Adsorption and Desorption of Phosphorus in Biochar-Amended Black Soil as Affected by Freeze-Thaw Cycles in Northeast China

Ying Han,Byoungkoo Choi,Xiangwei Chen

doi:10.3390/su10051574

Ying Han, Byoungkoo Choi + Show 1 more

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https://doi.org/10.3390/su10051574

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Abstract

Substantial soil phosphorus (P) losses often occur in the northern temperate regions owing to soil freeze-thaw cycles (FTCs). Presumably, biochar amendment is an efficient method of conserving P and sustaining agricultural production in the black soil region of northeast China. However, how biochar interacts with FTCs to affect soil P adsorption and desorption is unclear. A simulated laboratory FTC experiment was conducted on untreated and biochar-amended soil with varying moisture content to assess their effects on P adsorption and desorption. Soil P adsorption and desorption values were fitted with Langmuir and Freundlich isotherms to determine the interaction of the frequency of FTCs with moisture content and biochar amendment. Higher soil moisture content increased soil P adsorption, whereas biochar amendment mitigated decreased P retention by decreasing soil P adsorption capacity. Biochar amendment significantly increased the desorption ratio (Davg) under all the FTCs. The desorption ratio of soil and biochar-amended soil in saturated moisture content treatment was significantly higher than that of 12 FTCs. The FTCs decreased the P availability of biochar-amended soil by enhancing P desorbability. Our results suggest that biochar amendment in arable black soil should not be conducted during FTCs, particularly during snowmelt.

Highlights

Phosphorus (P) is an important nutrient, which determines agricultural productivity, because it plays key roles in plant metabolism, structure, and energy transformation [1,2]
According to Arthur et al [21] and Trazzi et al [12], the values of pH and Soil organic carbon (SOC) increased after biochar amendment
The increases in pH, total P (TP), and total nitrogen (TN) of soil after biochar amendment are most likely due to the effects of biochar [40,41], whereas the increases in available P (AP) and available nitrogen (AN) were due to the interaction between biochar and soil [15]

Summary

Introduction

Phosphorus (P) is an important nutrient, which determines agricultural productivity, because it plays key roles in plant metabolism, structure, and energy transformation [1,2]. Plants can acquire P as phosphate anions (H2PO4− and HPO42−) from the soil solution [3,4]. The P transformation rate between soil solution and soil solids was reported to be highly dependent on phosphate adsorption and desorption characteristics [5]. P adsorption and desorption restricts the capacity of supplying soil P, which affects P uptake and utilization by plants [6]. A better understanding of P adsorption and desorption in agricultural systems is critical for improving P sustainability and increasing crop productivity. Phosphorus fertilizers have been intensively applied to cope with this situation; eutrophication [9] and low utilization of P fertilizers [10] followed

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