On Sandy, Boron-Poor Soils, Liming Induced Severe Boron Deficiency and Drastically Reduced the Dry Matter Yield of Young Olive Trees

Abstract

In the northeast of Portugal, like in many parts of the world, most soils are acidic, which may hamper crop productivity. This study presents the findings of a factorial experiment on olive (Olea europaea L.) involving three factors: (i) soil type [schist (Sch) and granite (Gra)]; (ii) cultivars [Cobrançosa (Cob) and Arbequina (Arb)]; and (iii) fertilizer treatments [liming (CaCO3) plus magnesium (Mg) (LMg), phosphorus (P) application (+P), boron (B) application (+B), all fertilizing materials combined (Con+), and an untreated control (Con-)]. Dry matter yield (DMY) did not show significant differences between cultivars, but plants grown in schist soil exhibited significantly higher biomass compared to those in granite soil. Among the treatments, +B and Con+ resulted in the highest DMY (50.8 and 47.2 g pot−1, respectively), followed by +P (34.3 g pot−1) and Con- (28.6 g pot−1). Treatment LMg yielded significantly lower values (15.6 g pot−1) than Con-. LMg raised the pH above 7 (7.36), leading to a severe B deficiency. Although Con+ also raised the pH above 7 (7.48), it ranked among the most productive treatments for providing B. Therefore, when applying lime to B-poor sandy soils, moderate rates are advised to avoid inducing a B deficiency. Additionally, it seems prudent to apply B after lime application.

Methylobacterium symbioticum Applied as a Foliar Inoculant Was Little Effective in Enhancing Nitrogen Fixation and Lettuce Dry Matter Yield

“…Soluble B in the soil is primarily in the form of boric acid (H 3 BO 3 ), which is the main form taken up by plants at pH levels between 5 and 9 [49,52], making it less likely for antagonistic or synergistic interactions to occur with N in absorption. On the other hand, soils low in organic matter and clay have a very limited capacity to supply B to plants [5,52], as has been demonstrated in many other studies in the region [53,54]. It was likely the limitation in B supply to plants that facilitated the occurrence of the dilution effect, as the N rate stimulated an increase in biomass production.…”

Omitting the Application of Nitrogen or Potassium Reduced the Growth of Young Chestnut (<em>Castanea sativa</em>) Trees, While a Lack of Boron Decreased Fruit Yield

“…Perhaps for these reasons, B deficiency is more widespread globally than that of any other micronutrient [6,7]. In this region, where soils have limited available B, the nutrient's importance in fertilization programs for dicots species is considered equivalent to that of N, despite being a micronutrient [30,31]. Thus, based on this study, the relationship between B deficiency and the plant's difficulty in fruit production seems evident, even though there was no recorded reduction in shoot growth.…”

“…On the other hand, in vast regions of the world, soils do not provide B to plants in adequate amounts, making it important to apply the nutrient as a fertilizer to maintain crop productivity [28][29][30]. In the north of Portugal, the importance of B in fertilization programs has been considered equivalent to that of macronutrient [30,31].…”