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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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.

With the continually growing amounts of municipal sewage sludge, the problem of its recycling becomes more and more important. Sewage sludge is a noxious but unavoidable by-product of sewage and wastewater treatment. According to the Main Statistial Office (GUS), the total amount of sewage sludge generated in Poland in 2012 was 533.3 thousand tons of d.m., of which 115 thousand tons were then used in agriculture [GUS 2013]. Apart from farming, sewage sludge can also be used to rehabilitate degraded land (50.3 thousand tons of dry matter) and to cultivate plants grown for compost (33.3 thousand tons of d.m.). One of the most rational ways to utilize this ABSTRACT Municipal sewage sludge can be used in agriculture provided that the permissible levels of heavy metals are not exceeded in either the sewage sludge or in the top layer of soil to be amended by this substance, and that its application does not deteriorate the soil quality. The purpose of this study was to determine the effects of different forms of sewage sludge on the content of Cu and Zn in soil and in soil leachate. The study comprised 2 rotations (potato, spring barley, winter oilseed rape, winter wheat). Each series was composed of the following treatments: NPK, FYM, municipal sewage sludge composted with straw, dried and granulated municipal sewage. FYM and composted sewage were applied once in the rotation (under potato) in a dose of 10 Mg d.m. ha -1 and twice (under potato and under winter oilseed rape) in a dose of 5 Mg d.m. ha -1 . In the other years (under spring barley and winter wheat), soil received only mineral fertilization. In order to evaluate the effect of the composts on the leaching of Cu and Zn from soil, a lysimetric experiment was conducted under controlled conditions. Before the experiment, the soil content of Cu was low (1.47 mg kg -1 ) and Zn was medium (10.11 mg kg -1 ). The content of copper in the composts ranged from 4.5 to 340.1 mg kg -1 d.m. and that of zinc was from 109.5 to 1310.1 mg kg -1 d.m. The composted sewage sludge significantly raised the soil content of available forms of Cu and Zn, but did not change the soil nutrient abundance class. Fertilization modified the content of the microelements in the soil leachate.

The purpose of the study has been to determine the direct and residual effect of farmyard manure and composts made from sewage sludge on the content and uptake of copper and zinc by crops growing in a four-field crop rotation system. In 2004-2007, a field experiment was established on proper grey-brown podzolic soil, originating from light boulder clay, rich in P, moderately abundant in K and low in Mg, whose reaction was pH = 5.04. The experiment involved a four-field crop rotation cycle with the following crops: potato, spring barley, winter oilseed rape and winter wheat. The design of the experiment, set up according to the random block method, consisted of 8 object (2 x 4): 1) FYM, 2) composted sewage sludge, 3) compost (sewage sludge + straw), 4) dried and granulated sewage sludge. The composts and farmyard manure were applied once in the rotation system (under potato) at a rate of 10 t d.m. ha-1 or twice, each time 5 t d.m. ha-1 (under potato and under winter oilseed rape). In the objects fertilized with organic fertilizers and manure, nitrogen was balanced to 150 kg⋅ha-1 (under potato) and to 120 kg⋅ha-1 (under oilseed rape) depending on their total content of nitrogen. Spring barley and winter wheat received only mineral fertilizers. Before the experiment was set up, samples of soil, manure and composts had been collected for determination of Cu and Zn in 1 mol HCl dm-3 by atomic absorption spectrophotometry.