Monitoring Sustainable Land Use: From Land Management Practices to Sustainable Land Use Indicators.

Land degradation has often been referred to as one of the main causes of poor crop productivity in sub-Saharan Africa. Sustainable intensification in smallholder farming system is currently recognized as a prerequisite for addressing hunger and poverty in the region, and overcoming further land degradation. Approaches for continuous monitoring of land used in agricultural production to ensure a path towards sustainability are needed. We define five indicators that need to be monitored to assess whether land is used, or is on the path of being used, sustainably: soil nutrient balances, crop productivity, soil acidification, soil erosion, and soil carbon. However, the direct measurements of metrics associated with the indicators involve massive field measurements, sampling and/or laboratory analyses, which are impossible to conduct to cover a wide range of farms. The objective of this study is therefore to design and develop methods for monitoring land use without massive field measurements. Based on the knowledge that the proposed indicators are mainly influenced by management practices implemented on the land, we first focus our assessment on the practices that influence the indicators, referred to as sustainable land use (SLU) practices. We then developed proxy and algorithms to estimate each indicator metric based on the SLU practices implemented on the land. We have been able to estimate each of the five indicators, and attempt to aggregate them to define the status of a given land towards sustainability. There are limitations to the approaches that are discussed.