The Crucial Role of Soil Organic Matter in Satisfying the Phosphorus Requirements of Olive Trees (Olea europaea L.)

Abstract

Under high organic matter content, even under low extractable soil P concentrations, sufficient or over-sufficient foliar P levels may be found. This multi-year study aimed at examining the effects of organic matter content and irrigation management on (a) soil fertility, (b) P-cycle related soil enzymes (acid and alkaline phosphatase, pyrophosphatase) and (c) foliar nutrient concentrations. Irrigated and non-irrigated groves of fully productive trees of the cultivar “Chondrolia Chalkidikis” with low organic matter (LOM < 1.5%), medium organic matter (1.5% < MOM < 2.5%) and high organic matter (HOM > 2.5%) were selected for the experimentation. It was hypothesized that olive groves receiving high inorganic fertilization and irrigation inputs (usually with medium to relatively low organic matter content) would show higher soil and foliar P concentrations compared to the non-irrigated groves with higher organic matter content receiving manure applications. Most of the soil variables (including the three enzymes’ activities) were affected by differences in organic matter content. However, organic matter content did not show a significant influence on foliar nutrient concentrations. Olive trees, especially those cultivated in soils with high organic matter content (receiving organic fertilization), can over-satisfy their P nutritional needs, even though soil analyses show low soil extractable P concentrations, probably due to the high enzymatic activity of acid and alkaline phosphatases. The practical conclusion of this study is that P fertilizer recommendations should be primarily based on foliar P rather than on extractable soil P.

Effect of soil management practice on soil phosphorus dynamics: A meta‐analysis

“…For example, application of organic fertilizers can increase phoD gene and phoD‐harbouring bacteria in the soil, which promoted the solubility of inorganic P (Bi et al., 2019; Hu et al., 2018). At the same time, organic matter addition enhances soil phosphatase activity, which converts organic P into inorganic phosphorus (Christopoulou et al., 2021). We found that the application of organic fertilizer increased the Olsen‐P content increased by 82% compared with soils without fertilizers, which could promote crop growth and development.…”

Effect of macronutrient fertilization on olive oil composition and quality under irrigated, intensive cultivation management

“…Clear P‐deficiency symptoms in olives are rare 44,45 and P used to be applied only on the basis of leaf analyses, with 0.1% as a threshold value below which deficiency was considered 1,34,46 . Furthermore, some studies claimed that olives do not require P fertilization at all, especially if they are grown in soils that are rich in organic matter 47 . This was based on the presence of large amounts of total P in most soils on the one hand, and the extensive root system of olives coupled with mycorrhizal symbiosis on the other 48 .…”

“… 1 , 34 , 46 Furthermore, some studies claimed that olives do not require P fertilization at all, especially if they are grown in soils that are rich in organic matter. 47 This was based on the presence of large amounts of total P in most soils on the one hand, and the extensive root system of olives coupled with mycorrhizal symbiosis on the other. 48 Consequently, the number of studies dealing with the effect of P fertilization on olive oil quality and composition is limited.…”