Soil structural quality and development of second-crop corn intercropping with forage grasses under no-tillage

The intercropping of corn with forage grasses increases soil cover and may improve soil structural quality. The objective of the study was to evaluate the soil structural properties and the development of second-crop corn intercropping with forage grasses under no-tillage system. The experiment was carried out in an area of Sitio Santo Antonio, located in the municipality of Borrazopolis, Parana state, Brazil, on a Red Latosol with a very clayey texture. The experiment consisted of five treatments: corn + Urochloa brizantha cv. Marandu (T1), corn + Urochloa brizantha cv. Piata (T2), corn + Urochloa brizantha cv. Xaraes (T3), corn + Urochloa ruziziensis (T4), and non-intercropping corn (T5). In the corn crop, the following characteristics were evaluated: plant height, first ear in insertion height, stem diameter, corn yield, dry mass of corn straw mulch, dry mass of grasses shoots and dry mass of grasses root. Dry mass of the aerial part and roots of the grasses were evaluated. In the 0-0.10 and 0.10-0.20-m soil depth, soil physical properties were also determined: tensile strength and friability, stability of aggregates, bulk density and total porosity, and degree of compactness. The treatments of corn in intercropping with grasses showed positive results regarding the stability of aggregates, reduction of bulk density and increase of total porosity in the 0-0.10-m soil depth. The intercropping of corn + U. ruziziensis showed the lowest values of degree of compactness and higher production of dry mass of the aerial part.