Aggregation and organic matter in subarctic Andosols under different grassland management
Lehtinen, T. ; Gisladottir, G. ; Lair, G.J. ; Leeuwen, J.P. van; Blum, W.E.H. ; Bloem, J. ; Steffens, M. ; Ragnarsdottir, K.V. - \ 2015
Acta Agriculturae Scandinavica Section B-Soil and Plant Science 65 (2015)3. - ISSN 0906-4710 - p. 246 - 263.
c-13 nmr-spectroscopy - soil microbial biomass - mediterranean conditions - structural stability - cultivated soils - farming systems - volcanic soils - carbon stocks - land-use - tillage
Quantity and quality of soil organic matter (SOM) affect physical, chemical, and biological soil properties, and are pivotal to productive and healthy grasslands. Thus, we analyzed the distribution of soil aggregates and assessed quality, quantity, and distribution of SOM in two unimproved and improved (two organic and two conventional) grasslands in subarctic Iceland, in Haplic and Histic Andosols. We also evaluated principal physicochemical and biological soil properties, which influence soil aggregation and SOM dynamics. Macroaggregates (>250 µm) in topsoils were most prominent in unimproved (62–77%) and organically (58–69%) managed sites, whereas 20–250 µm aggregates were the most prominent in conventionally managed sites (51–53%). Macroaggregate stability in topsoils, measured as mean weight diameter, was approximately twice as high in organically managed (12–20 mm) compared with the conventionally managed (5–8 mm) sites, possibly due to higher organic inputs (e.g., manure, compost, and cattle urine). In unimproved grasslands and one organic site, macroaggregates contributed between 40% and 70% of soil organic carbon (SOC) and nitrogen to bulk soil, whereas in high SOM concentration sites free particulate organic matter contributed up to 70% of the SOC and nitrogen to bulk soil. Aggregate hierarchy in Haplic Andosols was confirmed by different stabilizing mechanisms of micro- and macroaggregates, however, somewhat diminished by oxides (pyrophosphate-, oxalate-, and dithionite-extractable Fe, Al, and Mn) acting as binding agents for macroaggregates. In Histic Andosols, no aggregate hierarchy was observed. The higher macroaggregate stability in organic farming practice compared with conventional farming is of interest due to the importance of macroaggregates in protecting SOM and soils from erosion, which is a prerequisite for soil functions in grasslands that are envisaged for food production in the future.
Evaluation and Selection of Indicators for Land Degradation and Desertification Monitoring: Methodological Approach
Kosmas, C. ; Karis, O. ; Karavitis, C. ; Ritsema, C.J. ; Salvati, L. ; Acikalin, S. ; Alcala, S. ; Alfama, P. ; Atlhopheng, J. ; Barrera, J. ; Belgacem, A. ; Sole-Benet, A. ; Brito, J. ; Chaker, M. ; Chanda, R. ; Coelho, C. ; Darkoh, M. ; Diamantis, I. ; Ermolaeva, O. ; Fassouli, V. ; Fei, W. ; Fernandez, F. ; Ferreira, A. ; Gokceoglu, C. ; Gonzalez, D. ; Gungor, H. ; Hessel, R. ; Juying, J. ; Khatteli, H. ; Kounalaki, A. ; Laouina, A. ; Lollino, P. ; Lopes, M. ; Magole, L. ; Medina, L. ; Mendoza, M. ; Morais, P. ; Mulale, K. ; Ocakoglu, F. ; Ouessar, M. ; Ovalle, C. ; Perez, C. ; Perkins, J. ; Pliakas, F. ; Polemio, M. ; Pozo, A. ; Prat, C. ; Qinke, Y. ; Ramos, A. ; Riquelme, J. ; Romanenkov, V. ; Rui, L. ; Santaloia, F. ; Sebego, R. ; Sghaier, M. ; Silva, N. ; Sizemskaya, M. ; Soares, J. ; Sonmez, H. ; Taamallah, H. ; Tezcan, L. ; Torri, D. ; Ungaro, F. ; Valente, S. ; Vente, J. de; Zagal, E. ; Zeiliguer, A. ; Zhonging, W. ; Ziogas, A. - \ 2014
Environmental Management 54 (2014)5. - ISSN 0364-152X - p. 951 - 970.
mediterranean conditions - aggregate stability - soil properties - rock fragments - organic-matter - vegetation - tillage - biomass - erosion - greece
An approach to derive relationships for defining land degradation and desertification risk and developing appropriate tools for assessing the effectiveness of the various land management practices using indicators is presented in the present paper. In order to investigate which indicators are most effective in assessing the level of desertification risk, a total of 70 candidate indicators was selected providing information for the biophysical environment, socio-economic conditions, and land management characteristics. The indicators were defined in 1,672 field sites located in 17 study areas in the Mediterranean region, Eastern Europe, Latin America, Africa, and Asia. Based on an existing geo-referenced database, classes were designated for each indicator and a sensitivity score to desertification was assigned to each class based on existing research. The obtained data were analyzed for the various processes of land degradation at farm level. The derived methodology was assessed using independent indicators, such as the measured soil erosion rate, and the organic matter content of the soil. Based on regression analyses, the collected indicator set can be reduced to a number of effective indicators ranging from 8 to 17 in the various processes of land degradation. Among the most important indicators identified as affecting land degradation and desertification risk were rain seasonality, slope gradient, plant cover, rate of land abandonment, land-use intensity, and the level of policy implementation.
Editorial : Is it possible to extrapolate results of aquatic microcosm and mesocosm experiments with pesticides between climate zones in Europe?
Daam, M.A. ; Cerejeira, J. ; Brink, P.J. van den; Brock, T.C.M. - \ 2011
Environmental Science and Pollution Research 18 (2011)1. - ISSN 0944-1344 - p. 123 - 126.
mediterranean conditions - zooplankton community - species sensitivity - risk-assessment - chlorpyrifos - traits - ecosystems - scenarios
Soil Erosion and runoff response to plant-cover strips on semiarid slopes (SE Spain)
Martinez-Raya, A. ; Duran Zuazo, V.H. ; Francia-Martinez, J.R. - \ 2006
Land Degradation and Development 17 (2006)1. - ISSN 1085-3278 - p. 1 - 11.
mediterranean conditions - sediment production - climate - water - infiltration - vegetation - rainfall - area
Over a four-year period (1997-2000), soil loss and surface-runoff patterns were monitored in hillside erosion plots with almond trees under different plant-cover strips (thyme, barley and lentils) on the south flank of the Sierra Nevada (Lanjaron) in south-eastern Spain. The erosion plots (580 m a.s.l.), located on a 35 per cent slope, were 144 m2 (24 m×6 m) in area. The plant-cover strips, 3 m wide, ran across the slope. The most effective plant cover proved to be thyme, reducing soil loss by 97 per cent and runoff by 91 per cent, compared to bare soil. Barley reduced soil loss by 87 per cent and runoff by 59 per cent, compared to bare soil, while these percentages were 58 per cent and 18 per cent for lentils. Thyme proved 77 per cent more effective than barley and 93 per cent more effective than lentils in reducing soil loss; thyme was also 79 per cent more effective than barley and 90 per cent more than lentil in blocking runoff. The present study demonstrates the effectiveness of plant-cover strips in controlling soil erosion and runoff on sloping agricultural land