Pros and cons of furrow irrigation on smallholdings in northeast Brazil

摘要

Smallholder farming is the basis of agricultural production in developing regions. Irrigation improves the household livelihood and welfare of smallholders. Furrow irrigation is the most common type of irrigation on the small farms of public irrigation schemes set up in the Northeast of Brazil during the 1970s and 1980s. However, furrow irrigation triggers environmental problems related to deep percolation, runoff and soil erosion. The objective of this research was to determine how soil was lost from irrigation furrows as a result of their management and performance. Experiments were carried out in the Curu-Pentecoste irrigation scheme located in the state of Ceara, Brazil. Three inflow rates (corresponding to the three sizes of syphons used to apply water to the furrows) were compared on 60-m long furrows in the two predominant soil classes (sandy loam and silty day loam) during 4 or 5 irrigation events throughout the irrigation season. Runoff represented between 20 and 70% of the water applied, carrying sediments amounting up to 2.8 Mg ha(-1) in 4 irrigation events. Simple irrigation practices that could improve furrow irrigation performance in the scheme are suggested. However, the environmental problems of the furrow irrigation in practice seem inherent to the irrigation method used under those conditions. The paper discusses the adoption and performance of traditional and modern irrigation technology in smallholdings in developing regions.