Effect of Soil Mixtures Based on a Gneiss-Derived Soil and Two Forest Floor Types on Growth and Nutritional Status of Castanea sativa Mill. Seedlings

Aiming at the production of robust chestnut plants suitable for the establishment of plantations or for their use in afforestation of forest ecosystems, we studied the effect of soil mixtures on growth, physiological characteristics, and nutritional status of chestnut seedlings. In a complete randomized-block design pot experiment, the soil used was derived from gneiss weathering (GN) and the treatments included GN and GN with fertilization (GN-FER) as well as mixtures of GN with forest floor (FF) from chestnuts (GN-CFF) and from evergreen broad-leaved trees (GN-EFF). Both types of forest floor and fertilization had similar positive effect on seedlings growth and photosynthetic parameters. The most significant effects on soil nutrients were found in GN-CFF and GN-EFF treatments, except for extractable phosphorus (P) and exchangeable potassium (K), whose highest concentrations were observed in GN-FER. Leaf analysis showed that the concentrations of almost all nutrients in all treatments were within the adequacy limits, with the exception of nitrogen (N) in GN, copper (Cu) in GN-EFF, and K in all treatments. Both types of forest floor satisfied the nutritional needs of chestnut seedlings to a large extent and their incorporation in this type of soil combined with limited addition mainly of K and to a lesser degree of P could enhance adequacy of these nutrients in soil and plants. Thus, forest floor application may be an appropriate alternative to integrated nutrient management for robust chestnut seedlings production with significant forestry and environmental impacts.

Automated summary

This study investigated the impact of soil mixtures on the growth, physiological characteristics, and nutritional status of chestnut seedlings. The results showed that both types of forest floor and fertilization had positive effects on seedlings growth and photosynthetic parameters. The GN-CFF and GN-EFF treatments had the most significant effects on soil nutrients, while the highest concentrations of extractable phosphorus (P) and exchangeable potassium (K) were observed in the GN-FER treatment. Leaf analysis revealed that most nutrient concentrations were within the adequacy limits, except for nitrogen (N) in GN, copper (Cu) in GN-EFF, and potassium (K) in all treatments. The incorporation of forest floor in the soil, combined with limited addition of potassium and phosphorus, could improve the nutrient adequacy in soil and plants, making it a suitable alternative for robust chestnut seedlings production.