Soil Sustainability: Analysis of the Soil Compaction under Heavy Agricultural Machinery Traffic in Extensive Crops

Crop establishment depends mostly on the soil preparation and sowing methods used. Our main goal was to evaluate soil compaction and its effects on wheat (Triticum aestivum L.) and soybean (Glycine max L.) yields and seedling emergence with two different tillage methods: no-tillage (NT) and conventional tillage (CT). The study was done in the Western Pampas Region during three cropping seasons. The soil of the study site is a Mollisol. The variables measured were: (1) cone index (CI), (2) dry bulk density (DBD), (3) seedling emergence (SE), and (4) crops yield (CY). For both crops, seedling emergence was slower in NT than in CT, but results were similar 22 days after sowing. After 3 years, the results show that in NT the DBD and CI reached values of 1653 kg m−3 and 3210 kPa, respectively (between 275 and 300 mm). While in CT the values of DBD and CI reached were 1540 kg m−3 and 2300 kPa respectively at the same depth. The highest yields were found in CT (3.31 and 4.10 tons/ha−1, for soybean and wheat, respectively) compared to NT (2.91 and 3.53 tons/ha−1). Topsoil horizon has to be tilled to improve crop yields. In spite of the high number of equipment passes in CT, both tillage systems caused subsoil compaction.