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The need for efficient use of local resources in agricultural production grows with the increasing demand for sustainable production. One of such sources are both above-ground (stubble) and underground (roots) plant residues left in the field after harvesting a crop. This study quantifies the share of nutrients (N, P, K) in plant residues after the harvest of four different oil crops (raps, sunflower, mustard, and soybean) in seven soil-climatically heterogeneous regions of Slovakia during the nine years. The results showed that the most residues in the soil were left by rape and mustard (more than 10 tons of dry biomass per hectare). After harvesting the sunflower, 5-10 tons of plant residues remained in the soil, and soybeans left the least residues (less than 5 t/ha). Based on these data and the analytically determined content of nutrients in plant residues, the coefficient of nutritional potential was calculated by polynomial regression, i.e. the amount of nutrients that remain after harvesting per ton of the main product. Using these coefficients and the known yield of the given crop, it is subsequently possible to calculate how many nutrients will leave each crop in the soil after harvest. The results showed that the amount of remaining nitrogen in plant residues ranges from 91 to 132 kg, phosphorus from 14 to 22 kg, and potassium from 72 to 218 kg per hectare. The above must be considered when calculating the need for fertilizers for the following crop, to reduce the risk of environmental pollution, especially regarding nitrogen. |
