Search
Search Results
-
Az avar rövid életű keresztesvirágú (Brassicaceae) gyomfajok csírázásra gyakorolt hatása
3-8Views:64Recruitment by seeds is essential both in vegetation dynamics and in supporting grassland biodiversity. Recruitment by seeds is feasible in suitable microsites from the seed rain and/or by establishment from persistent soil seed banks. Cessation of grassland management by grazing or mowing results in litter accumulation, which leads to the decrease of species richness by the decreased availability of open patches. Low amounts of litter are often beneficial, while high amounts of litter are detrimental for seed germination and seedling establishment of short-lived species. However, the magnitude of these effects on germination and seedling establishment in relation to litter and seed attributes are scarcely studied. This motivated us to design an indoor experiment to explore the effects of litter on seedling establishment. We germinated six short-lived Brassicaceae species (Arabidopsis thaliana, Capsella bursa-pastoris, Descurainia sophia, Erophila verna, Lepidium campestre, and Lepidium perfoliatum) with different seed mass under increasing litter cover. We found that both seed mass and litter had significant effect on germination and establishment of the sown species. Small-seeded species were significantly negatively affected by the 300 g/m2 and/or 600 g/m2 litter layers. No negative litter effect was detected for species with high seed masses (Lepidium spp.). No overall significant positive litter effect was found, although for most of the species; total seedling numbers was not the highest at the “bare soil” pots. Our results suggest that the effects of litter accumulation on the germination and establishment of short-lived species are less feasible in case of large-seeded species than on small-seeded ones.
-
Effect of fertilization on the mineral element uptake of an established all-grass sward 4.
3-10Views:57The effects of different N, P and K supply levels and their combinations were examined on the mineral element uptake of an established all-grass sward with seed mixture of eight grass species in the 28th year of a long term fertilization field experiment set up on a calcareous chernozem loamy soil. The lay-out and method of the trial as well as the fertilizer responses on the hay yield, nutritional values and element content were published elsewhere (Kádár, 2005, 2005a; Kádár és Győri, 2005). The soil of the growing site contained around 3% humus, 5% CaCO3, 20-22% clay in the ploughed layer and was originally, moderately well supplied with available K, Mg, Mn and Cu and poorly supplied with P and Zn. The trial included 4Nx4Px4K=64 treatments in 2 replications, giving a total of 128 plots. The fertilizers applied were Ca-ammonium nitrate, superphosphate and potassium chloride. The groundwater table was at a depth of 13-15 m, the area was prone to drought. In 2001, however, the area had satisfactory amount of 621 mm precipitation with a fairly good distribution. The grass was established on 21. September 2000. The main results and conclusions can be summarised as follows:
1. As a function of NxP positive interactions the element uptake of the 1st cut hay expressed as mean of K treatments increased between the N0P0 control and the maximum N3P3 levels as follows: K 62-190, N 45-218, Ca 16-51, S 5-24, P 4-24, Mg 4-16, Na 0.5-5.0 kg/ha; Mn 282-968, Sr 35-170, Zn 32-73, Ba 29-55, B 18-44, Cu 8-40 g/ha. The uptake of Ba increased from 23 to 62 g/ha, that of Ni from 1.5 to 8.9 g/ha as a result of KxP positive interactions. Uptake of Mo measure on K0P0 soil, however, dropped from 1.6 g/ha to 0.4 g/ha on the K3P3 soil as a function of negative KxP interactions.
2. The 2nd cut hay harvested on 9th October 2001 showed only N-effects. The hay yield measured on N-control soil was 1.0 t/ha while on 300 kg/ha/yr N-treatment 3.9 t/ha. The uptake of Fe, Ba and Mo increased 2-fold; uptake of Ca, S, P, Sr, Zn and Co 3-4-fold, uptake of K, N, Mg, Mn, Ba and Cu 5-6-fold, while uptake of Na 33-fold with the maximum N-rate, compared to the N-control and as means of PK treatments.
3. The 2 cuts together gave on the unfertilised control 3 t/ha, while on the N3P3K3 maximum supply level 13 t/ha hay yield. The uptake of Fe, Cr, B, Ni, Mo and Co increased 2-3 times, uptake of Ca, Mg, Mn, K, Zn, Ba and Cu 5-6 times, uptake of S, Sr and P 7-8 times, uptake of N 10 times, while uptake of Na 16 times on the maximum N3P3K3 supply levels, compared to the unfertilised control. The maximal mass of uptaken K and N made up 388 kg/ha, Ca 80 kg/ha, S 49 kg/ha, P 42 kg/ha (96 kg/ha P2O5), Mg 24 kg/ha in 2001.
4. To have 1 t of air-dry hay it was used by grasses as a mean of 25 kg K (30 kg K2O), 20 kg N, 6 kg Ca (8-9 kg CaO), 2-3 kg S, 2 kg P (5 kg P2O5) and 2 kg Mg (3-4 kg MgO). For microelements: 300 g Na, 200 g Fe, 120 g Mn, 100 g Al, 16 g Sr, 13 g Zn, 8 g Ba, 5 g B, 5 g Cu, 1-2 g Ni, 1 g Mo, 0.2 g Cr and 0.1 g Co. The As, Hg Cd, Pb and Se were under detection limit of 1 g. Data may serve for assessing the nutrient demand of all-grass sward.