Elsevier

Field Crops Research

Volume 296, 15 May 2023, 108921
Field Crops Research

Winter wheat yield and soil critical phosphorus value response to yearly rainfall and P fertilization on the Loess Plateau of China

https://doi.org/10.1016/j.fcr.2023.108921Get rights and content

Abstract

Context

The critical value of soil available phosphorus (AP) plays a key role in crop P fertilization, and this value is based on a soil test, but the guidelines for P fertilization of winter wheat based on soil AP in northern China do not yet consider different rainfall patterns, such as above- or below-average annual rainfall or wheat-yearly rainfall (rainfall from June (when crop harvest was normally complete) until the following May).

Objective

To determine the responses of winter wheat yield to wheat-yearly rainfall and P fertilization, calculate the soil critical P value in different rainfall patterns and then provide some suggestions on how to manage the P fertilization of winter wheat.

Methods

Based on 781 pairs of datasets from field experiments with (+P) and without (−P) P fertilizer input on the Loess Plateau of China in 2005 − 2018, wheat yield, P uptake by wheat shoots were measured. Soil Olsen P (0 − 20 cm, sampled at harvest of previous season wheat) and wheat-yearly rainfall from 781 wheat fields were also determined.

Results

The wheat grain yield followed a piecewise linear model with the amount of wheat-yearly rainfall, with a threshold rainfall of 527 and 550 mm for the −P and +P treatments, respectively; the P uptake by wheat was also fitted to a piecewise model with wheat-yearly rainfall. When each site-year was classified into dry, intermediate, and wet rainfall years, a P uptake response to Olsen P was evident only in dry and intermediate years. Olsen P at harvest was 18.9% lower in dry/wet years than in intermediate years. Across all years, the critical Olsen P values were higher for −P (16.2 mg kg-1) than for +P (15.3 mg kg−1) and were lower in dry and intermediate years than in wet years. In addition, an empirical model is proposed to manage P fertilization, where P application rates are calculated from the expected wheat P uptake and the Olsen P level in the soil based on wheat-yearly rainfall or summer-season rainfall.

Conclusions

Wheat-yearly rainfall is the main factor affecting wheat yield, and the wheat-yearly rainfall and P input strongly affected the soil critical Olsen P values in the drylands of the Loess Plateau. A soil critical Olsen P value of 14 − 18 mg kg−1 was determined for dryland wheat production.

Implications

This research implied that the management of P fertilization for green wheat production should consider the rainfall and soil critical Olsen P value in dryland grain production systems.

Introduction

Winter wheat (Triticum aestivum L.) dominates dryland crop production on the Loess Plateau of China, where there is a wide range of annual rainfall (from <200 mm to >900 mm). In this area, winter wheat is seeded in late September/early October and harvested in early June and is planted on more than 4.35 million hectares (2020) under rainfed farming. Therefore, wheat grain yield is strongly affected by rainfall (annual rainfall, summer-season rainfall, wheat-yearly rainfall (defined as the rainfall from June until the following May)) or stored soil water within the 300 cm soil profile at planting (Huang et al., 2003, Dai et al., 2015, Wang et al., 2016, Dai et al., 2022, Qiu et al., 2022). For example, wheat yield varies from 2246 to 6429 kg ha−1 when summer-season rainfall ranges from 95 to 475 mm (Qiu et al., 2022) and from 1603 to 3976 kg ha−1 when stored soil-water ranges from 719 to 616 mm (Huang et al., 2003). In addition, soils in this area have low organic matter, high pH, and strong phosphorus (P) fixation (Gong et al., 1999). The wheat fields in this area received a high rate of phosphorus (P) fertilizer at 53.9 kg P ha−1 yr−1, i.e., approximately 2 times the P uptake by wheat (Zhao et al., 2016, Huang et al., 2018), which resulted in a net build-up of P in the soils due to utilization by crops (10 − 25%) (Zhang et al., 2008b) and thus high available P in soils (Li et al., 2011). Although many previous researchers have focused on the relationships between crop yield and rainfall worldwide (Monti and Venturi, 2007, Ma et al., 2012, Sherrod et al., 2014, Wang et al., 2016, Zachariah et al., 2020, Bozorg-Haddad et al., 2021), there is still a lack of information on the quantitative relationship between yield and wheat-yearly rainfall in the Loess Plateau of China. Therefore, under P input conditions, understanding the links between wheat yield and wheat-yearly rainfall (especially for different rainfall patterns (dry, intermediate, and wet rainfall years)) and soil P is important for P management in dryland wheat green production.

Soil available P (e.g., Olsen P (Olsen et al., 1954), Colwell P (Colwell, 1963), Bray P (Bray and Kurtz, 1945)), together with other soil nutrients, is important for ensuring optimal wheat yields and is the basis for the recommendation of wheat P fertilization. However, if the available P in the soil is higher than a critical threshold, there is no response to the input of fresh P fertilizer and crop yields. Therefore, some researchers have proposed soil critical P values for different crops to manage P fertilization (Bai et al., 2013, Johnston et al., 2013, Poulton et al., 2013, McCaskill et al., 2020), which can improve the soil P status in P-deficient soils, limit soil P accumulation, and save phosphate resources. For soil Olsen P, the soil critical P value (at a depth of 23 cm) for wheat was 13 mg kg−1 at the Exhaustion Land site of Rothamsted based on a Mitscherlich response function and 98% of maximum yield (Poulton et al., 2013), 14.7 mg kg−1 (at a depth of 20 cm and based on a hyperbolic function and 95% of maximum yield) in Switzerland (Cadot et al., 2018), and 10.9 – 21.4 mg kg−1 (at a depth of 20 cm and based on a linear-plateau model and 90% of maximum yield) in different regions of China (Bai et al., 2013). For soil Colwell P, the proposed threshold value was 15 − 47 mg kg−1 for wheat in all of Australia (at a depth of 10 cm and based on a BFDC Interrogator function and 90% of maximum yield) (Bell et al., 2013) and 52 mg kg−1 for wheat and 59 mg kg−1 for canola in the high-rainfall zone of southern Australia (at a depth of 10 cm and based on a BFDC Interrogator function and 95% of maximum yield) (McCaskill et al., 2020). These results suggest that the soil critical P value varied in different sites and crops due to different sampling depths, extractants, choices of mathematical model and definitions of critical value (90 − 98%), agricultural systems, and crops. Meanwhile, these critical levels are in a wide range and not specific to dryland wheat, indicating that a soil critical Olsen P value for winter wheat in the Loess Plateau has not yet been determined. In this area, Huang et al. (2017) proposed a wheat P fertilization method based on soil Olsen P (P input rate (kg P ha−1) = target wheat yield (kg ha−1)÷1000 × 11 ×Pc, where Pc is a coefficient based on the testing values of soil Olsen P). If a critical Olsen P value for wheat is proposed, it will optimize this method, further helping to reduce the input of P fertilizer and save P resources.

Based on 781 pairs of datasets (with (+P) and without (−P) P fertilizer input) from field experiments over 14 years on the Loess Plateau of China, this study aimed to determine the responses of winter wheat yield to wheat-yearly rainfall and P fertilization, calculate the soil critical P value in different yearly rainfall patterns (dry, intermediate, and wet years) and then provide some suggestions to manage wheat P fertilization.

Section snippets

Study site description and experimental design

The study sites located within the province of Shaanxi, China (the center of the Loess Plateau), covered a range of climate types (semiarid and semihumid). The annual total rainfall in Shaanxi Province averages between 400 and 900 mm, while the average temperature varies from 7 °C to 16°C (http://data.cma.cn). The soil in this region is calcareous and is derived from loess parent material. The average soil properties (with a soil depth of 20 cm) in 2005 were pH 7.92, soil organic matter

Wheat grain yield and rainfall

During the experimental period, the average wheat-yearly rainfall was 543 mm (Fig. 2). For the two treatments, the wheat grain yield ranged from 858 to 9008 kg ha−1, and the average wheat grain yield was 5501 kg ha−1 (Fig. 3). Regression analysis showed that wheat grain yield in the two treatments followed a piecewise linear model with wheat-yearly rainfall (Fig. 3), with a threshold value of wheat-yearly rainfall at 527 mm for the −P treatment and 550 mm for the +P treatment. When wheat-yearly

Effect of rainfall and P fertilization on wheat yield in drylands

In rainfed cropping systems, rainfall determines soil water and thus strongly affects crop yield (Anderson et al., 2016, Wang et al., 2016). In the present study, the wheat yield increased with increasing yearly rainfall, but when rainfall reached a threshold of 550 mm (+P treatment), no significant additional yield was gained (Fig. 3). For the different types of wheat-yearly rainfall years (dry, intermediate, and wet years), wheat yield significantly increased from dry years to

Conclusions

The 781 pairs of field experiments showed that the wheat grain yield reached a high level at a wheat-yearly rainfall of 527 – 550 mm (the threshold). The +P treatment significantly increased wheat yield only in the dry years when compared with the −P treatment. In total, uptake of P fitted a piecewise linear model with wheat-yearly rainfall, but in dry and intermediate years, P uptake had a linear relationship with the amount of yearly rainfall. The soil critical Olsen P values were highest in

Funding

This work was supported by grants from the National Key Research and Development Program of China (2021YFD1900700 and 2018YFD0200400), the National Natural Science Foundation of China (32072669), and the Science and Technology Research Program of Shaanxi Province (2022PT-06).

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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