Agricultural subsidies lead to changes in the use of chemical fertilizer by farmers. Using data from a household survey conducted annually by the Rural Economy Research Center of the Ministry of ...Agriculture of China from 2014 to 2018, Control Function (CF) approach and Heteroskedasticity-based identification strategy were employed to analyze the impact of agricultural subsidies on chemical fertilizer use by rice farmers. After addressing the problem of endogeneity, we found that agricultural subsidies have a significantly negative impact on the use of chemical fertilizer. Precisely, every 100% increase in agricultural subsidies would result in an average decrease of 3.4% in chemical fertilizer use. In addition, results of heterogeneity analysis showed that agricultural subsidies had a stronger negative impact on fertilizer use as rice-planting experience increases. But the ability of rice-planting management and off-farm labor within household could reduce this negative impact. We also found that the effect of arable land productivity conservation subsidies policy was short-lived. Furthermore, based on the frame of structural equation model (SEM), the results of mediation analysis showed that agricultural machine and rice-planting area had partial mediation of 5.3% and 41%, respectively. It implied that agricultural subsidies reduced fertilizer use by promoting the adoption of agricultural techniques and expanding the planting area. In brief, agricultural subsidies had both technical effect and scale effect. But the mediating effect of household income was not significant. This study is intended to assist the concerned authority and agriculture sector to understand the positive role of agricultural subsidies in sustainable production, and provides some feasible policy proposals.
•Higher agricultural subsidies in China reduce chemical fertilizer use.•We study the heterogeneous effects of agricultural subsidies on fertilizer use.•Agricultural subsidies have both technical effect and scale effect, but not income effect.•The effect of agricultural subsidies policy is short-lived.
This paper quantifies the extent of pesticide overuse in vegetable production systems in Southeast Asia. Pesticide overuse was defined as levels of use in excess of an economic (profit-maximizing) ...optimum. A production function with an exponential damage abatement term was estimated. Data come from a representative sample of 1000 farmers producing leaf mustard and yard-long bean in Cambodia, Laos and Vietnam. The results show that 100% of the sampled farmers in Vietnam, 73% in Cambodia and 59% in Laos overused pesticides. Pesticide expenditure in excess of the economic optimum was 96% for Vietnam, 92% for Cambodia, and 42% for Laos. Pesticide overuse was positively associated with men in charge of pest management decisions, farmers seeking advice from pesticide sellers and a strong belief that pesticides are effective. It was negatively associated with the use of non-chemical methods of pest control. These results imply that farmers in Southeast Asia are spraying excessively and inefficiently and could increase their profits by applying fewer pesticides.
•We quantify pesticide overuse in vegetable production in Cambodia, Laos and Vietnam.•Production function with damage control term was estimated with data for 1000 farms.•77% of farmers overused pesticides; 77% of pesticide expenditures are overuse.•Greater overuse was observed among male applicators.•Greater overuse was also observed where pesticide sellers advised farmers.
This paper shows the endogeneity test in linear instrumental variable models using the control function approach resembles the Hausman test. Test statistics used in these tests can be numerically ...ranked, revealing their relative power properties in finite samples.
•An endogeneity test employing the control function approach is investigated.•The test is found to be similar to the Hausman test.•Test statistics used in these tests can be numerically ranked in finite samples.
This paper proposes IV-based estimators for the semiparametric distribution regression model in the presence of an endogenous regressor, which are based on an extension of IV probit estimators and ...the idea of control functions. We discuss the causal interpretation of the estimators and two methods (monotone rearrangement and isotonic regression) to ensure a monotonically increasing distribution function. Asymptotic properties and simulation evidence are provided. An application to income equations with German SOEP data reveals statistically significant and heterogeneous differences to the inconsistent non-IV-based estimator.
•IV-based estimators for the semiparametric distribution regression model are proposed.•Methods for ensuring a monotonically increasing distribution function.•Asymptotic properties and simulation evidence.•Application to German SOEP data.
In this article, stochastic highly nonlinear delay systems with neutral term are studied, which does not satisfy the linear growth condition. Under the local Lipschtiz condition and the polynomial ...growth condition, we study the existence and uniqueness, as well as boundedness, of global solution for stochastic highly nonlinear delay systems with neutral term. By designing a discrete-time feedback control function, the stabilization of stochastic highly nonlinear delay systems with neutral term is presented. Different from the previous literature, our discrete-time feedback control function depends on Markov switching signals with a delay. An illustrative example is given to show the effectiveness of the obtained results.
The aim of this paper is to propose a new φ-coupled fixed point theorem for a mixed monotone mapping in a metric space, which is taken no account of the continuity of the mapping. To this end, we ...introduce the notions of φ-coupled fixed point and modified F-control function. Our obtained results are applied to derive some φ-coupled fixed point theorems in partial metric spaces and quasi-metric spaces, respectively. Some applications to matrix equations and integral equations are also presented so as to illustrate our results.
Natural rock, such as sandstone, has a large number of discontinuous, multi-scale, geometry-irregular pores, forming a complex porous structure. This porous structure essentially determines the ...rock’s physical and/or mechanical properties, which are of great significance to a variety of applications in the fields of science and engineering. As a supplement to experimental observation, a reliable reconstruction model of porous structure could provide an effective and economical way to characterize the physical and mechanical properties of a porous rock. In this paper, we present a novel method for reconstructing the well-connected porous structure of sandstones, which are often intractable to handle for current reconstruction methods. A fractal descriptor is here proposed for better characterizing complex pore morphologies. The reconstruction procedure of a 3D well-connected porous structure is optimized by integrating the improved simulated annealing algorithm and the fractal system control function. The proposed reconstruction method enables us to represent a large-size 3D porous structure. To verify the accuracy of reconstruction, we have analyzed the geometrical, topological, and mechanical properties of the reconstructed porous medium and compared them with those of prototype rock samples. The comparisons show good agreement between the reconstructed model and the real porous sandstone.
A Stein-type control function maximum likelihood (CFML) estimator is suggested for the probit model in the presence of endogeneity. This novel estimator combines the probit maximum likelihood and ...CFML estimators. The asymptotic distribution and risk function for the new estimator is derived. It is demonstrated that, subject to certain conditions of the shrinkage parameter, the asymptotic risk of the new estimator is strictly smaller than the risk of the CFML. Monte Carlo simulations illustrate the method's superiority in finite samples. The method is also applied to analyze the impact of managerial incentives on the use of foreign-exchange derivatives.
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