It has been thirteen years since the successful launch of the first-ever dedicated satellite for global soil moisture monitoring. Looking towards the future, P-band (0.3-1 GHz) is a promising technique to enhance the current L-band (1.4 GHz) missions, due to the postulated greater moisture retrieval depth and reduced roughness and vegetation impact because of its lower frequency. Accordingly, this research has established a long-term (2017-2021) tower-based experiment and demonstrated the above-postulated benefits at P-band under various moisture, roughness, and vegetation conditions, therefore paving the way for a successful P-band mission to obtain deeper and more accurate global soil moisture information.