Distribution Characteristics of Soil Organic Phosphorus Fractions in the Inner Mongolia Steppe

Abstract

Phosphorus (P) is one of the limiting nutrients in Inner Mongolia steppe soil, which seriously affect steppe productivity. Therefore, it is necessary to understand the distribution characteristics of organic P (P o) fractions and their influencing factors in Inner Mongolia steppe soil and to identify the contribution of P o fractions to soil available P (AP) to maintain the sustainable development of the Inner Mongolia steppe by improving the utilization rate of P o. The contents of soil P o fractions such as H 2 O-extractable P o (H 2 O-P o), NaHCO 3-extractable P o (NaHCO 3-P o), HClextractable P o (HCl-P o), NaOH-extractable P o (NaOH-P o), and phytate P (Phyt-P) were determined in soil samples (0-15 cm) from 15 sampling sites representing three types of grassland (i.e., desert steppe, typical steppe, and meadow steppe) in Inner Mongolia. The influencing factors of the soil P o fractions were determined by redundancy analysis (RDA). Soil P o content accounted for 61.0% of the total P (TP) on average. NaOH-P o was the main fraction of P o , accounting for 49.1% of P o on average; H 2 O-P o content accounted for the least amount of P o (mean 1.3 mg kg −1). H 2 O-P o and HCl-P o were not significantly different among the three steppes. The contents of NaHCO 3-P o increased in the order of desert steppe < typical steppe < meadow steppe, and the trend of NaOH-P o and Phyt-P contents were desert steppe < meadow steppe < typical steppe. Pearson correlation analysis showed that NaHCO 3-P o was positively correlated with AP (r = 0.86, p < 0.01). HCl-P o was negatively correlated with AP (r = − 0.56, p < 0.05). NaOH-P o and Phyt-P were significantly positively correlated with NaHCO 3-extractable inorganic P (NaHCO 3-P i); Phyt-P was also negatively correlated with HCl-extractable P i (HCl-P i) (r = − 0.61, p < 0.05). These correlations were mainly caused by differences in steppe types and soil properties caused by climatic conditions, as shown by the result of RDA analysis. Soil P o plays an indispensable role in the supply of soil P in the semi-arid steppe of Inner Mongolia, where NaHCO 3-P o and HCl-P o strongly contributed to AP. In addition, NaOH-P o and Phyt-P as a part of stable pools are important for providing P to other P pools. P o fractions in steppe soils were mainly regulated by climatic conditions and are closely related to the soil organic matter and pH.

Phosphorus deficiencies invoke lipids-like enrich in sweetpotato rhizosphere to stimulate bacterial inositol phosphate metabolism

“…Soil pH was measured in a suspension with a 1:2.5 soil to water ratio (w/v) and using an acidometer (Mettler Fe20, Shanghai). Soil TN content was determined by steam distillation after Kjeldahl digestion at 370°C (Zhu et al 2020). Soil TP content was determined by HClO 4 -H 2 SO 4 digestion method followed by colorimetric spectrophotometry (Thomas et al 1967).…”

Distribution Characteristics of phoD-Harbouring Bacterial Community Structure and Its Roles in Phosphorus Transformation in Steppe Soils in Northern China

“…The soil type at each site was identified based on FAO-UNESCO 1974. More sampling details are showed in Table 1 and provided in Zhu et al (2020).…”

“…Soil AP was extracted by 0.5 M NaHCO 3 with a soil/solution ratio of 1:20 (Olsen et al 1954), and the P in solution was determined using molybdenum blue colorimetry at 880 nm (Murphy and Riley 1962). The soil P fractions were obtained according to a previously published article (Zhu et al 2020). Potential ALP activity at pH 11.0 was analysed using the method described by Wu et al (2006).…”

“…The Inner Mongolia steppe represents approximately 22% of the grassland in China (Zhu et al 2020) and has an indispensable position with regard to ecosystem protection, sandstorm prevention, soil and water conservation and climate regulation (Miu and Liu 2013). However, previous studies have shown that soil P levels have seriously restricted the development of Inner Mongolia steppe productivity (Compton et al 2000;Elser et al 2007) and soil P exists mainly in the form of P o (Zhu et al 2020). Therefore, it is urgent to improve soil P availability in this region through biotic processes such as P o mineralization.…”

An assessment of various pools of organic phosphorus distributed in soil aggregates as affected by long‐term P fertilization regimes

“…The method of Hedley et al (1982) has gained considerable attention as a valuable tool to examine different forms of soil P, which provides a comprehensive assessment of available P in soils (Yang & Post, 2011). Despite the disputes about characterizing Po in chemical P fractionation (Gu & Margenot, 2020; Liu et al, 2013; Zhu et al, 2020), the method is still in vogue. This P fractionation includes NaHCO 3 ‐extractable Po, NaOH‐extractable Po and HCl‐extractable Po, which represent labile Po, moderately labile Po and nonlabile Po, respectively (Khan et al, 2021; Xavier et al, 2009; Zhu et al, 2020).…”