Changes in the soil organic matter supply in topsoil and subsoil caused by cereals grown in crop rotations

Abstract

The paper evaluates seven years (1993–1999) of Soil organic matter supply monitoring in multifactor field trials conducted by the Agricultural Research Institute in Kroměříž, Czech Republic, (mean annual temperature 8.9 °C, total annual precipitation 599 mm, medium Luvi-Haplic Chernozem). The studied plots were a part of nine-crop rotation: alfalfa the 1st and 2nd year, winter wheat, spring barley, sugar beet, spring barley, winter wheat, silage maize and spring barley. The Soil organic matter supply was measured on four plots: winter wheat after spring barley (var. 1), winter wheat after alfalfa (var. 2), spring barley after winter wheat (var. 3) and spring barley after sugar beet (var. 4). Soil samples were taken from April to July (14–day period) from topsoil (0–30 cm) and subsoil (30–60 cm). The content of Soil organic matter was determined by wet oxidation. Using bulk density, the C content (%) was converted to C supply (t. ha−1). Average yield (t. ha−1) reached 6.54 t/ha (var. 1), 7.47 t/ha (var. 2), 6.52 t/ha (var. 3) and 7.20 t/ha (var. 4). Evaluation of the results was carried out by the analysis of variance and time changes by the second-degree regression analysis. Results demonstrated that Soil organic matter supplies were significantly changed in topsoil. The highest supplies were found in barley after sugar beet (118 t. ha−1), the lowest ones in wheat after alfalfa (111 t. ha−1). As for the cereal species generally, it was documented that in topsoils under barley the supplies were higher than under winter wheat. In subsoil, there were significant differences between wheat after alfalfa (111 t. ha−1) and barley after wheat (104 t. ha−1). As for a difference in the Soil organic matter supply in subsoil according to the cereal species the situation was contrary than in topsoil. Higher supplies were under wheat. Generally (topsoil and subsoil), the highest supply of Soil organic matter was in barley after sugar beet (224 t. ha−1) and similarly in wheat after alfalfa (222 t. ha−1). The smallest supply was in the variant of wheat after barley (217 t. ha−1). In topsoil, the average supply of humus was 114 t. ha−1 and that in subsoil was 107 t. ha−1 the difference being statistically significant.

Keywords

• soil organic matter supply
• topsoil
• subsoil
• Luvi-Haplic Chernozem