Drip Tape Placement Depth and Emitter Spacing Impact Phosphorus Availability to Potato Crops Under Phosphorus Fertigation

Fertigating with phosphorus (P) through drip irrigation has recently emerged as a promising strategy to enhance phosphorus use efficiency (PUE) in potato produc- tion. However, due to P’s limited mobility in soil—particularly in the lateral direc- tion—and the relatively sparse root system of potatoes, its uptake remains subopti- mal under conventional practices. This study, conducted from 2021 to 2022 in Inner Mongolia, China, investigated whether modifying drip tape depth and emitter spac- ing could improve the spatial alignment between soil-applied P and potato roots, thereby boosting PUE. Two variables were tested: the depth of drip tape placement and the distance between emitters. Key parameters measured included plant dry weight, leaf area index (LAI), soil Olsen P concentration, root distribution, tuber yield, and partial factor productivity of fertilizer P (PFPP). Results showed that sub- surface drip tape placement at a 10 cm depth or reducing emitter spacing to 15 cm significantly improved root-P alignment. These adjustments led to increased P uptake, higher LAI, greater biomass accumulation, and improved tuber yield and PFPP compared to the conventional setup (surface drip tape with 30-cm emitter spacing). The findings underscore the importance of optimizing drip tape configu- ration to synchronize P availability with crop demand. Deep placement and closer emitter spacing can significantly enhance PUE and yield in drip-fertigated potato systems, offering valuable guidance for more efficient P management in potato production.