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Soil erosion evaluation and modeling under different production practices on shade coffee plantation under steep lands (Ultisols)

Abstract : The main objective of this work was to better understand soil erosion processes and dynamics on steep lands cultivated with a permanent crop (shade coffee).Eight large experimental plots were installed in a 65% average slope coffee plantation with Erythrina sp. as shade tree. The superficial runoff was measured every 5 min. and collected for sediment concentration measurement and soil loss assessment.Rainfall depth was 2206, 1778 and 2220 mm in 2011, 2012 and 2013 respectively with a marked succession of dry season and rainy season. Total runoff was 103, 54 and 33 mm along those three years. Annual average sediment concentration at plot scale was about 1.3 g l-1 with reduced temporal variations between years or rainfall events. The plots' average annual soil loss (under normal management) decreased from 1.69 to 0.91 and 0.58 t ha-1 from 2011 to 2013. An analysis of the temporal dynamics was performed in three time scales: annual-monthly, event and intra-event. Around 60% of rainfall and 90% of runoff and soil loss occurred each year during the August-October periods and more than half of it in October. Total event rainfall and soil water content explained most of surface runoff and soil loss dynamics, while inherited soil water storage from previous year played an important role on the relationship between rainfall and runoff dynamics the following year. A simple infiltration model (Diskin and Nazimov) was used to estimate runoff during a rainfall event.In 2012 four treatments were applied with two replicates each: no mini-terraces renewal, weed control with herbicide, reduced pruning pressure on shade trees and reference management. Three periods were considered: P1 before treatment application, P2 the next two months afterwards and P3 the year after (2013). The significant differences between treatments/reference ratios for the three periods suggested higher runoff and sediment concentration when mini-terraces were renewed and the effect decreased but was still present in P3. Chemical weed control did not show a clear trend. The reduced pruning treatment reduced erosion only for superficial soil moisture >30%.Superficial runoff, average sediment concentration and soil loss were monitored at the outlet of a small watershed (31 ha, 60% average slope) during 2012 and 2013. Rainfall events greater than 5 mm (169 events) produced runoff at both scales and most of runoff amount was produced for strong rainfalls (> 40 mm). The runoff coefficients were very low (0.9%) at both scales in 2013. But it was 2.44% for plots and 0.9% for watershed in 2013. The base flow was also very low on this watershed (13-16% of total rainfall) with a large part of the rainfall (about 20%) being lost by percolation. The average sediment concentration at the plots was about 1.65 g l-1 and the maximum value was 5.64 g l-1. The average sediment concentration at watershed scale was 0.51 g l-1. Estimated annual soil loss were 0.73 and 0.36 t ha-1 yr-1 at plots scale (all managements included) for 2012 and 2013 respectively and 0.46 and 1.24 t ha-1 yr-1 at watershed scale for thesame years.The shade coffee system studied showed a tolerable soil loss compared to the potential erosion due to the efficient vegetal surface protection.
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Submitted on : Thursday, November 17, 2016 - 4:53:34 PM
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  • HAL Id : tel-01398775, version 1
  • PRODINRA : 384489

Citation

Mario Villatoro. Soil erosion evaluation and modeling under different production practices on shade coffee plantation under steep lands (Ultisols). Agricultural sciences. Montpellier SupAgro, 2015. English. ⟨NNT : 2015NSAM0029⟩. ⟨tel-01398775⟩

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