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DSpace at VNU: Impact of fodder cover on runoff and soil erosion at plot scale in a cultivated catchment of North Vietna...
Geoderma 177–178 (2012) 8–17 Contents lists available at SciVerse ScienceDirect Geoderma journal homepage: www.elsevier.com/locate/geoderma Impact of fodder cover on runoff and soil erosion at plot scale in a cultivated catchment of North Vietnam Hai An Phan Ha a, b, Sylvain Huon b,⁎, Thierry Henry des Tureaux c, Didier Orange c, Pascal Jouquet c, Christian Valentin c, Anneke De Rouw c, Toan Tran Duc d a Vietnam National University (VNU), Faculty of Chemistry, 19 Le Thanh Tong, Hanoi, Viet Nam Université Pierre et Marie Curie (UMPC), UMR 7618 Bioemco, Case 120, place Jussieu, 75 252 Paris Cedex 05, France IRD, UMR 7618 Bioemco, 32 Avenue Henri Varagnat, 93143 Bondy Cedex, France d Soil and Fertilizer Research Institute (SFRI), Dong Ngac Tu Liem, Hanoi, Viet Nam b c a r t i c l e i n f o Article history: Received 21 May 2010 Received in revised form 19 January 2012 Accepted 23 January 2012 Available online March 2012 Keywords: Soil conservation Paspalum atratum Panicum maximum Stylosanthes guianensis Slope length Plant cover a b s t r a c t In Vietnam soil erosion is a major environmental problem with respect to soil fertility, water quality and downstream property damages and involves 40% of total land surface Due to a continuous and persistent decrease of soil quality under annual crops, farmers gradually convert their fields to grazing lands and their crops to fodder cultures or tree plantations Experimental 1-m2 field plots with three replicates each were monitored for two years (2006–2007) to evaluate the impact of three different fodder treatments (Paspalum atratum, Panicum maximum and Stylosanthes guianensis) on runoff and soil detachment in a cultivated catchment of North Vietnam These experiments were designed to monitor at local scale the protective effect of vegetation cover against splash and rain-impacted erosion The lowest runoffs (ca 3.0–4.4%), sediment yields (ca 14–19 g m − yr − 1) and soil organic carbon losses (ca 0.7 g C m − a− 1) were obtained for P maximum that provided the best soil protection with respect to the two other treatments These values were low as compared to cultivated crops (cassava and rainfed rice) Soil surface characteristics (mainly biological activity and crusting) did apparently not play a key role, most likely because each plant cover provided, with its own efficiency, protection against rainfall erosivity and rapid plant regrowth wiped out traces of flow detachment The extent of soil detachment and sediment export, mainly controlled by cut and carry operations of fodder management, was reduced by increasing slope length from to m The choice of dense fodders such as P maximum appears to be, in terms of improved livelihood and environment sustainability, an interesting issue for uplands farmers © 2012 Elsevier B.V All rights reserved Introduction In South-East Asian regions runoff and soil erosion are significantly related to agricultural land use in particular on sloping lands of headwater catchments (i.e., Sidle et al., 2006; Valentin et al., 2008) The amplitude of erosion seems to be more related to anthropogenic factors such as land use change, deforestation, cultivation practice and crop type than to climatic conditions (Chaplot et al., 2005; Craswell and Niamskul, 1999) In Vietnam, a country covered at 75% by hills and mountains, erosion involves 13 × 106 ha, that represents 40% of total land surface (Vezina et al., 2006) A large part of the former rain forest was lost between the 1970s and 1990s to expand cultivation of cassava, arrowroot, taro, maize or tree plantations (De Koninck, 1999; Meyfroidt and Lambin, 2008; Sharma, 1992) Soil erosion involved with cultivation affects the livelihood of farmers and thoroughly ⁎ Corresponding author Tel.: + 33 44 27 72 82; fax: + 33 44 27 41 64 E-mail addresses: phanhahaian@gmail.com (H.A Phan Ha), sylvain.huon@upmc.fr (S Huon) 0016-7061/$ – see front matter © 2012 Elsevier B.V All rights reserved doi:10.1016/j.geoderma.2012.01.031 hinders the economic development of upland catchments (Bui, 2003; Pimentel, 2006) Due to the continuous decrease of soil organic carbon with soil erosion, farmers gradually tend to convert their fields formerly under annual crops, into grazing land, forage cultures or tree plantations (Castella et al., 2006; Horne and Stür, 1997; Tran et al., 2004) The introduction of fodders opens new perspectives in sustainable development as it responds to a political desire to integrate crops and livestock in upland farming systems of South East Asian countries (Clement and Amezaga, 2008; Orange et al., 2008) Conversion of cultivated lands to forage is considered as a tool for conservation and stabilization of soil resources (Karlen et al., 2006) as well as for soil structure improvement and maintenance (i.e., Juo et al., 1995; Stone and Buttery, 1989; Tisdall and Oades, 1979) Perennial forages strengthen the soil structure and stability by reducing rainfall kinetic energy, soil aggregates breakdown, splash and inter-rill erosion due to more efficient leaf cover whereas higher root density increases soil carbon storage capacity (Conant et al., 2001; Gebhart et al., 1994; Lal, 2003; Reeder et al., 1998; Uri and Bloodworth, 2000) Fodder cultivation is also effective for the reduction of runoff and H.A Phan Ha et al / Geoderma 177–178 (2012) 8–17 rill erosion (Gilley et al., 2000; Rachman et al., 2008; Raffaelle et al., 1997) by increasing surface roughness, lowering runoff velocity and favoring infiltration and sediment deposition (Dabney et al., 1993; Karlen et al., 2006) It is well established that soil physical properties (Auzet et al., 1995) as well as surface characteristics such as crusting, soil roughness and crop cover are major factors controlling runoff and interrill erosion (Arnau-Rosalén et al., 2008; Durán-Zuazo and Rodríguez-Plequezuelo, 2008; Le Bissonnais et al., 2005; Ribolzi et al., 2011) Additional features particularly active in tropical environments, such as earthworm casts also decrease runoff (Bochet et al., 1999; Jouquet et al., 2008; Podwojewski et al., 2008) If the connections between soil surface characteristics, sediment yield and runoff are well established (i.e., Janeau et al., 2003; Ribolzi et al., 2011), the protective role of plant cover is not well constrained at plot's scales where splash and rain-impacted flows are the dominant soil detachment processes (Bellanger et al., 2004; Chaplot and Poesen, 2012; Wainwright et al., 2000) However, longer slope lengths are also required to assess the impact of soil erosion at landscape's scale, mainly because additional processes such as runoff– runon due to local variability of infiltration, rill and gullies erosion, deposition along slopes as well as stream bank erosion control sediment transport and export across catchments (Chaplot et al., 2009; Van Noordwijk et al., 2004; Wang et al., 2010) The main objective of this study was to assess, within a small agricultural catchment in North Vietnam, the impact of three different fodder types on runoff and soil erosion and soil organic carbon erosion using experimental field plots with two different slope lengths (1 m and m) These experiments were designed to monitor at local scale the protective effect of plant type against splash and rain-impacted sediment mobilization using × m microplots (splash and inter-rill erosion) and to monitor with a slightly longer slope length (5 × m microplots) the extent of flow detachment and sediment transport (incipient rill erosion) Because the comparison between the behavior of fodders in terms of improved livelihood (i.e., biomass production for cattle) and environment sustainability (i.e., soil protection) was the major issue of this experimental study for uplands farmers, two main questions have been addressed: 1) what fodder type among the chosen species insured the best soil protection against splash and rain-impacted erosion? and, 2) what was the local impact of slope length on runoff and sediment yield? Materials and methods 2.1 Site loca 6) Fig Precipitation (vertical bars) and cumulated runoff (top) and sediment yield (bottom) for the three PM 1-m2 microplots in 2007 Dashed lines correspond to cutting days PM = Panicum maximum However a better management of the soil erosion risk by programming cutting operations during periods of low rainfall remains difficult as the distribution of precipitation during the wet season changes from year to year, i.e as shown in this study for 2006 and 2007 Because of its tufted and dense structure (Fig 2), PM acted as a physical barrier that reduced runoff and improved water infiltration Fig Plots of precipitation (vertical bars), cumulated runoff and sediment yield for PA, PM and SG 1-m2 microplots in 2007 Open and closed squares refer to runoff and sediment yield, respectively Dashed lines correspond to cutting days PA= Paspalum atratum, PM= Panicum maximum, SG= Stylosanthes guianensis 14 H.A Phan Ha et al / Geoderma 177–178 (2012) 8–17 by channeling rainwater via its root system This fodder also provided the best soil protection with respect to flow detachment and suspended particles transport as pictured by low sediment yields (ca 14–19 g m − a − 1, Table 2) and reported in other studies (Nyangito et al., 2009; Rietkerk et al., 2000) Although its growth rate was equivalent, the distribution of PA sprouts (Fig 2) had more limited influence on runoff and soil detachment than PM Accordingly interrill erosion was responsible of higher sediment yields (ca 100–250 g m − a − 1, Table 2) Lower plant height, leaf size and pedestal thickness for SG provided even more limited shelter against raindrop impacts (Fig 2) With total sediment yields of ca 70–120 g m− a − (Table 2) soil protection of SG was intermediate between the two others This behavior was supported by lower conductivities (K5, Table 1) in regard to those measured in PA and PM plots, favoring runoff with respect to infiltration during rainfall events The best soil protection was thus obtained for PM with 5–20 times and 2–8 times lower yields than for PA and SG, respectively The results of these experiments can be compared to those carried out with 1-m microplots in 2004–2005 in the Dong Cao watershed (Podwojewski et al., 2008) and in 2003 in the Houay Pano watershed in Laos (Chaplot and Poesen, 2012) Plot of annual mean runoff against soil detachment highlights the impact of soil protection by different plant covers and for different rainfall conditions but with slightly steeper slopes than in our study (Fig 7) Mean annual runoff and sediment yield determined for PM are consistent with those reported for Bracharia, another fodder that provides high plant cover of soil surface The two other fodders, PA and SG, with higher values fell in the range of young fallow and cassava (for one of the two years) known to favor, due to weeding and to its architecture, more soil erosion than other cultivated plants (Putthacharoen et al., 1998; Valentin et al., 2008) However all three fodders had much lower sediment yields than for rice, extensively cultivated by slash and burn along steep slopes in Laos (Chaplot and Poesen, 2012) As expected, tree covers provided a better soil protection than fodders because the canopy intercepts part of the raindrops and reduces as much splash at ground level (Kozak et al., 2007), except for some species with large leaves (i.e teak, Nair, 1993) In the Dong Cao watershed Podwojewski et al (2008) also showed a positive correlation between soil surface crusting and annual runoff under cassava and Bracharia Negative correlations between runoff and earthworm cast surface cover were also reported by Jouquet et al (2008) for various soils under cassava, Bracharia and Eucalyptus In our study, soil surface properties were not significantly different between PA and PM treatments although contrasted runoff and sediment yields were determined For both treatments, soil surfaces were mainly occupied by free soil aggregates and the percentages of soil surface cover by crusts, casts and vegetation residues were rather low It is also likely that root density (0.9–1.1 g cm − 3, Table 1) did not play a key role with respect to infiltration and sediment transport in our study as shown elsewhere with experimental and modeling approaches (De Baets and Poesen, 2010; Zhou and Shangguan, 2008) The overall experiments showed that runoff and soil detachment were linked both to rainfall intensity (with a threshold effect for soil detachment with respect to runoff) and vegetation cover Fig shows that erosion was detachment limited due to a densification of vegetation cover Conversely, cutting operations of the fodder enhanced soil losses but rapid regrowth limited soil losses over the cycle (e.g., Durán-Zuazo and Rodríguez-Plequezuelo, 2008) It is possible that temporary rills not observed during soil surface surveys appeared after major erosive rainfall events but were filled up or hidden by plant growth The impact of fodder cultivation on soil erosion is also supported by decreasing annual sediment yields at the outlet of the Dong Cao watershed, from 3.6 Mg ha− a − before 2002 to 0.1–0.3 Mg ha− a − after 2004, following the replacement of cassava by fodder and acacia in the catchment (Orange et al., 2008) Low TOC/TN ratios for suspended organic matter recovered at the outlet of the plots indicated that most of soil detachment originated from the breakdown of surface soil aggregates These ratios rather matched the composition of fine sized clay-bound organic matter than coarse vegetation debris (Feller and Beare, 1998) and were consistent with high occurrences of free soil aggregates These aggregates tend in turn to be embedded in packing crust when soil is bare or insufficiently covered (Janeau et al., 2003; Podwojewski et al., 2008; Ribolzi et al., 2011) but resist here to crusting due to the dense vegetation cover of fodder crops With high TOC enrichment ratios (1.4– 1.7, Table 3) suspended organic matter was also enriched in TOC with respect to soil average TOC contents as shown for the Houay Pano catchment in Laos (e.g., Rumpel et al., 2006) However in contrast, particle size sorting by rain-impacted erosion and runoff was more likely responsible for the TOC enrichment of detached sediments than residual “charcoal fragments” Light organic matter bound to clay size fractions with low TOC:TN ratios was preferentially released during the breakdown of soil aggregates (i.e., Bellanger et al., 2004; Legout et al., 2005; Palis et al., 1990; Wan and El-Swaify, 1997) Because TOC releases were proportional to sediment yields (e.g., Gregorich et al., 1998), lower TOC deliveries were found in 2007 for PM treatments (ca 0.65 g C m − a − 1, Table 3) than for the two others (ca 3.3 and 4.7 g C m − a − 1, for PA and SG, respectively, Table 3) All soil organic carbon losses were low when compared to 1-m experiments under rainfed rice carried out in Laos (11.2– Fig Mean annual runoff and soil detachment determined for 1-m2 microplots with different plant covers in the Dong Cao watershed Data for cassava, Bracharia, fallow, Eucalyptus and trees from Podwojewski et al (2008) The values for rainfed rice in the Houay Pano watershed in Laos are from Chaplot and Poesen (2012) H.A Phan Ha et al / Geoderma 177–178 (2012) 8–17 30.8 g C m − a − 1, Chaplot and Poesen, 2012) These results indicate that the decline of soil fertility (in terms of soil organic carbon content) will be more limited with fodders and in particular with PM as compared to the two other plants 4.2 Local impact of slope length on runoff and sediment yield Field observations carried out in the course of this study showed that the extension of plant cover was similar at 1-m and 5-m plot sizes Therefore the observed deviations were mainly linked to slope length It is known that when transport distance increases infiltration along slope is favored, reducing as much runoff (Le Bissonnais et al., 1998; Poesen et al., 2003) Moreover, grass pedestal bands also contribute to a reduction of runoff velocity and to trapping or sorting of detached sediments The scale ratios of 5-m to 1-m plots runoffs and soil detachment are reported in Fig together with precipitation and plant cover change Because scale ratios were always lower than 1.0 for the two treatments, our results showed that runoff and sediment yield were both reduced when slope length increased from m to m This effect was more pronounced for PA (in average 80% and 90% for runoff and sediment yield, respectively, Table 2) than for PM (in average 30% for runoff and sediment yield, Table 2) The combined impact of rainfall intensity and plant cover on scale ratios is difficult to assess because only a limited number of surface cover surveys was performed (Fig 8) However, the lower ratios were found for PA at the end of the rainy season when vegetation growth and cover were low and precipitation still important These results are in agreement with those displayed by Stomph et al (2002) who observed a reduction of runoff on bare soil experiments with increasing 1.5, 3, and m slope lengths Equivalent conclusions are drawn for splash erosion and sediment yields reported by Chaplot and Poesen (2012) when plot size increased from to 2.5 m However lower runoff and soil detachment values for 1-m than for 5-m experiments were also observed, when vegetation cover was reduced and accompanied by the 15 extension of structural crusts and small temporary ponds along slopes (Chaplot and Le Bissonnais, 2003) It was not the case in our study because crusted areas always represented less than 10% of soil surface within each plot favoring infiltration whereas plants acted as physical barriers against splash and rain impacted soil detachment and sediment transport Conclusion A two years' monitoring of runoff and sediment yield from 1-m microplots under different fodder cover, set up on moderate 15% slopes of the Dong Cao catchment in North Vietnam, showed that P maximum provided the best soil protection with respect to splash and rain-impacted soil detachment compared to P atratum and S guianensis, the two other fodders tested These differences are most likely linked to the morphological characteristics of the plant species in terms of soil cover Because total soil organic carbon losses were proportional to sediment yields, soil quality (in terms of total organic carbon content) should also be better preserved with P maximum This fodder also provided a better protection compared to other vegetation covers (young fallow, cassava and rainfed rice) tested with comparable experiments In this study, runoff and sediment yields were mainly controlled by rainfall intensity and soil cover extension with a threshold when plant covers exceeded 40% of plot surface Changes in soil surface characteristics (mainly biological activity and soil surface crusting) did apparently not play a key role, most likely because plant covers favored infiltration and reduced soil detachment by rainfall Maximum runoff and suspended sediments yields were recorded when the cut and carry operations of fodder management were followed by heavy rainfalls Cutting of the fodder enhanced soil losses but rapid regrowth limited soil losses over the cycle The increase from to m in slope length contributed to reduce runoff and sediment yield by favoring sediment deposition and water infiltration, in particular for P atratum that involved higher flow and soil detachments than P maximum The integration of crops and Fig Plots of precipitation and plant cover (upper graphs), runoff (middle graphs) and sediment yield (bottom graphs) 5-m2 to 1-m2 scale ratios in 2007 for PA and PM treatments Vertical bars are for precipitation, runoff and sediment yield, open and black circles for plant cover The dashed line refers to cutting operations PA = Paspalum atratum, PM = Panicum maximum 16 H.A Phan Ha et al / Geoderma 177–178 (2012) 8–17 livestock in upland farming systems should be better supported by the use of dense fodders with high soil cover capacities Acknowledgments This study is part of H.A Phan Ha doctorate thesis (UMPC, Paris, France) and was supported by a PhD grant from AUF (Agence Universitaire de la Francophonie) This work was also integrated in the Management of Soil Erosion Consortium (MSEC) activity and the DURAS program supported by the French Ministry of Foreign Affairs The authors are grateful to Dr P Podwojewski (IRD), Nicolas Péchot (UMR Bioemco), MSEC team members for their help during fieldwork and two anonymous reviewers for their comments of a former version of this manuscript References AFNOR NF X31-130, 1993 Détermination de la capacité d'échange cationique et des cations extractibles Qualité des sols 1996 AFNOR, Paris, pp 103–106 Arnau-Rosalén, E., Calvo-Cases, A., Boix-Fayos, C., Lavee, H., Sarah, P., 2008 Analysis of soil surface component patterns affecting runoff generation An example of methods applied to Mediterranean hillslopes in Alicante (Spain) Geomorphology 101, 595–606 Auzet, A.V., Boiffin, J., Ludwig, B., 1995 Concentrated flow erosion in cultivated catchments: influence of soil surface state Earth Surface Processes and Landforms 20, 759–767 Bellanger, B., Huon, S., Velasquez, F., Vallès, V., Girardin, C., Mariotti, A., 2004 Monitoring soil organic carbon erosion with δ13C and δ15N on experimental field plots in the Venezuelan Andes Catena 58, 125–150 Bochet, E., Rubio, J.L., Poesen, J., 1999 Modified topsoil islands within patchy Mediterranean vegetation in S.E Spain Catena 38, 23–44 Bogdan, A.V., 1977 Tropical Pasture and Fodder Plants (Grasses and Legumes) Longman Pub., New York, pp 181–191 Bui, D.T., 2003 Land use systems and erosion in the uplands of the central coast, Vietnam Environment, Development and Sustainability 5, 461–476 Casenave, A., Valentin, C., 1992 A runoff capability classification system based on surface features criteria in semi-arid areas of West Africa Journal of Hydrology 130, 231–249 Castella, J.C., Boissau, S., Nguyen, H.T., Novosad, P., 2006 The impact of forestland allocation on land use in a Mountainous Province of Vietnam Land Use Policy 23, 147–160 Chaplot, V., Le Bissonnais, Y., 2003 Runoff features for interrill erosion at different rainfall intensities, slope lengths and gradients in an agricultural loessial hillslope Soil Science Society of American Journal 67 (3), 844–851 Chaplot, V., Poesen, J., 2012 Sediment, soil organic carbon and runoff delivery at various spatial scales Catena 88, 46–56 Chaplot, V., Giboire, G., Marchand, P., Valentin, C., 2005 Dynamic modelling for gully initiation and development under climate and land-use changes in northern Laos Catena 63, 318–328 Chaplot, V., Podwojewski, P., Phachomphon, K., Valentin, C., 2009 Spatial variability and controlling factors of soil organic carbon under steep slopes of the tropics Soil Science Society of America Journal 73, 769–779 Clement, F., Amezaga, J.M., 2008 Linking reforestation policies with land use change in northern Vietnam: why local factors matter Geoforum 39, 265–277 Conant, R.T., Paustian, K., Elliott, E.T., 2001 Grassland management and conversion into grassland: effects on soil carbon Ecological Applications 11, 343–355 Coquet, Y., Boucher, A., Labat, C., Vachier, P., Roger-Estrade, J., 2000 Caractérisation hydrodynamique des sols l'aide de l'infiltromètre disques Aspects théoriques et pratiques Etude et Gestion des Sols (1), 7–24 Craswell, E.T., Niamskul, C., 1999 Watershed management for erosion control on sloping lands in Asia In: Lal, R (Ed.), Integrated Watershed Management in the Global Ecosystem CRC Press, Boca Raton, Florida, pp 65–72 Dabney, S.M., McGregor, K.C., Meyer, L.D., Grissinger, E.H., Foster, G.R., 1993 Vegetative barriers for runoff and sediment control In: Mitchell, J.K (Ed.), Integrated Resources Management and Landscape Modification for Environmental Protection American Society of Agricultural Engineers, St Joseph, MI, pp 60–70 De Baets, S., Poesen, J., 2010 Empirical models for predicting the erosion-reducing effects of plant roots during concentrated flow erosion Geomorphology 118, 425–432 De Koninck, R., 1999 Deforestation in Vietnam International Development Research Center (IDRC), Ottawa, Canada 110 pp Durán-Zuazo, V.H., Rodríguez-Plequezuelo, C.R., 2008 Soil-erosion and runoff prevention by plant covers A review Agronomy for Sustainable Development 28, 65–86 Felipe-Morales, C., Meyer, R., Alegre, C., Vitorelli, C., 1977 Determination of erosion and runoff under various cultivation systems in the Santa Amahuancayo region I Preliminary results of the 1974–1975 and 1975–1976 seasons: An Cient U.N., vol 15, pp 1–4 75–84 Feller, C., Beare, M.H., 1998 Physical control of soil organic matter dynamics in the tropics Geoderma 79, 69–116 Gebhart, D.L., Johnson, H.B., Mayeux, H.S., Polley, H.W., 1994 The CRP increases soil organic matter carbon Journal of Soil and Water Conservation 49, 488–492 Gilley, J.E., Eghball, B., Kramer, L.A., Moorman, T.B., 2000 Narrow grass hedge effects on runoff and soil loss Journal of Soil and Water Conservation 55, 190–196 Girardin, C., Mariotti, A., 1991 Analyse isotopique du 13C en abondance naturelle dans le carbone organique : un système automatique avec robot préparateur: Cahiers ORSTOM, série Pedologie, vol 26, pp 371–380 Gregorich, E.G., Greer, K.J., Anderson, D.W., Liang, B.C., 1998 Carbon distribution and losses: erosion and deposition effects Soil and Tillage Research 47, 291–302 Horne, P.M., Stür, W.W., 1997 Current and future opportunities for introduced forages in smallholder farming systems of South-East Asia Tropical Grassland 31, 359–363 Janeau, J.L., Bricquet, J.P., Planchon, O., Valentin, C., 2003 Soil crusting and infiltration on steep slopes in northern Thailand European Journal of Soil Science 54 (3), 543–554 Jouquet, P., Bernard-Reversat, F., Bottinelli, N., Orange, D., Rouland-Lefèvre, C., Tran, D.T., Podwojewski, P., 2007 Influence of change in land use and earthworm activities on carbon and nitrogen dynamics in a steep land ecosystem in Northern Vietnam Biology and Fertility of Soils 44, 69–77 Jouquet, P., Podwojewski, P., Bottinelli, N., Mathieu, J., Ricoy, M., Orange, D., 2008 Above-ground earthworm casts affect water runoff and soil erosion in Northern Vietnam Catena 74, 13–21 Juo, A.S.R., Franzluebbers, K., Dabiri, A., Ikhile, B., 1995 Changes in soil properties during long-term fallow and continuous cultivation after forest clearing in Nigeria Agriculture, Ecosystems & Environment 56, 9–18 Kalmbacher, R.S., Martin, F.G., Kretschmer, A.E., 1997 Performance of cattle grazing pastures based on Paspalum atratum cv Suerte Tropical Grasslands 31, 58–66 Karlen, D.L., Lemunyon, J.L., Singer, J.W., 2006 Forages for conservation and improved soil quality In: Barnes, R.F., Nelson, C.J., Moore, K.F., Collins, M (Eds.), Sixth Edition of Forages : The Science of Grassland Agriculture, Volume II Blackwell Publishing, Inc., Ames, IA, pp 149–166 Kozak, J.A., Ahuja, L.R., Green, T.R., Ma, L., 2007 Modelling crop canopy and residue rainfall interception effects on soil hydrological components for semi-arid agriculture Hydrological Processes 21, 229–241 Lal, R., 2003 Soil erosion and the global carbon budget Environment International 29, 437–450 Le Bissonnais, Y., Benkhadra, H., Chaplot, V., Fox, D., King, D., Daroussin, J., 1998 Crusting and sheet erosion on silty loamy soils at various scales and upscaling from m2 to small catchments Soil and Tillage Research 46, 69–80 Le Bissonnais, Y., Cerdan, O., Lecomte, V., Benkhadra, H., Souchère, V., Martin, P., 2005 Variability of soil surface characteristics influencing runoff and interrill erosion Catena 62, 111–124 Legout, C., Leguédois, S., Le Bissonnais, Y., Issac, O.M., 2005 Splash distance and size distributions for various soils Geoderma 124, 279–292 Mannetje, L.T., 1992 Stylosanthes guianensis (Aublet) Swartz In: Mannetje, L.T., Jones, R.M (Eds.), Plant Resources of South-East Asia No Pudoc Scientific Publishers, Wageningen, The Netherlands, pp 211–213 Meyfroidt, P., Lambin, E.F., 2008 The causes of the reforestation in Vietnam Land Use Policy 25, 182–197 Nair, P.K.R., 1993 An Introduction to Agroforestry Kluwer Academic Publishers (in cooperation with ICRAF) 499 pp Nyangito, M.M., Musimba, N.K.R., Nyariki, D.M., 2009 Hydrologic properties of grazed perennial swards in semiarid southeastern Kenya African Journal of Environmental Science and Technology (2), 26–33 Orange, D., Tran Duc, T., Nguyen, D.P., Nguyen, V.T., Salgado, P., Clément, F., Le, B.H., 2008 Different interests, common concerns and shared benefits Leisa 24, 12–13 Palis, R.G., Okwach, G., Saffigna, P.G., 1990 Soil erosion processes and nutrient loss II The effect of surface contact cover and erosion processes on enrichment ratio and nitrogen loss in eroded sediment Australian Journal of Soil Research 28 (4), 641–658 Parsons, A.J., Brazier, R.E., Wainwright, J., Powell, D.M., 2006 Scale relationships in hillslope runoff and erosion Earth Surface Processes and Landforms 31, 1384–1393 Pimentel, D., 2006 Soil erosion: a food and environmental threat Environment, Development and Sustainability 8, 119–137 Podwojewski, P., Orange, D., Jouquet, P., Valentin, C., Nguyen, V.T., Janeau, J.L., Tran, D.T., 2008 Land-use impacts on surface runoff and soil detachment within agricultural sloping lands in Northern Vietnam Catena 74, 109–118 Poesen, J., Nachtergale, J., Vertstraeten, G., Valentin, C., 2003 Gully erosion and environmental change Importance and research needs Catena 50, 91–134 Putthacharoen, S., Howelerb, R.H., Jantawata, S., Vichukita, V., 1998 Nutrient uptake and soil erosion losses in cassava and six other crops in a Psamment in eastern Thailand Field Crops Research 57 (1), 113–126 Quarín, C.L., Valls, J.F.M., Urbani, M.H., 1997 Cytological and reproductive behavior of Paspalum atratum, a promising forage grass for the tropics Tropical Grasslands 31, 114–116 Rachman, A., Anderson, S.H., Alberts, E.E., Thompson, A.L., Gantzer, C.J., 2008 Predicting runoff and sediment yield from a stiff-stemmed grass hedge system for a small watershed American Society of Agricultural and Biological Engineers 51, 425–432 Raffaelle, J.B., McGregor, K.C., Foster, G.R., Cullum, R.F., 1997 Effect of narrow grass strips on conservation reserve land converted to cropland Transaction of ASAE 40, 1581–1587 Reeder, J.D., Schuman, G.E., Bowman, R.A., 1998 Soil C and N changes on conservation reserve program lands in central Great Plains Soil and Tillage Research 47, 339–349 Ribolzi, O., Patin, J., Bresson, L.M., Latsachack, K.O., Mouche, E., Sengtaheuanghoung, O., Silvera, N., Thiébaux, J.P., Valentin, C., 2011 Impact of slope gradient on soil surface features and infiltration on steep slopes in northern Laos Geomorphology 127 (1–2), 53–63 Rietkerk, M., Ketner, P., Burger, J., Hoorens, B., Olff, H., 2000 Multiscale soil and vegetation patchiness along a gradient of herbivore impact in a semiarid grazing system in West Africa Plant Ecology 148, 207–224 H.A Phan Ha et al / Geoderma 177–178 (2012) 8–17 Rumpel, C., Chaplot, V., Planchon, O., Bernadou, J., Valentin, C., Mariotti, A., 2006 Preferential erosion of black carbon on steep slopes with slash and burn agriculture Catena 65, 30–40 Sharma, P.N., 1992 Status and future needs for forest watershed management in Vietnam Applied Engineering Agronomy 8, 461–469 Sidle, R.C., Ziegler, A.D., Negishi, J.N., Nik, A.R., Siew, R., Turkelboom, F., 2006 Erosion processes in steep terrain — truths, myths, and uncertainties related to forest management in Southeast Asia Forest Ecology & Management 224, 199–225 Snedecor, G.W., Cochran, W.G., 1980 Statistical Methods The Iowa State University Press Stomph, T.J., De Ridder, N., Steenhuis, T.S., Van de Giessen, N.C., 2002 Scale effects of Hortonian overland flow and rainfall–runoff dynamics: laboratory validation of a process based model Earth Surface Processes Landforms 27, 847–855 Stone, J.A., Buttery, B.R., 1989 Nine forages and the aggregation of clay loam soil Canadian Journal of Soil Science 69, 165–169 Tisdall, J.M., Oades, J.M., 1979 Stabilisation of soil aggregates by root systems of ryegrass Australian Journal of Soil Research 18, 423–434 Tran, D.T., Podwojewski, P., Orange, D., Nguyen, D.P., Do, P.D., Bayer, A., Nguyen, V.T., Pham, V.R., Renaud, J., Koikas, J., 2004 Effect of land use and land management on water budget and soil erosion in a small catchment in northern part of Vietnam Proceedings in : International conference on Innovative Practices for Sustainable Sloping Lands and Watershed Management, September 5–9, Chiang Mai, Thailand Uri, N.D., Bloodworth, H., 2000 Global climate change and the effect of conservation practices in US agriculture Global Environmental Change 10, 197–209 17 Valentin, C., Agus, F., Alamban, R., Orange, D., Phachomphonh, K., Do, D.P., Podwojewski, P., Ribolzi, O., Silvera, N., Subagyono, K., Thiébaux, J.P., Tran, D.T., Vadari, T., 2008 Runoff and sediment losses from 27 upland catchments in Southeast Asia: impact of rapid land use changes and conservation practices Agriculture, Ecosystems & Environment 128, 225–238 Van Noordwijk, M., Poulsen, J.G., Ericksen, P.J., 2004 Quantifying offsite effects of land use change: filters, flows and fallacies Agriculture, Ecosystems & Environment 104, 19–34 Vezina, K., Bonn, F., Pham, V.C., 2006 Agricultural land-use patterns and soil erosion vulnerability of watershed units in Vietnam's northern highlands Landscape Ecology 21, 1311–1325 Wainwright, J., Parsons, A.J., Abrahams, A.D., 2000 Plot-scale studies of vegetation, overland flow and erosion interactions: case studies from Arizona and New Mexico Hydrological Processes 14, 2921–2943 Wan, Y., El-Swaify, S.A., 1997 Flow-induced transport and enrichment of erosional sediment from a well-aggregated and uniformly textured Oxisol Geoderma 75, 25–265 Wang, Z., Govers, G., Steegen, A., Clymans, W., Van den Putte, A., Langhans, C., Merckx, R., Van Oost, K., 2010 Catchment-scale carbon redistribution and delivery by water erosion in an intensively cultivated area Geomorphology 124, 65–74 WRB, 2006 Word Reference Base for soil resources, 1998 World Soil Resources Reports, No 84 FAO, Rome 88 pp Zhou, Z.-C., Shangguan, Z.-P., 2008 Effect of ryegrasses on soil runoff and sediment control Pedosphere 18 (1), 131–136 ... Effect of land use and land management on water budget and soil erosion in a small catchment in northern part of Vietnam Proceedings in : International conference on Innovative Practices for Sustainable... than 10% of soil surface within each plot favoring in ltration whereas plants acted as physical barriers against splash and rain impacted soil detachment and sediment transport Conclusion A two... et al (2008) also showed a positive correlation between soil surface crusting and annual runoff under cassava and Bracharia Negative correlations between runoff and earthworm cast surface cover