Cover crops allow you to reduce the use of urea without losing productivity

Research carried out in Dois Vizinhos, in the Southwest of Paraná, has investigated the possibility of reducing the use of nitrogen fertilizers in corn plantations. For this purpose, the cultivation of some types of winter ground cover plants in the off-season is used. Among the species tested are vetch, lupine and turnip. In some cases, the urea equivalence for nitrogen cycled in the soil by plants reaches up to 175 kilos per hectare. In practice, the producer in these circumstances could save around 40% on the dose of urea applied as fertilizer without losing productivity.

The study “Cover plants and soil preparation systems: impacts on soil compaction and crop productivity” is part of the AgroResearch and Applied Training Network Paraná (Rede AgroParaná), an initiative that has resources from the State government and the SENAR-PR. In the Southwest, the survey that has accumulated information from the last 12 years takes place within an experimental area of ​​the Federal Technological University of Paraná (UTFPR).

To arrive at the equivalence numbers in kilos of urea made available by plants in the soil, the researchers used an expected yield of nine tons of grain per hectare. As projected in the study hypothesis, the greatest equivalence in urea per hectare occurred for lupins (161 kilos) and vetch (175 kilos). In intercropped systems (which use more than one type of cover at the same time, this equivalence varies from 102 kilos (oats + vetch) to 129 kilos (oats + vetch + turnip). Turnip alone presents an equivalence of 76 kilos per hectare.

“In this sense, when we consider this ecosystem benefit to corn cultivation, we can reduce production costs and increase the sustainability of the cultivation system, especially by reducing the amount of chemical nitrogen applied to the crop when the predecessor crop is a cycling cover crop/ fixing this element”, points out the researcher Paulo Conceição, professor at UTFPR.

Soil preparation

On another front of the same subproject, the effects of soil disturbance using scarifiers are being investigated. Some producers in the region have adopted the technique under the pretext of avoiding supposed soil compaction. Research, however, has demonstrated that in the case of a Direct Planting System (SPD) done technically correctly, the use of the equipment is not justified.

In the study in partnership with UTFPR, in the medium term there is no longer any difference between the areas where soil preparation with scarification was adopted. “Both after 12 months of scarification and after 36 months, the soil presents the same compaction condition as the area maintained in PD without disturbance during the six years in which we have been carrying out this particular experiment”, warns the researcher.