Adoption of interrelated sustainable agricultural practices in smallholder systems: Evidence from rural Tanzania

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Abstract

Soil fertility depletion is considered one of the main biophysical limiting factors for increasing per capita food production for smallholder farmers in Sub-Saharan Africa. The adoption and diffusion of sustainable agricultural practices (SAPs), as a way to tackle this challenge, has become an important issue in the development policy agenda in the region. This paper examines the adoption decisions for SAPs, using recent primary data of multiple plot-level observations collected in 4 districts and 60 villages of rural Tanzania. The paper employs a multivariate probit technique to model simultaneous interdependent adoption decisions by farm households. The analysis reveals that rainfall, insects and disease shocks, government effectiveness in provision of extension services, tenure status of plot, social capital, plot location and size, and household assets, all influence farmer investment in SAPs. Policies that target SAPs and are aimed at organizing farmers into associations, improving land tenure security, and enhancing skills of civil servants can increase uptake of SAPs in smallholder systems.

Introduction

The economies of most countries in sub-Saharan Africa, including Tanzania, heavily depend on agriculture that is dominated by smallholder farmers that are partially integrated into markets. The fate of the agricultural sector directly affects economic development, food security and poverty alleviation. However, the performance of agriculture in this region has not lived up to expectations, characterized by decades of stagnation and volatility in production and marketed volume. While the sector employs about 65% of labor force, it contributes only about 25–30% of the total gross domestic product [1].

Several biophysical and socioeconomic factors have been identified as key constraints limiting productivity growth in agriculture in sub-Saharan Africa [2], [3], [4]. Soil fertility depletion is considered as the main biophysical limiting factor for increasing per capita food production for most smallholder farmers in the region. The average annual nutrient balance for the region for the period 1983–2000 was estimated to be minus 22–26 kg of nitrogen (N), 6–7 kg of phosphorus (P), and 18–23 kg of potassium (K) per hectare [5]. On the other hand, the average intensity of fertilizer use in sub-Saharan Africa is only 8 kg/ha of cultivated land, much lower than in other developing countries [6]. In our study of over 1500 plots merely 4% of the plots received chemical fertilizers, despite the fact that 52% of the plots were planted with improved maize varieties.

When no external inputs are used, plots require long fallow periods to replenish nutrients taken up by crops and washed away by erosion. However, as the population increases and the availability of new land to exploit decreases, allowing plots to lie fallow has become more and more difficult, and continuous cropping has become commonplace in Africa. This has resulted in a vicious cycle of poor agricultural productivity, low investment capacity, continued soil degradation, and further pressure on available lands to generate necessary food supplies [2], [4].

The adoption and diffusion of specific sustainable agricultural practices (SAPs) have become an important issue in the development policy agenda for sub-Saharan Africa [7], [3], especially as a way to tackle these impediments. The Food and Agricultural Organization (FAO) argues that sustainable agriculture consists of five major attributes: (1) conserves resources, (2) environmentally non-degrading, (3) technically appropriate, (4) economically, and (5) socially acceptable [8]. Accordingly these practices broadly defined may include conservation tillage, legume intercropping, legume crop rotations, improved crop varieties, use of animal manure, complementary use of organic fertilizers, and soil and stone bunds for soil and water conservation [9], [10], [11], [12].

The potential benefits of SAPs lie not only in conserving but also in enhancing the natural resources (increasing soil fertility and soil organic matter) without sacrificing yield levels. This makes it possible for fields to act as a sink for carbon dioxide, to increase the capacity of the soil to hold water, and reduce soil erosion [13]. Furthermore, by retaining fertile and functioning soils, SAPs can also have positive impacts on food security and biodiversity [12]. Diversification via intercropping and crop rotation enable farmers to grow products that can be harvested at different times and that have different climate or environmental stress-response characteristics. These varied outputs and degrees of resilience are a hedge against the risk of drought, extreme or unseasonal temperature, and rainfall variations that affect productivity of stallholder systems.

Notwithstanding their benefits, the adoption rate of SAPs is still low in rural areas of developing countries [12], [14], [15], [16], [17], despite a number of national and international initiatives to encourage farmers to invest in them. This is true for Tanzania, where, despite accelerated erosion and considerable efforts to promote various soil and water conservation technologies, the adoption of many recommended measures is minimal and soil degradation continues to be a major constraint to productivity growth and sustainable intensification [18], [15]. Moreover, relatively little empirical work has been done to examine the factors that impede or facilitate the adoption and diffusion of SAPs, especially conservation tillage, legume intercropping, and legume crop rotations [19].

The objective of this paper is to fill this gap. We use a rich primary data set, generated by Selian Agricultural Research Institute (SARI) of Tanzania in collaboration with the International Maize and Wheat Improvement Center (CIMMYT), to identify the key factors influencing simultaneous adoption of several agricultural technologies and practices, and their impact on household welfare in the maize-legume cropping system zones. We use multiple plot observations to jointly analyze the factors that facilitate or impede the probability of adopting multiple SAPs in smallholder system in Tanzania. We particularly investigate interdependent adoption of legume intercropping (LI), legume crop rotations (LCR), animal manure, conservation tillage (CT- that entails zero/minimum tillage), soil and water conservation practices (SWC), chemical fertilizer (CF), and introduction of improved seeds (improved crop varieties). Understanding the determinants of household choices of SAPs can provide insights into identifying target variables and areas that enhance the use of these practices.

The contributions of the paper are threefold: First, although there is a well-developed literature on the impact of a host of explanatory variables on technology adoption, the analysis provides new evidence on policy relevant variables such as on the impact of governance indicators (e.g., government effectiveness in the provision of extension services and political connections), kinship, rainfall shocks, and farmers’ expectations on social safety nets (social insurance) during crop failure (more on these variables in Section 3.1). Second, we provide a more comprehensive and rigorous analysis of the interdependent adoption of SAPs in Tanzania. Past studies [18], [20], [15] assessed the specific technology adoption decision (fertilizer or soil and water conservation structures), which fails to account for complementarities and/or substitutabilities among different practices. Earlier studies also did not take into account important variables, such as plot characteristics, shocks, governance indicators and institutional factors.

Section snippets

Conceptual framework and econometric estimation strategy

Farmers are more likely to adopt a mix of technologies to deal with a multitude of agricultural production constraints than adopting a single technology. A shortcoming of most of the previous studies on adoption of SAPs is that they do not consider the possible inter-relationships between the various practices [21]. These studies mask the reality faced by decision-makers who are often faced with technology alternatives that may be adopted simultaneously and/or sequentially as complements,

Data and description of variables

We use detailed primary household and plot survey data from 681 farm households and 1,539 plots (defined on the basis of land use), in 60 villages in 4 districts of Tanzania. The survey was conducted in November and December 2010 on a one-to-one interview basis using a structured survey questionnaire administered by well trained and experienced enumerators who have knowledge of the farming system and the local language. The enumerators were trained by CIMMYT scientists in collaboration with

Results and discussion

In this section, we discuss results obtained from the multivariate probit models. For comparison purposes, random effects probit models were also estimated although results not reported to conserve space.6

Conclusions and implications

In sub-Saharan Africa, where farming is characterized by poor soil fertility condition and low levels of agricultural technology use, understanding the probability of adoption of productivity and sustainability enhancing practices is a policy issue. This paper uses detailed multiple plot observations to investigate the factors that influence farmers’ decisions to adopt sustainable agricultural practices using multivariate probit regression model. The likelihood ratio test of the independence of

Acknowledgment

The household survey for this research were supported by the Australian Center for International Agricultural Research (ACIAR) under the CIMMYT led SIMLESA project for Sustainable Intensification of Maize-Legume Cropping Systems in Eastern and Southern Africa.

Menale Kassie (Development Economist) is a scientist working at the International Maize and Wheat Improvement Center (CIMMYT). He is currently coordinating the socioeconomic components of two large scale projects: Sustainable intensification of maize-legume cropping systems for food security in eastern and southern Africa (SIMLESA) and Sustainable Intensification of Maize-Legume Systems for the Eastern Province of Zambia (SIMLEZA). Menale's research focuses on adoption and impact of crop and

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  • Cited by (0)

    Menale Kassie (Development Economist) is a scientist working at the International Maize and Wheat Improvement Center (CIMMYT). He is currently coordinating the socioeconomic components of two large scale projects: Sustainable intensification of maize-legume cropping systems for food security in eastern and southern Africa (SIMLESA) and Sustainable Intensification of Maize-Legume Systems for the Eastern Province of Zambia (SIMLEZA). Menale's research focuses on adoption and impact of crop and natural resource management technologies on rural household welfare using advanced cross-section-panel econometrics and mathematical programming models. He has analyzed the contribution of sustainable land management technologies on agricultural productivity and production risks and crop technologies such as groundnuts and pigeonpeas on poverty and food security.

    Moti Jaleta is an Associate Scientist-Agricultural Economist working at the International Maize and Wheat Improvement Center (CIMMYT). He obtained his PhD in Agricultural Economics and Rural Policy from Wageningen University (The Netherlands) in 2007. Before joining CIMMYT in February 2011, Moti worked as a Postdoctoral Scientist-Market Economist at the International Livestock Research Institute (ILRI) for 3 years, as a Senior Research Officer at the Ethiopia Strategy Support Program (ESSP) and as an Assistant Professor in agricultural economics at Hawassa University (Ethiopia).

    Bekele Shiferaw (Development and Resource Economist) is a Director of the socioeconomics program of CIMMYT. His research interests span analysis of development strategies and poverty dynamics, bio-economic modeling of farm household resource use decisions, the role of institutions and policies for sustainable intensification of production, adoption and impact of agricultural innovations, analysis of market relations and value chains, policy and institutional innovations for remedying market failures and adaptation to and mitigation of climate change in agriculture. He has previously worked for over 8 years as the regional program leader and principal economist in Africa and South Asia with the International Crops Research Institute for the Semi Arid Tropics (ICRISAT). He has published over 40 scientific papers in peer-reviewed international journals and books widely cited in the literature.

    Mulugetta Mekuria is a Senior Scientist (Agricultural Economics) with the Socioeconomics Program, based in CIMMYT Southern Africa Regional Office based in Harare, Zimbabwe. Since joining CIMMYT in 1997 he has spearheaded capacity building activities and organized and led regional training workshops on tools and methods in socio economics research for NARS in Southern Africa. Dr. Mulugetta Mekuria has been actively involved in resource mobilization for a number of special projects supported by the Rockefeller Foundation, IDRC and IFAD for enhancing the development and adoption of Conservation agriculture and Integrated Soil Fertility Management Practice in Southern Africa. Since 2010, he is the Projects Leader of the Australian Government supported through the ACIAR Food security initiative on the Sustainable Intensification of Maize-Legume cropping System for food security in Eastern and Southern Africa(SIMLESA).

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