Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

2 Polish Journal of Environmental Studies

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Conversion of cropland to grassland and forest mitigates global warming potential in Northeast China

100%

Miao S. , Qiao Y. , Zhang F.

Polish Journal of Environmental Studies

2015

tom 24

nr 3

In converting cropland to grassland and forest, more carbon is sequestered in grassland soil and forest biomass, but the mitigation of global warming potential (GWP) is not clear. In this study, we use the longterm conversion from cropland to grassland (28 y) and forest (14 y) to comprehensively assess the impact on GWP of soil carbon (C), nitrogen (N), CO₂, and N₂O emissions. The results showed that compared to the original cropland, conversion to grassland increased soil C content by 51.1%, soil N content by 28.4%, soil C stock (SCS) by four times, CO₂ emission by 17%, and N₂O emission by 40%; soil N stock (SNS) decreased by half. The corresponding values after afforestation were 7.2%, 5.2%, three times, 3%, -80%, and half, respectively. Overall GWP in the cropland system was calculated using the fuel used for farming production, the change in soil C, and N₂O emissions. Due to large C sequestration, the GWP of conversion to grassland (-1667 kg CO₂-C equivalent ha⁻¹·y⁻¹) and forest (-324 kg CO₂-C equivalent ha⁻¹·y⁻¹) were significantly lower than the cropland system (755 kg CO₂-C equivalent ha⁻¹·y⁻¹). The relationship between GWP and greenhouse gas, between GWP and the change of total C and N, suggest that in rain-fed agricultural systems in northeast China, the conversion from cropland to grassland and forest can mitigate GWP through changing CO₂ and N₂O emissions.

How 23-year continuous soybean cultivation led to more SOC and thermal energy stored in Mollisol micro-aggregates

88%

Qiao Y. , Miao S. , Yue S. , Wu H. , Han X.

Polish Journal of Environmental Studies

2016

tom 25

nr 3

Aggregate has been recognized as a key element in the stabilization of soil organic carbon (SOC). Several researchers have done outstanding work on identifying and isolating aggregates and their physiochemical properties. However, thermal stability of SOC in soil aggregates has not yet been adequately explored. The main objective of the study was to clarify the protection of aggregation on SOC from thermal characters, and provide evidence on whether thermal analysis could be a potential rapid method to determine SOC stability in aggregates. We separated 20-cm surface soil into six fractions (>2, 1-2, 0.5-1, 0.25-0.5, 0.053-0.25 and <0.053mm) before and after 23-yr continuous soybean cultivation. The study measured the change of SOC and its thermal characteristics across aggregates using thermogravimetry-differential scanning calorimetry (TG-DSC), which also showed that the thermal stability mechanism of SOC is protected by aggregates. Results showed that 23-yr continuous soybean cultivation led to an SOC increase in 0.053-0.5 mm size aggregates, but a decrease in other large-size aggregates. Energy density in the > 0.5 mm fraction was decreased by 23-yr continuous soybean cultivation, but increased to < 0.5 mm size fraction. The largest energy density was in < 0.053 mm size fractions. In conclusion, long-term continuous soybean cultivation led to more energy transferred to micro-aggregates associated with the protection of micro-aggregates on soil SOC.