Effects of Management Systems and Biofertilizer on Labile Carbon Stocks in Sandy Soil in the Cerrado-Pantanal Transition Region

Labile carbon (Labile C) is the most sensitive fraction of soil organic matter (SOM), reflecting the possibility of long-term modification of total soil carbon stocks.In sandy soils, its maintenance depends on the input of plant biomass, as these soils are considered fragile and have a low capacity for carbon preservation.Thus, this study evaluated the influence of agricultural systems with the application of biofertilizer on labile C stocks in sandy soil in the municipality of Aquidauana,Mato Grosso do Sul,Brazil.The experiment was established in 2021 under a completely randomized design in a 3 × 2 factorial scheme,consisting of three management systems: (No-Tillage System (NTS),Minimum Tillage (MT) and Pasture (PA)), with (CB) and without biofertilizer application (SB).In 2024,soil samples were collected at depths of 0–5,5–10,10–20,and 20–40 cm to determine labile C stocks using the potassium permanganate oxidation method.After three years,no significant interaction was observed between the management systems and biofertilizer application. However, there were significant differences among the management systems, regardless of biofertilizer application,with NTS showing higher stocks in the 0-5 cm layer (0.48 Mg ha^-1),surpassing PA (0.38 Mg ha^-1) and MT (0.34 Mg ha^-1).In the deeper layers, PA showed the highest labile C stocks.In the 0–40 cm layer, PA (1.90 Mg ha^-1) and NTS (1.85 Mg ha^-1) showed significantly higher values ​​compared to MT (1.35 Mg ha^-1).Therefore,systems with high and continuous residue inputs,such as NTS and PA,promote the accumulation of labile carbon in sandy soils,even in subsurface layers,reinforcing labile carbon as an early indicator of soil quality,especially in less resilient soils.