Nutrient status and production of fodder beet irrigated with saline-sodic water in Mediterranean calcareous soils

Abstract

ABSTRACT The impact of drip irrigation with saline-sodic water on the nutrient status and productivity of fodder beet (Beta vulgaris) was evaluated in rainy and dry Mediterranean cropping seasons. Two field experiments were conducted during two growing seasons (winter and summer) in calcareous soil (31% CaCO3) of Sais area, Northwestern Morocco. The rainfall was 337 mm for winter and 53 mm for summer. Four salinity levels of irrigation water (ECi) were investigated: control (1ds m−1), 4, 6, and 10 ds m−1. The ECi levels were prepared by adding sodium chloride (NaCl, laboratory grade, 99.5%) to water. The results showed that the soil salinity (ECs) was related to the growing season and the irrigation water salinity (ECi). The depressive effect of salinity on the whole plant dry biomass (−25% as average) was observed only in the summer crop cycle at different ECi ≥ 4 ds m−1 compared to control. The plant NaCl uptake for both seasons could be predicted by a linear model: Y (kg ha−1 of NaCl) = 36.3 ECi + 23.6 Q − 101.3 (adjusted R2 = 0.88) where Q = total dry biomass (t ha−1). Saline-sodic irrigation water reduced the contents of boron, calcium, and magnesium in the plants. The exchangeable sodium percentage (ESP) in the soil exceeded 41% at ECi ≥ 4 ds m−1 for both seasons. The study demonstrated that fodder beet escapes the negative impact of salt stress in the rainy season. However, the high ESP recorded at harvest did not reveal the efficacy of fodder beet in NaCl removal from the soil.