Agronomic use of by-product of guava processing industry--I--chemical soil properties/Uso fertilizante do subproduto da agroindustria processadora de goiabas I--atributos quimicos do solo

The use of alternative sources of nutrients coming especially from waste and industrial by-products can be an important strategy in nutrient cycling, ensuring proper destination of materials that would otherwise be discarded. The objective was to evaluate the application of doses of by-product of guava processing industry on fertility of an Ultisol in a guava orchard. Doses of waste were established on the basis of N content in the material. The experimental design was a randomized block design with five treatments and four replications, the doses of the residue equal to zero, 9, 18, 27 and 36 t [ha.sup.-1] (dry weight of the material). There were five applications residue: in 2006, 2007, 2008, 2009 and 2010. The by-product of the guava processing industry promoted changes in soil fertility in the orchard. With increasing doses increased the concentrations of phosphorus in the soil in all analyzes. The manganese concentrations increased and decreased the soil pH value in the last years of the experiment. It was observed in the subsuperfical layer (0.20-0.40 m) after continuous application of by-product an increase in phosphorus concentration as a function of the doses of the by-product. Index terms: Psidium guajava; Fertilization; Fertility of soil. A utilizacao de fontes alternativas de nutrientes, provenientes especialmente de residuos e subprodutos da agroindustria, pode ser estrategia importante na ciclagem de elementos essenciais, garantindo destino adequado de materiais que seriam descartados. Assim, objetivou-se avaliar a aplicacao de doses do subproduto da industria processadora de goiabas sobre a fertilidade de um Argissolo, sob pomar de goiabeiras. As doses de residuo foram estabelecidas em funcao dos teores de N no material. O delineamento empregado foi o de blocos casualizados, com cinco tratamentos e quatro repeticoes, sendo as doses do residuo (moido) iguais a: zero; 9; 18; 27 e 36 t [ha.sup.-1] (peso do material seco). Foram feitas cinco aplicacoes do subproduto em: 2006, 2007, 2008, 2009 e 2010. O subproduto da industria processadora de goiabas promoveu alteracoes na fertilidade do solo do pomar. Com o aumento das doses, houve incremento das concentracoes de fosforo no solo em todas as analises realizadas. As concentracoes de manganes aumentaram, e houve reducao do valor pH do solo nos ultimos anos de conducao do experimento. Observou-se, na camada subsuperfical (0,20-0,40 m), apos a aplicacao continua do subproduto, aumento na concentracao