Soil organic carbon (SOC) plays a fundamental role in the global carbon (C) cycle and represents a key element of soil ecosystem services. Thus, the response of agricultural soils to climate change is important when assessing their C accrual potential and fertility. In this research we investigate the influence of global warming on SOC pools, and on the yields of two crops, namely sugar beet (SB) and soybean (SOY). A temperature increase of ~2°C was simulated using Open Top Chambers (OTCs) in a randomized complete block design field experiment. An uncultivated soil was used as a further control. A total of 64 plots (32 for SB and 32 for SOY) were obtained. Topsoil samples (0-20 cm) were collected from all plots before and after the experiment and characterized from the physical and chemical point of view. Particulate organic matter (POM) and mineral associated organic matter (MAOM) were also isolated and analysed. Data collected from sensors confirmed that soil and air temperatures inside the OTCs were higher than those outside the OTCs, both in the control and in the cultivated plots. Results obtained during the first year of the experiment showed that, following warming, SOC slightly decreased in SB (by 1.4%/yr), while it surprisingly increased (by 1.6%/yr) in SOY. Both in the uncultivated control and in cultivated soils, the temperature increase resulted in a general decrease of the OCMAOM/OCPOM ratio, although in SOY such a reduction was negligible. Furthermore, the C/N ratio in MAOM was always lower than in POM (10 vs. 13, respectively) for both crops and under both conditions, thus confirming a different contribution of microbial derived SOM. Although both SB and SOY are C3 plants, a quite different response to warming in terms of SOC input and relative distribution between pools was observed, possibly because of both a) the different root architecture, and b) the lower susceptibility of SOY to increasing temperatures. Beside affecting SOC distribution between SOM pools, the 2 °C temperature increase had also a strong impact on the yield of both crops, with average values 3× (SB) and 5× (SOY) lower within the OTCs than those obtained outside the OTCs, corresponding to a loss of income for farmers of 1,000-3,000 €/ha.
Assessing the influence of warming on soil organic matter pools and crop yields
Abdelkefi F.;Galluzzi G.;Zaccone C.
2024-01-01
Abstract
Soil organic carbon (SOC) plays a fundamental role in the global carbon (C) cycle and represents a key element of soil ecosystem services. Thus, the response of agricultural soils to climate change is important when assessing their C accrual potential and fertility. In this research we investigate the influence of global warming on SOC pools, and on the yields of two crops, namely sugar beet (SB) and soybean (SOY). A temperature increase of ~2°C was simulated using Open Top Chambers (OTCs) in a randomized complete block design field experiment. An uncultivated soil was used as a further control. A total of 64 plots (32 for SB and 32 for SOY) were obtained. Topsoil samples (0-20 cm) were collected from all plots before and after the experiment and characterized from the physical and chemical point of view. Particulate organic matter (POM) and mineral associated organic matter (MAOM) were also isolated and analysed. Data collected from sensors confirmed that soil and air temperatures inside the OTCs were higher than those outside the OTCs, both in the control and in the cultivated plots. Results obtained during the first year of the experiment showed that, following warming, SOC slightly decreased in SB (by 1.4%/yr), while it surprisingly increased (by 1.6%/yr) in SOY. Both in the uncultivated control and in cultivated soils, the temperature increase resulted in a general decrease of the OCMAOM/OCPOM ratio, although in SOY such a reduction was negligible. Furthermore, the C/N ratio in MAOM was always lower than in POM (10 vs. 13, respectively) for both crops and under both conditions, thus confirming a different contribution of microbial derived SOM. Although both SB and SOY are C3 plants, a quite different response to warming in terms of SOC input and relative distribution between pools was observed, possibly because of both a) the different root architecture, and b) the lower susceptibility of SOY to increasing temperatures. Beside affecting SOC distribution between SOM pools, the 2 °C temperature increase had also a strong impact on the yield of both crops, with average values 3× (SB) and 5× (SOY) lower within the OTCs than those obtained outside the OTCs, corresponding to a loss of income for farmers of 1,000-3,000 €/ha.
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