Subjects: Biology >> Ecology submitted time 2017-11-29 Cooperative journals: 《中国生态农业学报》
Abstract： To elucidate the impact of climate factors on the seasonal variations of soil salinity and to explore the effects of plant cover and straw mulching on soil desalination and salinity control in coastal areas, a field experiment was conducted in the medium-heavy salinity of coastal areas in Rudong, Jiangsu Province. Four treatment were applied in the present study: Control (bare land, CK), straw mulching (straw cover amount for 15 t∙hm-2, SM), plant cover (PC) and plant cover combined with straw mulching (straw cover amount for 7.5 t∙hm-2, PC+1/2SM). Climate factors (rainfall and atmospheric temperature) and topsoil salinity dynamic changes were determined from May 2014 to May 2015. Results showed that: (1) seasonal variations in some extent were shown in the bare land of coastal areas, with obviously salt accumulating from October to December and the highest EC1:5 3.90 dS·m-1 in October; (2) the correlation analysis showed that soil salinity changes in the CK treatment had a significant negative correlation with the cumulative rainfall of the seven-day before sampling (P < 0.01) and with the cumulative rainfall of the fifteen-day before sampling (P < 0.05), but had no obviously significant correlations in SM, PC and PC+1/2SM treatments (P > 0.05); Under CK treatment, the multifactor and interphase analysis of the climate factors indicated that rainfall increase could promote soil desalinization (P < 0.01), atmospheric temperature rise could exacerbate soil salt accumulation in surface (P < 0.01), simultaneously, the increasing interaction between rainfall and atmospheric temperature would have a positive effect on soil salt accumulation (P < 0.01); (3) ground mulching, including plant cover and straw mulching, could significantly alter the effects of climate factors on the seasonal variations of soil salinity. Under the PC and PC+1/2SM treatment, the relationship of soil desalinization ratio (%) changes (Y) and treatment time (days, X) was expressed as quadratic function equations with YPC= 0.001X2-0.345X+54.41 (R² = 0.456, P <0.01) and YPC+1/2SM = 0.001X2-0.293X + 57.121 (R² = 0.526, P < 0.01), respectively; Under the SM treatments, the relationship was expressed as Logistic curve equation: YSM = 94.912 /(1+e1.482-0.052X) (R² = 0.980, P <0.001); In addition, the soil desalination rate could increase rapidly after 29 days of straw mulching treatment (that is June to August) and trend to be stable with the rate reaching 94.91 % after 70~80 days of straw mulching treatment; Moreover, large amounts of straw mulching (15 t∙hm-2) had a more obvious effect on soil desalination, but it also caused more obvious alkalinity problems. Therefore, to consider the desalination and salinity control, suitable amount of straw mulching (such as straw cover amount for 15 t∙hm-2) or suitable amount of straw mulching (straw cover amount for 15 t∙hm-2) combined with plant cover (such as Sesbania cannabina Pers and Brassica juncea (L.) Czern. et Coss.), at the same time taking full advantage of the characteristics of rainfall concentration in coastal areas, may be adopted to promote soil desalting effects and soil reclamation in the future direction of warming-wetting climate in the coastal area of coastal reclamations.
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