Long-term effectiveness of Sustainable Land Management practices to control runoff, soil erosion and nutrient loss in Mediterranean rainfed agroecosystems
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Mr Victor Castillo, Soil Erosion and Conservation Research Group, Spain. Global Symposium on Soil Erosion (GSER19), 15 - 17 May 2019 at FAO HQ.
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Long-term effectiveness of Sustainable Land Management practices to control runoff, soil erosion and nutrient loss in Mediterranean rainfed agroecosystems
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- 2. Long-term effectiveness of Sustainable Land Management practices to control runoff, soil erosion and nutrient loss in Mediterranean rainfed agroecosystems Martínez-Mena, M1., Carrillo-López, E1., Boix-Fayos, C1., Almagro, M2., García Franco, N3., Díaz Pereira, E1., Castillo, V1., de Vente, J1 1Soil erosion and conservation research Group CEBAS-CSIC 2Basque Centre for Climate Research BC3 3Technical University of Munich 2
- 3. • Soil erosion is recognized as a major threat to soil functions in the Mediterranean region • Soil erosion results in the loss of soil nutrients and organic matter decreasing the productivity of soil and its capacity to sustain life: that is particularly worrying for rainfed crops • Things can get worse 3 Scarce and torrential rainfall Rugged relief Shallow and poor soils Long lasting human interventions Eekhout et al. https://doi.org/10.5194/hess-22-5935-2018 Introduction: The problem
- 4. 4 • Sustainable land use and management (SLM) has the potential to reduce soil, organic carbon and nutrient losses by erosion but… • Response depend on local socio-environmental conditions • Poorly adopted • Competition of spontaneous plant for water and nutrient • Not immediate positive effects on yield • Lack of (socio-economic)incentives Objectives: • How effective are SLM in reducing runoff soil erosion and associated losses in two Mediterranean rain fed crops • Is the efficiency depending on rainfall characteristics? Introduction: The solutions ?
- 5. • Duplicate the slide as needed 5 MethodsStudy areas 2009: Sustainable management practices implementation Six years (2010-2015): Erosion monitorization and OC and nutrients mobilization.
- 6. Reduced tillage (RT) chisel ploughing (2 times yr-1) 15 cm depth Implemented management practices in almond Conventional tillage (CT) chisel ploughing (4-5 times yr-1) 20 cm depth Reduced tillage+green manure (RTG) chisel ploughing (2 times yr-1) at 20 cm depth Avena sativa & Vicia sativa 1:3 at 150 kg ha-1 Reduced tillage (RT) chisel ploughing (2 times yr-1) 20 cm depth
- 7. Implemented management practices in Cereal Conventional mouldboard tillage after harvest 40 cm 3 times (chisel plough ) during fallow (20 cm) Reduced contour tillage Labours/year : 2 Depth: 20 cm
- 8. Almond orchard Cereal Lithology Limestones Marls Clay (%) 17.76±3.7 30.65±3.9 Silt (%) 48.9±11.5 59.6±2.8 Sand (%) 33.2±14.8 9.6±5.9 OC (g/kg) 20.1 7.4 T N (g/Kg) 2.12 0.7 Polsen (ppm) 47 6.1 K (ppm) 815,18 126 CaCO3 (%) 44±9.2 56±10.1 pH 8.8±0.14 9.14±0.17 CE (S/cm) 90.8±14.7 73.3±5.9 Study areas: general characteristics
- 9. Experimental design: Open Erosion plots Study period (2010-2015) Slope: 10-15% Three replicates per treatment: 15 plots (9 almond;6 cereal). Drainage are: 25-126 m2 (almond) ; 44-265 m2 (cereal)
- 10. 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 I30(mm/h) Rainfall(mm) R I30 2011 20152012 2013 2014 2010 Results: Climatic characteristics 0 50 100 150 200 250 300 350 400 450 2010 2011 2012 2013 2014 2015 Rainfall(mm) year Total Rainfall Rainfall events 35% (1940-2007)
- 11. 0.0 0.1 0.2 0.3 0.4 0.5 CT RT RTG Runoff(mm) Management practice Almond orchard 0.0 2.0 4.0 6.0 8.0 10.0 CT RT Soilloss(g/m2) Management practice 65% 62% 0.0 0.5 1.0 1.5 2.0 2.5 3.0 CT RT RTG Soilloss(g/m2) Management practice ~85% Results: Average runoff and erosion Cereal
- 12. 71 % 83 % 69% 0 10 20 30 40 50 60 0 5 10 15 20 25 30 35 40 45 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Rainfallintensity(I30;mm/h) CumulativeSoilloss(g/m2) RTG RT Almond orchard CT Results: Cumulative soil loss 0 10 20 30 40 50 60 0 50 100 150 200 250 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 RainfallIntensity(I30;mm/h) Cumulativesoilloss(g/m2) Event CT RT Cereal 4 events mobilized between 55 and 67 % of the total soil loss 4 events mobilized between 60 and 68 % of the total soil loss
- 13. 13 Results: total mobilized OC and nutrients by erosion 0 5 10 15 20 25 CT RT OCkg/ha 0 2 4 6 8 10 12 14 16 CT RT RTG OCkg/ha 0 0.5 1 1.5 2 2.5 3 CT RT Nkg/ha 0 0.2 0.4 0.6 0.8 1 1.2 1.4 CT RT RTG Nkg/ha 0 0.01 0.02 0.03 0.04 0.05 0.06 CT RT Pkg/ha 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 CT RT RTG Pkg/ha Almond orchard Cereals 61% 57 % 60 % ~ 70-90% ~ 99% ~ 95% OC total mobilized represented 11% of the total sediment (CT) and 3% (RT and RTG).
- 14. Results: effect of soil quality. 0 1 2 3 4 5 6 7 8 EROC ERN ERP CT RT Almond Orchard OC (%) NT (%) P (ppm) CT 1,94±0.13b 0.14±0.02b 40,19±4.58a RT 2.38±0.10a 0.19±0.02a 53,20±6.76a RTG 2.56±0.14a 0.23±0.01a 30,64±2.32a OC (%) NT (%) P (ppm) CT 0.59±0.03b 0.07±0.02a 3.46±0.16b RT 0,85±0.04a 0.08±0.007a 5.0±0.31a Cereal Soil OC and nutrients 0 0.5 1 1.5 2 2.5 3 EROC ERN ERP CT RT RTG b b a Enrichment ratios
- 15. 15 Results: Effectiveness and rainfall characteristics. Season Spring Summer Autumn Winter Total Numberofeventsineacherosivityclass(%) 0 20 40 60 80 100 Class I Class II Class III Effectiveness of RTG Effectiveness of reduced tillage Almond crops Cereals Almond crops Runoff Erosion
- 16. The SLM practices evaluated resulted in reduced runoff, erosion, and mobilization of organic carbon and nutrients in sediments and subsequently increased organic carbon (OC) and nutrients (N and P) contents in the soil. Main remarks Our results support the key role of SLM practices under semiarid conditions as useful tools for climate change mitigation and adaptation, given the expected increase in high-intensity rainfall events in semiarid areas Highest (soil erosion and nutrient exportation) during the most intense rainfall events, which are responsible for the highest erosion rates in Mediterranean areas. Short-term effect (18 months) of the evaluated SLM practices on erosion control, making their implementation especially attractive for farmers. • How effective are SLM in reducing runoff soil erosion and associated losses in two Mediterranean rain fed crops • Is the efficiency depending on rainfall characteristics?
- 17. Thank you for listening http://www.soilwaterconservation.es/ This study site has been funded by several national (CYCIT AGL201125069//CGL2014-55-405-R), Regional projects (Séneca Foundation: 08757/PI/08//19350/PI/14] and European projects (F6 DG RTD 037046 and DIVERFARMING H2020 RUR-06-2016 728003). UNCCD provided a grant for Victor M. Castillo to attend the Global Symposium on Soil Erosion
Editor's Notes
- Scenarios of climate change predict for Segura basin in SE Spain decreasing annual average precipitation while increasing of heavy rainfall events
- Almond crops is expanding because of subsidies but also increase value at market and development of late varieties. It is typically cultivated in tree rows spaced with bare soil between them. Cereals is quite residual crop but still occupying significant area. Rotational system with long period of fallow
- La cubierta verde se siembra en otoño y se siega en mayo/junio dependiendo de las precipitaciones y se incorpora al suelo: vicia sativa and barley The tested SLM practices were selected as result of a participatory exercise with relevant stakeholders
- Muy brevemente las prácticas aplicadas consisten en: Cereales sometidos a un sistema de rotación de barbecho (siembra en otoño y cosecha en junio) seguido por un periodo de descanso de un año donde los residuos de la cosecha se dejan en el campo a lo largo del otoño y el invierno. Laboreo en paralelo a las líneas de contorno. El cereal: laboreo reducido (consistente en 2 labores al año a 20 cm depth) frente al laboreo tradicional con labores 4/5 veces al año y una vez vertedera con volteo del suelo en los primeros 40 cm. The wheat field under CT was plowed with a moldboard plow to 40 cm depth following harvest in June, leaving the land fallow for one year. During the fallow period, the land was plowed three more times with a chisel plow before the seeding in the next autumn. Under RT, the wheat field was not plowed after harvest, leaving the stubble during the fallow year, until the next autumn, when the land was prepared for seeding with a chisel plow (0.20 m).
- Ambas zonas tienen características litológicas contrastadas, texturas franco limosas pero con diferencias en los contenidos de arcilla y arena. Bajos contenidos de materia orgánica y alto contenido de carbonatos…
- Aquí presentamos el diseño de las parcelas que se utilizan para cuantificar tasas de erosión y movilización de nutrientes por dicho proceso. Son parcelas abiertas de tipo caja gerlach donde se recoge el material más grueso las cuales están conectadas a un depósito que a su vez se conecta con un segundo. La recogida de sedimento se realiza tras cada evento. La superficie de drenaje de las distintas parcelas oscila entre 82-54-27 en los almendros y 140 m2 en el cereal.
- Variabilidad interanual Descenso de P gradual del 2010 al 2014 y reducción en un 35% respecto de un periodo de 30 años (1940-2007). Lluvias que generan escorrentía y erosión fluctuando entre un 39 y un 85% de la precipitación total anual (ligado con la intensidad). Años más secos producen menos eventos erosivos pero más fuertes Total de 33 eventos en 6 años. Años más secos (2013 y 2014) tuvieron mayores intensidades y precipitaciones. 42% de los eventos que generaron erosion pertenecen a la clase 1 de erosividad; mientras que el 29% pertenecen a las clases 2 y 3. Umbrales bajos de precipitación e intensidad generadores de erosión en las dos zonas de estudio y prácticamente todos los eventos que generan escorrentía movilizan sedimento (100% en cereal y entre 66 y 88% en el almendro)
- Effect of reducing the number tillage operations on runoff was observed for both crops. But impact was greater in almond than in cereal ( not significant for this crop, maybe because of large (intrinsic) variability of runoff response along the measured events ) Impacts of SLM practices were greater on soil erosion. Cereal showed highest avaerage soil los rates due to managemnet practices ( long fallow period: bare , unprotected soil)
- In terms of total soil losses a positive effect of implementing SLM can be observed in both crops. This positive effect was observed at soon as 1 and half year after the implementation of the practices and the effects are increasing as time goes by. By the end of the period of study, conventional tillage erodes four fold soil than reduced tillage in cereal and 2 and half ties the soil eroded by reduced tillage in almonds We also observe that four events are responsible for mobilization of around 55-70% de total eroded soil.
- Six years after its implementation, RT had increased the SOC, relative to that in CT, in both crops. However, increments in the soil N content due to RT were only observed in the almond field, while the soil P concentration was increased in RT, compared to CT, only in the wheat field (Table 1). En cuanto al OC movilizado es interesante recalcar que a pesar de que las prácticas sostenibles revirtieron tambien en una mejora de OC y nutrientes en el suelo estos no se vieron reflejados enel sedimento como podemos ver por las razones de enriquecimiento….Así, concentraciones de OC mayores en el suelo conllevan menores enriquecimientos. Esto es así claramente para el almendro, mientras en el cereal simplemente no existen diferencias entre tratamientos… Even at seemingly low rates, eroded sediments are rich in OM and nutrients (Marques et al., 2008). The loss is, therefore, qualitatively important and may have a considerable impact on almond sustainability (Quiquerez et al., 2008). This selective transport by erosion is highlighted by our estimates of the enrichment ratios of nutrients in the sediments. These findings are similar to those of other authors and may be attributed to the greater amount of clay occurring in the sediment than in the soil where the nutrients originated (Xingchang et al., 2004). They are more easily transported by erosion, especially by interrill erosion (Schiettecatte et al., 2008), which is the erosion type that the system of plots used in this study is capable of measuring.
- The events were classified in three classes according to their RE values (KE*I30): Class I: RE≤ 25, Class II: 25< RE ≤ 90, and Class III: RE >90, representing low, medium, and high erosive events, respectively, according to the rainfall characteristics of this area (Martinez-Mena et al., 2001). In the wheat field the greatest reduction in runoff (50%) was found for the least erosive rainfall events (class I), while the reduction in erosion was not dependent on the rainfall erosivity. By contrast, in the almond field the greatest reduction in runoff and erosion was found for the most erosive events (classes II and III) (Figure 6). The correlations between erosion and rainfall erosivity were stronger in conventional tillage than in reduced tillage. For RTG in the almond field there was no significant correlation between the rainfall intensity and erosion rates With the RTG management, where the average reduction in erosion for the less erosive events (class I) was about 40%, the reduction in class III was almost double (70%)