Even though soil degradation challenges sustainable development, the use of degradation indicators such as nutrient export (NE) and nutrient replacement cost is not well documented at landform level. This study is aimed to investigate the extent of soil degradation, NE rates, and their replacement cost across landforms in the Mai-Negus catchment, northern Ethiopia. Different erosion-status sites (aggrading, stable, and eroded) in the landforms were identified, and soil samples were randomly collected and analysed. Nutrient export, replacement cost, and soil degradation were calculated following standard procedures. This study showed that soil degradation in the eroded sites ranged from 30 to 80% compared to the corresponding stable site soils, but the highest was recorded in the mountainous and central ridge landforms. Average NE of 95, 68, 9.1, 3.2, 2.5, and 0.07 kg ha？1 y？1 for soil calcium, carbon, nitrogen, potassium, magnesium, and phosphorus, respectively, was found from the landforms. Significantly strong relationships between NE and sediment yield in the landforms were observed. Annual nutrient replacement costs varied among the landforms though the highest was in the reservoir (€9204 in May 2010). This study thus suggests that while introducing antierosion measures, priority should be given to erosion sources to the reservoir such as mountainous and central ridge landforms. 1. Introduction Soil erosion is a challenge for sustainable agricultural development in many developing countries [1, 2]. The problem is more serious in the Ethiopian highlands such as the Tigray region [3–5]. Inappropriate agricultural practices, high population pressure from human and livestock, higher rainfall intensity, and rugged topography have been reported as the main facilitators for having severe erosion [6, 7]. In the Tigray region, average soil loss by erosion on cultivated land is more than 49？t ha？1？y？1 [8], which exceeds the average soil loss of 42？t？ha？1？y？1 for Ethiopia as a whole [3]. Such soil loss through water erosion is almost always accompanied by losses of essential soil nutrients. Erosion is selective for fine soil particles, which are relatively richer in soil nutrients [9, 10]. In line with this, Stoorvogel and Smaling [11] and UNDP [12] reports showed that compared to rates in sub-Saharan Africa, Ethiopia has the highest soil nutrient outflow rates of 60？kg？ha？1 (30？kg？ha？1 nitrogen and 15–20？kg？ha？1 phosphorous), while inflows from fertilizers are very low (<10？kg？ha？1). In the long term, such soil nutrient losses by erosion adversely affect soil
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