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.

The purpose of this study was to evaluate the effect of meat and bone meal (MBM) on cultivation of winter triticale, winter oilseed rape, winter wheat and maize. The average annual yields and protein yield achieved in crop rotation were studied. The field trials were carried out in north-eastern Poland in 2006-2010. The factor was dose of MBM: 1.0, 1.5, 2.0 and 2.5 t ha -1 year -1 or 2.0, 3.0, 4.0 and 5.0 t ha -1 every other year. The four-year experiment has proven that MBM is a valuable nitrogen and phosphorus fertilizer in cultivation of cereals and oilseed rape. By amendment of the tested meal into the soil it produced crop yield and protein yield similar to that achieved by mineral fertilization. However, the crude fat yield of rape was significantly higher under the influence of all the MBM doses. The yield-stimulating effect of MBM did not depend on the frequency of its application; therefore it is more convenient to apply it once every two years. Increasing MBM from 1.5 to 2.5 t ha -1 did not significantly increase any of the four crop yields, therefore for soils that had satisfactory nutrients content, 1 or 1.5 t ha -1 MBM is enough and increasing MBM will only increase economic burden for farmers and environmental risks.

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.

The objective of this study has been to follow modifications in the content of Cu, Zn and Mn in the topmost layer of soil which had been fertilized for many years with farmyard manure and mineral fertilizers or with mineral fertilizers alone. Soil samples were collected in 2002-2005 from a trial established in 1986 on proper brown podsolic soil, according to the random block design with four replication. The first factor consisted of organic fertilization (manure applied every two years or without manure). The second factor involved different rates of mineral fertilization. Rates of nutrients in the mineral fertilizers were identical in both experimental series-with or without manure. In each year, the same crop was grown on both fields, in a crop rotation system: sugar beet (2002), spring barley (2003), maize (2004) and spring wheat (2005). Plant available forms of nutrients were extracted from soil in 1 mol HCl dm-3 solution. After extraction, the content of metals was determined by atomic absorption spectrophotometry. The results underwent statistical processing using analysis of variance for a two-factor experiment. The content of available forms of copper, zinc and manganese in soil regularly amended with manure was evidently higher than analogous concentrations determined in soil receiving only mineral fertilization since 1986. Manure most strongly improved the concentration of Cu (nearly 1.7-fold), while producing the weakest influence on manganese (over 1.3-fold more). In absolute values, however, the increase in availability of manganese was the highest, reaching on average 52 mg kg-1 of soil. Differentiated mineral fertilization with nitrogen or potassium as well as manganese and liming to a lesser extent than manure modified the availability of Cu, Zn and Mn in soil. Among these nutrients, nitrogen most often increased the content of plant assimilable forms of metals in soil, which may have been caused by its acidifying influence.