In-depth insight into the short-term effect of floor management practice on young apple trees development and soil microbial biodiversity and activity

PLOS One | https://doi.org/10.1371/journal.pone.0329979 August 7, 2025 6 / 15 Nutrient cycling in soil and trees The two mixtures affected both soil nutrients content and their seasons dynamics, as well as the soil chemical buffering capacity (Fig 1 and S1 Table). The presence of T. repense, a leguminous, in Mix1 induced a higher N-NO3 content in the soil, particularly compared to the control, through the spring and summer sampling points, and avoid- ing the decrease occurring during summer observed in the control. Even though the seasonal dynamics of N-NH4 was only slightly affected by the mixtures, being in general similar to the control (any potential differences arise only from observed deviations between replicates), a higher content was determined in the summer samples from Mix2 treatment. Considering the other nutrients, both mixtures only marginally affected their dynamics, changes occurring only in case of Mix2 for K and P. Considering the level of the other nutrients both mixtures induced a reduction of K content, but not always significant, while no differences were observed for the other cations and P contents. Both mixtures stabilized the pH during the season compared to control, while no major changes occurred to the salinity level (S1 Table). The two kinds of living mulches did not affect N content in leaves, but Mix1 statistically reduced K and P content, while increasing Mg content compared to control and Mix2, which only induced a reduction in Ca content in the leaves (Table 2).

However, the analysis of all macroelements levels in leaves discriminated both Mix1 and Mix2 treatments from the control and among them (Fig 2). Fig 1. Dynamic and concentration of soil nutrients as affected by the introduction of two kinds of living mulches. Mean±SD, n = 3. Letters show statistically significant differences for p ≤ 0.05 (A-C for the same treatment in different timepoints, a-b for different treatments in the same timepoint). https://doi.org/10.1371/journal.pone.0329979.g001 Table 2. Macroelements content in leaves (% of dry weight) as affected by two kinds of living mulches. Treatment N P K Ca Mg Control 2.36 a 0.18 a 1.80 a 1.66 a 0.27 b Mix1 2.27 a 0.16 b 1.48 b 1.75 a 0.33 a Mix2 2.32 a 0.18 a 1.80 a 1.42 b 0.25 b Different letters show statistically significant differences for p ≤ 0.05. https://doi.org/10.1371/journal.pone.0329979.t002