Natural Resources Institute Finland, Tietotie 4, Jokioinen, FI-31600, Finland.
Natural Resources Institute Finland, Latokartanonkaari 9, Helsinki, FI-00790, Finland.
J Environ Qual. 2021 Jan;50(1):172-184. doi: 10.1002/jeq2.20170. Epub 2020 Dec 8.
Declining carbon (C) content in agricultural soils threatens soil fertility and makes soil prone to erosion, which could be rectified with organic soil amendments. In a 4-yr field trial, we made a single application of three different organic sludges from the pulp and paper industry and studied their effects on cereal yield, soil C content, and fungal and bacterial composition. In laboratory rainfall simulations, we also studied the effects of the soil amendments on susceptibility to erosion and nutrient mobilization of a clay-textured soil by measuring the quality of percolation water passing through 40-cm intact soil monoliths during 2-d rainfall simulations over four consecutive years after application. A nutrient-poor fiber sludge reduced wheat yield in the first growing season, but there were no other significant effects on cereal yield or grain quality. An input of ∼8 Mg ha C with the soil amendments had only minor effects on soil C content after 4 yr, likely because of fast microbe-mediated turnover. The amendments clearly changed the fungal and bacterial community composition. All amendments significantly reduced suspended solids (SS) and total phosphorus (TP) concentrations in percolation water. The effect declined with time, but the reduction in SS and TP was still >25% 4 yr after application. We attributed the lower tendency for particle detachment in rain simulations to direct interactions of soil minerals with the added particulate organic matter and microbe-derived compounds that stabilize soil aggregates. In soils with low organic matter content, pulp and paper industry by-products can be a viable measure for erosion mitigation.
农业土壤中碳（C）含量的下降威胁着土壤肥力，并使土壤容易受到侵蚀，这可以通过有机土壤改良剂来纠正。在为期 4 年的田间试验中，我们一次性应用了三种来自纸浆和造纸工业的不同有机污泥，并研究了它们对谷物产量、土壤 C 含量以及真菌和细菌组成的影响。在实验室降雨模拟中，我们还研究了土壤改良剂对粘土质地土壤侵蚀敏感性和养分迁移的影响，方法是在应用后连续 4 年的 2 天降雨模拟期间，测量通过 40 厘米完整土柱的渗流水的质量。一种养分贫乏的纤维污泥降低了第一个生长季节的小麦产量，但对谷物产量或谷物质量没有其他显著影响。土壤改良剂输入约 8 Mg ha C 后，4 年后对土壤 C 含量的影响较小，可能是因为微生物介导的快速转化。这些改良剂明显改变了真菌和细菌群落的组成。所有改良剂都显著降低了渗流水中的悬浮固体（SS）和总磷（TP）浓度。随着时间的推移，这种效果会下降，但在应用 4 年后，SS 和 TP 的减少仍超过 25%。我们将降雨模拟中颗粒脱附的趋势降低归因于土壤矿物质与添加的颗粒有机物质和微生物衍生化合物的直接相互作用，这些化合物稳定了土壤团聚体。在有机物质含量低的土壤中，纸浆和造纸工业的副产品可以是一种可行的减缓和侵蚀措施。
