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- #Soil sampling based on disturbed and undisturbed sampling full
- #Soil sampling based on disturbed and undisturbed sampling trial
#Soil sampling based on disturbed and undisturbed sampling full
These calculations allowed establishing a full GHG balance. The cumulative N2O emissions measured continuously for three years were highly correlated with the calculated gaseous N losses (volatilization and denitrification), with higher losses in the conservation system. The fate of this N surplus also varied between systems with wide variations in SON storage and gaseous losses but no differences in N leaching. the difference between N inputs and N exports at the field scale, varied widely between treatments. No difference of specific SOC and SON mineralization rates was found between systems in vitro or in silico : we conclude that the higher C and N storage in soil observed in the conservation and organic systems was mainly driven by increased crop residues, rather than by the effect of no tillage practiced in conservation agriculture. Significant annual SOC and SON accumulation was found under conservation agriculture and organic farming at La Cage, whereas no significant change was observed in the low input and the conventional systems.
#Soil sampling based on disturbed and undisturbed sampling trial
While La Cage trial enabled an in situ quantification of soil organic C and N storage, N leaching, nitrous oxide (N2O) emissions and greenhouse gas (GHG) balance in alternative cropping systems compared to conventional, the Swiss and Danish experiments were used for in silico estimation of the C and N fates in organic cropping systems, after adaptation of the STICS model, followed by calibration and evaluation of the model. The methodological approach combined experimentation and modelling.
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For this purpose, we studied three long-term field trials: the experiment of La Cage (France) established in 1998, the DOK (Switzerland) started in 1978 and the Foulum Organic (Denmark) established in 1998. The objectives of this work were i) to quantify the long term impact of different alternative cropping systems on the fate of C and N in the soil-plantatmosphere system and ii) to simulate C and N dynamics with the agro-environmental model STICS. To reduce these environmental impacts, innovative and sustainable farming systems are promoted, such as low inputs cropping systems, “conservation” agriculture or organic farming. Among these prejudices, decreased soil C and N stocks, increased nitrate leaching in waters and gaseous N emissions towards the atmosphere are of a major concern. Based on the results from pot experiments treated with soil initial nitrate leaching and native soil, the mineralization of disturbed soil samples can give provide better results for predicting soil N-supplying capacity for in situ structure soil conditions on the Loess Plateau than undisturbed soil samples.Īgricultural activities can lead to imbalanced carbon (C) and nitrogen (N) dynamics compared to natural terrestrial eco-systems, causing potential damages for soil, water and air quality. Without soil initial nitrate leaching, the effect of disturbed and undisturbed soil samples incubated under laboratory conditions for estimating soil N-supplying capacity was not good however, with soil initial nitrate leaching, this method could give better results for soil N-supplying capacity. We concluded that NO3 −-N in soil extracted by CaCl2 before aerobic incubation can reflect soil N-supplying capacity but cannot reflect soil potential N-supplying capacity.
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Except the correlation coefficients for soil initial nitrate (NO3 −)-N and mineral N extracted by calcium chloride (CaCl2) before aerobic incubation with ryegrass uptake without soil initial nitrate leaching, the correlation coefficients for soil initial NO3 −-N and mineral N extracted by CaCl2 before aerobic incubation with ryegrass uptake with soil initial nitrate leaching and those for mineralizable N extracted by aerobic incubation, soil initial mineral N and mineralizable N extracted by aerobic incubation, potentially mineralizable N (N0) and soil initial mineral N + N0 with ryegrass uptake N under the two cases in disturbed treatment were all higher than those in undisturbed treatment. The results indicated that the entire indexes and ryegrass (Lolium perenne) uptake N with soil initial nitrate leaching showed a better correlation than that without soil initial nitrate leaching. Based on the results from pot experiments treated with soil initial nitrate leaching and native soil, long-term alternate leaching aerobic incubation was conducted to study the disturbed and undisturbed soil N-supplying capacity of surface soil samples in 11 sites with different fertilities on the Loess Plateau. Application of nitrogen (N) fertilizers without knowing the N-supplying capacity of soils may lead to low N use efficiency, uneconomical crop production, and pollution of the environment.