XVII INTERNATIONAL PLANT NUTRITION COLLOQUIUM
PLANT NUTRITION FOR NUTRIENT AND FOOD SECURITY
August 19-22, 2013 Istanbul, Turkey
Call for Papers
Template to Assist Authors Submitting Abstracts
Two-Page Abstracts should be submitted in MS-Word format as follows:
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Selected Sessions:
1st Choose: Nutrient Management and Fertilizers in Crop Production 2nd Choose: Mineral Nutrition and Abiotic/Biotic Stress
The deadline for submission of abstracts is March 25, 2013. All submissions will be acknowledged.
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The organizers of the XVII IPNC are gratefully acknowledge the 3rd Intl' Zinc Symposium (2011), Hyderabad, India and 8th ICOBTE Conference (2005), Adelaide, Australia, from which this template is taken.
Multi plant parameter calibration for soil P tests
Liebisch F.
1, Huguenin-Elie O.
2, Sinaj S.
3, Bünemann E.K.
1, Oberson A.
1and Frossard E.
11Institute of Agricultural Sciences, Eschikon 33, CH 8315 Lindau, SWITZERLAND
2Research Station Agroscope Reckenholz-Tänikon (ART), Reckenholzstrasse 191, 8046 Zürich, SWITZERLAND
3Research Station Agroscope Changins-Wädenswil (ACW), Route de Duillier 50, Case Postale 1012, CH-1260 Nyon 1, SWITZERLAND
(frank.liebisch@usys.ethz.ch)
INTRODUCTION
Clear definitions of deficient, sufficient and surplus phosphorus (P) availability are a prerequisite to precisely characterize soil P status for plant nutrition and environmental purposes. Often, reported thresholds and sufficiency ranges are different between studies. Differences in applied methods for estimation of soil available P and expectations of plant yield or P content are reasons for derivation of different values. In agricultural permanent grasslands such thresholds are not yet well defined. In this study we aimed to establish thresholds for soil available P using yield and plant P nutrition status response curves in a combined approach.
METHODS
We investigated three permanent grasslands managed at different harvest intensities (two to five cuts year-1) with no (P0), sufficient (P1) or surplus P (P2) inputs (Fig.1). A detailed description on management, fertilizer input and botanical composition can be found in Liebisch et al.
(2013).
To estimate soil available P we used three soil P indicators based on different principles: a chemical extraction method (Pox), an isotopic exchange kinetic (E1min) and an ion sink method (Pres). The soils were investigated in four depths from 0 to 40 cm). The procedures for soil sampling and analysis are reported in Liebisch et al.
(2011).
The yield response was determined as
the percentage of the expected yield using management specific average yield from the Swiss fertilizer recommendation as 100% (Flisch et al. 2009). Sward P status was determined in the grass fraction as P concentration and the P nutrition index (PNI) (Liebisch et al., (Liebisch et al. 2013).
We established exponential functions with a maximum (f=y0+a*(1-exp(-b*x))) for the relations of relative yield, P concentration and PNI (y-axis) to different soil P indicators (x-axis). To define the soil available P classes deficient, sufficient and surplus for plant growth the three thresholds low, middle and high (Fig. 1) were set for relative yield as 90, 95 and 100%, for grass P concentrations and PNI the thresholds 2.1, 3.0 and 3.5 mg P g-1 80, 100 and 120 as reported by Liebisch et al. (Liebisch et al.
2013) were used, respectively.
Fig. 1: Scheme of the Relationship of relative yield and the phosphorus nutrition index to soil available P (here shown exemplarily for resin extractable P, Pres), adapted from Liebisch et al. (2011).
RESULTS AND DISCUSSION
Relative yield, P concentrations and the PNI resulted in different soil P thresholds making a selection of the suitable values necessary. For the low threshold, relative yield was related to higher values for each of the soil P indicators than PNI in grass. For the high threshold PNI in grass resulted in higher values of soil P indicators than relative yield. The highest maximum of the curves (PNI) indicated values substantially beyond the high soil P threshold which were related to significant increases of P in the subsoil (20-40 cm). Given the relative changes of P nutrition status among the plant indicators a combination ofyield and plant P status for the identification of soil P status seems practical (Table 1).
Table 1. Thresholds (mean) and ± 95% confidence ranges of Pox, E1min and Pres of the threshold derived by the combined approach using relative yield, plant P conentration and PNI. For the synthesis of the threshold derived by the three plant parameters the highest observed value was selected. For the maximum of the function no 95% confidence range is shown.
Plant indicator P
oxE
1minP
resmg kg
-1Total range 141-908 1.46-73.2 0.53-69.3
CV 58 131 120
mean ± 95% mean ± 95% mean ± 95%
Combined thresholds
Low 90% 230 +190 -290 4 +3.2 -5.4 3 +2.0 -4.5
Middle 95% 280 +250 -375 6.5 +5.3 -7.5 6 +5.0 -7.3
High 100% 380 +320 -510 9.8 +8.0 -12.0 10.2 +8.6 -14
Maximum 700 30 24
CONCLUSIONS
The combination of yield and plant P nutrition information seems to improve the reliability of threshold derivation for soil P availability classes. By using the highest plant indicator for each threshold level ensures that the other plant indicators reach their required level as well. The highest observed maximum of the fitted functions of each soil P indicator could serve as threshold for severe over fertilization. Among the three soil P indicators Pres had the strongest coefficients of determination with grass P concentration and PNI, thus it reflected sward P nutrition status better than Pox or E1min.
ACKNOWLEDGEMENTS
We thank the SNF, COST and ETH Zürich for funding.
REFERENCES
