Extraction and export of nitrogen, phosphorus and potassium by maize fertilized with pig slurry

The objective of this work was to evaluate the nitrogen (N), phosphorus (P) and potassium (K) extraction by the maize crop fertilized with liquid pig manure (LPM). The experiment was carried out in a clayey Red Latosol (540 g kg(-1)) from October 2013 to April 2014 at Fontes do Saber Farm, located at the University of Rio Verde, State of Goias, Brazil. Treatments consisted of the application or not of liquid pig manure at the rate of 30 m(3) ha(-1). After the manure application to the soil surface, the maize crop was sowing and the N, P and K extraction by the plants were evaluated in eight times, with mean intervals of 15 days, during the growth and development cycle of the crop. The results showed that the use of liquid pig manure increased maize grain yield compared to the control treatment (non-fertilized with manure). The rate of 30 m(3) ha(-1) of liquid pig manure with density of 1013 g cm(-3) is not sufficient to result in grain yields above 9000 kg ha(-1). The nutrient extraction by maize plants follows the decreasing order of absorption: K > N > P and period N > K > P, respectively, for the vegetative and reproductive stage.