Erosion on steep and fragmented lands under maize cropping: viability of soil conservation

Transcription

1 SFB 564 The Uplands Program Sustainable Land Use and Rural Development in Mountainous Regions of Southeast Asia Erosion on steep and fragmented lands under maize cropping: viability of soil conservation V.D. Tuan, T. Hilger, G. Clemens, A. Keil, G. Cadisch,K. Stahr funded by the EnBW Rainforest Foundation Son La, May 2012 Slide 1 Son La, May 2012

2 SFB 564 Introduction Strong anthropogenic changes of the terrestrial biosphere Population pressure Agricultural intensification People s encroachment on steep slopes Consequences Erosion Soil degradation Flooding & sedimentation Soil conservation Old debate & long list of scientific publications Various concepts proposed Poorly adopted by farmers Slide 2 Son La, May 2012 In a decade ( ): Maize production in Sơn La increased triple, mainly relied on area expansion (2,56 times), as yield increased only 1.5 Can soil conservation be attractive to farmers?

3 SFB 564 Context Connection upland lowland: Automatic water sampler (discharge proportional) P. Schmitter et.al, 2008 Slide 3 Son La, May 2012

4 SFB 564 Context maize Conventional, soil loss ~ 60 ton/ha/year (crop season), on steep field soil erosion reached 130 ton/ha/year or >300 kg urea + OM and micro nutrient. Erosion mainly occurred at onset of season when high rainfall intensities coincided with a low soil cover Slide 4 Son La, May 2012

5 SFB 564 Objectives 1. Quantifying soil loss, assessing crop production & benefits under Soil Conservation Technologies 2. Discuss constraints and perspectives of soil conservation adoption Slide 5 Son La, May 2012

6 Trial set up in Chieng Hac Elevation: 296 m Slope: o RCBD setup T0 T4 T0 T1 T0 T4 T2 T3 T1 T3 T2 T4 T1 T3 T1 T2 T4 T1: Maize / Farmers practice T3 T2 T2: Maize with a grass barrier (Panicum maximum) T3: Maize under minimum tillage (hoe only for maize seedling rows) with cover crop (Arachis pintoi) T4: Maize under minimum tillage relay cropping with a legume (Phaseolus calcaratus). Slide 6 Son La, May 2012

7 Trial set up in Chieng Khoi Elevation: 516 m Slope: o T3 T1 T4 T2 T4 T1 T3 T2 T1: Maize / Farmers practice Slide 7 Son La, May 2012 T2 T4 T3 T1 T2: Maize with a grass barrier (Panicum maximum) T3: Maize under minimum tillage (hoe only for maize seedling rows) with cover crop (Arachis pintoi) T4: Maize under minimum tillage relay cropping with a legume (Phaseolus calcaratus).

8 Runoff/soil loss collection collection trough two buckets upper bucket functioned as divisor box with 16 outlets, one connected with lower bucket measure and collect samples after every rain event Yield measurement Maize Grass A. pintoi and P. calcaratus Slide 8 Son La, May 2012

9 T2: Maize with a grass barrier (Panicum maximum) Slide 9 Son La, May 2012

10 T3: Maize under minimum tillage +cover crop Slide 10 Son La, May 2012

11 T4: Maize under minimum tillage + relay cropping with a legume Slide 11 Son La, May 2012

12 Chieng Hac trial, after three years of establishment Slide 12 Son La, May 2012

13 Soil loss vs maize yield in Chieng Hac (2011) Soil loss (ton.ha -1 ) a b Yield (Mg.ha -1 ) a c b a 20 b b 1 0 T0 T1 T2 T3 T4 0 T0 T1 T2 T3 T4 Slide 13 Son La, May 2012

14 Soil loss vs maize yield in Chieng Khoi (2011) Soil loss (ton.ha -1 ) a b c c Yield (Mg.ha -1 ) a c b a 0 T1 T2 T3 T4 0 T1 T2 T3 T4 Slide 14 Son La, May 2012

15 Conservation provides additional income... Treatment Carcass weight of G. carp from grass* A. pintoi P. calcaratus Kg/ha Kg folder FW/ha Kg grain DW/ha T T2 281/ T3-3300/ T /n.a Chieng Hac/Chieng Khoi *80kg fresh grass is converted to 1 kg Grass carp Slide 15 Son La, May 2012

16 ... in year with drought period: Grass barrier overcome (drought) 2011 Converted to G. Carp Kg/ha Kg/ha Kg/ha Chieng Hac Chieng Khoi Grass carp production from P. maximum 80kg fresh grass is converted to 1 kg G. carp Slide 16 Son La, May 2012

17 Conclusions Soils under maize are prone to erosion at onset of rainy season due to tillage and poor soil cover rate; Fertile top soil => lost in the long run if no measures against erosion are applied; Soil conservation measures reduced soil loss; Maize yield under minimum tillage +relay cropping = conventional, and provide bean additionally. Other measures decreased maize yield but provided high quality folders => animal husbandry promotion; Extra-benefits from soil conservation => adoption by local farmers, particularly in view of markets and/or in drastic condition; Minimum tillage (T3, T4) => higher infiltration rate, less run-off & soil loss => less flood risk; Conservation contributes to Nghị quyết TW41, and Envi. Law Slide 17 Son La, May 2012

18 Thank you for your attention! Slide 18 Son La, May 2012