Abstract:

The Jiangsu muddy coastal zone is one of the key bases of cropland complementary resources in China. In 2009, the Chinese government approved the development plan of the Jiangsu coastal zone, wherein the tidal flat will be reclaimed and developed into new farmland. Potential land productivity in the coastal area can reflect its capacity to supply food for the country, and is the basis for maintaining the sustainability of the regional agricultural production. There exist various potential land productivity models in China and worldwide. Models based on the process of crop physiology and ecology were used at the field scale, such as the Crop-Environment Resource Synthesis System (CERES) and World Food Studies (WOFOST). Land productivity models based on light, temperature, precipitation, and soil properties—the Classification and Evaluation Techniques of Farmland and Evaluation System of Land Productivity (ESLP)—have been used in China. However, the soil validation coefficients in these two models are based on the evaluation of soil quality and did not consider the relationship between crop yields and soil properties. This article takes the reclamation zones in Rudong County, Jiangsu Province as a case study and attempts to improve the soil validation coefficient in potential land productivity models. It incorporates the percentage of soil fertility contribution (PSFC) and soil salinity factor as soil validation coefficients into the model of potential land productivity to reflect the quality of land. We used the field survey data on rice and wheat yields to verify the feasibility of the potential land productivity model in the coastal area of China. The results show that the PSFC of rice production in the Jiangsu coastal area was about 55%~59%. The PSFC of wheat production in the study area was 50%~80%. The rice and wheat production in the reclamation zones in 1951 and 1974 was not affected by soil salinity because the soils in these reclamation zones were not saline. The rice and wheat production in the reclamation zones in 1982 and 2007 were influenced by soil salinity. The salinity factors of rice and wheat production in the reclamation zones in 1982 were 0.73 and 1.00, respectively. The salinity factors of rice and wheat production in the reclamation zones in 2007 were 0 and 0.35. In 2007 the soil in the reclamation zone was no longer suitable for growing rice paddy. The rice and wheat potential productivity corrected by PSFC in the un-desalinized reclamation zones in 1982 were 12235.84 and 6502.23 kg/hm². The rice and wheat potential productivity corrected by soil salinity in the un-desalinized reclamation zones in 1982 were 15677.42 and 10329.39 kg/hm². The rice and wheat potential productivity corrected by PSFC and soil salinity in the un-desalinized reclamation zones in 1982 were 8934.97 and 6502.23 kg/hm². The actual field yields of rice and wheat (9750 and 6000 kg/hm²) are consistent with the potential productivity corrected by PSFC and soil salinity, and is far less than the potential productivity corrected by soil salinity. Improved fertilization can increase land production. The result of this research can be useful for evaluating newly reclaimed farmland resources and for calculating crop production in the coastal reclamation zones.

Key words: potential land productivity, percentage of soil fertility contribution, salinity factor, soil validation coefficient, Jiangsu coastal area