Effect of mineral fertilization and tillage system on the yield of wheat grown in four-field crop rotation

During the period 2020-2023 field experiments have been carried out -of soil type Leached Smolnitsa

(Haplic Vertisol) in the experimental station of ISSAP “N. Poushkarov”, the town of Bozhurishte, Sofia region.

The aim of this study is to identify the impact of two rates of nitrogen-phosphorus mineral fertilization, nonfertilizer variant and two soil tillage systems (plowing and discing) on the yield of wheat grown in a four-field

crop rotation. The wheat was included in the structure of a four-field crop rotation: 1) maize, 2) wheat, 3) maize, 4) wheat. It was established that the studied fertilizer rates, regardless of the soil tillage system, are essential

for increasing yields of wheat, determining more than 78.73% of the data variation. Increasing the nitrogen and

phosphorus fertilizer rate by about 20% at T2

norm compared to T1

(from 120 to 140 kg/ha for nitrogen and

from 80 to 100 kg/ha for phosphorus) does not lead to significantly higher wheat yields. It was established that,

on average over the study period, the applied lower rate of nitrogen and phosphorus fertilization T1 (N120P80) in

wheat cultivation was more effective. The use of nitrogen-phosphorus mineral fertilization for both the soil tillage

systems, contributes to more than twice the yields compared to those obtained from the non-fertilizer variants

with a very well-proven statistical difference. Irrespective of the fertilization rate, no significant influence of the

applied soil tillage systems (disking or plowing) on wheat yield was observed. The influence of the soil-climate

conditions (rainfall and temperature conditions) during this period was also analyzed. It was established that

they are a significant factor, which has a strong influence on the obtained high (good) yields of wheat cultivated

in the field of Bozhurishte.