Wierzbowska J., Cwalina-Ambroziak B., Głosek-Sobieraj M., Sienkiewicz S. 2015. Effect of biostimulators on yield and selected chemical properties of potato tubers. J. Elem., 20(3): 757-768. AbstractGrowth regulators stimulate life processes in plants, improving their stress resistance and health, which translates into higher and better quality yield. Growth regulators can improve biochemical parameters of tubers and enhance the potato's resistance to adverse environmental conditions or pathogens. The purpose of this research was to examine the effect of biostimulators on yield and selected chemical properties of potato tubers. Four table potato cultivars were grown in a field experiment: very early Volumia and medium early Irga, Satina and Sylvana. Starting from stage 39 on the BBCH scale (crop cover complete), potato plants were treated thrice, in 10-to 14-day intervals, with the growth regulators Asahi SL, Bio-Algeen S90 and Kelpak. The reference treatment was composed of potatoes untreated with the bioregulators. The growth regulators, especially Bio-Algeen S90 (6.3 -16.3%) and Kelpak SL (14.2-24.7%) raised the tuber yield, but the effect was statistically verifiable only in the second year, with less precipitation and lower temperature of the vegetation period. The quality of potato tubers was more strongly dependent on the cultivar-specific traits than on the applied biostimulators. In the second year, too, potato tubers contained on average 34% more N-total than in the first year. During storage, the content of N-total in tubers increased by 35-50%. After a five-month storage period, potato tubers contained more NO 3 abut less N-NH 4 + .

Field trials were conducted in 2004–2015, in Bałcyny, on haplic Luvisol formed out of light boulder clay. The experiment consisted of the following treatments: control (no fertilization), NPK, manure (FYM), dried pelleted sewage sludge (DPSS), composted sewage sludge (CSS), compost made from municipal sewage sludge and straw (SSCS), compost Dano made from unsorted household waste (CUHW), and compost produced from urban green waste (CUGW). Over a period of 12 years, 30 t DM/ha of each manure and composts were used, that is, 10 t DM/ha in each rotation of a crop rotation sequence. Nitrogen fertilization was kept on the same level on all experimental plots. Soil samples from the 0- to 20-cm horizon were collected after the third rotation crop, which was winter wheat harvested in 2015. It has been demonstrated that CUHW raised the soil total Cu content the highest, while the soil content of Zn was elevated the most by DPSS. The content of the remaining heavy metals (Pb, Ni, Cr, Mn, and Fe) increased as well, but to a lesser extent. The soil abundance of phytoavailable forms of copper improved even greater (from 75% when fertilized with CUGW or CSS, up to 124% when treated with CUHW). Soil content of soluble forms of such metals as Zn, Pb, Cr, Mn, and Fe changed less. The content of all analyzed heavy metals in soil (a form approximating the total content) was significantly positively correlated with the content of organic carbon (C-org.). This is the evidence for stronger adsorption of the above elements in soil richer in organic matter. On the other hand, the content of available forms of heavy metals depended more on the soil pH than on its content of C-org.

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The purpose of this study was to evaluate the effect of ash from combustion of plant biomass of energy willow and Pennsylvania fanpetals on yields of willow grown as an energy crop and on soil properties. A three-year pot experiment was carried out on substrates with a loamy sand texture. Ash application rates were based on the potassium fertilisation demand. An incubation experiment was carried out to determine the effect of biomass-based ash on soil properties. Three soils with textural categories were incubated for 3 months with the ashes, the doses of which were determined on the basis of the hydrolytic acidity of soils (¼; ½ and 1.0 Hh). It was found that ashes generated from burning willow or Pennsylvania fanpetals can be applied instead of phosphorus, potassium and magnesium fertilisers in the cultivation of energy willow. The plant uptake of P, K and Mg from the ashes did not diverge from their absorption by plants when supplied with mineral salts. The application of these alkaline ashes will increase the soil content of phytoavailable forms of phosphorus, potassium and magnesium. The examined ashes enriched the soil with micronutrients.

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