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Effects of Silicon Application and Groundwater Level in a Subirrigation System on Yield of a Three-Cut Meadow
The increasing demand for food and animal products makes it important to ensure that animals have sufficient fodder obtained from grassland. Unfortunately, there has been a recent decline in grassland areas, which makes it essential to find solutions to increase the grassland’s productivity and the quality of the fodder it yields. One of these solutions may be the use of appropriate irrigation and fertilization. The present study investigated the effect of the foliar application of silicon fertilizer and the groundwater level in a subirrigation system on the yield of a three-cut meadow. Four different experimental plots were used: high groundwater level (HWL), high groundwater level with silicon application (HWL_Si), lower groundwater level (LWL), and lower groundwater level with silicon application (LWL_Si). The analyses showed that silicon significantly reduced the amount of dry matter obtained in each of the three meadow cuts during the year. Furthermore, the plot with a higher groundwater level had an annual yield of 12.69 Mg·ha−1, whereas when silicon was applied to this area, it was 10.43 Mg·ha−1 (17.8% reduction in dry matter). A similar trend was noted at lower water levels, in which silicon also caused a dry matter reduction. However, the experiment did not indicate a statistically significant effect of silicon application on plant height and NDVI values. These results show that further research is still needed to better understand silicon’s effect on meadow sward.
The Role of Stand Age in Soil Carbon Dynamics in Afforested Post-Agricultural Ecosystems: The Case of Scots Pine Forests in Dfb-Climate Zone
Land use changes inevitably lead to changes in the carbon stocks stored in the soil. However, despite numerous studies investigating soil organic carbon (SOC) dynamics following the afforestation of post-agricultural lands, findings remain diverse and often inconclusive. In this study, the effect of stand age on the carbon content and stock in Scots pine (Pinus sylvestris) stands located in the Dfb-climate zone was investigated. Five research plots, characterized by similar soil types, geological structures, and tree cover, but differing in stand age (14-, 27-, 37-, 55-, 90-year-old stands), were selected. Additionally, one plot was located at arable soil as a reference. The soil was sampled from both organic and mineral horizons. The content of organic carbon in the organic horizion increased with years that passed from afforestation and amounted to 234.0, 251.6, 255.0, 265.0 and 293.0 g·kg−1 in 14-, 27-, 37-, 55- and 90-year-old stands, respectively. Such a pattern was also observed in the upper mineral horizons where the contents of SOC gradually increased from 7.27 g·kg−1 up to 17.1 g·kg−1. In the organic horizon, the stock of OC increased significantly with stand age up to 55 years after afforestation, while in the former plough layer, SOC stocks were found to slowly increase with stand age. The afforested soils, with the organic horizon, reached levels of carbon stocks observed on arable land after 17 years. Notably, the SOC stock in the mineral A horizon reach this level after 83 years. The obtained results indicate that in the years immediately following afforestation, SOC content is notably higher in arable soils compared to forest soils. However, as stand age increases, the SOC contents of upper horizons in forest soils surpass those of comparable agricultural soils. The observed SOC variability pinpoints the necessity of long-term monitoring in forest ecosystems in order to better understand the temporal dynamics of carbon turnover and to optimize afforestation strategies for long-term carbon sequestration.