Effect of crops residues used as soil surface mulching to control water direct evaporation - DOI: 10.4025/actasciagron.v26i2.1882

No presente trabalho analisou-se a influência dos resíduos das culturas do milho, feijoeiro e trigo nas demandas evaporativas e duas classes texturais de solos. Os tratamentos constaram de três taxas de resíduos de culturas, 0, 50 e 100% da matéria seca produzida pelas culturas em sistemas irrigados; e três demandas evaporativas de 3, 6 e 8mm d-1 e duas classes texturais de solos, areia franca e muito argiloso, contendo 84% de areia e 76% de argila respectivamente. O experimento foi conduzido em laboratório, com o solo acondicionado em colunas. A taxa de evaporação da água do solo descoberto apresentou comportamento distinto para as três demandas evaporativas utilizadas. Para a demanda evaporativa de aproximadamente 3mm d-1 em tratamentos com resíduos da cultura do milho e do trigo para as taxas de 50 e 100% de matéria seca permaneceram no primeiro estádio de evaporação, enquanto para o tratamento com 50% de matéria seca produzida pela cultura do feijoeiro isto não ocorreu. Para a taxa de resíduos de 100% da matéria seca, para a cultura do feijoeiro, a demanda evaporativa influenciou a taxa de evaporação da água do solo, e a relação entre a evaporação para o tratamento com 100% de matéria seca e as demandas evaporativas de 7,0, 5,0 e 2,5mm d-1 foi de 46, 41 e 47%, respectivamenteThe influence of corn, bean and wheat crops residues used as soil surface mulching to control the water evaporation demands, for two soils textural classes, was analyzed in the present work. The treatments consisted of three layers of crop residues, corresponding to 0, 50 and 100% of dry matter produced by irrigated cropping systems, and three water evaporative demands of 3, 6 and 8mm d-1, for two soil textural classes, silty sand and heavy loamy soils, with 84% of sand and 76% of clay, respectively. The experiment was carried out in laboratory, with the soil sample conditioned in a 45-cm high and 20-cm nominal diameter PVC pipes columns. The water evaporation rate from the bare soil column presented different behavior for the three water evaporation demands tested. For water evaporative demand of approximately 3mm d-1, the treatments with corn and wheat crops residues, which represented mulching layer of 50 and 100% of dry matter, the water evaporation rate reached only the first evaporation stage. For treatment with 50% of dry matter with residues produced by bean crop, the evaporation stage moved beyond the first evaporation stage. Finally, for mulching with 100% of bean crop dry matter, the rate of soil water evaporation was influenced by the evaporative demand tested. The relationship among evaporation rate for treatment with 100% of dry matter and the water evaporative demands of 7,0, 5,0 and 2,5mm d-1 were 46, 41 and 47%, respectivel