Preventing soil erosion by water
- Small dams between ploughing furrows
- Post-fire mulching in forests
- Terraces on mountainous agricultural land
Water infiltration: Dye tracer experiments showed that in treated furrows, water infiltrates the compacted subsoil below the ploughed horizon, while in untreated furrows hardly any water infiltrates deeper than 20 cm below the surface.
Soil erosion: More surface runoff in untreated furrows led to higher rates of soil erosion. In a steep section of a field, the average cross-sectional area of untreated furrows increased by almost 45% until the potato plant reached maximum vegetation cover while the changes during the same period were much smaller for treated furrows (24%).
Waterlogging: In addition, a series of drone photographs showed that less surface runoff also reduces the amount of stagnant water in depressions: while in treated furrows rainwater was evenly retained in small holes and infiltrated the soil locally, in untreated furrows it drained to the lowest point of the plot. In depressions, collected water caused saturation excess and anaerobic conditions, and resulted in crop failure.
Below are links to national media articles about the experiment:
- Der Dkyker bremst die Erosion aus
- Der Dyker bremst die Erosion
- Wo der Dyker locht, staut kein Wasser
- Der Lockstern grabt Kartoffeln das Wasser ab
- Dyker bremst Erosion in Kartoffeln
Burnt areas in forests can reveal some extreme responses in runoff generation and associated sediment losses. Such responses exacerbate the direct effects of fire on vegetation and on the soil physical, chemical and biological properties, compromising their recovery from heat-induced changes. Post-fire soil erosion also represents a serious threat to off-site "values-at-risk", through flood generation and transfer of sediments, organic matter, nutrients and pollutants to downstream water bodies. Recent field trials in the Portugese case study area have clearly demonstrated that mulching with forest logging residues (widely available in the region) is highly effective in reducing erosion in recently burnt areas. The RECARE experiment is testing the effectiveness of mulching to reduce post-fire soil (fertility) losses. It involves mulching with eucalyptus logging slash at 2 contrasting application rates.
|Post-fire mulching experment
The main results of the field experiment were the following:
- Without treatment, total sediment losses over the first post-fire year amounted to eight times the widely recognised threshold for tolerable soil losses of 1 Mg ha-1 y-1
- Both mulch application rates strongly reduced these total sediment losses, the reduced rate with 86 % to 1.1 Mg ha-1 y-1 and the standard rate with 96 % to 0.3 Mg ha-1 y-1
- Both mulch application rates also strongly reduced the total organic matter losses, the reduced rate with 87 % to 0.2 Mg ha-1 y-1 and the standard rate with 96 % to 0.1 Mg ha-1 y-1
- The two mulch application rates did not seem to have an impact on the abundance and diversity of ground-dwelling arthropods, but did appear to have a negative effect on vegetation cover, both of higher plants and of mosses.
J.J. Keizer, M.A.S. Martins, S.A. Prats, S.R. Faria, O. González-Pelayo, A.I. Machado, M.E. Rial-Rivas, L.F. Santos, D. Serpa, M.E.T. Varela (20015) Within-in flume sediment deposition in a forested catchment following wildfire and post-fire bench terracing, north-central Portugal. Cuadernos de Investigación Geográfica Vol 41, No. 1 doi: http://dx.doi.org/10.18172/cig.2700
A.I. Machadoa, D. Serpaa, R.V. Ferreiraa, M.L. Rodríguez-Blancob, R. Pintoa, M.I. Nunesa, M.A. Cerqueiraa, J.J. Keizera(2015) Cation export by overland flow in a recently burnt forest area in north-central Portugal Science of the Total Environment Volumes 524–525, 15 August 2015, Pages 201–212 doi: 10.1016/j.scitotenv.2015.04.026
Ferreira R.V., Serpa D., Cerqueira M.A., Keizer J.J. (2016) Short-time phosphorus losses by overland flow in burnt pine and eucalypt plantations in north-central Portugal: A study at micro-plot scale. Published in: Science of the Total Environment 551–552, 631–639 https://dx.doi.org/10.1016/j.scitotenv.2016.02.036
Campos I., Abrantes N., Keizer J.J., Vale C., Pereira P. (2016) Major and trace elements in soils and ashes of eucalypt and pine forest plantations in Portugal following a wildfire. Published in:Science of the Total Environment 2016 Dec 1;572:1363-1376 https://dx.doi.org/10.1016/j.scitotenv.2016.01.190
Tavares Wahren F., Julich S., Nunes J.P., Gonzalez-Pelayo O., Hawtree D., Feger K.-H., Keizer J.J. (2016) Combining digital soil mapping and hydrological modeling in a data scarce watershed in north-central Portugal. Published in: GEODERMA 264, part B, 350- 362 http://dx.doi.org/10.1016/j.geoderma.2015.08.023
The creation of agricultural terraces on steep terrain can provide an effective solution to preventing soil erosion. The experiment involves testing the effectiveness of maintenance/rehabilitation of dry-stone terraces. It involves a participatory monitoring process.
|mitigating erosion by water on mountainous agriculture land
|Cyprus experimental site
- Based on two-year field measurements (Dec 2015 – Nov 2017), erosion from standing terrace sections was 3.8 times less than the erosion from collapsed sections. We also found that 43% of soil erosion occurred in two very intense rainfall events.
- Although terrace construction and maintenance is labour-intensive with high establishment costs, it is a cost effective practice in the long-run when considering the soil erosion reduction.
- The direct benefit of agricultural terraces is the harvested crop yields. According to land users, yields could be up to 20% higher in well-maintained terraces. Since the terraces are part of the cultural landscape, proper maintenance would also help restore and sustain the cultural landscape and rural mountain livelihoods.
- Apart from preventing erosion and maintaining the productive capacity of soils in mountains, terraces also prevent erosion of unpaved rural roads. Sediment from the slopes also affects the water quality of streams and causes sedimentation in downstream areas. Thus, reducing erosion could lower water infrastructure maintenance costs.
Camera, C., Djuma, H., Bruggeman, A., Zoumides, C., Eliades, M., Charalambous, K., Abate, D. and Faka, M., 2018. Quantifying the effectiveness of mountain terraces on soil erosion protection with sediment traps and dry-stone wall laser scans. Catena, 171, pp.251-264. https://doi.org/10.1016/j.catena.2018.07.017
Christos Zoumides, Adriana Bruggeman, Elias Giannakis, Corrado Camera, Hakan Djuma, Marinos Eliades, Katerina Charalambous (2016) Community-Based Rehabilitation of Mountain Terraces in Cyprus. Published in Land Degradation & Development (2016) August 1 DOI: 10.1002/ldr.2586
Hakan Djuma, Adriana Bruggeman, Corrado Camera, Christos ZoumidesDjuma, H., Bruggeman, A., Camera, C. and Zoumides (2016) Combining qualitative and quantitative methods for soil erosion assessments: an application in a sloping mediterranean watershed, Cyprus