Kreider Andrew N, Fernandez Pulido Carlos R, Bruns Mary Ann, Brennan Rachel A
J Environ Qual. 2019 Mar;48(2):469-475. doi: 10.2134/jeq2018.05.0207.
Excessive N and P in surface waters can promote eutrophication (algae-dominated, low-O waters), which decreases water quality and aquatic life. Duckweed (Lemnaceae), a floating aquatic plant, rapidly absorbs N and P from water and its composition shows strong potential as a soil amendment. Therefore, it may be used to transfer N and P from eutrophic water bodies to agricultural fields. In this work, dried duckweed was incorporated into agricultural soil in microcosm, column, and field tests to evaluate biological N cycling, nutrient retention, and crop yield compared with compost, diammonium phosphate (DAP), and an amendment-free control. In microcosm tests, 25 ± 13% of duckweed N was mineralized, providing on average less mineral N than DAP (107 ± 21%), but more than compost (11 ± 12%). In columns, duckweed treatments leached only 2% of the N added, significantly less than DAP, which leached 60% of its N. Compared with the control, DAP leached significantly more phosphate (78%), whereas duckweed and compost treatments leached less (56 and 27%, respectively). Crop yield, as well as runoff N and P, were measured in field tests growing forage sorghum [ (L.) Moench.]. Although less total N was applied to duckweed plots than to DAP plots (75 vs. 130 kg ha, respectively), duckweed was found to retain 30% more total mineral N in a tilled agricultural field than DAP, while supporting a comparable yield. These tests indicate that duckweed may provide a sustainable source of N and P for agriculture.
地表水中过量的氮和磷会促进水体富营养化（藻类主导、低氧水体），从而降低水质和水生生物数量。浮萍（浮萍科）是一种漂浮水生植物，能迅速从水中吸收氮和磷，其成分作为土壤改良剂具有很大潜力。因此，它可用于将富营养水体中的氮和磷转移到农田中。在本研究中，通过微观试验、柱试验和田间试验，将干浮萍施入农业土壤，以评估与堆肥、磷酸二铵（DAP）和无改良剂对照相比，其对生物氮循环、养分保持和作物产量的影响。在微观试验中，25±13%的浮萍氮被矿化，平均提供的矿质氮比DAP（107±21%）少，但比堆肥（11±12%）多。在柱试验中，浮萍处理仅淋溶了添加氮的2%，显著低于DAP，后者淋溶了其60%的氮。与对照相比，DAP淋溶的磷酸盐显著更多（78%），而浮萍和堆肥处理淋溶较少（分别为56%和27%）。在种植饲用高粱[（L.）Moench.]的田间试验中测量了作物产量以及径流中的氮和磷。尽管施用于浮萍地块的总氮量低于DAP地块（分别为75和130千克/公顷），但发现在翻耕的农田中，浮萍比DAP多保留30%的总矿质氮，同时产量相当。这些试验表明，浮萍可为农业提供可持续的氮和磷来源。
