One of the main causes of unfavorable changes occurring in the soil, often leading to its degradation is the excessive chemization of the natural environment while reducing the use of calcium fertilizers. According to the data published by the Central Statistical Office, chemical companies delivered nearly 2400,000 tons of mineral fertilizers to the domestic market for planting crops grown in 2015 recalculated to pure component, i.e. about 4% more than in the analogous, earlier growing season. However, in 2015, the use of calcium fertilizers per 1 ha of agricultural land decreased by 20% compared to the previous year and amounted to only 40 kg. Hence, the very low level of calcium fertilization maintained is insufficient in relation to the acidity level of Polish soils. It should be remembered that growing cereal plants requires the supply of many nutrients, including calcium. It is a nutrient that is important in shaping production and environmental effects. After the introduction of integrated pest management in Poland in 2014, there has been a search for and implementation of environmentally friendly methods to reduce the adverse effects of cereal crops, including maize, on the soil environment. A number of calcium fertilizers offered by various chemical companies are available in the domestic market, hence the large scale producer has a large selection of suitable fertilizers for his/her farm.
Maize belongs to plants quite sensitive to low pH and the accompanying increased concentration of aluminum and manganese ions. It is less demanding than e.g. barley or medicago, but its requirements are still similar to that of winter wheat. Lower pH value at which maize can still yield decently is 5.5-5.8; the upper one is pH 7.5. With the lowering of the reaction, the yield of maize grain decreases, and the yield of green mass also drops to a similar extent. At a pH of 5.5 a yield reduction of 15% can be expected, while at pH 4.5, the drop in the maize yield reaches as much as 40%. Research by UNG in Puławy demonstrated that liming very acidic soil can increase the yield of maize even by 60%.
Figure 1. The dynamics of the initial maize growth expressed as the plant dry matter crop [kg/ha] in the 6-7 leaf phase
Figure 2. Corn grain yield [dt/ha] depending on different mineral fertilization
Figure 3. Soil acidity after 60 days from the date of application of mineral fertilization [pH in KCl]
OrCal organic and mineral fertilizer is becoming more and more successful on the Polish and global market. Probably because it is a solution that deals with several most important problems at the same time, and its effects are quickly noticed by large scale producers. Regulation of soil reaction, clear improvement of its structure, the possibility of limiting NPK mineral fertilization translate into increased profitability of maize cultivation. Due to the fact that the use of OrCal in maize cultivation proved to be effective, in the Department of Agronomy of the University of Life Sciences in Poznan, field research was also undertaken on the use of this fertilizer in the cultivation of winter oilseed rape. The results of this experiment will be published in the later issue of Przedsiębiorca Rolny.
Table 1. Simplified calculation of cultivation of 1 ha of maize for grain taking into account only the direct costs of mineral fertilization
(data of fertilizer and maize prices by ODR Sielinko, September 2017)
| Type of the fertilizer | Dose | Price PLN/uom | Value PLN/ha | NPK zł/ha | NPK + 1 t OrCal zł/ha | ½ NPK + 1 t OrCal zł/ha |
|---|---|---|---|---|---|---|
| Urea | 150 kg | 3,00 | 450 | 450 | 450 | 225 |
| Enriched superphosphate | 100 kg | 3,55 | 355 | 355 | 355 | 177,5 |
| Sylvinite | 140 kg | 2,43 | 340,2 | 340,2 | 340,2 | 170,1 |
| Total mineral fertilization | – | – | – | 1145,2 | 1145,2 + 700 | 572,6 + 700 |
| Revenue – grain yield (B) | – | – | – | 6391 | 6706 | 6601 |
| Direct surplus (B-A) | – | – | – | 5245,8 a) | 4860,8 b) | 5328,4 c) |
| Difference | – | – | – | – | – 385 zł/ha b-a) | + 82,6 zł/ha c-a) |
