Adubação orgânica e manutenção da palhada na cana-de-açúcar: efeitos na volatilização de amônia, parâmetros químicos e físicos do solo e produtividade

Abstract

Objective: to evaluate how to reduce N by ammonia volatilization system, such as changes in the physical and chemical attributes of the soil promoted by the use of organic fertilizer, degradation of the palette in the soil and research of the sugarcane culture. For this, two experimental years were imposed. In the first year, sugarcane crops (RB 92579, RB 867515 and RB 863129) were evaluated, where RB 867515 performed better and was selected for the second experimental year. As nitrogen sources applied were liquid manure (DS), chicken litter (CF), urea (URE), coated urea (URE R), and control treatment (CON) where there was no fertilizer application. After the application of organic and mineral sources of N, chemical and physical substances of the soil were applied, in the depths (0-5, 5-10 and 10-20 cm), being these: pH, Ca, Mg, K, Al, H + Al, P, COT, total density and total porosity. Palette decomposition and nitrogen losses due to ammonia volatilization were also quantified. In general terms, if organic nitrogen sources demonstrate beneficial effects on soil chemicals, where DS will provide no pH value, and comparisons with a CF will provide records on COT levels. reduction in density and increase in the amount of soil pores. For the results of ammonia volatilization, as organic sources demonstrated as lower volatilization rates with average values of 3.4 kg ha-1, being 70% less than the values found for the N analysis by volatilization when the mineral nitrogen sources have been applied. As for a straw decomposition, as organic sources demonstrated significant effect (p <0.05), where the DS treatment presented the lowest T1/2 (173 days) with daily decomposition of approximately 0.0040 g, followed by the CF tests ( 192.5; 0.0036), URE R (198; 0.0035), URE (203; 0.0034) and CON (216; 0.0032). Regarding the crop yield, it was possible to observe that the DLS and URE R provided the highest yields of the cultivar, with an order of 93 and 92 t. ha-1 respectively. It is possible to conclude that the use of organic sources offers improvements in the fractions of soil chemistry and physics, providing increases in the contents of COT, pH and decomposition of the pallet, coupled with less damage by volatilization of N, and increased use at a lower cost, when compared to mineral fertilizers.