Soil roughness evolution in different tillage systems under simulated rainfall using a semivariogram-based index

Abstract

Among the factors that contribute to greater changes in soil surface roughness are the tillage systems and rainfall conditions. This study evaluated the changes of surface roughness under different tillage systems and the application of artificial rain. The experiment was conducted in 2009 and 2010 for conventional tillage (CT), reduced tillage (RT) and no tillage (NT), in micro plots with 1m×1m size for each treatment. Simulated rainfall with intensity of 80mmh−1 was applied. Soil microrelief was measured with a portable laser scanner with a 1-cm horizontal resolution. The height readings were submitted to geostatistical analysis through the semivariogram method, and the index used to represent the roughness of the soil (RI) was extracted from the semivariograms. The RT and NT systems presented higher roughness in the first year, but in the second year, the greatest RI was observed in the NT system. The RI values in the same treatment differed between applied rainfalls only in NT for the second year. In CT, the RI did not differ between the applied rainfalls, but showed the same trend in the two years studied: initially an increase of roughness occurred until a maximum rain amount, then it decreased. Differences between the years studied occurred only in NT, which showed greater RI in the second year in comparison to the first one, CT and RT were similar and did not differ between the two years evaluated.