Adubação com cama de galinha poedeira peletizada no desenvolvimento inicial da cultura do milho

Abstract

The amount of commercial laying hens in Brazil is estimated at 90 million, with an average production of 2.20 kg of poultry litter per bird. Therefore, it is necessary to seek appropriate management practices for the final destination of the waste, in order to minimize environmental impacts. Transforming waste into a by-product with economic value has been an important strategy, especially as an alternative source of nutrients to reduce the production costs of important agricultural crops. The 2013/2014 Brazilian maize crop reached 78 million tons. For technified crops, with expected productivity above 10 t ha-1, the crop may require amounts of nitrogen (N) greater than 150 kg ha-1, of which a large part can be supplied by alternative organic sources, such as pelleted laying hen litter (PLHL). The objective of this study was to evaluate the use of PLHL, applied at different times, as a source of N for the initial development of maize, AG-8061PRÓ hybrid. The experimental design used was completely randomized, consisting of seven treatments with four replications: T1 - control; T2 - conventional chemical fertilization; T3 - organic fertilization with incorporation of PLHL at sowing; T4 - organic fertilization with PLHL split application at sowing and topdressing; T5 - organic fertilization with PLHL at sowing, followed by 50% of the dose indicated for topdressing chemical fertilization; T6 - organic fertilization with PLHL at sowing, followed by 100% of the dose indicated for topdressing chemical fertilization; T7 - organic fertilization with PLHL at sowing, followed by 200% of the dose indicated for topdressing chemical fertilization. The effect of treatments on the supply of N by the PLHL was compared with those obtained by the treatment that provided N with ammonium sulfate and by the control treatment without fertilization. The biometric parameters evaluated at 90 days after planting were: height, stem diameter, and dry biomass. The results were subjected to analysis of variance, with subsequent comparison of means by the Tukey test (p<0.05). The management of N from PLHL, whose content was 21.0 g kg-1, considered the annual mineralization rate of 10% throughout the experimental period, resulting in the application 80 t ha-1 of PLHL at sowing, in the treatment T3, and 14 t ha-1 in treatments T4, T5, T6, and T7. Miaze plants grown with PLHL, either exclusively or in combination with chemical fertilizer, showed better results in height, stem diameter, and dry biomass than plants grown with conventional chemical fertilization. The application of PLHL incorporated in the soil provided greater increments in the biometric parameters of the maize plants. Fertilization with PLHL, as the only source of N applied at sowing, promoted better results than chemical fertilization or chemical fertilization combined with organic. It should be noted that the organic source as PLHL provides N gradually, decreasing the chances of toxicity or leachate losses. In the case of complete replacement of the mineral source of N by PLHL, a large amount of material is necessary to supply the requirements of the maize crop, which residual effect benefits subsequent crops, such as winter crops. There is, however, the option of combining the application of chemical and organic sources of N, with satisfactory results when compared to conventional chemical fertilization.