Elsevier

Agricultural Systems

Volume 103, Issue 1, January 2010, Pages 51-62
Agricultural Systems

Constraints to farmers’ adoption of direct-seeding mulch-based cropping systems: A farm scale modeling approach applied to the mountainous slopes of Vietnam

https://doi.org/10.1016/j.agsy.2009.09.001Get rights and content

Abstract

Substantial initiatives are under way in the tropical world to develop and promote direct-seeding mulch-based cropping systems (DMC) in order to reduce soil erosion and improve crop nutrient and water balances. DMC have been adopted by large-scale mechanized farmers, especially in America and Australia, but seldom by resource-poor farmers in the developing world. This study was conducted in Vietnam with the aim of evaluating the feasibility of farmers’ implementing DMC in a mountainous area. The method involved simulation of rational households maximizing their income subject to food security constraints and availability of resources. It generated insight into why farmers of a small region were reluctant to adopt DMC due to the extra labor and input required to implement these techniques during the first years, which hampers their economic performance. In another region, under different biophysical and economic environmental conditions, the study showed that DMC were more likely to be adopted provided that possible constraints at the community level are overcome. The method also allowed us to discuss the types of technical improvements that would make DMC more attractive to farmers. For most farm types, labor required by mulch establishment would have to be reduced by more than 30%. This would mean spreading much less biomass than the 7 t ha−1 currently necessary, compromising the weed-control function of mulch. This would be technically feasible only by using herbicides but this would not be economically sound since it would increase cash requirements. The study showed that subsidies of 50 to more than 200 USD ha−1 were necessary to enable the conversion of all conventionally managed sloping land into DMC in the simulations. These amounts are high relatively to gross margins (250–750 USD ha−1) under conventional management.

Introduction

Significant initiatives are under way in the tropical world to develop and promote conservation agriculture, particularly direct-seeding mulch-based cropping systems (DMC). DMC aim at maintaining the soil covered and protected by organic mulch (dead or living) at least during the crop establishment period. Many studies have highlighted the potential of this technology for achieving relatively high yields while effectively protecting the soil against erosion and improving water and nutrients balances (LAL, 1988, Steiner et al., 1998, Derpsch, 2001, Fowler and Rockstrom, 2001, Hobbs, 2006, Hobbs et al., 2008). The actual agronomic performances of DMC vary greatly across studies, however. The yield effect of DMC tends to be neutral in the short term and neutral to positive in the longer term, as physical, chemical and biological soil functions are gradually improved. Indeed these beneficial effects may accumulate over time and eventually overcome constraints found in many studies such as increases in weed and pest incidence, reduction of the germination and/or emergence rate, competition between the main crop and the cover crop when present, N-immobilization by microorganisms, etc (Erenstein, 2003). DMC have been adopted by large-scale mechanized farmers, especially in America, Australia, and central Brazil, but seldom by resource-poor farmers in the developing world (Carsky et al., 2003, Erenstein, 2003, Bolliger et al., 2006, Lal, 2007). The review from Erenstein (2003) suggested that many socio-economic factors underlie the rejection of DMC by smallholders in the tropics. Cultural reluctance might be involved, since DMC imply breaking with a sometimes long-standing tradition of soil tillage and cleaning. It is also a complex technique which involves a learning period with a risk of low yields that may not be affordable by smallholders. Even when technically mastered, DMC may not always show an immediate comparative advantage. Besides, the positive impact on the environment is not always immediately visible. Furthermore, smallholders in developing countries often give priority to their short term objectives, such as meeting household food security requirements (Lipton, 1997b, Dao Kim Nguyen Thuy et al., 2008). More generally, it has been shown that it is not always possible for smallholders to invest in natural resource conservation if it does not provide an immediate advantage, even when the populations are aware of the long term advantages such as the capacity of the agrarian system to support an increasing population (Lipton, 1997a, Barbier, 1998, Shiferaw and Holden, 1998).

DMC modify the use of resources that are often managed at community level, like crop residues. They introduce the need for specific inputs such as seeds of cover crops or herbicides. And they generate specific outputs such as fodder or other by-products of cover crops that may also be marketed. Therefore institutional factors such as the characteristics of markets and communities may play a role in adoption. Moreover, farm economy must always be considered since DMC typically introduce major transformations in the allocation of farm resources such as soils, labor, cash and capital.

The present paper focuses on identifying farm-level constraints to adoption of DMC by smallholders. It assumes that a necessary (but not sufficient) condition for adoption is that DMC are economically sound at farm level from a short term perspective. The main hypothesis is that the short term economic benefit varies greatly across farms according to farm resources and access to market and it is an important component to address among the numerous determinants of adoption or rejection of the technology. The paper builds on the case study of two communities in the northern Vietnamese uplands and suggests a methodology for analyzing the potential behavior of contrasted farming systems when information about this new technology reaches them.

In this region annual crops are grown on steep slopes, thus seriously boosting the risk of soil erosion. From 1998 to 2004 a team of researchers developed and promoted among farmers a number of DMC suited to the main types of environment found in Bac Kan (Husson et al., 2001), a province chosen for a pilot program aimed at developing eco-regional approaches to ensure sustainable development in the mountain region of Vietnam (Castella et al., 2002). More recently, NGOs and governmental development projects also began promoting DMC in other mountainous provinces, encouraged by the potential of the technology to reverse the alarming effects of the growing pressure of agriculture on the slopes. To date, however, no large-scale dissemination of DMC has been reported in the area. Moreover, economic analyses of these techniques for smallholders in northern Vietnam are lacking, despite the fact that such analyses could help explain farmers’ attitude regarding DMC.

In a few recent studies, a farm model was used for ex-ante evaluation of alternative cropping systems at the farm level (Yiridoe et al., 2006, Alary et al., 2007, Janssen and van Ittersum, 2007), but this approach has not yet been applied to assess DMC.

The main objective of this study was to conduct an ex-ante analysis of DMC, using a farm modeling approach, in order to identify: (a) which type of farmers (if any) were more likely to be interested in these new cropping systems, considering their current environment and the information brought to them by promoters of the technique, (b) which technological adjustments, and (c) which changes in the farm economic environment, through policy changes, would foster adoption by farmers.

Section snippets

Research methods

The method presented here involved the use of a farm model simulating strategic decisions of farmers. The model was built using data from agronomic on-farm trials and surveys. The study was conducted at two sites with contrasting biophysical and economic environments.

Agronomic and economic performances of DMC

In the Na Son trial, mulch increased grain yields by 45% for maize and 18% to 31% according to years for rainfed rice, as compared to the conventional system. But in the Ngoc Phai trial, the two DMC options tested did not increase yield markedly (Fig. 1A).

The economic return to land, calculated as (value of production – variable costs) per unit area, was increased by DMC at Na Son but was not markedly modified at Ngoc Phai (Fig. 1B).

At Ngoc Phai, they reduced labor productivity by about 30% (

Discussion

A review dealing with DMC adoption by resource-poor farms (Erenstein, 2003) noted that cash and/or labour constraints would likely affect several agrarian systems, without proposing methods for identifying whether these constraints would arise or not. Due to a lack of universal variables to explain the adoption or rejection of conservation agriculture in past analyses, Knowler and Bradshaw (2007) suggested that further “efforts to promote conservation agriculture will have to be tailored to

Conclusion

The method used in this study, combining agronomic tests and farm modeling for the analysis of farm level attractiveness of an innovation, enabled us to gain further insight into the reluctance of resource-poor farmers of the studied region to adopt DMC. It showed that DMC is not yet a ready-to-use solution for farmers in the mountainous regions of Vietnam or similar areas in Southeast Asia. In fact, the attractiveness of DMC varied greatly between identified farm types since the simulated

Acknowledgements

This work was conducted within the framework of the SAM (French acronym for Systèmes Agraires de Montagne, or mountain agrarian systems) project, a joint project of VAAS (Vietnam Academy of Agricultural Science), IRRI (International Rice Research Institute) and CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement).

The authors wish to thank the farmers of the areas studied for their time and willingness to take part in our research and for their warm welcome

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