长期耕种对江苏沿海围垦区滨海盐土理化性质和小麦产量的影响

江苏沿海地区拥有丰富的滩涂资源滩涂围垦长期以来为国家提供了大量土地利用后备资源,而耕地又是其围垦后最主要的土地利用方式之一。利用实验室土壤理化分析调查江苏东台滩涂围垦区耕种60a内耕地土壤理化属性及对应小麦产量的变化。结果表明:(1)在58a的耕种过程中耕地土壤整体表现出脱盐、脱碱和养分积累的的趋势土壤电导率(EC_(1:5))、pH_(1:2.5)由耕种前的5.29dS/m和8.76下降至0.11dS/m和7.93,土壤有机质(SOM)和全氮(TN)则由2.64g/kg和0.15g/kg上升至13.72g/kg和1.12g/kg;(2)土壤碱解氮(AH-N)、有效磷(AP)和速效钾(AK)受施肥和作物生长影响强烈,除AK持续流失外,AHN和AP均表现出先增长后减少的趋势;(3)土壤碳氮比(C/N)和阳离子交换量(CEC)在耕种15-53a经历了剧烈波动,反应出此期间该地区土壤的脆弱性,除AK外,各土壤理化指标均在耕种53a后开始影响20cm以下的深层土壤;(4)随着土壤环境的改善,小麦产量的上升经历了快速增产(0—15a)、波动中产(15—53a)和稳定高产(53a以上)3个阶段,在耕种53年后可达到该品种小麦(扬麦16)正常产量。虽然高强度的农业开发使土壤质量和小麦产量的都有了大幅提升,但耕种0—40年间所表现出的土壤环境的剧烈变化和波动,以及化肥投入与小麦产量之间不对应所可能导致的生态系统问题却应当引起重视,为日后的农业开发提供参考依据。

Effects of long-time cultivation on physicochemical properties of coastal saline soil and wheat production at reclamation areas of Jiangsu Province

The coastal regions of the Jiangsu Province have abundant tidal flat resources. Tidal flat reclamation has supported vast land backup resources and provided land primarily for farming. Soil analyses were carried out to investigate physicochemical properties of the farmland soil and changes in wheat productions at reclaimed areas in Dongtai County over the 60-year period. The results demonstrated the following: (1) In general, during 58 years of cultivation, soil underwent desalination, dealkalization, and nutrients accumulation, soil electronic conductivity (EC_1:5) and pH_1:2.5 decreased from 5.29 dS/m and 8.76 before cultivation to 0.11 dS/m and 7.93 after that, respectively, and soil organic matter and total nitrogen increased from 2.64 g/kg and 0.15 g/kg to 13.72 g/kg and 1.12 g/kg, respectively; (2) Alkali-hydrolysable nitrogen (AH-N), available phosphorus (AP), and available potassium (AK) were strongly affected by fertilization and crop growth; AH-N and AP dropped after initial increase, whereas AK levels continuously decreased; (3) Soil carbon/nitrogen ratio and cation exchange capacity fluctuated sharply between 15 and 53 years of cultivation, reflecting the vulnerability of soil at this region. Studied physicochemical properties revealed that the soil at a depth of more than 20 cm was affected after 53 years of cultivation with the exception of AK; (4) With the improvement of soil environment, there were three stages in wheat production increase: high-speed increase (0-15 years), fluctuation in the production (15-53 years), and stable high production (over 53 years); wheat can reach stable production of this cultivar (Yangmai-16) after 53 years. Although heightened agricultural development greatly enhanced soil quality and wheat production, it also caused dramatic changes and fluctuations in soil environment triggering ecosystem problems; hence, the correlation between chemical fertilization and wheat production should be carefully assessed.