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Long-term application of P fertilizers may eventually result in excess and/or toxic accumulations of trace elements and microelements in soil. The effect of monoammonium-phosphate (MAP) on basic soil properties (pH, CEC, texture), the total content of C, N, and F, hot acid-extractable Cu, Zn, Ni, Cr, Pb, Cd, Co, As, Hg, and F, and the content of extractable macro- and trace elements (P, K, Ca, Mg, Al, Fe, Zn, Cu, Ni, Pb, Cd, F) were studied on a Stagnosol soil. Phosphate fertilizer had been applied (26, 39, and 52 kg P ha(-1)) over a 40-yr period. Phosphorus fertilization significantly decreased pH and increased clay content of the soil. Increases were detected in available P, exchangeable Al, Ca, cation exchange capacity (CEC), and clay content. The content of hot acid-extractable Pb increased, whereas the content of diethylenetriaminepentaacetic acid-extractable Pb decreased in accordance with applied rates of MAP. The status of some hot acid-extractable trace elements (Cu, Zn, Ni, and Co) did not change after 40 yr of MAP application, whereas Hg and Cd increased. However, despite the statistically significant increases in the amounts of some potentially toxic elements, they did not accumulate to concentrations considered toxic as overall concentrations are far below the maximum allowed concentrations for natural unpolluted soils.

Raspberries thrive best in an acid soil. However, if the soil pH is lower than 5.6, lime application is necessary. In this study the effects of lime and dolomite application in combination with NPK 15:15:15 fertilizer (600 kg ha -1 ) on the macroelement contents (N, P, K, Ca, and Mg) in an extremely acid soil (pH 4.35) and raspberry leaves were evaluated during a three-year period. Optimal pH value for raspberry cultivation (5.84) was achieved with the application of 9 t ha -1 of lime. The mineral nitrogen (NH 4 + NO 3 )-N content and P content in the soil after liming increased significantly, but P concentration stayed below the optimal values. Additionally, no changes were noted in K concentration in the soil. The Ca concentration increased significantly in all treatments, while the Mg content increased significantly only in the treatment with dolomite. The N content in the raspberry leaves increased, but K content decreased after liming. There was no change in P content in the leaves affected by liming. Lime increased Ca content in the leaves above the optimal values, while it did not affect the initially optimal Mg content in the leaves. After liming and NPK fertilization, the concentrations of N, P and K in the leaves were still below the optimal values, indicating a need for the combination of higher rates of fertilizer with lime in raspberry cultivation in very acid soils.Additional key words: amelioration of acid soils; macronutrient concentration; raspberry cultivation; Rubus idaeus L. ResumenOptimización del contenido en macroelementos en hojas de frambueso mediante encalado en suelos muy ácidos Los frambuesos crecen mejor en suelos ácidos. Sin embargo, si el pH del suelo es inferior a 5,6, es necesario aplicar cal. En este estudio se evaluaron durante un período de tres años los efectos de aplicar cal y dolomita, en combinación con fertilizantes NPK 15:15:15 (600 kg ha -1 ), en el contenido de macroelementos (N, P, K, Ca y Mg) en un suelo extremadamente ácido (pH 4,35) y en hojas de frambueso. El pH óptimo para el cultivo del frambueso (5,84) se logró con la aplicación de 9 t ha -1 de cal. En el caso del suelo, después del encalado el contenido en nitrógeno mineral (NH 4 + NO 3 )-N y de P aumentó significativamente, pero la concentración de P se mantuvo por debajo de los valores óptimos; además, no se observaron cambios en la concentración de K; la concentración de Ca aumentó significativamente en todos los tratamientos, pero el contenido de Mg aumentó significativamente sólo en el tratamiento con dolomita. En las hojas de frambueso, después del encalado el contenido de N aumentó, pero el contenido de K disminuyó; no hubo cambios en el contenido de P; el contenido de Ca aumentó por encima de los valores óptimos, mientras que no se afectó el contenido inicial óptimo de Mg. Después del encalado y la fertilización NPK, las concentraciones de N, P y K en las hojas estaban todavía por debajo de los valores óp-timos, lo que indica la necesidad de combinar mayores tasas de abono con cal en el cultivo...

A diverse group of soil bacteria found in the rhizosphere which can colonize plant roots and improve plant growth are designated as plant growth promoting rhizobacteria. The aim of this study was isolation and screening of different rhizobacterial strains for plant growth promoting characteristics and their ability to improve growth of two grass species, orchardgrass (Dactylis glomerata L.) and meadow fescue (Festuca pratensis Huds.). The strains investigated, belonging to the genera Azotobacter, Bacillus, Pseudomonas and rhizobial bacteria, showed various plant growth promoting traits, such as phosphate solubilisation, siderophore production, and indole-3-acetic acid (IAA) production. Co-inoculation of meadow fescue with Azotobacter chroococcum A2 and Sinorhizobium meliloti or Pseudomonas sp., and A. chroococcum A5 with S. meliloti, significantly increased shoot dry weight (SDW)(25-33%), as well as total N (26-33%), P (24-31%) and K (26-28%) contents in plants (mg pot ), compared to uninoculated control. In addition, inoculation of orchardgrass with A. chroococcum strain A1, as well as co-inoculation with B. megaterium and A. chroococcum A1 or A31, significantly increased SDW (51-59%) and total N (54-59%), P (51-74%) and K (49-55%) contents, compared to uninoculated control. Nitrogen percentage in SDW was slightly higher than sufficiency ranges, while K percentage was optimal in all treatments in both species. Phosphorous percentage was lower than sufficiency ranges as a consequence of very low soil P content. The results emphasize the potential of particular rhizobacteria to improve the growth of forage grasses.

Microbially mediated soil organic matter is an extremely sensitive pool that indicates subtle changes in the quality parameters responsible for the soil’s ecological and productive functions. Fifty years of mineral fertilization of a wheat-corn cropping system has a strong impact on soil quality parameters. The goal of the research was to study the dynamics and quality of soil biological parameters affected by increasing amounts of mineral nitrogen. Soil respiration, potentially mineralizable C and N, microbial biomass C and N and light-fraction OM on Cambisol were analyzed in the following treatments: (1) Control (without fertilization); (2) NPK (60/51/67); (3) NPK (90/51/67); (4) NPK (120/51/67); (5) NPK (150/51/67 kg ha−1). The parameters studied were significantly affected by the long-term application of mineral fertilizer compared with both the control and the adjacent native soil. The highest amounts of nitrogen (N150) did not significantly differ from N120 and N90 for most of the parameters studied. Potentially mineralizable C represented the largest labile carbon pool, while microbial biomass N was the largest labile nitrogen pool. The mineralization rates for C and N were oppositely distributed over the seasons. The sensitivity index correlated with the amount of light-fraction OM. The results give a deeper insight into the behavior and distribution of different pools of labile SOM in the agro-landscapes and can serve as a reliable basis for further research focused on zero soil degradation.