The acidic exopolysaccharide (EPS) produced by Rhizobium leguminosarum bv. trifolii is required for the establishment of effective symbiosis with compatible host plants (Trifolium spp.). In the rhizobium-legume interaction, early stages of root infection and nodule development have been well studied from a genetic standpoint. However, factors important for colonization of several surfaces by rhizobia, including soil particles and roots, have not yet been thoroughly investigated. The aim of this study was establishing of environmental factors affecting production of EPS by R. leguminosarum bv. trifolii strain 24.2 and the role of this polysaccharide in bacterial surface properties and attachment ability.

Zeolites, naturally possessing a high negative surface charge and large specific surface, are used in agriculture as cationic fertilizers, water holders, heavy metals, and organic pollutants sorbents. Since some nutrients occur in anionic forms, there is a need to modify the zeolite surface to hold anions. In this study, hydrogen (hydrochloric acid), iron (Fe²⁺ and Fe³⁺), and aluminum cations as well as the influence of sodium hydroxide modifiers on the specific surface area, water vapor, adsorption energy, fractal dimension, mesopore volumes and radii, electrokinetic (zeta) potential, and isoelectric point were investigated. The use of alkali solution did not affect the zeolite properties significantly, whereas hydrogen, iron, and treatments with aluminum cations resulted in an increase in the specific surface area, mesopore volumes, and radii, and a decrease in the water-binding forces. Aluminum cations were the most effective in recharging the zeolite surface from negative to positive, shifting the isoelectric point toward the highest values. Calcination enlarged the negative surface charge and mesopore radius, and diminished the surface area and mesopore volume. The modified zeolites are promising carriers of anionic nutrients, large surface area sorbents, and suppliers of water for plant roots in soil.

This paper presents the application of a frequency-domain reflectometry (FDR) sensor designed for soil salinity assessment of sandy mineral soils in a wide range of soil moisture and bulk electrical conductivity, through the determination of soil complex dielectric permittivity spectra in the frequency range 10–500 MHz. The real part of dielectric permittivity was assessed from the 380–440 MHz, while the bulk electrical conductivity was calculated from the 165–325 MHz range. The FDR technique allows determination of bulk electrical conductivity from the imaginary part of the complex dielectric permittivity, without disregarding the dielectric losses. The soil salinity status was determined using the salinity index, defined as a partial derivative of the soil bulk electrical conductivity with respect to the real part of the soil complex dielectric permittivity. The salinity index method enables determining the soil water electrical conductivity value. For the five sandy mineral soils that have been tested, the relationship between bulk electrical conductivity and the real part of dielectric permittivity is essentially linear. As a result, the salinity index method applied for FDR measurements may be adapted to field use after examination of loam and clayey soils.

In order to improve optical properties of materials made of nanocellulose and also minimalize costs, small amounts of mineral fillers such as different forms of calcium carbonate are added. In this work nanocellulose was obtained from apple pomace. The precipitated calcium carbonate (PCC) in amount of 3.74 ± 1.36% of a sample dry matter was deposited on cellulose fibers during isolation process. Isolated cellulose was then treated with ultrasonic method in order to obtain apple cellulose nanofibrills (ACNF)/PCC nanocomposites. Different ultrasonication conditions were applied in order to evaluate how time (0–60 min) and power (0–400 W) influence on the ACNF/PCC nanocomposites properties. Moreover structure, chemical composition, morphology and rheological properties of both cellulose and composites were characterized. Also the mechanical properties of nanopapers made of ACNF/PCC nanocellulose were measured. The nanofibril structure of ultrasound processed cellulose was confirmed. In all cases samples were pseudoplastic fluids with quite low viscosity. The mean hydrodynamic diameter of particle dispersions decreased the most after use of ultrasounds for 60 min and the obtained dispersions were also the most homogeneous. The elastic modulus of obtained nanopapers were 2–3 GPa and tensile strength 60–70 MPa and in general ultrasonication improved their rigidity.