Reducing the amount of fertilizer during the main application was the best financial result in the potato fields last year. This is evidenced by the demonstration project of the Belgian research institute Inagro.
Inagro started testing fertilizers in April 2020, focusing on fractionation and in-row fertilization. The experiment was started on April 25 on plots with the Fontane variety.
After an initial analysis of the soil, it turned out that there was still little nitrogen in the profile, which meant that the total recommended amount of nitrogen was high: 229 kg of nitrogen per hectare. Various plants received only 70 percent of the recommended amount of fertilizer, either across the field or in a row.
During the growing season, the difference between the two methods of fertilization was clearly visible. This also affected income.
Unfertilized plants had the lowest yield. Full fertilization without foliar application in June/July also resulted in lower yields, with a 100% nitrogen recommendation producing slightly better results than a 70%.
Plants fertilized in the field with foliar fertilization had the highest yields. The difference in yield between row fertilizer at 70% of the norm or 70% of the norm supplemented with foliar application during the growing season was not significant.
The researchers can state that when the main fertilizer was applied in the row, the fertilizer granules were more evenly distributed. Nitrogen was immediately in the root zone. After fertilization throughout the field, there was too much nitrogen in the upper part of the soil. Due to the lack of adequate rainfall, this nitrogen could not migrate to the root zone.
Financially, the plot with a reduced amount of basic fertilizer in the row performed better in 2020. “If we calculate the cost of 1 euro per kilogram of nitrogen and the selling price of 80 euros per tonne of potatoes, we get a plus of 400 euros for 70 percent in-row fertilization compared to 100 percent in-field fertilization advice,” concluded researchers.