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Long-lasting effects of bentonite on properties of a sandy soil deprived of the humus layer

100%

Czaban J. , Czyz E. , Siebielec G. , Niedzwiecki J.

International Agrophysics

2014

tom 28

nr 3

Bentonite has been recognized as a very good material for the improvement of coarse textured soils. In microplot experiment, of a sandy soil deprived of the humus layer was enriched in 1973 with waste bentonite at the rates of 0, 3, 6 and 12 kg m -2 . Until 2002, the microplots were planted with different crops and regularly enriched with mineral a nd organic fertili zers. Since 2003, the microplots were left barren. In 2009, determinations of several features of the soils (in 5-30, 30-55 and 55-80 cm layers) showed that the historical amendment of the sandy soil with bentonite (especially its highest dose) ensured significantly higher contents of water, organic C, clay, silt and a sand fraction with particle diameter <0.1 mm in 5-30 cm layer. Proportions of non-dispersible clay in the total clay of bentonite soils in the two upper soil layers were significantly lower than those of the control soil. A significant increase in the penetrometer resistance was observed in 40-58 cm layers of the control soil and the soil with 3 kg m -2 bentonite amendment, contrary to the soils with two highest bentonite doses.

Size-fractionated chlorophyll a and phycocyanin temporal variations in a highly eutrophic lake and its isolated karstic springs

100%

Tsola S. L. , Renta C. , Macingo S. C. , Karayanni H.

Oceanological and Hydrobiological Studies

2018

tom Vol. 47, No. 2

118--127

Monthly variations of size-fractionated chlorophyll a and phycocyanin were studied in Lake Pamvotis between August 2016 and January 2017. Sampling was conducted at two sampling sites: in the main lake (Site 1: Lake) and in an adjacent man-made water ski lake with karstic springs (Site 2: Springs). Samples were fractionated into three size classes: 0.2–2 μm (pico), 2–20 μm (nano) and 20–180 μm (micro). According to chlorophyll a values, eutrophic to hypereutrophic conditions prevail at Site 1 and oligotrophic to mesotrophic conditions – at Site 2. Similarly, Site 1 was distinguished by higher concentration of phycocyanin compared to Site 2. Fractionated chlorophyll a showed monthly variations at Site 1 with alternations in the dominance between the two larger fractions. The maximum of the 0.2–2 μm fraction was observed in October but it contributed less to the total chlorophyll a content than nano- or microphytoplankton. Its contribution was higher at Site 2, reaching occasionally ~ 40% of the bulk chlorophyll a. However, nanophytoplankton was the fraction found to respond faster when disturbances occurred. At Site 1, phycocyanin correlated well with total chlorophyll a as well as with the micro- and nanophytoplankton fractions, indicating that cyanobacteria represent an important component of the large-sized phytoplankton in Lake Pamvotis.

Zmiany masy i objętości bulw ziemniaka w wyniku absorpcji wody

67%

Sobol Z.

Inżynieria Rolnicza

2006

tom R. 10, nr 11(86)

437-445

W pracy wykonano ocenę dynamiki zmian masy i objętości bulw ziemniaka w wyniku absorpcji wody. Do badań przyjęto cztery odmiany ziemniaka tj. Drop, Ibis, Irga i Salto oraz trzy frakcje wielkościowe bulw tj. >60 mm, 50-60 mm i 40-50 mm. Badania wykonano na bulwach nie obranych i obranych po ośmiomiesięcznym okresie przechowywania. Czas absorpcji wynosił 3,5 h, a częstotliwość pomiaru 0,5 h. Przyrost masy bulw obranych w ciągu 3,5 h absorpcji wody wyniósł średnio około 9%, a przyrost objętości ponad 10,5%. Zmiany masy i objętości bulw nie obranych nie przekraczały 0,5%. Wykazano istotną zmianę absorpcji wody przez bulwy dla badanych odmian i frakcji wielkościowych. Przebieg zmian przyrostu masy i objętości od czasu absorpcji wyrażono równaniami nieliniowymi przy pomocy estymacji metodą najmniejszych kwadratów.

The work shows analysis of change dynamics for potato tuber weight and volume due to water absorption. Four potato varieties were used in tests: Drop, Ibis, Irga and Salto, and three tuber size fractions: >60 mm, 50-60 mm and 40-50 mm. The tests were carried out for unpeeled and peeled tubers after eight months of storage. Absorption time was 3.5 h, and measurement frequency: 0.5 h. At the average, peeled tuber weight gain after 3.5 h of water absorption was approximately 9%, and volume gain exceeded 10.5%. Changes in unpeeled tuber weight and volume did not exceed 0.5%. The analysis proved significant change in water absorption by tubers for tested varieties and size fractions. The relation between changes in weight and volume gain and absorption time was expressed by non-linear equations using the least squares method estimation.