Is yield increase sufficient to achieve food security in China?

Abstract

Increasing demand for food, driven by unprecedented population growth and increasing consumption, will keep challenging food security in China. Although cereal yields have substantially improved during the last three decades, whether it will keep thriving to meet the increasing demand is not known yet. Thus, an integrated analysis on the trends of crop yield and cultivated area is essential to better understand current state of food security in China, especially on county scale. So far, yield stagnation has extensively dominated the main cereal-growing areas across China. Rice yield is facing the most severe stagnation that 53.9% counties tracked in the study have stagnated significantly, followed by maize (42.4%) and wheat (41.9%). As another important element for production sustainability, but often neglected is the planted area patterns. It has been further demonstrated that the loss in productive arable land for rice and wheat have dramatically increased the pressure on achieving food security. Not only a great deal of the planted areas have stagnated since 1980, but also collapsed. 48.4% and 54.4% of rice- and wheat-growing counties have lost their cropland areas to varying degrees. Besides, 27.6% and 35.8% of them have retrograded below the level of the 1980s. The combined influence (both loss in yield and area) has determined the crop sustainable production in China to be pessimistic for rice and wheat, and consequently no surprise to find that more than half of counties rank a lower level of production sustainability. Therefore, given the potential yield increase in wheat and maize, as well as substantial area loss of rice and wheat, the possible targeted adaptation measures for both yield and cropping area is required at county scale. Moreover, policies on food trade, alongside advocation of low calorie diets, reducing food loss and waste can help to enhance food security.

Fig 1. Identification matrix of food productivity sustainability ranks.

Sustainability ranks based on yield-area trend relationships. Ranks diagonally increase from 1 to 5, suggesting decreasing sustainability of food productivity.

Fig 2. Pattern of the yield trends for main cereals.

At each county where rice (a), wheat (b) and maize (c) crop yield were tracked, yield trends were divided into four types and color coded.

Fig 3. Pattern of the planted area trends for main cereals.

At each county where rice (a), wheat (b) and maize (c) crop-growing area were tracked, area trends were divided into four types and employed the same color strategy.

Fig 4. Pattern of the productivity sustainability for main cereals.

Combining effects of both yield and area on production sustainability were color coded followed by the Tab.1 strategy.

Fig 5. Static comparison in production between 1980 and 2008 of the main cereals.

We compared the static change in yield, area and production for rice (a), wheat (b) and maize (c) undertaking different assignment of crop production and/or marketing, from 1980 to 2008. The horizontal and vertical axis shows changes in yield and area. Size of each circle shows the ratio of area in 2008 relative to 1980. Blue points denote counties assigned for marketing, while yellow points for both production and marketing, and orange for production. The ratio greater than 1 implies an increasing trend in yield or area. If the ratio is less than 1, yield or area has decreased from 1980 to 2008. Change in production is expressed by the product of yield ratio multiplying area ratio. Dots above the dotted line imply increasing production from 1980 to 2008. The statistical relationships of yield and area ratio among the three cereal crops are illustrated in figure (d).