Sodium substitutes potassium requirements of sugar beet under saline-sodic conditions

BackgroundPotassium (K) substitution by sodium (Na) in sugar beet nutrition has been investigated during the last two decades and promising results have been revealed. However, substitution is still not used in agriculture although it has been recommended that Na can replace K to a large degree, proposing an interesting fertilization strategy for such plants. This study investigates the feasibility of sugar beet production on saline-sodic soils considering Na as a substituent for K. AimsThe aim of this study is to develop a fertilizer strategy considering Na concentration in saline-sodic soils as a partial substituent to K fertilizer and to determine the level of substitution. MethodsTwo saline-sodic soils (SAR15 and SAR19 representing sodium adsorption ratios 15 and 19 [mmol L-1](1/2), respectively) with low plant-available K were selected to investigate the substitution of K fertilizer requirements with indigenous soil Na. A pot experiment was conducted with 20 kg soil per pot having four treatments, that is, K-A: recommended K; K-B: recommended K-K equivalent to 2.5% of soil Na; K-C: recommended K-K equivalent to 5% of soil Na; and control without K fertilizer application were established mixing potassium sulfate (K2SO4) in the soil at the time of sugar beet sowing. The sugar beet plants were harvested 90 days after sowing. ResultsThe results revealed that total plant biomass was significantly improved in K-B as compared to K-A. This indicates that K requirement of sugar beet was substituted by Na, and K-B provided optimum results on SAR15 as compared SAR19 considering all other K combinations. ConclusionIn sugar beet nutrition, K can be replaced by Na to a large degree on saline-sodic soils under K-deficient conditions. Therefore, sugar beet production on marginal saline-sodic soil can be a win-win strategy boosting sugar beet production and reducing input cost.