Soil Organic Matter Dynamics in Cotton Systems with Cover Crops in the Tocantins Cerrado

Soil organic matter (SOM) is an essential indicator of quality in agricultural systems under conservation management. This study aimed to evaluate the effect of different cover crops on SOM contents in an area cultivated with cotton (Gossypium hirsutum L.) under a no-tillage system in Palmas, TO, Brazil. The experiment used a randomized block design with four treatments: cotton in succession to marandu grass (Urochloa brizantha), crotalaria (Crotalaria spectabilis), pearl millet (Pennisetum americanum), and a control (fallow). The cover crops were established pre-sowing. Soil sampling (0–20 cm layer) occurred after the desiccation of the cover crops. Data were subjected to analysis of variance (ANOVA), and means were compared using Tukey's test (p < 0.05) via SISVAR software. The mean SOM contents were 1.56% in control, 1.67% for marandu grass, 1.70% for crotalaria, and 1.63% for pearl millet. There was no significant statistical difference among the treatments (p > 0.05). It is concluded that, although the short-term adoption of the system did not promote immediate statistical changes, the use of cover crops shows potential to increase SOM contents in the long term. This practice contributes to the sustainability and improvement of soil quality in the cotton production system in the Cerrado.