Results of the long-term field experiment IOSDV Jable at the beginning of the 21st century

The impact of organic fertilization and the level of mineral nitrogen fertilization on organic nitrogen and humus balance was studied in a long-term field experiment IOSDV Jable in central Slovenia (sub-Alpine climate, average annual precipitations 1345 mm, average annual temperature 9.5°C, heavy hydromorphic silty loam, umbric Planosols). During the period 1993–2010, precipitation increased significantly at an average rate of 19 mm a^?1; over the same period, average annual temperature increased by 0.025°C (l.f.). The increase in annual precipitation had a negative impact on the yield of all crops (maize, wheat and oats). Increases in mineral N rate led to increased yields. At the highest mineral nitrogen rate, farmyard manure (FYM) did not have a positive impact on yield in the investigated crops, although there was a positive effect of straw incorporation on the yield of maize and oats, and a negative impact on the yield of winter wheat. The organic carbon (Corg) level in the soil increased for all treatments, including FYM or straw and mineral N fertilization. The N content in the soil decreased in the treatment with no organic fertilization and no mineral N, and in the treatment with straw and no mineral N. Corg was increased in treatments with organic fertilization and the highest N rates and remained the same in treatments with moderate N fertilization. All C balances were negative.     

Sulphur isotope characteristics of two north Bohemian forest catchments

Sulphate concentrations and ³⁴S ratios were monitored in bulk precipitation, spruce throughfall, and soil water (depth of 30 and 90 cm) at ervená jáma (CER) and Naetín (NAC), two severely polluted sites in the Czech Republic, between December 1992 and September 1994. Throughfall [SO₄ ^2–], up to 80 mg L^–1 in winter and as low as 7 mg L^–1 in summer, was higher than [SO₄ ^2–] in bulk precipitation (annual average 6 mg L^–1). There was a distinct seasonaity in S isotope abundances, with lower ³⁴S_BULK in summer (+4 per mil CER, + 6 per mil NAC) and lower ³⁴S_TF in winter (+3 per mil CER, +4 per mil NAC). Wintertime ³⁴S_BULK was around +8 per mil at CER and +10 per mil at NAC, summertime ³⁴S_TF was close to +7 per mil at both sites. For only a 1- month period in spring, bulk precipitation S became isotopically lighter than throughfall S. Bulk precipitation data from CER were in good agreement with those from the nearby monitoring station Lesná (LES), typically differing by less than 10 mg L^–1 and 2 per mil in [SO₄ ^2–] and ³⁴S, respectively. Suction lysimeters (soil depth of 30 and 90 cm) yielded higher sulphate concentrations and lower ³⁴S ratios compared to both bulk and throughfall precipitation. Little seasonality was observed in [SO₄ ^2–] at 30 cm (around 40 mg L^–1); at 90 cm [SO₄ ^2–] was higher in winter (70 mg L^–1) than in summer (45 mg L^–1). ³⁴S at 90 cm was <+5 per=" mil=" in=" 1993=" and=" up=" to=" +7.5=" in=" 1994,=" lower=" in=" the=" first=" year=" and=" higher=" in=" the=" second=" year=" compared=" to=" the=" depth=" of=" 30=" cm.=" sulphur=" fluxes=" at=" cer=" and=" nac=" are=" characterized=" by=" distinct=" isotope=" compositions=" and=" can=" therefore=" be=" used=" to=" trace=" s=" pathways=" and=" transformations=" in=" the=" forest=">     

Variation in Alnus glutinosa susceptibility to Phytophthora ×alni infection and its geographic pattern in the Czech Republic

Variation in natural susceptibility of the black alder population to Phytophthora ×alni (PA), the oomycete pathogen causing a devastating disease of alder, and its possible relationship to geographic origin, was studied in vitro using branch inoculation tests. Ninety black alder genotypes from different regions of the Czech Republic and two isolates of PA were employed. Host susceptibility varied significantly. After 1 week of infection, the lesion surface areas ranged from 254 to 2051 mm² and from 19 to 970 mm² for the two isolates, respectively. The differences were also dependent on the geographical origin and altitude of the sites from which particular host genotypes were taken. These findings have important implications for restoration plantings and for PA resistance breeding programmes, as there is potential to make selections from natural populations.     

Biovolatilization of Arsenic by Different Fungal Strains

The quantification of arsenic biovolatilization by microscopic filamentous fungi Aspergillus clavatus, A. niger, Trichoderma viride and Penicillium glabrum under laboratory conditions is discussed in this article. The fungi were cultivated on a liquid medium enriched with inorganic arsenic in pentavalent form (H₃AsO₄). Filamentous fungi volatilized 0.010 mg to 0.067 mg and 0.093 mg to 0.262 mg of arsenic from cultivation systems enriched with 0.25 mg (5 mg.l^?1 of arsenic in culture media) and 1.00 mg of arsenic (20 mg.l^?1 of arsenic in culture media), respectively. These results represent the loss of arsenic after a 30-day cultivation from cultivation systems. The production of volatile arsenic derivatives by the A. niger and A. clavatus strains was also determined by hourly sorption using the sorbent Anasorb (CSC) on the 29th day of cultivation.     

Soil respiration of karst grasslands subjected to woody‐plant encroachment

The transition of grasslands to forests influences many ecosystem processes, including water and temperature regimes and the cycling of nutrients. Different components of the carbon biogeochemical cycle respond strongly to woody plant encroachment; as a consequence, the carbon balance of the invaded grasslands can change markedly. In our research, we studied the response of soil respiration (R_S) to natural succession of calcareous grassland. We established two research sites, called grassland and invaded site, at each of which eddy flux measurement were also performed. Within these sites, triplicate plots were fenced for soil flux measurements. At the invaded site, measurements were performed for forest patches and grassy spaces separately. Soil respiration was strongly dependent on temperature and reached 8–12 µmol CO₂ m^?2 s^?1 in mid‐summer; it was greater at the grassland than at the invaded site. R_S dependence on temperature and soil water content was similar between the different vegetation covers (grassland, gaps and forest patches). At a reference temperature of 10°C, the average R_S was 2.71 µmol CO₂ m^?2 s^?1. The annual sums of R_S were also similar between years and sites: 1345 ± 47 (2009) and 1150 ± 37 g C m^?2 year^?1 (2010) for grassland and 1324 ± 26 (2009) and 1268 ± 26 g C m^?2 year^?1 (2010) for the invaded site, which is at the upper range of the values reported in the literature. Cumulative R_S peaked in July, with about 200 g C m^?2. Large mid‐summer R_S rates rely on strong biological activity supported by high, but non‐extreme soil temperatures and by regular summer precipitation. A coupling of photosynthesis and R_S was revealed by a 24‐hour measurement, which showed asymmetrical clockwise hysteresis patterns.     

Field efficacy of three insecticides against cabbage stink bugs (Heteroptera: Pentatomidae) on two cultivars of white cabbage

Abstract

In 2002 – 2003, three insecticidal substances were tested for their ability to reduce the damage inflicted on plants of white cabbage by cabbage stink bugs, Eurydema ventrale and E. oleracea (Heteroptera: Pentatomidae). The two cultivars of cabbage tested were: the early cultivar, ‘Tucana F₁’, which requires about 60 days from transplanting to harvest, and the mid-early cultivar ‘Hinova F₁’, which requires about 120 days. In a field experiment, the growth and damage on cabbage plants sprayed with malathion (two sprays), potassium soap [potassium salts of fatty acids] (five sprays), and refined rape oil (five sprays) were compared to the growth and damage on unsprayed plants. Potassium soap and refined rape oil are considered to be environmentally friendly insecticides. In 2002, plants of the cultivar ‘Tucana’, that were treated with malathion had the highest plant weights [PW], head weights [HW], HW/PW ratio, and the lowest number of frame leaves. In the drier year of 2003, there were no significant differences in damage between the three treatments for either cultivar, except during the last assessment done on 13 August. In 2003, plants of ‘Tucana’, treated with potassium soap, had the highest PW and HW. The significantly lowest PW and HW values were recorded from the untreated plants. For the cultivar ‘Hinova’, the PW and HW were heaviest from the plants treated with malathion. In both years, the HW/PW ratio of Hinova (mid-early cultivar) did not differ between treatments, while the plants of ‘Tucana’ (early cultivar) treated with malathion had the highest ratio. Of the three substances tested, malathion was the most effective at reducing the damage on white cabbage plants caused by cabbage stink bugs. However, in an attempt to reduce the use of synthetic insecticides, instead of malathion, we recommend the use of refined rape oil (49 EUR/ha), as it is as effective as potassium soap (81 EUR/ha), but much cheaper.