Integrated remote sensing and GIS approaches for land degradation neutrality (LDN) assessment in the agricultural area

Abstract

Healthy soils sustain humans. Yet these essential land resources are often overlooked and threatened by human activities. Such changes lead to an unbalanced state of soil functions. The land degradation neutrality (LDN) concept has been developed to serve the sustainable development goals (SDGs), in particular goal No.15. Our goal was to move an idea from LDN concept to reality. We assessed the LDN status of the agricultural area in Saraburi Province, Thailand by using three indicators: (i) land use/land cover (LULC) change, (ii) land productivity (LP) change, and (iii) soil organic carbon (SOC) change. The indicator datasets recorded in 2017 and 2020 were used to investigate the land resource changes. LULC and NDVI metrics were obtained using Landsat 8 satellite images and areas were classified into agricultural and non-agricultural uses. For the SOC stocks, 78 agricultural soil samples were collected from the top 30cm by the Land Development Regional Office 1 (Pathum Thani) in 2017 and by the research team in 2020. The standard procedure used for the SOC laboratory analysis was the Walkley-Black method. The LDN status was estimated by integration of results of the three indicators based on a “one out, all out” system. Over three years, the study metrics indicated that net loss occurred in LULC covering the area of 46.99 km2 and SOC stocks declined at an average of 0.02%. However, the NDVI obtained from the estimate did not show a difference in the three-year period. This research highlighted alarming signs of soil degradation in the agricultural economics zone. Negative changes occurred in two of the three indicators which showed a tendency towards the degradation of soil capital in the long run. Counterbalancing measures to achieve equivalent losses and gains should be implemented as quickly as possible.