Effect of Straw (Copernicia prunifera) Additions in a Yellow Oxisol Under Corn (Zea mays L.) Cultivation in the Microregion of Chapadinha-MA, Brazil.

The yellow oxisol predominates in the microregion of Chapadinha- MA, Brazil. This soil has a natural compaction tendency due the predominance of fine textured sand and silt.  The yellow oxidol’s physical characteristics have become a limiting factor for grain production, which tends to be aggravated by a high mechanization during seedbed preparation. Coexisting with this soil is an abundance of a common palm tree (Copernicia prunifera), known as carnauba, as well as plenty of straw, asub-product that results from the extraction of wax from its leaves. The straw of carnauba has a high carbon:nitrogen ratio that may have  a positive influence on humus buildup and resulting physical properties. Thus the objective of this study was to evaluate the effect of the addition of carnauba straw on the physical properties of a yellow oxisol under cultivation of corn in the microregion. The experimental design was a randomized block with factorial arrangement of 3 x 2, and the treatments consisted of three environments: native forest (NF) under maize cultivation, the treatments with straw of carnauba (CPC) and without straw (SPC) in two soil depths (0-10 cm and 10-20cm) with four replications (This last sentence is unclear – I do not understand).  Soil samples were collected at the depths of 0-10 and 10-20 cm for analysis of density, total porosity, macroporosity and microporosity. It was concluded that the addition of straw at both depths did not provide significant improvements in physical properties of soil. Total porosity (39.0%) and macroporosity (9.5%) were lower with the addition of straw compared to the native forest environments (45.0% and 15.9%) and without the carnauba straw (45.0% and 11.8%), respectively. Soil bulk density and microporosity did not differ significantly between the environments.