Chemical and physical attributes of a Yellow Latosol and soybean root distribution under different tillage systems in cerrado of Maranhão State

Abstract

This work aimed to evaluate the impact of tillage systems on chemical and physical soil attributes and on soybean root growth. The treatments were: conventional tillage (CT), escarification up to 20 cm (E20), escarification up to 30 cm (E30) and no-tillage (NT). A natural Forest adjacent to the experiment area was used as reference. Treatments were arranged in a complete randomized blocks design with four replicates. Chemical and physical soil attributes were evaluated from soil samples collected at 0-5; 5-10; 10-20 and 20-40 cm depths and root system was evaluated at 0-20 and 20-40 cm. At 0-5 cm, NT system showed higher bulk density (p<0.05) than E30 and CT systems. Phosphorus and calcium contents were also higher (p<0.05) at NT than at CT at 0-5 and 5-10 cm. Exchangeable aluminum content at surface (0- 5 and 5-10 cm) was lower at NT (0.16 and 0.21 cmolc.dm-3, respectively) and E20 (0.18 and 0.24 cmolc.dm-3) which is associated to higher stocks of total organic carbon observed in these treatments. For all variables, the soil under cerrado native Forest showed the lower nutrients contents indicating the chemical poverty of these soils. No differences were observed in soybean root density. However, in both depths, the higher lenght root was observed in the E30 treatment. In this treatment, 77% of root lenght was observed at 0-20 cm d. NT and E30 treatments showed an increase in soil quality but they did not influence soybean root growth.