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IMPACT OF GENETICALLY MODIFIED MAIZE ON SMALLHOLDER RISK IN SOUTH AFRICA 16 th ICABR Conference June 25-27, 2012 Ravello, Italy Greg Regier*, Timothy Dalton, Jeffery Williams Kansas State University Source: Google images
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Objective Is genetically modified (GM) maize a beneficial technology for smallholders in low-income countries? H 1 : GM maize reduces net returns risk H 2 : GM maize has higher output H 3 : GM maize leads to lower cost
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Literature Review Bt Maize, Philippines Higher yields and net returns; Yorobe and Quicoy 2006 ; same results when controlling for selection bias; Mutuc and Yorobe 2007 Yield advantage is smaller controlling for censoring; Mutuc, et al. 2012 Bt Maize, South Africa Higher output, declining as pest pressure decreases, net returns depends; Gouse, Piesse and Thirtle 2006, Gouse et. al 2006 RR Maize, South Africa Higher output, lower labor use; Gouse, Piesse, and Thirtle 2006 Seed cost cancels gain in yield efficiency; Gouse, Piesse, Thirtle and Poulton 2009
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Location: KwaZulu-Natal, South Africa
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Background Information Hlabisa and Simdlangetsha Annual rainfall of 980 mm (38 inches) Marginal land - 13% arable Average maize yield is 1500 kg/ha (24 bu/acre) 39% land ownership by smallholders Labor supply characteristics Urban migration 26% working age population HIV-positive
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Data 212 maize plots (184 households) Plot size 0.49 hectares, farm size1.85 hectares One season, 2009-10 Farmer Characteristics: Head of household average age of 55 years Pension is top income source for 53% ($168/month) A majority of maize consumed at home High access to credit
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Maize Types Conventional Hybrids Pannar Carnia GM Hybrids Bt – insect resistant Roundup Ready © (RR) – herbicide tolerant BR “stacked”
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Maize Yield, Cost, and Net Returns * Indicates significantly higher at 5% using a one-sided t-test Seed TypeNYield (kg/ha) Maize Revenue ($/ha) Input Cost ($/ha) Labor Cost ($/ha) Net Returns ($/ha) HlabisaBR151910918531143244 Pannar151788866297335234 RR671880910458149304 GM821885912 471*148293 Non-GM151788866297 335*234 SimdlangetshaBR201347512609186-283 Bt181351502600251-349 Carnia341227463642268-447 Pannar331659640549317-226 RR101953737556230-48 GM481475555595219-259 Non-GM671440550596 292*-338
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H 1a : GM Maize Reduces Risk - Stochastic Dominance
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H 1b : GM Maize Reduces Risk - Stochastic Efficiency with Respect to a Function (SERF) RRAC = 2 (moderately risk averse) RRAC = 4 (extremely risk averse) RRAC = 0.37 (slightly risk averse)
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H 1b : GM Maize Reduces Risk – SERF RRAC= 2RRAC = 4
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H 2 : GM Maize has Higher Output Maize output = f(labor, fertilizer, herbicide, seed, land, land prep cost, Hlabisa, RR, Bt, assets, experience with herbicide, education)
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Production Function Results OLS: LinearOLS: QuadWLS: Quad2SLS: Herbicide2SLS: Labor Coef. Intercept-336.32***-167.63-52.32-710.6*5.3 Labor3.26***2.73*1.774.9***-0.4 Fertlizer1.35*-0.58-1.191.02.1** Herbicide0.2839.4523.14128.6**-26.3 Seed-26.16-33.725.22-56.4-7.0 Land993.56***1976.90*1702.90*493.71360.9*** Total Cost Land Prep1.27-13.20*-15.28**2.90.1 Hlabisa Dummy308.83***154.6588.13371.0**215.9* RR Dummy217.27***137.45**131.61*332.0***38.9 Bt Dummy-12.24-4.905.39-86.46.4 N212 Adjusted R- squared0.45 0.62 0.85 0.17 0.32 ***,**,* indicates significantly different than zero at 1%, 5% and 10% respectively
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H 3a : GM Maize has Lower Cost Total Cost = f(maize output, labor price, fertilizer price, herbicide price, seed price, land, land prep price, Hlabisa, RR, Bt, assets, experience with herbicide, education)
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Cost Function Results OLS - LinearOLS - Quadratic WLS - Quadratic Treatment Effects- Quadratic Coef. Intercept-138.92*-2947.07**-2839.86**-2352.97** P(labor)134.59***436.95290.7731.99 P(fertilizer)237.79**6558.10**6598.81**5410.83** P(herbicide)2.91**-41.96-39.81-44.59* P(seed)14.64***79.49*75.83*70.78* Land389.67***1630.07***1547.03***1558.06*** P(land prep)-0.75***9.28*9.68**8.75** Maize Output0.05***0.69***0.61***0.62*** Hlabisa Dummy-168.77***-187.69***-170.97***-149.05*** RR Dummy-63.83***-77.67***-69.60***-162.31*** Bt Dummy6.574.512.907.75 Inverse Mills Ratio λ 49.77** Adjusted R-squared 0.84 0.88 0.91 ***,**,* indicates significantly different than zero at 1%, 5% and 10% respectively
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H 3b : GM Maize has Lower Cost - Kernel Density Estimator Total Cost
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H 3b : GM Maize has Lower Cost - Kernel Density Estimator Average Cost
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Conclusion H 1 : GM Maize Reduces Risk SERF RR maize producers must be compensated between $18 and $221 per hectare to switch varieties H 2 : GM Maize has Higher Output Production function 8-13% RR maize advantage; N.S.-20% controlling for endogeneity bias H 3 : GM Maize leads to Lower Cost Cost function 18-23% lower costs for RR maize; 33% controlling for selection bias Nonparametric regression At least 17% lower costs for RR maize
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THANK YOU! Acknowledgements: Bill and Melinda Gates Foundation by the provision of data under the Global Development Grant OPP 53076, “Measuring the Ex-Ante Impact of Water Efficient Maize for Africa.” Assistance from Marnus Gouse in the understanding of data. Source: Google images
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Future Research More advanced techniques to control for selection bias Control for censoring Tradeoff between no-till and intercropping Labor supply Constrained or not Effect on GM maize adoption by country Impact over several years in multiple regions
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Weighted Risk Premiums Relative to BR, Simdlangetsha
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Weighted Risk Premiums Relative to BR, Hlabisa
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Two-Stage Least Squares (2SLS) Regression = predicted value of endogenous variable = parameter of all exogenous variables = parameter of instrumental variables
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Treatment Effects Model Step 1: Probit Model Step 2: Include inverse Mills ratio in least squares regression
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Histogram of Total Cost
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Kernel Density Estimator: Average Cost RR = 0.5, non-RR = 0.6 17% lower costs estimate
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Family and Hired Labor (Hours/Hectare) SiteSeed TypeChildMaleFemaleHiredWorkgroup Total HlabisaBR 237623947187 Pannar 181531776820437 RR 241522276194 GM 2415425 71**192 Non-GM 18** 153** 177** 68**20 437** SimdlangetshaBR 2147588728242 Bt 42701223954327 Carnia 55931154245350 Pannar 75961215962414 RR 48771033933300 GM 3562915939286 Non-GM 65** 94** 118*5053 381** **,* Indicates significantly higher at 1% and 5% respectively using a one-sided t-test.
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