Wheat yield prediction by zero sink and equilibrium-type soil phosphorus tests
Section snippets
INTRODUCTION
Phosphorus (P) is an essential macronutrient in crop production (Ma et al., 2009). Globally, low P status of soil is considered a main limiting factor of productivity, resulting in yield gaps relative to the yield potential if P is not supplied in appropriate amounts (Foley et al., 2011). Conversely, long-term input of P at high fertilization rates has been related to many problems, including unsustainable mining of the limited resources of rock phosphate (Jedelhauser and Binder, 2015),
Experimental sites and soils
We obtained archived soil samples and grain yield data of wheat (Triticum aestivum L.) from six long-term experiments in southern and central Sweden. These experiments have been documented in detail in previous publications (Kirchmann, 1991; Kirchmann and Eriksson, 1993; Kirchmann et al., 1999; Carlgren and Mattsson, 2001). The sites differ in climate conditions, with a mean annual temperature range of 7.1–8.1 °C at the southern sites and 5.0–5.5 °C at the central sites. Mean annual
Soil P tests
The extraction yields of P-AL ranged between 1.00 and 227 mg kg-1, with a mean of 29.3 mg kg-1 (Table III). The range of P-H2O was 0.019–19.9 mg kg-1 (corresponding to 0.001 9–1.99 mg L-1 at solution:soil ratio of 10:1), with a mean of 3.14 mg kg-1. The P-DGT varied between 1.41 and 457 μg L-1, with a mean of 80.8 μg L-1. The coefficient of variation (CV) for the P tests was the largest for P-AL (167%), followed by P-H2O (125%) and P-DGT (112%).
The relationships between the P concentrations
DISCUSSION
For all responsive trials approaching a yield plateau, the prediction of RY was generally poor, with a somewhat better performance of P-DGT (R2 = 0.25) (Fig. 2e). This observation is consistent with previous investigations of European soils by Nawara et al. (2017), who reported an R2 of 0.37 for the RY response to P-DGT. The fit between P-H2O and RY in our study (R2 = 0.18) (Fig. 2c) was worse than that between P-CaCl2 and RY (R2 = 0.31) reported by Nawara et al. (2017). However, in our study,
CONCLUSIONS
Our work adds to the available information on DGT calibration for soil P testing. It shows that P-DGT can well explain the variation in RY of wheat in the moderately weathered temperate zone soils of Scandinavia and outperforms both quantity and intensity tests, likely because of its ability to integrate intensity, diffusion, and resupply from the solid phase into one measurement. This is in line with diffusion-controlled P uptake by crops grown in temperate zone soils and the related vast
ACKNOWLEDGEMENTS
We acknowledge the support of Dr. Olivier Duboc and Ms. Veronika Slavik in the laboratory. Funds were received from the Austrian Research Promotion Agency (FFG) through the Research Studio Austria FERTI-MINE (No. 844744).
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