An improved methodology to evaluate crop salt tolerance from field trials

G. van Straten, A. C. de Vos, J. Rozema, B. Bruning, P. M. van Bodegom

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The salt tolerance of crops is commonly expressed in descriptive parameters such as threshold or 50%-yield soil salinity and shape parameters describing the yield curve. Estimation by visual or simplified ordinary least squares (OLS) regression methods has multiple issues: parameter bias due to uncertainty in soil salinity, lack of independent estimates of the reference yield, questionable robustness of the threshold parameter and missing information about uncertainty and correlation of the parameter estimates. Here, we present a comprehensive OLS method together with an analysis of its statistical properties to alleviate and overcome such issues, on the basis of a numerical experiment that mimics observed yield responses to saline groundwater across a range of salinities in the experimental test facility Salt Farm Texel. The results indicate under which experimental conditions bias is not a major problem. The method allows estimation of the zero-observed-effect yield from the data, which is relevant to agricultural practice. Estimates for zero-observed-effect yield and threshold ECe are negatively correlated, underlining the difficulty of obtaining reliable threshold values. The estimated confidence regions are reliable and robust against soil salinity uncertainty, but large observation error jeopardizes the confidence intervals, especially for the slope parameter. Data uncertainty alone can be responsible for substantial differences from experiment to experiment, providing a partial explanation for the wide variety in reported parameters in the literature, and stressing the need for long-term repetitions. Given the lack of robustness of the threshold parameter, we propose to adopt the 90%-yield EC (ECe90) as tolerance parameter. Its confidence bounds can be obtained from a simple reformulation of the original models. We also present uncertainty ellipses as a suitable tool to unite multiple-year estimates. The method is offered as a solid and generic basis for reliable assessment of the cultivation potential of varieties and crops on salt-affected soils.

LanguageEnglish
Pages375-387
Number of pages13
JournalAgricultural Water Management
Volume213
Early online date6 Nov 2018
DOIs
Publication statusPublished - 1 Mar 2019

Fingerprint

salt tolerance
field experimentation
tolerance
salt
crop
methodology
uncertainty
crops
soil salinity
least squares
Texel
soil salts
trial
parameter
yield response
experiment
confidence interval
ellipse
least squares method
groundwater

Keywords

  • Crop salinity tolerance
  • Parameter estimation
  • Salinization

Cite this

van Straten, G. ; de Vos, A. C. ; Rozema, J. ; Bruning, B. ; van Bodegom, P. M. / An improved methodology to evaluate crop salt tolerance from field trials. In: Agricultural Water Management. 2019 ; Vol. 213. pp. 375-387.
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An improved methodology to evaluate crop salt tolerance from field trials. / van Straten, G.; de Vos, A. C.; Rozema, J.; Bruning, B.; van Bodegom, P. M.

In: Agricultural Water Management, Vol. 213, 01.03.2019, p. 375-387.

Research output: Contribution to JournalArticleAcademicpeer-review

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