sustainability Article Irrigation, Technical Efficiency, and Farm Size: The Case of Brazil Gabriel A. Sampaio Morais 1, * , Felipe F. Silva 2 , Carlos Otávio de Freitas 3 and Marcelo José Braga 1   Citation: Morais, G.A.S.; Silva, F.F.; Freitas, C.O.d.; Braga, M.J. Irrigation, Technical Efficiency, and Farm Size: The Case of Brazil. Sustainability 2021, 13, 1132. https://doi.org/10.3390/ su13031132 Academic Editor: Boon Lee Received: 5 December 2020 Accepted: 12 January 2021 Published: 22 January 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Public Policy and Sustainable Development Institute (IPPDS), Universidade Federal de Viçosa (UFV), Viçosa, Minas Gerais 36570-900, Brazil; mjbraga@ufv.br 2 Agricultural Sciences Department, Clemson University, Clemson, SC 29634, USA; fdsilva@clemson.edu 3 Departamento de Ciências Administrativas, Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropédica, Rio de Janeiro 23890-000, Brazil; carlos.freitas87@gmail.br * Correspondence: gabriel_morais@yahoo.com.br; Tel.: +55-21-982217395 Abstract: In developing countries, irrigation can help to decrease poverty in rural areas through increased employment in the agricultural sector. Evidence shows that irrigation may increase farm productivity and technical efficiency. In this paper, we estimate the effect of irrigation on farm technical efficiency in Brazil using the 2006 Agricultural Census dataset on more than 4 million farms. We estimate a stochastic production frontier at farm level, considering potential selection bias in irrigation adoption. We find that farms using irrigation are on average 2.51% more technically efficient compared to rain-fed farms. Our findings also suggest that while small farms are more efficient than medium and large farms, the largest difference in technical efficiency between rain-fed and irrigated farms is among large farms. Our results indicate that policies that seek to support expansion of irrigation adoption has also the potential to achieve greater rural development given the estimated effects estimated in this paper among very small and small farms, which are more than 70% of the farms in Brazil. Keywords: irrigation; entropy balancing; stochastic production frontier; technical efficiency 1. Introduction The great variability of precipitation in Brazilian regions led farmers to adopt irrigation to mitigate the adverse effects of climate change [1]. The implementation of irrigation systems by farms in Brazil can potentially raise the standard of living of rural population by reducing poverty and increasing food security. The adoption of irrigation systems is an important technology that can lead to increases in agricultural productivity [2]. It also has potential to minimize the risks caused by climate change, which is associated with one of the main causes of agricultural production vulnerability [3]. Irrigation adoption can be used as a tool to reduce dependency on variable rainfall and water availability [4], decreasing the uncertainty surrounding crop yields and securing income and employment in the rural areas [5]. Several studies analyzed the irrigation adoption as an adaptive strategy under climate change scenarios in Brazil and find that adoption is also driven by climate change and used as a response to the precipitation reduction [1,6]. Although the use of irrigation is not uniform across Brazilian regions, it is expected to increase in the next 30 years given that irrigation is used as an adaptive strategy [7,8] and the agricultural sector is the sector most affected by climate change [9]. Irrigation systems are increasingly becoming more efficient in relation to water us- age [10,11]. The actual debate about water scarcity supports studies that are testing the ability of irrigation systems to alleviate water scarcity, which can also provide useful infor- mation to policymakers [12]. As argued by [13], the greatest interest lies on the arid and semi-arid regions, where non-uniform precipitation constrains the natural development of Sustainability 2021, 13, 1132. https://doi.org/10.3390/su13031132 https://www.mdpi.com/journal/sustainability