Bionucleares 2020
Vol. 12 No. 3 (2020): Aplicaciones Nucleares (2021)
Currently, agriculture is increasingly dependent on nitrogenous fertilizers due to the need to produce more to satisfy the great demand for food in the world. In this sense, the incorporation of green manures can help to increase the bioavailability of Nitrogen (N), a fundamental element for the development of plants. The N use efficiency can be measured using the conventional (differential) and the isotopic (15N) method. In this context, a research was implemented to evaluate the effect of two green manure species: (Lupinus mutabilis and Vicia sp.) and a cereal species (Avena sativa); and five nitrogen levels (0, 45, 90, 135 and 180 kg ha-1) on the biomass (forage) and grain yield of corn in the highlands of Ecuador. Additionally, the efficiency of the nitrogen fertilizer was evaluated at three times: at planting, 45 and 75 days after planting (dap). In both experiments, a split plot design was used, where the large plot contained the crop incorporated into the soil, and the small plots had the levels of N or application time, with three repetitions. The incorporation of green manures did not produce any significant effect on the corn yield, except in the isotopic test, where the incorporation of lupine significantly increased the production of forage to 22.69 t ha-1. The highest yield of corn grain (6.76 t ha-1) was obtained with the dose of 135 kg ha-1 of N, differing statistically from the dose of 0 and 45 t ha-1. The isotopic method with the use of 15N allowed to differentiate the levels of N adsorption among the application times, observing that the highest adsorption of this element and the highest efficiency of N occurred at 75 dap (V6-V7). These results demonstrate the importance of isotopic techniques for plant nutrition studies and will allow adjusting the nitrogen fertilization recommendations for the cultivation of corn in the Ecuadorian highlands.
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