Biopores in the subsoil: Formation, nutrient turnover and effects on crops with distinct rooting systems (BioFoNT)

多年生饲料作物通过形成广泛的根系和暂时的土壤休息，潜在地增加了土壤下的生物矿物质密度。我们将在工作组建立和维护的应用研究单位的中央田间试验(CeFiT)中，对紫花苜蓿、菊苣和高羊茅分别生长1、2和3年后的根长密度、蚯蚓丰度和生物孔大小进行量化。包括蒸腾作用、气体交换和叶绿素荧光在内的地上部参数将经常被记录下来。将从作物产量、养分转移和氢气释放等方面量化种植前对油菜和谷物的影响。与生物孔相关的土壤(即旱生土壤)与散体土壤相比，通常营养丰富，因此被认为是一个潜在的养分获取热点。然而，据报道，根和孔壁之间的接触面积很低。目前还不清楚在多大程度上利用了旱层中存在的养分，以及底土生物孔对作物的养分供应可能具有哪些潜在的相关性。我们将使用灵活的视频显微镜来确定生物孔中的根与土壤的接触。将使用15N作为示踪剂来量化蚯蚓对旱圈的氮素输入以及具有不同生根系统的后续作物(油菜与谷物)从旱圈重新吸收氮素的可能性。

Perennial fodder cropping potentially increases subsoil biopore density by formation of extensive root systems and temporary soil rest. We will quantify root length density, earthworm abundance and biopore size classes after Medicago sativa, Cichorium intybus and Festuca arundinacea grown for 1, 2 and 3 years respectively in the applied research unit’s Central Field Trial (CeFiT) which is established and maintained by our working group. Shoot parameters including transpiration, gas exchange and chlorophyll fluorescence will frequently be recorded. Precrop effects on oilseed rape and cereals will be quantified with regard to crop yield, nutrient transfer and H2-release. The soil associated with biopores (i.e. the driloshpere) is generally rich in nutrients as compared to the bulk soil and is therefore supposed to be a potential hot spot for nutrient acquisition. However, contact areas between roots and the pore wall have been reported to be low. It is still unclear to which extent the nutrients present in the drilosphere are used and which potential relevance subsoil biopores may have for the nutrient supply of crops. We will use a flexible videoscope to determine the root-soil contact in biopores. Nitrogen input into the drilosphere by earthworms and potential re-uptake of nitrogen from the drilosphere by subsequent crops with different rooting systems (oilseed rape vs. cereals) will be quantified using 15N as a tracer.