Land Use Changes Impact Distribution of Phosphorus in Deep Soil Profile

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.

Section: Introductionmentioning

confidence: 99%

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

Zhu

Zhao

Lin

et al. 2020

“…But, still, over fertilization has its own issues like waste of natural resources, accompanied by a decrease in farmers' economic output. Moreover, it has several environmental demerits like eutrophication (Khan et al 2019;Jahan and Amiri 2018).…”

Section: Introductionmentioning

confidence: 99%

Optimizing Phosphorus Levels in Wheat Grown in a Calcareous Soil with the Use of Adsorption Isotherm Models

Saeed

Jamal

Muhammad

et al. 2020

Crop response to phosphorous (P) application is often erratic in most soil types in the world. In alkaline calcareous soils, P retention and mobilization take place due to precipitation and adsorption. P adsorption isotherms are the powerful tools for assessing optimum P levels for different crops and soils. Laboratory and field studies were carried out to evaluate P sorption capacity in a highly calcareous soil and corresponding fertilizer levels for yielding 0.1 to 1.0 mg P L −1 of soil solution. Although Freundlich adsorption isotherm model showed a better fit than Langmuir model, P fertilizer levels used in the field, ranging from 20 to 150 kg P 2 O 5 ha −1 , were based on Langmuir model to yield the estimated P solution. Moreover, nitrogen (N) and potassium (K) were applied at the rates of 120 and 60 kg ha −1 as urea and potassium sulfate (K 2 SO 4), respectively, in a basal treatment at the time of sowing. Grains per spike, 1000-grain weight, grain yield, spike length, and biological yield were increased as the level of P increased, but the non-significant differences among 90, 100, and 120 kg P 2 O 5 ha −1 for most of the above parameters suggested that the former rate could be the maximum level for wheat fertilization in the calcareous soil. Similarly, plant N, P, and K were increased with application of P, but non-significant differences were observed from doses 90 to 120 kg P 2 O 5 ha −1. Moreover, the rate of 90 kg P 2 O 5 ha −1 could yield 0.6 mg P L −1 of soil solution as per Langmuir adsorption isotherm model, while as per Freundlich model, this value could reach only 0.3-0.4 mg P L −1 , which is close to the published literature. It is concluded that Freundlich adsorption isotherm is more suitable to be used for the calculation of phosphatic fertilizer rate and its adsorption capacity in the given soil than Langmuir adsorption isotherm.

“…In addition, soil C is often associated with major nutrients, especially N, and hence influences the cycling and availability of nutrients for crop and pasture production (Zhou et al 2015). Appropriate land use and soil management can improve the soil quality (Zhou et al 2015;Khan et al 2019). It not only improves land productivity, but also regulates the balance of soil C and N, and improves surface soil structural properties (Lal 2002;Su 2007).…”

Section: Introductionmentioning

confidence: 99%

Recovery Role in Soil Structural, Carbon and Nitrogen Properties of the Conversion of Vegetable Land to Alfalfa Land in Northwest China

Lin

Liu

et al. 2020

Soil structural, carbon (C), and nitrogen (N) properties could be influenced by land-use change. The objective of this study was to investigate the effects of the conversion from vegetable (Brassica pekinensis) planting for 7 years (2007-2014) to alfalfa (Medicago sativa L.) planting with 5 nitrogen levels (N 0~N4) for 3 years (2015-2017) on soil structural, C, and N properties. After vegetable cultivation, soil structural, C, and N properties declined significantly. However, after alfalfa planting, especially in 2017, the lowest values of bulk density (N 1 = 1.32 g m −3 , N 2 = 1.33 g m −3) and the highest values of macroaggregate proportion (N 1 = 78.17%, N 2 = 77.33%) were obtained. The highest values of SOC (N 1 = 11.11 g kg −1 , N 2 = 11.08 g kg −1), SMBC (N 1 = 390.97 mg kg −1), and sucrase (N 1 = 17.47 mg g −1 d −1) were appeared. The maximum values of available nitrogen (N 1 = 57.83 mg kg −1 , N 2 = 59.82 mg kg −1), SMBN (N 1 = 56.01 mg kg −1 , N 2 = 58.14 mg kg −1), and urease (N 2 = 2.71 mg g −1 d −1) were obtained. Taken together, our findings suggest that the conversion of vegetable land to alfalfa land with low N level could significantly improve soil structural, C, and N properties.