Abstract
Food security remains a primary concern because of the large population and scarce land resources in China, and it is a core task to determine the appropriate proportion and scale of fallowing for fallow systems. The aim of this study was to systematically estimate the grain production potential (GPP) of existing and unexcavated cultivated land due to land use change from 1990 to 2017 and calculate the theoretical fallowing scale by using a population carrying capacity model. The reserved GPP from cultivated land to be excavated was 7470 × 104 t in China, and the GPP stored by the change in grain yield per unit, multiple crop index (MCI) decline, and agricultural structure adjustment were 921 × 104 t, 4321 × 104 t, and 7760 × 104 t, respectively, and the lost GPP caused by construction land expansion was 5287 × 104 t. The population carrying capacity of cultivated land in China was estimated to be 1.469 to 1.515 billion in 2017 on the basis of the national average living standard. The proportion of the population that could be fed more was between 6.28% and 9.54% depending on the number of people included, which provided an opportunity to implement the fallowing system in China. Meanwhile the proportions of the theoretical fallow scale were 6.28% and 9.54%, and the fallow scale ranged from 850 × 104 hm2 to 1296 × 104 hm2 under the premise of fully tapping the potential of cultivated land. In addition, taking the decline in MCI as an example, the grain yield reduction was equivalent to the grain yield of 829 × 104 hm2 of newly reclaimed cultivated land over the past 30 years, which saved 621.48 billion yuan. The costs and benefits when formulating relevant policies of land utilization should be considered, and exploiting the productive capacity of cultivated land that exists is better than reclaiming new cultivated land.
Highlights
The grain output of China has increased for 12 consecutive years since 2004, and the grain production capacity has greatly improved [1]
The quality and quantity of cultivated land in China are declining to varying degrees, and great challenges exist for increasing the grain supply under the dual pressures of increasing pollution in agriculture and future construction land expansion [11,13]
J=1 where CLPP1 is the recoverable grain production potential (GPP) of cultivated land; Qj1 is the GPP due to the yield per unit area reduction in the jth province, j = 1, 2, . . . , 31; Qj2 is the GPP due to multiple crop index (MCI) reduction in the jth province; and Qj3 is the GPP due to agricultural structure adjustment in the jth province
Summary
The grain output of China has increased for 12 consecutive years since 2004, and the grain production capacity has greatly improved [1]. The ecological environment has paid a large price, such as in the thinning of the black soil layer [2,3], soil erosion [4], soil acidification [5,6], excessive heavy metals in soil [7], and increased non-point source pollution [8,9]. Construction land continues to expand, and the corresponding cultivated land area decreases yearly with the rapid development of urbanization [10,11,12]. The quality and quantity of cultivated land in China are declining to varying degrees, and great challenges exist for increasing the grain supply under the dual pressures of increasing pollution in agriculture and future construction land expansion [11,13]. Public Health 2019, 16, 4329; doi:10.3390/ijerph16224329 www.mdpi.com/journal/ijerph
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