Azolla sp. as a substitute for nitrogen fertilizers in the rice crop of subsistence

Abstract

In the Casiciaco Haren Alde Farm School, located in the district of Las Minas, this research was carried out whose main objective was to establish the capacity of Azolla pinnata. as a substitute for ammoniacal nitrogen fertilization, without reduction in crop yield in subsistence rice cultivation. It consisted of two blocks of six treatments and three repetitions in each block. Each block represents a planting date 15 days apart. Each experimental unit consisted of plots of 2x5 meters, separated by one meter.  It was sown, at a distance of 40 cm between furrows and 15 cm between plant, placing 8 rice seeds. 6 treatments were analyzed, with different combinations of Urea and Azolla pinnata as a source of nitrogen fertilization for the crop. Physical-chemical analyses were performed on the field and the Azolla to be used, to determine the proportion to be applied in each experimental unit. The proportions of Urea and Azolla to be used, decreased by 25% of the previous treatment. The treatments were applied at 75 days of planting (dds) in the first block and at 60 dds in the second block. Among the treatments applied, (except in the case of the absolute control of the trial), no significant difference was observed in the results obtained in terms of harvest yield.

These results lead us to conclude that, under conditions similar to those presented in this trial, Azolla can be recommended for application in subsistence rice plots, especially the non-commercial variety known as Picaporte. It was, also established that the fertilization costs of Azolla treatments are considerably reduced from the second year of its application, once the construction costs of the planting lagoon are managed in the first year, while the costs of chemical fertilizers increase each year.