In our research we examined the effect of the hybrid, the nutrient supply, the number of plants and the abiotic factors (temperature, amount of precipitation) on the yield, crop quality and yield stability of maize. We devoted special attention to the natural nutrient utilization ability and fertilizer reaction of maize. The experiment took place in Hajdúszoboszló on chernozem soil, on a nearly 8 ha field. The size of one plot was 206 m2; therefore, this experiment was half-industrial. We tested six hybrids with different genetic characteristics and growing seasons. I analysed the correlation between the nutrient supply and the yield of maize hybrids with control treatment (treatment without fertilization) and with N 80, P2O5 60, K2O 70 kg ha-1 and N 160, P2O5 120, K2O 140 kg ha-1 fertilizer treatments. The yield increasing effect of the fertilizer also depended on the number of plants per hectare to a great extent. The number of plants of the six tested hybrids was 60, 70, and 80 thousand plants ha-1.
In Hajdúszoboszló in 2017, up to October, 445.8 mm of rain fell, which is in line with the average values of 30 years, and is only 45.7 mm less than those. In 2017, the effect of increasing the plant number was slighter. Averaged over the observed fertilizer treatments and hybrids, the yield was 9.10 t ha-1 with 60 thousand plants ha-1, 9.11 t ha-1 with 70 thousand plants ha-1 and 9.12 t ha-1 with 80 thousand plants ha-1. Without fertilization, in most cases, increasing the plant number from 60 thousand plants ha-1 to 70-80 thousand plants ha-1 does not increased the yield but decreased it. With N80+PK treatment the yield changed between 8.90 and 11.27 t ha-1. The effect of increasing the plant number was just slightly observable and did not show a clear tendency. The effect of changing the plant number, even with the highest dosage of fertilizers, could not be detected adequately. In contrast with the plant number, the effect of the different fertilizer treatments was expressly traceable. Compared to the control treatment (treatment without fertilization), with N80+PK fertilizer dosage with 60 thousand plants ha-1 the yield increased by 3.36–4.99 t ha-1. The smallest demonstrable proof, i.e. the LSD5% was 0.22 t ha-1, which means that fertilization, in each case, significantly increased the yield. When analysing the effect of fertilization in the average of the hybrids and the different plant numbers, a yield of 5.61 t ha-1 could be detected, which value was 10.12 t ha-1 with N80+PK treatment and 11.61 t ha-1 with N160+PK treatment. Thus, it can be calculated that compared to the treatment without fertilization, the N80+PK treatment increased the yield by 4.51 t ha-1, while compared to the N80+PK treatment, the N160+PK treatment increased the yield by 1.49 t ha-1. In addition to agrotechnical factors, in maize production, the impact of the crop year is specifically of high importance.
The average yield of hybrids (in the average of the different fertilizer treatments) was 6.81 t ha-1 in 2015, 11.86 t ha-1 in 2016 and 9.11 t ha-1 in 2017. When comparing the yield results against the precipitation data, it is clearly visible that the amount of rain fell in the January– October period is directly proportional to the average yield of maize. The effect of the crop year can be defined in a 5.05 t ha-1 difference in the yield.