Leaching Characteristics of Exogenous Cl<sup>−</sup> in Rain-Fed Potato Fields and Residual Estimation Model Validation
Potato (<i>Solanum tuberosum</i> L.) is a chlorine-sensitive crop. When soil Cl<sup>−</sup> concentrations exceed optimal thresholds, the yield and quality of potatoes are limited. Consequently, chloride-containing fertilizers are rarely used in actual agricultural production...
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| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-07-01
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| Series: | Plants |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2223-7747/14/14/2171 |
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| Summary: | Potato (<i>Solanum tuberosum</i> L.) is a chlorine-sensitive crop. When soil Cl<sup>−</sup> concentrations exceed optimal thresholds, the yield and quality of potatoes are limited. Consequently, chloride-containing fertilizers are rarely used in actual agricultural production. Therefore, two years of field experiments under natural rainfall regimes with three chlorine application levels (37.5 kg ha<sup>−1</sup>/20 mg kg<sup>−1</sup>, 75 kg ha<sup>−1</sup>/40 mg kg<sup>−1</sup>, and 112.5 kg ha<sup>−1</sup>/60 mg kg<sup>−1</sup>) were conducted to investigate the leaching characteristics of Cl<sup>−</sup> in field soils with two typical textures for Northeast China (loam and sandy loam soils). In this study, the reliability of Cl<sup>−</sup> residual estimation models across different soil types was evaluated, providing critical references for safe chlorine-containing fertilizer application in rain-fed potato production systems in Northeast China. The results indicated that the leaching efficiency of Cl<sup>−</sup> was significantly positively correlated with both the rainfall amount and the chlorine application rate (<i>p</i> < 0.01). The Cl<sup>−</sup> migration rate in sandy loam soil was significantly greater than that in loam soil. However, the influence of soil texture on the Cl<sup>−</sup> leaching efficiency was only observed at lower rainfall levels. When the rainfall level exceeded 270 mm, the Cl<sup>−</sup> content in all the soil layers became independent of the rainfall amount, soil texture, and chlorine application rate. Under rain-fed conditions, KCl application at 80–250 kg ha<sup>−1</sup> did not induce Cl<sup>−</sup> accumulation in the primary potato root zone (15–30 cm), suggesting a low risk of toxicity. In loam soil, the safe application range for KCl was determined to be 115–164 kg ha<sup>−1</sup>, while in sandy loam soil, the safe KCl application range was 214–237 kg ha<sup>−1</sup>. Furthermore, a predictive model for estimating Cl<sup>−</sup> residuals in loam and sandy loam soils was validated on the basis of rainfall amount, soil clay content, and chlorine application rate. The model validation results demonstrated an exceptional goodness-of-fit between the predicted and measured values, with R<sup>2</sup> > 0.9 and NRMSE < 0.1, providing science-based recommendations for Cl-containing fertilizer application to chlorine-sensitive crops, supporting both agronomic performance and environmental sustainability in rain-fed systems. |
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| ISSN: | 2223-7747 |