Toward a Robust Land Suitability Framework for Manure Management: Modeling Impacts and Evaluating Biophysical Characteristics

Manure application at the right place, time, and rate is critical for sustainable manure management. A land suitability framework (LSF) was previously developed for identifying suitable areas for manure utilization considering landscape vulnerability. This study aimed to evaluate the developed LSF and provide insights to build a new robust LSF for manure utilization. The study (1) evaluates the potential environmental impacts of manure application compared to inorganic fertilization, (2) evaluates the robustness of the previously developed LSF, and (3) identifies landscape biophysical attributes driving manure nutrient loss. The fertilization scenarios were evaluated using the Soil and Water Assessment Tool (SWAT) in a case study watershed located in Pennsylvania, USA. SWAT-simulated results showed 80% higher organic nitrogen loss and 44% lower nitrate loss with manure fertilization compared to inorganic fertilization scenarios. The previously developed LSF was a useful screening tool for identifying vulnerable areas for manure application. However, the simulation results indicated limitations in the LSF in representing the combined effect of multiple landscape biophysical attributes. The decision tree model using the landscape biophysical characteristics and nutrient loading simulations implied the LSF can be improved by considering soil biophysical characteristics. The study results provide critical insights toward developing a robust LSF for sustainable manure utilization.