沿海滩涂围垦区土地生产潜力模型构建与应用——以江苏省如东县为例

沿海淤泥质滩涂是中国重要的耕地后备资源之一,滩涂围垦新增的大量耕地资源的生产潜力能反映滩涂土壤粮食安全保障能力大小。本文以江苏省如东县滩涂围垦区为例,在现有的光温水气候生产潜力模型的基础上,引进基础地力贡献率和盐分限制因子作为土壤有效性系数,构建沿海地区土地生产潜力模型,并通过水稻和小麦产量对模型结果进行初步验证。研究表明：该模型具有一定可行性。滩涂围垦区水稻产量土壤基础地力贡献率为55%~59%;小麦基础地力贡献率为50%~80%。未脱盐的1982年滩涂围垦区水稻和小麦产量受到盐分阻碍的系数分别为0.73和1.00。2007年垦区由于盐分太高不能种植水稻,小麦产量受到盐分阻碍系数为0.35。未脱盐的1982年滩涂垦区土壤基础地力修正后的水稻和小麦土地生产潜力分别为12235.84和6502.23 kg/hm²;土壤盐分修正后的土地生产潜力分别为15677.42和10329.39 kg/hm²;土壤基础地力和盐分共同修正后的土地水稻和小麦生产潜力分别为8934.97和6502.23 kg/hm²。与实地调查的水稻产量(9750 kg/hm²)和小麦生产潜力(6000 kg/hm²)相比,目前土地生产力远小于盐分限制下的土地生产潜力,与基础地力和盐分双重限制下的土地生产潜力接近,改善土壤施肥技术可以进一步提高土地生产力。

Potential land productivity of the coastal reclamation zones of Rudong County,Jiangsu Province

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.