A Soil Analysis Approach to Assessing Potential Loss of Productive Lands Under Agricultural Land Conversion

Land provides physical space and is usually required for various sectoral developments needed to meet the needs of increasing population. Land is a finite natural resource; thus, conflict arises over land use and development.

The strategic location of the municipality of Pura in Tarlac province, Philippines within the urban beltway of Central Luzon and the recent opening of the Tarlac–Pangasinan–La Union Expressway provide Pura excellent opportunities for urban and industrial development. However, the precursor to this is agricultural land conversion (ALC), which can entail changes or reductions in the area of productive lands.

This paper assessed the degree of productivity of the agricultural lands in the study area that are predisposed to ALC using FAO’s land suitability framework and the revised Storie index for soil productivity. Soil survey and composite soil sampling at 20 cm depth in the selected 34 sampling points were done to analyze the relevant soil physical and chemical properties. Five soil mapping units (SMU) were grouped based on the soil surface texture. The results show that the SMUs are only marginally suitable (S3f) for producing rice and other crops due to their current low soil organic carbon content. However, these SMUs can be highly suitable (S1) for crop production with appropriate soil management. Using the Storie index, the entire tract of land of Pura has an index rating of 58 percent, which corresponds to a grade 3 soil suitable for planting a number of crops with expected good results. The results of the land suitability evaluation and soil productivity assessment further show that the land in the municipality of Pura is productive, and thus can benefit both agricultural production and ALC. As such, whichever spatial strategy or policy direction for ALC that the municipal government chooses to adopt, the municipality of Pura will lose productive land.