Nutrient Acquisition from the Subsoil: N Uptake in Biopores

在依赖于从固相获取养分的可持续农业生产系统中，必须考虑底土的作物营养。由植物根和蚯蚓产生的大的连续生物孔隙提供了高浓度的氮和植物有效磷以及增加的微生物丰度和活性。因此，它们是从底土中获取养分的潜在热点。为了确定作物从底土中吸收的氮量，必须考虑结构异质性，解决drilosphere的影响。在本项目中，研究了不同氮素水平下春大麦对氮素的吸收。总共的底土和ii.底土生物孔将在盆栽实验中通过标记i来量化。表层土或ii.用~（15）N标记的卢塞恩枯落物进行地下滴灌。将使用生物孔的治疗与不使用生物孔的治疗进行比较。此外，通过标记不同土壤深度部分中的drilosphere，来自不同土壤深度的氮吸收分析将与整个培养期间使用永久安装的柔性视频内窥镜监测生物孔隙中的根生长相关联。与所提出的方法，它将被调查是否是一个可观的氮源作物，如果因此结构化的底土与生物孔隙增加的份额来自底土的N。此外，从drilosphere在整个培养期间的氮吸收模式将阐明监测根-土壤接触的生物孔隙作为时间的函数。通过这种方式，将进一步了解生物孔隙在从底土中获取养分方面的作用。

In sustainable agricultural production systems relying on nutrient acquisition from the solid phase, the subsoil has to be considered for crop nutrition. Large continuous biopores generated by plant roots and earthworms provide elevated concentrations of nitrogen and plant available phosphorus as well as increased microbial abundance and activity. They are thus potential hot spots for the nutrient acquisition from the subsoil.To determine the amount of nitrogen taken up from the subsoil by crops, it is therefore essential to consider the structural heterogeneity, addressing the effect of the drilosphere. In the proposed project, nitrogen uptake by spring barley from i. the subsoil in total and ii. a subsoil biopore will be quantified in pot experiments by means of labeling i. the topsoil or ii. the subsoil drilosphere using 15N labelled lucerne litter. Treatments with biopore will be compared with treatments without biopore. Furthermore, by labeling the drilosphere in different soil depth sections, nitrogen uptake analyses from different soil depths will be linked to monitoring root growth in biopores throughout the cultivation period with a permanently installed flexible videoscope. With the proposed approach, it will be investigated whether earthworm casts are an appreciable source of nitrogen for crops and if consequently structuring the subsoil with biopores increases the share of N derived from the subsoil. Moreover, the pattern of N uptake from the drilosphere throughout the cultivation period will be elucidated monitoring root-soil contact in biopores as a function of time. This way, a further step will be taken towards understanding the role of biopores for the nutrient acquisition from the subsoil.