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Session 4 soil physical properties in southwestern nigeria by onasanya omolara


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Field research activity update on PhD proposal “Evaluation of agronomic practices on growth,
yield of cassava and some physical properties of soils in SW Nigeria” by Omolara Olabisi

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Session 4 soil physical properties in southwestern nigeria by onasanya omolara

  1. 1. Evaluation of agronomic practices on growth, yield of cassava and soil physical properties in southwestern Nigeria Olabisi Omolara Onasanya A PhD Project within the Africa Cassava Agronomy Initiative on the “Best Planting Practices” use case A research activity update on
  2. 2. Overall Objective • Provide site-specific recommendations on agronomic practices in cassava systems to conserve soil while maintaining high cassava yields in Nigeria. Introduction • Tillage is the physical, chemical or biological soil manipulation to optimize conditions for seed germination, emergence and seedling establishment, BUT • Tillage may either be beneficial or detrimental to the soil over time • Hence, it is important to look into improved agronomic practices in combination with tillage that will best conserve the soil under cassava systems
  3. 3. Agronomic practices and cassava growth, root yield and quality • To investigate the effects of basic tillage(ploughing), shaping the soil surface (ridging), weed control and fertilizer application on the establishment, growth, root yield and quality of cassava Tillage intensity and soil aggregate stability • To evaluate the impact of tillage intensity on soil aggregate stability, soil C and N in particle size fractions and determine their relationship with cassava yield Tillage Intensity and least limiting water range • To determine the effect of tillage on soil strength, compaction and the least limiting water range and relationship between physical- hydraulic properties and cassava root yield Specific objectives
  4. 4. Experimental Setup • Study in Oyo and Ogun State, Nigeria over 2 years • Researcher Managed Trials (RMTs) established in Saki, Ido and Odeda LGAs (1st year ongoing) • Multi-Location Trials were established on farmers’ field but with less detailed measurement (2nd year ongoing) Local Government Area Agro ecological zone Parent material * Average annual temperature (OC) *Average annual rainfall (mm) Ido Southern guinea savannah Basement complex 22.9 – 24.4 1136 - 1341 Odeda Derived savannah Sandstone 26.1 – 27.8 1136 - 1341 Saki Derived savannah Basement complex 22.9 – 24.4 934 - 1136
  5. 5. • RMT: four-factorial split-split-split-plot with a randomized complete block design replicated 3 times Experimental design and layout of the treatment
  6. 6. Cassava measurements to address the effects of agronomic practices • Sprout count: 2 and 4 • Plant height • Number of main stems per plant • Number of leaf (scars and alive) per plant • Light interception: 12 & 24 • Fresh root mass per plot • Root number and diameter • Dry matter content of roots • Number of bad (rot) roots per plot • Starch content 4, 8, 12, 16, 24 & 48 48 (harvest)
  7. 7. Preliminary results… Effect of tillage intensity on cassava germination at 2 weeks after planting by experimental sites SP: Single Plough ZP: Zero Plough
  8. 8. Treatment effects on number of leaves at 16 weeks after planting Preliminary results… Response: number of leaves Pr(>F) basic_tillage 0.6292 seed_bed 0.9722 fertilization 0.8919 Location <2e-16 *** No significant interactions either
  9. 9. Treatment effects on plant height at 16 weeks after planting Preliminary results… Response: plant height Pr(>F) basic_tillage 0.34175 seed_bed 0.42402 fertilization 0.36972 Location < 2e-16 *** No significant interactions either
  10. 10. MWD = ∑ 𝑋𝑖𝑤𝑖% & Van Bavel, 1949 Evaluating the effect of basic tillage and soil shaping on aggregate stability Xi= mean diameter of each size fraction Wi = proportion of the total sample weight corresponding size fraction
  11. 11. Effect of basic tillage and soil shaping on mean weight diameter at 8 weeks after cassava planting Preliminary results… Pr(>F) Basic_tillage 0.005112 ** Soil_shaping 0.658898 Location 0.000258 *** Basic_tillage:Soil_shaping 0.200977 Basic_tillage:Location 0.033402 * Basic_tillage:Soil_shaping:Location 0.636226 Response: Mean Weight Diameter
  12. 12. Observations to study the effect of tillage intensity on soil strength, compaction and cassava yield • Penetrologger is used to measure the resistance of soil to penetration as a proxy for soil strength and compaction. • Soil resistance to penetration is dependent on soil moisture content.
  13. 13. Preliminary results…(MPa) Soil resistance to basic and secondary tillage at 16 weeks after planting No significant interactions Pr(<F) Basic Tillage 0.002008** Seed bed 0.0873767. Location <2.2e-16****
  14. 14. Preliminary conclusions………… • Zero plough reduced sprout count, but no treatment effects on number of leaves. • Across locations, zero plough increased mean weight diameter and decreased resistance to penetration • I am looking forward to see if the treatments have an effect on the yield! And if they are related to the soil physical conditions…