This technical extension guide introduces the concept of land slope and explains the importance of slope measurement in upland agricultural production systems. The document discusses how slope affects soil erosion, runoff, soil fertility, irrigation, mechanization, and crop suitability. It emphasizes that lands with slopes greater than 5% require careful management to reduce soil degradation and maintain sustainable productivity. The publication presents two practical methods for measuring slope: using a water tube (Tio tube) and using a smartphone with an inclinometer application. Step-by-step instructions and illustrations are provided to support farmers, extension workers, and local practitioners. In addition to technical measurement methods, the guide links slope assessment with agroforestry system design, fertilizer management, weed control, soil conservation, and sustainable land-use planning for mountainous regions of Vietnam and Southeast Asia.
