Continuous and accurate sensing of water content in soil is an essential and useful measure in the agriculture industry. Traditional sensors developed to perform this task suffer from limited lifetime and also need to be calibrated regularly. Further, maintenance, support, and deployment of these sensors in remote environments provide additional challenges to the useof conventional soil moisture sensors. In this paper, a metamaterial perfect absorber (MPA) based soil moisture sensor isintroduced. The ability of MPAs to absorb electromagnetic signals with near 100% efficiency facilitates the design of highlyaccurate and low-profile radio frequency (RF) passive sensors. MPA based sensor can be fabricated from highly durablematerials and can therefore be made more resilient than traditional sensors. The creation of channels in the SIW cavity MPA’s substrate to accommodate the soil contact leads to high-resolution sensing. The proposed sensor does not require connectionfor both electromagnetic signals or for adding a testing sample. Importantly, an external power supply is not needed, makingthe MPA based sensor the perfect solution for remote and passive sensing in modern agriculture. The proposed MPA based sensor has three absorption bands due to the various resonance modes of the SIW cavity. By changing the soil moisture level,the absorption peak shifts by 10 MHz, 23.3 MHz, and 60 MHz, which is correlated with the water content percentage at the first, second and third absorption bands, respectively. Finally, a 6×6 cell array with a total size of 312 mm × 312 mm has been fabricated and tested. A strong correlation between measurement and simulation results validates the design procedure.