Towards Sound Strategies For Soil-Water And Nutrient Retention A Cawt Case…

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  • Great slideshow. This is what I am doing with my garden. As little tillage as possible. Keep soil covered at all times to mimic forest conditions (at the moment I have got tree leaves on my flower beds). Trying to build up soil organic content so that soil retains water in dry season. Lots of trees coming up.
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Towards Sound Strategies For Soil-Water And Nutrient Retention A Cawt Case…

  1. 1. TOWARDS SOUND STRATEGIES FOR SOIL- WATER AND NUTRIENT RETENTION A CAWT CASE STUDY OF KIBWEZI Kalinda Mhosi Chester Supervisors Prof Kamau Ngamau (JKUAT) Dr John Kihoro (JKUAT) Maimbo Malesu ( ICRAF)
  2. 2. Presentation LayoutIntroductionApproach -Experimental -StatisticalResultsRecommendations and Conclusion
  3. 3. Introduction continued Study done in Kibwezi Rainfall is erratic, majority lost to runoff and evaporation Dominant soils are Lixisols and Acrisols Soils are shallow and low in fertility Soils low in organic carbon and exchangeable cations Soil have low water retention capacity and infiltration rate due underlying hardpan
  4. 4. ObjectivesOverall ObjectiveTo determine whether the inclusion of trees in conservationagriculture is an effective land management strategy in conservingof soil water and nutrients.Specific ObjectivesTo determine soil water-retention characteristics of CAWT fieldsTo determine soil fertility levels of CAWT fieldsTo examine the suitability of Faidherbia albida, Tephrosia candidaand Gliricidia sepium through performance for CAWT under thesemi-arid conditions of Kibwezi
  5. 5. Methodology Two way experimental designFour tillage practicesMinimum tillage (Mt)Zero tillage (Zt)Farmer Innovation(FI)Conventional tillage was used as a control (Ct)Three tree speciesFaidherbia albidaGliricidia sepiumTephrosia candida
  6. 6. Tree species usedTephrosia Candida Gliricidia sepium Faidherbia albida
  7. 7. Methodology Continued Gypsum blocks installed at two depths for moisture measurements Double ring infiltrometer to measure infiltration Measures for CEC, gravimetric moisture content, TOC and Ph taken over time Four soil sampling times ( Feb, March, April and May)Analysis Methods Using Genstat 13th ed and R 2.13.2 version Repeated measure analysis of variance Correlation and Regression analysis LSD used to separate means α of 0.05 used in the analysis
  8. 8. Collecting sample for Bulk density and moisture characteristic determination Gypsum blocks and aMoisture content reader Double ring infiltrometer
  9. 9. Results  10 rain days the whole season  160.3mm total rainfall received
  10. 10. 13 years first season rain fall data  Below mean rainfall for past 13 years (231.26mm)  Cv 49.88%  Rain water can be harvested and used to supplement crop water requirements or lost completely
  11. 11. Benefits of water harvesting Farmer Innovation plotConventional tillage plot Water harvesting ponds
  12. 12. Effects of tillage on soil water content (SWc) (%)Tillage Depth DepthPractice 0-20cm 20-30cm Zt 9.22a 6.01b Mt 7.94b 6.92a FI 6.92c 4.51c Ct 3.49d 1.93d LSD 1.02 0.89 Means with the same letter are not statistically different at 5%
  13. 13. Influence of tree species on SWc (%)Tree species SWc F. albida 8.15b G. sepium 9.01a T. candida 6.85c LSD 0.95
  14. 14. Effect of tillage on soil TOC Source of variation d.f. s.s. m.s. v.r. F pr. Block stratum 2 3.41486 1.70743 7.65 Tillage 3 15.60944 5.20315 23.32 <.001 Residual 84 18.74125 0.22311 8.17 Tillage practice Mean factorZero tillage 1.35a Minimum tillage 1.25a Farmerinnovation 1.10bConventiona l tillage 0.61c LSD 0.127
  15. 15. Effect of tillage on soil CEC Source of variation d.f. s.s. m.s. v.r. F pr. Block stratum 2 445.832 222.916 1.7 Tillage 3 3308.5 1102.83 8.39 0.001 Residual 84 11042.2 131.454 39.44 Tillage Practice Mean factorZero tillage 19.16a Minimum tillage 18.46a Farmer innovation 16.47bConventional tillage 8.52c LSD 2.10
  16. 16. Effects of tree species on soil organic carbon (%) Source of variation d.f. s.s. m.s. v.r. F pr. Tillage stratum 2 3.33841 1.6692 6.32 Tree_Species 2 1.89927 0.94964 3.6 0.032 Residual 76 20.05688 0.26391 9.41 Tree Meanspecies factorG. sepium 1.26abT.candida 1.13bF.albida 1.31a LSD 0.137
  17. 17. Influence of Tree species on soil CEC  Fertilizer trees produce Tree TOC (%) CEC sufficient biomass to Species maintain or increase SOCG. sepium 1.26ab 19.53a  This SOC creates moreT. candida 1.13b 16.34b exchangeable site for cationF. albida 1.31a 20.24a LSD 0.137 3.14
  18. 18. Synergy between trees and tillage and their effect on fertility The mean maximum TOC 1.40 % was noted in Faidherbia albida plots prepared using Zero tillage 1.33% under Gliricidia sepium plots prepared under minimum tillage. SOC influences CEC Conventional tillage had the least amount of organic carbon (0.61%.)
  19. 19. Tillage practice influence on Infiltration Tillage Bd TOC CEC practices (g/cm3) (%) Zt 1.31 1.35 19.16 Mt 1.45 1.25 18.46 FI 1.51 1.10 16.47 Ct 1.60 0.61 8.59
  20. 20. Soil Compaction Tillage Bulk density(0-20cm) Bulk density (20- (g/cm3 ) 30cm) (g/cm3 ) Mt 1.45 1.53 Zt 1.31 1.64 FI 1.51 1.56 Ct 1.60 1.72Hard pan Bulk density of the soil
  21. 21. Impact of soil hardpan on crop development
  22. 22. Correlation and Regression between IR and some soil physical propertiesSoil Property r r2 Regression lineOrganic carbon 0.82 0.78 IR=35.5 + 143OCBulk density 0.67 0.62 IR=66-40.134BdTotal porosity 0.73 0.7 IR=-159.56+24.7TP
  23. 23. Moisture Characteristic curves
  24. 24. Tree performance and survival  SWc under CAWT plots was 2.2 to 2.9 times more than that in bare conventional tillage plots Tree  Increase in the amount of species Survival TOC % CEC SOC due to fertilizer trees rate (Cmol/k g) biomass F.albida 44.3 1.31 20.24  These type of trees that can be establishedG. sepium 43.5 1.26 19.53 depending on water harvesting technologiesT.candida 29.1 1.13 16.34 which can be easily adapted in an area
  25. 25. Conclusions Encourage the use of reduced tillage practices and fertilizer trees managed in sequential and simultaneous tree-crop systems Water harvesting will offer an opportunity for additional cropping season The practices offer a wider scope for resource-stressed farmers to produce sufficient food for consumption and market Hardpan need further research and attention as its influences infiltration and soil water content It can be suggested that land that has a fragile structure and other soil degradation problems invest in CAWT and water harvesting for improved organic matter build-up and soil water retention
  26. 26. Thank you all for coming

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