Influence of different fertilization system on weed seed-bank

Abstract

The aim of the research was to evaluate the different fertilization systems during the biennial review of the soil weed seed-bank. Sampling of soil by the ’’Square grill’’ method was carried out on the plots of the 50-year old crop rotation (corn, winter wheat, soybean) at the Institute of Field and Vegetable Crops Novi Sad (N 45° 19', E 19° 50'). Plots were used for testing where only mineral fertilizer in amount 50 kg ha-1 P and K and mineral N in amount 120 kg ha-1 was used each year (P1), mineral fertilizer in same quantities and manure in the amount of 40 t ha-1 every third year (P2) and a plot (P3) where fertilizer was not used for 50 years. It was sampled in the autumn of 2014, spring and autumn of 2015, so that it got real insight into the composition and size of the weed seed-bank in the plough layer (0-30 cm). A method of physical extraction of seeds was used whereby 500 ml of the soil sample was washed with a jet of water through a sieve of a different diameter and separate seeds were determined using the determination keys. After the harvest of maize in autumn 2014 it was determined that the number of weed seeds is the highest on plot P2 (22,275 seeds m-2), on plot P1 was 12,075 seeds m-2, while on the plot where it is not applied fertilizers (P3) was 11,700 seeds m-2. A similar relationship was in the spring of 2015. These method was served to conculded how fertilization affects the number of weed species, on the plots P1 and P2 dominated Amaranthus retroflexus, Chеnopodium album, Ch. hybridum, Veronica hederifoilia. In the non-fertilized variant of the species mentioned did not present a problem, the significant number of seeds were Ambrosia artemisiifolia, Ajuga chamaephytis, Stachys annua, Sorghum halepense, which certainly influences the selection of herbicides for the following period, is evident. In the autumn of 2015, after the harvest of wheat, the situation in P1 and P2 were 14,625 seeds m-2 and 23,700 seeds m-2. In non-fertilized treatment (P3) the number increased to 17,250 seeds m-2 and seed of those species which the method of assessment from the land samples of the previous year indicated that it would be a problem. Based on the results, it is concluded that the different fertilization systems affect the number and composition of the soil weed seed-bank.