Biomass Production and Nutrient Status of Alfalfa (Medicago Sativa L.) In Response to Boron Supply in Sandy Soil

Abstract

ABSTRACT Boron (B) fertilization management of alfalfa, as perennial crop, requires to identify its sensitivity to B and its nutrients status after B supply for different forage harvests. The response of alfalfa to B supply, when grown on a Mediterranean sandy soil, was evaluated at different cuts. The native soil B content was around 0.15 mg kg−1, which was considered as B deficient. 19 cuts were evaluated in container experiment during three successive production seasons: 2016 (5 cuts), 2017 (7 cuts), and 2018 (7 cuts). Six soil B supplies were tested: 0 (control), 0.2, 0.5, 1, 5, and 10 mg kg−1. B was added in the sodium form. It was split equally between sowing and after the first cut for each rate. The results revealed that B deficiency symptoms did not induce a negative impact on total biomass production and protein content. Shoot B content of all cuts increased with increasing B rates. The lowest shoot B levels (<35 mg kg−1) were recorded in control after five successive cuts. B uptake for each cut can be predicted using the regression model: y (mg kg−1 of soil) = 0.018 x–0.01 z + 0.14 (adjusted R2 = 0.61) where x = soil B supply (mg kg−1) and z = cut number during growing seasons (from 1 to 19). The residual soil B was less than 0.5 mg kg−1, after 19 cuts, for different B rates. The results suggest that alfalfa seems not to be affected by B deficiency particularly during the first 3 years of production in sandy soil.