Changes in Phosphorus Fractions and Its Availability Status in Relation to Long Term P Fertilization in Loess Plateau of China

Abstract

Excessive phosphorus (P) application can alter soil P availability and limit plant growth by compacting soil and fixation of P into different organic and inorganic forms. However, it remains uncertain whether these changes happen after limited fertilization or an excessive rate applied under the winter wheat cropping system. The current study aimed to identify the transformation of P into different organic (Po) and inorganic (Pi) fractions, and their role in the plant P uptake and winter wheat (Triticum aestivum L.) production. A long-term study (12 years) was conducted to assess the changes in soil Pi and Po fractions in response to different P rates (0, 50, 100, 150, and 200 kg P2O5 ha−1) applied to winter wheat. Phosphorus fractions were determined using the Hedley modified Tiessen and Moir fractionation scheme. Our findings demonstrated that different P rates significantly increased the available P, particularly NaHCO3-Pi, in the inorganic P fractions compared to P0 treatment. NaHCO3-Pi showed a strong relationship with grain yield (R2 = 0.91) and P uptake (R2 = 0.80). Grain yield was significantly higher in the P100 treatment, but no significant difference was observed between P100 and P200 treatments. The P200 treatment had a maximum grain P content and plant P uptake. Compared with the P0 treatment, all organic fractions yielded the highest Po with the P rate increase, ranging from 27.3 to 75.6 mg kg−1, 27.2 to 35.6 mg kg−1, and 58.8 to 124 mg kg−1 for NaHCO3-Po, NaOH-Po, and HCl-Po, respectively. Among all Pi fractions, the maximum fraction, known as apatite (HClD-Pi), was found in the P200 treatment with the range of 165 to 245.9 mg kg−1. HClD-Pi accounted for 32% of total P, which can be transformed into the available P form with the passage of time. An increase of 78% in residual P was found under the treatment of P200. The residual P fraction was positively correlated with grain yield, P uptake, and other inorganic fractions. It can be concluded that application of P increases P availability and grain yield with an increase in its application rate, but too much use of P can cause soil pollution and higher fixation of P. Consequently, a balanced application of fertilizer is recommended to reduce its fixation and increase its availability for higher crop yield.

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

“…Finally, increasing the degree of soil aggregation could sharply reduce the loss of P through leaching, thereby promoting Po lability and mineralization (Garland et al, 2018). The results of the current study support previous claims that accumulation of labile Po as part of soil organic matter (SOM) because of the Pi fertilizer addition from the medium to long‐term field trial (12–37 years) with varying P input (Mahmood et al, 2020; McLaren et al, 2015, 2020) or the P distribution within aggregate size classes (Deng et al, 2021; He et al, 2019), highlighting that Po in the NaHCO 3 pools is an important sink of fertilizer P over the medium to long‐term. It is worth noting that Po extracted with NaHCO 3 in soil aggregates was significantly and positively correlated with physiochemical properties such as SOC, indicating that SOC was the most important determinant of labile Po change in soil aggregates (Figure 4a).…”

“…Our finding was similar to the results observed by Jalali and Ranjbar (2010), who found that P was mainly bounded to Ca compounds (HCl-P, 63.7%) in some calcareous soil. It might be because the nonlabile P is considered an indication of the soluble forms in calcareous soil and was shown to accumulate because of the transformation from other fractions after long-term mineral P combined with organic manure (Figure 2c), which improved soil Po availability and fixed as a stable P over time (Aulakh et al, 2003;Jalali & Ranjbar, 2010;Khan et al, 2021;Mahmood et al, 2020). Several other reports have also provided data on nonlabile Po after adding long-term organic amendments (Dou et al, 2000;He et al, 2004He et al, , 2006Leinweber et al, 1997), who reported that organic manure contains high levels of P and Ca, that greatly facilitate the soil Ca-associated P formation, which is thought to transform crystalline Ca-P species into relatively soluble Ca-P species.…”

Influence of Phosphogypsum on The Performance of Wheat (Triticum Aestivum L.) and Properties of Sodic Soil of Alage, Central Rift Valley of Ethiopia

“…The increments in grain yield with increasing levels of PG was due to high P content in the PG-treated soil. The grain yield was decreased at every PG rate in the second cropping season due to decreasing soil available P. Additonally, strong positive linear relationships were observed between grain yield, P uptake, and soil available P. These results are in line with previous ndings (Saha et al 2014;Mahmood et al 2020). The relationships were relatively stronger under banded compared to broadcasted plots in the rst cropping season which might be due to increased concentration of available P in soil solutions in the banded plots.…”

Effects of Phosphorus Supply on the Leaf Photosynthesis, and Biomass and Phosphorus Accumulation and Partitioning of Canola (Brassica napus L.) in Saline Environment

“…Regarding biomass and P partitioning, the best improvements were recorded under either 120 kg P 2 O 5 ha −1 treatment or 150 kg P 2 O 5 ha −1 , and effects of these two treatments were comparable. Moreover, a balanced P fertilizer supply can improve plant growth and yield due to increased soil P availability, but excessive P input was reported to cause soil pollution and P fixation [44]. Therefore, to avoid over application of P fertilizer, the rate of 120 kg P 2 O 5 ha −1 is more appropriate.…”