Despite widespread efforts by governmental and nongovernmental organizations and local development projects to encourage shifts towards LEIA systems, adoption often remains limited to farmers who receive direct technical or financial support. With out such assistance LEIA practices are often readily abandoned, indicating that the underlying economic feasibility of LEIA systems is not always apparent to farmers. To improve retention rates, at least three issues must be addressed. First, instead of seeing LEIA as a universally applicable solution, its promoters should recognize that LEIA appeals primarily to small and medium- size farm households in remote regions with little access to labor markets. Second, chemical and nonchemical inputs are not mutually exclusive: labor productivity can be increased substantially when internal farm household inputs are combined with selectively applied external inputs. Third, the adoption and maintenance of these mixed internal/external input systems depend critically on supportive agrarian policies that enable farmers to invest their resources in better-integrated farming systems.

In the Kenyan highlands, farmers have been encouraged to construct waste deposits and produce green manure to intensify vegetable production. Because decomposition is time-consuming, applications of chemical fertilizers that decrease gradually to a minimum level produce the best results. In practice, farmers hesitate to refrain completely from using purchased inputs. This reluctance is understandable because external inputs permit a better timing of land preparation, sowing, and other crop maintenance activities; reduce the demands for labor in critical periods; and produce more attractive farm products for the market place.

Complementarities are also found in the IPM program for plantain in Zanzibar, Tanzania. Improved nutrient applications are considered a major device for controlling pests and diseases in this program. Farmers who use small amounts of chemical fertilizers suffer far less crop loss from competition for light and nutrients or infestation. When no fertilizers are applied, diseases easily penetrate into the fields. (At the other extreme, farmers who use high doses of fertilizers risk a yield-threatening increase in the incidence of weeds.)

West African farmers could improve their cereal and cotton yields by 20 to 40 percent using locally available phosphate rock as a substitute for imported fertilizers. Transport costs are, however, typically too high to make this an affordable investment to small farmers. Limited access to credit may be another impediment. Depressed crop prices also make farmers hesitate about the use of soil phosphate amendments. Because phosphate improves nitrogen efficiency, only farmers with access to fertilizers are likely to benefit from its availability. Policies that enhance phosphate and fertilizer availability and access to credit would help sustain LEIA adoption and produce significant yield returns.

In Southern India and East Java, farmers increasingly rely on cattle dung or agroforestry as partial substitutes for chemical fertilizers. Although cereal yields are some what lower, the reduced input costs make returns to labor acceptable to farmers. Small farmers on rented land, however, face major problems in adopting LEIA technology. The use of alternative sources for nutrients requires that some arable land be “sacrificed” for pasture or forestry purposes, but tenants have no certainty that they will have access to this land in subsequent years. Changes in land tenure regimes to promote more secure long- term access to land would yield positive outcomes for both technology adoption and food security.

Performance of high and low external input and traditional maize production systems in southern Nicaragua, per annual harvest
	High input	Low input	Traditional
Maize yields (kilo grams/hectare)	885	834	513
Labor use (days/hectare)	31.7	40.6	24.1
Gross returns (US$/hectare)	167	157	97
Material in put costs (US$/hectare)	64	36	13
Net returns per unit of
land (US$/hectare)	103	121	84
labor (US$/day)	3.2	3.0	3.5
capital (US$/US$)	1.6	3.4	6.2
Source: M.F.H. Bourgondien, “Low and High Input Agriculture in the Agrarian Frontier,” in R. Ruben and J. Bastiaensen, eds., Rural Development in Central America: Markets, Livelihoods and Local Governance (New York: Macmillan, 1999).

A central constraint facing the adopters of low external input systems is economic feasibility. Returns from LEIA practices must be sufficiently attractive compared to conventional production practices and income derived from off- farm employment. Even when cost- benefit appraisals of LEIA give positive results, farmers must carefully consider the opportunity costs of farm resources. The high labor requirements of many LEIA technologies may reduce returns to labor, and family labor constraints may hinder adoption. Additional reliance on some purchased inputs may be a preferred means for maintaining farmer incomes and improving food security prospects.

Finally, adjustment of agricultural resource management regimes and farmer adoption of production practices cannot be left wholly to local initiatives. Besides training, education, and extension, policy changes and institutional support can help reinforce farmers’ interest in LEIA. Well-targeted agricultural research can help reduce dependence on external inputs through work on problems such as pest resistance, drought tolerance, soil salinity, and nitrogen fixation. Stable and remunerative market prices for agricultural products are required to attract family labor to the ongoing use of yield-increasing inputs in the context of LEIA. Rural financial systems should facilitate farmers’ borrowing for input purchase and insurance purposes. Farmers will require secure land tenure to enhance their willingness to invest. Concerted action in these areas is imperative to ensure that small farmers will continue to benefit from low external input technologies.

Ruerd Ruben is an associate professor in the Department of Economics and Management, Wageningen Un versity and Research Centre, The Netherlands (email: Ruerd.Ruben@alg.oe.wau.nl), and David R. Lee is professor of agricultural and r esource economics at Cornell University, USA (email: DRL5@cornell.edu).

For more information, see Ruerd Ruben and Nico Heerink, “Economic Evaluation of Low External Input Farming,” in the Institute for Low External Input Agriculture Newsletter, vol. 11, no. 2, 1995; and Sean Neill and David R. Lee, “Explaining the Adoption and Disadoption of Sustainable Agriculture: The Case of Cover Crops in Northern Honduras,” Economic Development and Cultural Change (forthcoming, 2000).