Ongoing impacts of climatic change especially moisture stress remain a global challenge to agricultural production and food security. Such abiotic effects directly influence soil microbial communities. Previously we demonstrated that polymeric hydrogels, able to provide specific interactions with soil microbial communities, enhance the dynamics and selectivity of ingress and colonisation of plant beneficial bacteria at soil microcosm scales. We now show that small quantities of osmotic hydrogels containing mannose nanofibrils specifically situated in close proximity to developing root zones provide enhanced microbial ingress, colonisation and continuous wetting pathways when contacting developing wheat root systems. These effectively create extensions to the natural rhizosphere sustaining significant beneficial rhizobacterial communities when under moisture stress. Sequencing studies, on wheat production soils undergoing a season of low average rainfall clearly showed microbial abundance increases and taxa selectivity in the rhizosphere-hydrogel regions compared to controls. Here wheat yields increased by about 20% with hydrogel addition compared to controls, which represented a 15% increase in the overall average yield in the region. This represents the first reported demonstration that developing rhizospheres may be readily engineered to consistently select their own distinct microbiome as nodes of functional microbial abundance significantly benefiting grain yield during abiotic stress. Thereby suggesting new opportunities to maintain grain yields during periods of drying climate via these fibrillar hydrogels.