Response of fertilization on segetal weed composition in a long-term field experiment

The net-influence of mineral fertilization (N, P₂O₅, K₂O, CaCO₃, MgCO₃) were studied in a long term field experiment established in 1962, on a Haplic Luvisol under fragile agro-ecological circumstances at Nyírlugos in 2002. The soil had the following agrochemical characteristics: pH (H₂O) 5.9, pH (KCl) 4.7, hydrolytic acidity 8.4, hy₁ 0.3, humus 0.7%, total N 34 mg kg^-1, ammonlactate (AL) soluble-P₂O₅  43 mg kg^-1, AL-K₂O 60 mg kg^-1 in the plowed layer. The experiment consisted of 32x4=128 plots in randomized block designs. The gross plot size was 10x5=50 m². The average fertiliser rates in kg ha^-1 year^-1 were nitrogen 75, phosphorus 90 (P₂O₅), potassium 90 (K₂O), calcium 438 (CaCO₃) and magnesium 140 (MgCO₃). The main results and conclusions were as follows. With nitrogen application Cynadon dactylon -, total weed owergrown and the total No of weed species had been decreasing (100%, 99.3%, 17.9%) strongly, while Ambrosia elatior, Apera spica venti and Sinapis arvensis had not changed. In the case of phosphorus loaded plots the Ambrosia elatior and the total No of the weed species diminished with a 50% and 17%. On the potassium treated soils the Apera spica venti, the Cynadon dactylon and the total No of  weed species had had reduced in 75%, 67% and 20%, respectively.