Soil Fertility, Fertilizer, and the Maize Green Revolution in East Africa Tomoya Matsumoto and Takashi Yamano (FASID/GRIPS)

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Soil Fertility, Fertilizer, and the Maize Green
Revolution in East Africa Tomoya Matsumoto
and Takashi Yamano(FASID/GRIPS)
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Contents

• Introduction
• Maize and Fertilizer Use in Kenya and Uganda
• Data and Descriptive Analysis
• Data
• Dairy Production Systems and Organic Fertilizer
  Use
• Maize Costs, Income, and Profit
• Estimation Results
• Determinants of Fertilizer Use
• Determinants of Maize Yield
• Conclusions

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Introduction

• There is a growing interests in realizing an
  African Green Revolution.
• Kenya and Uganda provide an interesting contrast
  in maize production Kenya high inputs, Uganda
  low inputs.
• In this study, we compare maize production in
  these countries to identify constraints on maize
  production

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Purpose of This Study

• To describe fertilizer use and maize production,
  by calculating costs, income, and profit in Kenya
  and Uganda
• To Estimate the determinants of the maize yield,
  including soil fertility, inorganic and organic
  fertilizer applications.
• Is it profitable to use fertilizer?

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Maize in Kenya and Uganda
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Nitrogen Consumption in Kenya and Uganda
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Data

• RePEAT Panel data
• Kenya 2004 and 2007, 725 rural households
• Uganda 2003 and 2005, 895 households
• Soil Sampling at the first survey
• Kenya about 77 percent
• Uganda about 67 percent

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Survey Areas
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Table 1. Summary Statistics in Kenya
All Purchased HYV Maize Local/ Recycled Maize HYV Difference
Number of Plots 3,131 (100) 1,848 (59.0) 1,283 (41.0)
Maize Yield (kg/ha) 1,986 2,172 1,718 454
Inorganic Fertilizer Use (kg/ha) 94.7 119.4 59.2 60.2
Organic Fertilizer Used (kg/ha) 1,935 2,258 1,471 787
Carbon Content () 2.48 2.59 2.33 0.26
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Table 1. Summary Statistics in Uganda
All Purchased HYV Maize Local/ Recycled Maize HYV Difference
Number of Plots 3,198 (100) 680 (21.3) 2,518 (78.7)
Maize Yield (kg/ha) 1,561 1,719 1,518 202
Inorganic Fertilizer Use (kg/ha) 2.4 9.1 0.6 8.5
Organic Fertilizer Used (kg/ha) 86 142 71 71
Carbon Content () 2.35 2.15 2.40 -0.25
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• Soil Nutrient Indicator
• N soil nutrient indicator, E soil condition,
• C inorganic fertilizer, O organic fertilizer
• Maize Yield Function
• L plot size, S seed quantity, A TFP

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• We control for the household fixed effects to
  eliminate biases created by the correlation
  between the household fixed effects and
  independent variables.
• We apply the endogenous switching model to
  control for the maize seed type selection.

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• Main Hypotheses
• Does the soil fertility increase returns from
  external fertilizer applications?
• Is the inorganic fertilizer application optimal?

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Maize Yield
Fertilizer Price
Maize Price
Kenya
Uganda
Fertilizer Application (DAP)
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Main Findings

• We do not find that the returns from external
  fertilizer depend on the soil fertility.
• This suggests that the external fertilizer
  applications would be useful even on poor soils
  in Uganda and Kenya.
• The soil carbon content has a large impact on the
  maize yield.
• The inorganic fertilizer use in Kenya is at about
  the optimal application rate.

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Policy Implications

• To increase the inorganic fertilizer use. We need
  to reduce the fertilizermaize relative price.
• Because we find a large positive impact of the
  carbon content, the results suggest that it is
  important to improve the soil fertility.
• To do so, the organic fertilizer use has to
  increase. This is a new area for future research.

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Whats next for RePEAT Survey?

• In Uganda
• Experiments in Jan-Feb 2009, providing a package
  of HYV seeds, fertilizer, and extension to
  households in randomly selected villages of
  RePEAT Samples
• Conduct a survey in 2010 to evaluate the
  impacts
• In Kenya
• Experiments in 2010 on crop insurance?
• Conduct a survey in 2011