supply influence plant nutrient resorption (Chen et al, 2007). These findings remain highly controversial (Yuan and Chen, 2015; Lü et al, 2020), especially for N addition

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Discussion

Conclusion