干旱区不同土壤和作物灌溉量的无机碳淋溶特征实验研究

A leaching experiment on inorganic carbon characteristics in the different soil salinity and irrigation in arid area

为探讨干旱区作物灌溉对盐碱土无机碳传输的影响,通过选择不同含盐量的土壤,即耕地土(F)、混合土(C)和原生荒漠土(D),分别种植水稻(R)和棉花(C),进行了一个生长季的淋溶实验,并定期收取且分析土壤淋溶液中的可溶性无机碳(DIC)含量。结果表明:(1)水稻处理无机碳的淋溶主要集中在秧苗分蘖期和幼穗发育期,而棉花处理则集中在花铃期和吐絮期;(2)不同含盐量土壤在同一灌溉量下,土壤含盐量越高,其淋溶过程得到的无机碳总量越大,最高约为8.4 g·m^(-2)·a^(-1),最低仅约0.7 g·m^(-2)·a^(-1);(3)同种土壤不同灌溉量,其水稻高于棉花,高出值范围为2.9～4.1 g·m^(-2)·a^(-1);种植作物处理得到的无机碳总量均大于其相应对照处理的量(p<0.05)。研究结果表明,土壤的盐含量及作物灌溉量对土壤无机碳淋溶有重要影响。

Soil inorganic carbon is the most common form of C in arid and semiarid climate aras, transfer of dis- solved inorganic carbon in soil through the hydrologic cycle is an important component of global carbon budgets, un- derstanding the significance of soil dissolved inorganic carbon processes can enhance development of strategies to mitigate atmospheric carbon concentrations. In order to quantity the carbon loss character in soil by field irrigation, an leaching experiment was carried out in Fukang station of desert ecology in Xinjiang. This study measured inorgan- ic carbon leaching loses from different soil salinity （farmland soil, composite soil and native desert soil） with rice and cotton growing to explore the inorganic carbon transport mechanism with different irrigation in the saline-alkali soil of arid zone. Each kind of soil had 7 experiments with rice and cotton growing, respectively. Moreover, there were 3 controls that did not plant any crop with rice and cotton growing, respectively. The irrigation of rice was 1 100 mm, and the cotton was 470 mm. The results showed as follows： （1） The leaching inorganic carbon in the soil with rice growing mainly occurred in the period of seeding tillering and panicle development, but with cotton growing that in the period of blooming and boll opening. The amount of leaching inorganic carbon in the farmland with rice grow-ing was maximum in the period of seeding tillering, but the amount of leaching inorganic carbon in the farmland with cotton growing was maximum in the period of blooming and boll opening. （2） The total amount of leaching inorganic carbon was higher in high salinity soil than in low salinity soil with the same irrigation. The maximum value of leach- ing inorganic carbon was in DR-CK （the soil control treatment of native desert soil with rice growing） treatment （approximately 8.4 g· m-2· a-l） , but the minimum value was in FC-CK （the control treatment of farmland soil with cotton growing） treatment （approximately 0.7 g· m-2· a-1） in the leaching experiment. （3） The total amount of leach- ing inorganic carbon in the same soil type was higher in rice growing than in cotton growing. The total amount of leaching inorganic carbon in FR （farmland soil with growing rice） treatment is 2.9 g· m-2· a-1 higher than in FC （farmland soil with cotton growing）, and value in CR （composite soil with rice growing） is 4.1 g. m-2· a-1 higher than in CC （composite soil with cotton growing）, and with a 3.1 g· m-21· a-1 higher in DR （native desert soil with rice grow- ing） than in DC （native desert soil with cotton growing）. The total amount of leaching inorganic carbon was higher in the soil with crops growing than their corresponding control treatments （p 〈 0.05 ）. These conclusions indicate that soil salinity and irrigation are the important factors to affect quantity of leaching inorganic carbon.