Distribution characteristics of residual film over a cotton field under long-term film mulching and drip irrigation in an oasis agroecosystem
Distribution characteristics of residual film over a cotton field under long-term film mulching and drip irrigation in an oasis agroecosystem
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DOI：
10.1016/j.still.2018.03.013
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发表时间：
2018-08-01
影响因子：
6.5
通讯作者：
Fan, Bihang
中科院分区：
文献类型：
--
作者：
He, Huaijie;Wang, Zhenhua;Fan, Bihang
如果没有有效的地膜回收，残留的塑料薄膜（RPF）会对农艺系统和自然环境造成污染危害。在这里，我们研究了中国西北绿洲农业生态系统表土（0-40 cm）中RPF的分布特征。 2016年棉花收获后，我们从连续覆盖管理不同年限（5年、9年、11年、13年、15年和19年）的6块棉田中采集了2304份土壤样品。总共分离并称重了 2471 块 RPF。每个 RPF 碎片的重量通过数字图像中测量的其尺寸进行校准。结果表明，6个田地的RPF含量在121.85至352.38 kg ha(-1)之间，明显超过中国国家标准（75 kg ha(-1)）。 RPF 碎片的出现频率在 5-15 厘米深度处最大。随着土层深度的增加，RPF碎片变小，总质量线性减小。持续覆盖后，RPF年累积量为15.69 kg ha(-1)，主要发生在0-30 cm深度。较大 RPF 碎片（每片 > 25 毫克）的积累主要发生在覆盖开始后 5 至 15 年内。较大的RPF碎片需要15年以上的时间才能降解为较小的RPF碎片（每片<25毫克），占覆盖19年田间RPF碎片总数的65%。重量大于100 mg的RPF碎片主要集中在表面（0-10 cm），而其他较小的RPF碎片则表现出明显的向下迁移。也就是说，随着持续的覆盖管理，RPF 碎片变得更加分散且分布更深，使得地膜恢复更具挑战性。据我们所知，这是首次对长期覆盖后土壤剖面中 RPF 分布的动态进行表征。如果继续采用目前的覆盖方法，累积的RPF将造成严重的土壤污染，并危及绿洲农业生态系统的可持续性。
Without an efficient mulch film recovery, the residual plastic film (RPF) causes pollution hazards to agronomic systems and natural environments. Here, we examined the distribution characteristics of RPF in the topsoils (0-40 cm) in an oasis agroecosystem in Northwest China. After cotton harvest in 2016, we collected 2304 soil samples from six cotton fields with different years of continuous mulching management (5, 9, 11, 13, 15 and 19 a). A total of 2471 pieces of RPF were separated and weighted. The weight of each RPF fragment was calibrated by its size measured in digital images. Our results showed that the amount of RPF ranged from 121.85 to 352.38 kg ha(-1) across the six fields, remarkably exceeding the national standard of China (75 kg ha(-1)). The occurrence frequency of RPF fragments maximized at 5-15 cm depth. With the increase in soil depth, RPF fragments became smaller, and their total mass decreased linearly. After the constant mulching practice, RPF accumulated at an annual rate of 15.69 kg ha(-1), mainly occurring at 0-30 cm depth. The accumulation of the larger RPF fragments (> 25 mg per piece) primarily took place from 5 to 15 years after mulching started. It took over 15 years for the larger RPF fragments to degrade into smaller ones (< 25 mg per piece), which accounted for 65% of the total number of RPF fragments in the field with 19-year of mulching. RPF fragments with a weight larger than 100 mg mostly concentrated at the surface (0-10 cm), whereas, the other smaller RPF fragments showed an evident downward migration. That said, with the constant mulching management, RPF pieces became more fragmented and distributed deeper, making mulch film recovery more challenging. To the best of our knowledge, this is the first time that the dynamics of RPF distribution in the soil profile after long-term mulching have been characterized. If the current mulching method continues, the accumulated RPF is going to cause severe soil pollution and risk the sustainability of the oasis agroecosystem.