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Based on the analysis of the grain supply and demand gap’s current situation in China, this paper establishes an indicator system for the influence factors of grain supply and demand gap. Then this paper calculates the correlation degree between the main grain varieties’ supply and demand gap and its influence factors. The results show that sown area and unit yield have the greatest impact on wheat supply and demand gap; per capita disposable income and unit yield have the greatest impact on corn supply and demand gap; per capita disposable income and agricultural mechanization level have the greatest impact on the supply and demand gap of soybean and rice. From the analysis results, we can obtain the difference between the factors affecting the grain supply and demand gap, and provide a certain theoretical basis and new ideas for the balance of grain supply and demand in China.

As a big grain country, the grain issue has always been a foundation for the stable development of the country’s economy and social stability, a significant issue concerning the international people’s livelihood. In recent years, many scholars have studied the balance of supply and demand of grain. Yu [

The grey system theory is a new method proposed by Professor Deng Julong to study the problem with less data and poor information uncertainty [

Step 1: Determine the analysis sequence.

Set as the reference sequence:

X 0 = ( x 0 ( 1 ) , x 0 ( 2 ) , ⋯ , x 0 ( n ) ) (1)

Set as the comparison sequence:

X i = ( x i ( 1 ) , x i ( 2 ) , ⋯ , x i ( n ) ) ( i = 1 , 2 , ⋯ , m ) (2)

Step 2: Nondimensionalize the original data.

The initialized reference sequence is:

X ′ 0 = x 0 ( k ) / x 0 ( 1 ) = ( x 0 ( 1 ) , x 0 ( 2 ) , ⋯ , x 0 ( n ) ) ( i = 1 , 2 , ⋯ , m ) (3)

The initialized comparison sequence is:

X ′ i = X i ( k ) / x i ( 1 ) = ( x ′ i ( 1 ) , x ′ i ( 2 ) , ⋯ , x ′ i ( n ) ) ( i = 1 , 2 , ⋯ , m ) (4)

Step 3: Calculate difference sequence.

The calculation formula of sequence difference is:

Δ 0 i ( k ) = | x 0 ( k ) − x i ( k ) | ( i = 1 , 2 , 3 , ⋯ , m , k = 1 , 2 , 3 , ⋯ , n ) (5)

The maximum and minimum calculated by the Formula (5) are:

Maximum: M = max i max k Δ i ( k ) = Δ max

Minimum: m = min i min k Δ i ( k ) = Δ min

Step 4: Calculate grey correlation coefficient.

The calculation formula of grey correlation coefficient is:

γ 0 i ( k ) = m + ρ M Δ 0 i ( k ) + ρ M (6)

where, ρ ∈ ( 0 , 1 ) , i = 1 , 2 , 3 , ⋯ , m , ρ is called resolution coefficient, set ρ = 0.5 usually.

Step 5: Calculate grey correlation degree.

The calculation formula of grey correlation degree is:

γ 0 i = 1 n ∑ k = 1 n γ 0 i ( k ) (7)

The γ 0 i is the comparison sequence x i to reference sequence x 0 , which can reveal the degree of their association.

Record the grey correlation degree of the comparison sequence to the parameter sequence as γ ( X 0 , X i ) , the weight of each feature information should be different due to the different importance of each feature information when calculating the target grey correlation degree. Let the weight be a ( k ) , k = 1 , 2 , ⋯ , n , n is the weight coefficient of each feature information and ∑ i = 1 n a ( k ) = 1 , a ( k ) ≥ 0 , the Weighted correlation degree is γ i = ∑ j = 1 M ε i ( j ) a ( j ) , i = 1 , 2 , ⋯ , m k . The larger the γ i , the greater the degree of association, and vice versa.

The concept of entropy comes from thermodynamics. The entropy weight method is to calculate the weight by using the amount of information contained in the indicator monitoring value. If the information entropy of an evaluation index is larger, it indicates that the amount of information provided by it is greater, and the greater the role played in the comprehensive evaluation. If there are n objects, m evaluation index, the original data matrix is

X = [ x i j ] n × m , x i j ≥ 0 ( i = 1 , 2 , ⋯ , n ; j = 1 , 2 , ⋯ , m ) . Since the variable in entropy has a value range of [0, 1], in order to ensure compliance with the requirements, the original evaluation data needs to be processed by normalization, i.e. P i j = x i j / ∑ j = 1 m x i j . The processed matrix is P i j = [ p i j ] n × m , relative to an indicator x i j in the system. Information entropy is E j = − k ∑ i = 1 n [ p i j ln p i j ] , and in the equation k = 1 / ln n . The entropy weight of the indicator j is W j = ( 1 − E j ) / ( m − ∑ j = 1 m E j ) . The entropy weight method not only has the advantage of objectivity, but also the evaluation problem with a large degree of difference in indicators, which can lead to the weight with higher accuracy [

The weight of each indicator indicates the importance and status of the feature in the judgment decision, and also reflects the reliability of different features in the signal characteristics. The grey correlation analysis algorithm based on entropy weight can objectively weight each index according to the entropy value of the data sample; it does not overly rely on the subjective judgment of the expert.

According to experts’ opinion a Chinese consumes about 370 kilograms of grain one year. Among them, 250 kg of rations, 2 kg of grain for food industry, 5 kg of grain for alcoholic beverages, and 110 kg of feed grain are included. According to this standard, 1.4 billion people in China consume about 1.04 trillion catty of grain per year [

It can be seen from

Select China’s grain supply and demand gap (Y_{0}) as the main research object from 2011 to 2016. At the same time, based on the current social and economic development in China, this paper selects the following factors from the perspective of supply and demand as the correlation factors affecting the fluctuation of grain supply and demand gap. X_{1} is the sown area of main grain varieties, which reflecting the planting area of wheat, corn, soybean and rice in a certain period of time. It is the most direct influence factor for the change of grain supply. X_{2} is the yield per unit area of major grain varieties. It is a comprehensive reflection of various factors such as technological progress, investment changes, institutional innovation, and disaster climate. X_{3} is disaster area of crops. It is a direct factor affecting crop production and has a direct impact on grain supply in the short term. X_{4} is the total power of agricultural machinery. It reflects the level of mechanization of agriculture during a certain period of time; it is a direct influencing factor of grain supply. X_{5} is the population quantity of China, which is a directly impact factors of grain demand. X_{6} is per capita disposable income, which is a symbol of the level of social development and represents people’ living standards. The living standards of people will affect the consumption structure of grain, which is an important factor influencing grain demand. Refer to the existing literature and the availability of data. The influence factors index selected in this paper are shown in

The correlation degree of influences factors and the supply-demand gap are calculated by the grey combined correlation model and the results are shown in the following

Variety | Year | Yield | Demand | Supply-Demand Gap |
---|---|---|---|---|

wheat | 2011 | 11740.09 | 12465.00 | −724.91 |

2012 | 12102.32 | 11765.00 | 337.32 | |

2013 | 12192.64 | 11600.00 | 592.64 | |

2014 | 12620.84 | 11780.00 | 840.84 | |

2015 | 13018.52 | 10960.00 | 2058.52 | |

2016 | 12884.50 | 11400.00 | 1484.50 | |

corn | 2011 | 19278.11 | 18155.00 | 1123.11 |

2012 | 20561.41 | 18585.00 | 1976.41 | |

2013 | 21848.90 | 18775.00 | 3073.90 | |

2014 | 21564.63 | 15535.00 | 6029.63 | |

2015 | 22463.16 | 16855.00 | 5608.16 | |

2016 | 21955.15 | 19030.00 | 2925.15 | |

soybean | 2011 | 1448.53 | 7320.00 | −5871.47 |

2012 | 1301.09 | 7335.00 | −6033.91 | |

2013 | 1195.10 | 7650.00 | −6454.90 | |

2014 | 1215.40 | 8730.00 | −7514.60 | |

2015 | 1178.50 | 9220.00 | −8041.50 | |

2016 | 1225.00 | 9630.00 | −8405.00 | |

rice | 2011 | 20100.09 | 19585.00 | 515.09 |

2012 | 20423.59 | 19590.00 | 833.59 | |

2013 | 20361.22 | 19625.00 | 736.22 | |

2014 | 20650.74 | 19685.00 | 965.74 | |

2015 | 20822.52 | 19495.00 | 1327.52 | |

2016 | 20707.51 | 19470.00 | 1237.51 |

Primary Indicators | Secondary Indicators | Code | Unit |
---|---|---|---|

yield | sown area | X1 | thousand hectare |

yield per unit area | X2 | kilogram/hectare | |

disaster area | X3 | thousand hectare | |

total power of agricultural machinery | X4 | ten thousand kilowatts | |

demand | population quantity | X5 | ten thousand people |

per capita disposable income | X6 | yuan |

Variety | X1 | X2 | X3 | X4 | X5 | X6 |
---|---|---|---|---|---|---|

wheat | 0.8473 | 0.8438 | 0.8375 | 0.8435 | 0.7805 | 0.8333 |

corn | 0.7969 | 0.793 | 0.7777 | 0.7951 | 0.7406 | 0.8108 |

soybean | 0.9643 | 0.9776 | 0.9595 | 0.9833 | 0.8724 | 0.9953 |

rice | 0.9115 | 0.9125 | 0.895 | 0.9169 | 0.8264 | 0.9347 |

From

The sown area and yield as the main influence factors of wheat and corn’s supply and demand gap, are mainly reflected in the grain supply. However, as the world’s forefront in grain production, the improvement is not so large. In case that production can not be significantly increased, expanding the cultivated area is a practical adjustment method. Per capita disposable income is the biggest influence factor in the supply and demand gap of corn, soybean and rice. It can be seen that the people’s living standards play a vital role in the supply and demand of China’s grain. It is mainly reflected in the demand for grain. With the improvement of people’s living standards, the demand for grain has changed. As the main influence factor of soybean and rice supply-demand gap, the total power of agricultural machinery plays a significant role in the production of grain. It can pay attention to the improvement of agricultural mechanization level and increase the attention to mechanization level. We can pay attention to the improvement of agricultural mechanization level and increase the attention to the level of mechanization.

From the grey correlation degree analysis of the influence factors and the suppy-demand gap, we can find that the biggest impact on the supply and demand gap of wheat is the sown area and yield per unit area. The most influence factors

on corn are per capita disposable income and sown area. The biggest influence factors on soybean and rice are per capita disposable income and the total power of agricultural machinery. The supply and demand balance of main grain varieties can be improved from the following aspects.

1) Mobilize the enthusiasm of grain farmers through effective incentive mechanisms. As a major factor affecting grain production, sown area plays a vital role in the improvement of grain yield. Various grain subsidy policies can be introduced to encourage farmers to increase the grain sown area. At the same time, it is necessary to guide the moderate scale operation of cultivated land for different varieties. 2) The government should optimize the consumption structure, increase investment in scientific research, strengthen the scientific and technological research on the staple food, overcome the shortcomings of poor grain taste and easy gelatinization, and process coarse grain staple food to meet the needs of residents. 3) Strengthen the level of mechanization in agricultural development. On the one hand, it is necessary to increase the subsidy policy for agricultural machinery and mobilize the enthusiasm of farmers to purchase agricultural machinery. On the other hand, it is vital to actively promote land transfer, accelerate the scale operation of grain production, and provide a basic land platform for agricultural mechanization. In addition, we ought to develop the agricultural machinery leasing market to solve the mechanized operation of small farmers and migrant workers. Last but not least, the government should focus on cultivating large agricultural machinery service and agricultural machinery cooperation organizations to promote the promotion and application of large-scale and multi-type agricultural machinery.

The work was supported in part by the Soft-science Foundation of Henan Province (172400410015); Philosophy and Social Science Program of Henan Province (2016BJJ022).

The authors declare no conflicts of interest regarding the publication of this paper.

Li, B.J. and Yang, W.M. (2018) Analysis of the Influence Factors of Grain Supply-Demand Gap in China. Agricultural Sciences, 9, 901-909. https://doi.org/10.4236/as.2018.97062