Machinery traffi c and cover crop eff ects on water infi ltration rate in a Xanthic Hapludox

- The e ff ects of machinery tra ffi c and cover crops on soil physical properties have been underexplored under no-till agricultural production in subtropical environments. The objective of this study was to quantify the soil water in fi ltration rate and related soil physical properties in response to tractor tra ffi c levels (0, 2, 5, and 20 passes) and the presence or absence of cover crops in a Xanthic Hapludox soil over two growing seasons under no-till conditions. The experiment was carried out in a randomized block design arranged in a factorial scheme with four replications. The tra ffi c factor was constituted by the number of passes with a 6 Mg weight tractor. The winter crop management practices factor consisted of the cover crops (i) black oat ( Avena strigosa ) in 2017 and turnip ( Raphanus sativus var. oleiferus ) in 2018 compared with (ii) fallow with spontaneous vegetation. The soil water in fi ltration rate increased with cover crops when compared to fallow. Regarding tractor tra ffi c levels, shortly after soil compaction, there was a lower water in fi ltration rate at 20 passes, 45 mm h -1 lower than the absence of tractor tra ffi c. The soil water in fi ltration rate was positively correlated with macroporosity and negatively correlated with soil bulk density. After 14 months of soil compaction caused by tractor tra ffi c, an improvement in the soil physical properties and the water in fi ltration rate was found, which were enhanced by the inclusion of cover crops.