Irrigation water management and quality in two Rocha pear orchards

Tackling human malnutrition resulting from mineral deficits in foods is currently an agro-industrial problem. To address this problematic, an agronomic workflow to enrich Rocha pears in calcium (Ca) was considered in two orchards of Portugal. This study aims to assess quality differences in irrigation water of two orchards (of Rocha pear) where an agronomic Ca enrichment workflow would be performed, and identify possible conditioning to Ca increases in fruits. Thus, electrical conductivity (EC), pH, pHs, cations (Na⁺, K⁺, Ca²⁺, Mg²⁺) and anions (HCO₃^-, Cl^-, SO₄^2-) were attained to calculate Sodium Adsorption Ratio (SAR) index and Langelier Saturation Index (LSI) and assess the agricultural use. Values of EC, pH, pHs, SAR index and LSI of both orchards varied between 1198 – 1211 µS/cm, 7.4 – 7.5, 7.7 – 8.1, 3.5 – 7.4 and -0.69 – -0.21. Regarding Piper classification, irrigation waters were classified as sodium bicarbonate (orchard 1) and sodium chloride bicarbonate (orchard 2). Both orchards presented different classifications regarding the agricultural use, namely C3S1 (orchard 2) and C3S2 (orchard 1). The water of both orchards presented the same salinity hazard (C3), but the use of these irrigation waters is enabled since these trees can be considered salt-tolerant. However, regarding the alkalinization hazard to soils, irrigation water from orchard 2 offers less danger (S1) in comparison to orchard 1 (S2). But a slight inferior LSI (orchard 1) can favor a higher tendency to dissolve calcium carbonate. In conclusion, although slightly different, analysis indicate that waters of both orchards did not induce toxicity to Rocha pear trees.