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施肥措施是影响稻田土壤和作物重金属镉(Cd)累积的关键因素之一,探讨长期定位施肥后稻田土壤和作物Cd累积的变化特征,为双季稻区科学施肥和土壤环境保护提供科学理论依据。以双季稻田长期定位施肥试验为研究平台(31年),分析了5种施肥措施[化肥(MF)、秸秆还田+化肥(RF)、30%有机肥+70%化肥(LOM)、60%有机肥+40%化肥(HOM)和无肥(CK)]对土壤和大麦植株Cd累积的影响。结果表明,与CK处理相比,HOM和LOM处理均显著提高了大麦成熟期稻田耕层(0~20cm)土壤Cd全量和有效态含量,分别提高了36.67%、80.91%和141.86%、79.07%。大麦植株Cd积累量和富集系数均以根系为最高,其次是叶和茎,籽粒为最低。LOM处理提高了大麦植株根系、叶和籽粒Cd含量,分别比CK处理增加0.270、0.235和0.039 mg·kg~(-1);RF处理提高了植株茎Cd含量,比CK处理增加0.076 mg·kg~(-1)。各施肥处理稻田土壤重金属Cd单项污染指数变幅在1.100~1.990之间,其PCd均大于1,表现为HOM>LOM>CK>MF>RF,其中LOM和HOM处理PCd均显著高于其他处理(P<0.05);MF、RF和CK处理间PCd均无显著性差异。以上结果表明,长期施用化肥和秸秆还田条件下,稻田土壤未见明显的Cd积累,但有机肥施用条件下稻田土壤呈现显著Cd积累。
Fertilization is one of the key factors that affect the accumulation of heavy metal Cd in soils and crops in paddy soils. The characteristics of Cd accumulation in paddy soils and crops after long-term fertilization are discussed to provide a scientific basis for scientific fertilization and soil environmental protection in double cropping rice fields . Based on the long-term fertilization experiment of double cropping rice fields (31 years), five fertilization measures (fertilizers, RF, 30% LOM, 60% % Organic fertilizer + 40% fertilizer (HOM) and no fertilizer (CK) on Cd accumulation in soil and barley plants. The results showed that HOM and LOM treatment significantly increased the contents of total Cd and available Cd in paddy soil (0 ~ 20cm) paddy soil during paddy maturity compared with CK treatment by 36.67%, 80.91% and 141.86%, 79.07% . The Cd accumulation and enrichment coefficient of barley plants were highest in roots, followed by leaves and stems, with the lowest in grains. LOM treatment increased the Cd content in roots, leaves and kernels of barley plants by 0.270, 0.235 and 0.039 mg · kg -1, respectively, compared with CK treatment. RF treatment increased the Cd content of stems and increased 0.076 mg · kg ~ (-1). The individual pollution indices of heavy metal Cd in paddy soils varied from 1.100 to 1.990. The PCd values of all the paddy soils were greater than 1, showing HOM> LOM> CK> MF> RF. The PCd of LOM and HOM treatments were significantly higher than those of other treatments P <0.05). There was no significant difference in PCd between MF, RF and CK treatments. The above results show that under the condition of long-term application of chemical fertilizers and straw returning, there is no obvious accumulation of Cd in paddy soil, but significant accumulation of Cd in paddy soil under the application of organic manure.