Many national research systems have launched major on-farm research efforts aimed at generating relevant technologies for resource-poor farmers, but institutional and policy factors have often hindered the effectiveness of these efforts. Experience has shown that on-farm research, linking farmers, researchers, and technology transfer agents, poses special organizational and managerial challenges. Institutional innovations and strong policy commitment are needed if on-farm research is to succeed in meeting the needs of resource-poor farmers. Sound research methods alone are not sufficient.

This paper reviews key policy, organizational and managerial considerations for integrating on-farm client-oriented research as an effective and stable component of national agricultural research systems. It summarizes the findings of a major study sponsored by the International Service for National Agricultural Research on institutional factors affecting the performance and sustainability of such research systems. The conclusions are based on the systematic analysis of over 25 discrete on-farm research efforts in nine developing countries. The objective is to provide research managers, on-farm researchers and on-farm research advisors with concrete and practical insights for strengthening on-farm research and its contribution to the generation and transfer of relevant technologies.

Integración de la investigación de granja con los sistemas nacionales

A farm survey conducted in Ethiopia in 1986 identified seasonal food shortage as an important problem facing farmers. The researchers proposed the development of an early maturing maize variety to alleviate the problem and by 1988, on-farm trials of a selected variety were initiated. About two-thirds of the farmers retained part of the harvested crop as seed for planting, indicating their strong interest in the variety. Farmer-designed trials were found to be especially effective for obtaining farmers' assessment of the new variety and for monitoring how they incorporated it into the farming system.

Maíl con maduración temprana para Etiopía

Trials were conducted in 1987 and 1988 to test methods of intercropping annual Ethiopian clovers, Trifolium spp, with wheat. Several different clover varieties, sowing methods, plant spacings, planting dates and rates of phosphorus application were compared. Planting in single or double alternative rows 20 cm apart did not affect wheat grain and straw yield but broadcast sowing of Trifolium in wheat rows 20 cm apart reduced wheat yield. The Trifolium species used significantly affected legume yield. Phosphorus fertilizer increased yield significantly, especially that of the legume component. The trials indicated that the intercropping of Ethiopian clovers in wheat has potential under African highland conditions.

Siembra simultanea de trigo/ Trifolium en Etiopía

Field experiments were carried out under irrigation in Central Saudi Arabia during the winters of 1987–88 and 1988–89 to examine the productivity and quality (grain protein content) of wheat intercropped with inoculated and uninoculated alfalfa with or without additional nitrogen. Nitrogen increased wheat grain yield and protein percentage but inoculation of the alfalfa had no additional effect. Herbage yield of intercropped alfa4fa was unaffected by nitrogen application. Added nitrogen reduced the protein percentage in alfalfa but increased its protein yield. Intercropping had benefits for alfalfa, increasing its protein content and yield.

Siembra simultánea de trigoy alfalfa

Two tropical and one temperate genotypes of maize were grown during the cool dry winter seasons in northern Nigeria. The tall tropical genotypes produced a greater leaf area index and more above-ground dry matter, and so had a higher crop growth rate, than the dwarf temperate genotype. However, the early flowering temperate genotype yielded more grain than the late flowering tropical genotypes. Although the initial low winter temperatures prolonged the preflowering growth period in the tropical genotypes, the terminal high temperatures hastened maturity and were associated with poor grain filling.

Maíz de temporada seca en Nigeria

Insect infestation and damage in cowpea (Vigna unguiculala), planted sole or intercropped with tomato (Lycopersicon esculentum) was monitored in 1987 and 1988 in Akure, Nigeria. Infestation of cowpea by Empoasca dolichi was significantly reduced by intercropping with tomato in both years, except in the early season of 1988. Infestation of cowpea by Ootheca mutabilis, Aphis craccivora, Megalurothrips sjosledti and Maruca testulalis was not affected by intercropping with tomato in either year. Damage by pod-sucking bugs and Heliothis armigera was significantly higher in sole cowpea than in cowpea intercropped with tomato, in both years. Sole cowpea had a significantly lower seed yield than cowpea intercropped with tomato.

Observaciones en cuanto a la infestación de insectos y daños en el caupí (Vigna unguiculata) sembrado en forma simultánea con tomate (Lycopersicon esculentum) en una zona de bosque tropical en Nigeria

The principles that control effectiveness of rock phosphates as fertilizer are now fairly well understood so that the potential effect of a material can be predicted with some confidence from laboratory analysis of the raw material. Soil characteristics, especially acidity, and calcium and phosphate status, are important: if these are not conducive to dissolution, crop response to rock phosphate is small. Some crop characteristics, especially the extent of root systems and whether they are infected with mycorrhizae, also affect utilization of rock phosphate. Dissolution of rock phosphates may be too slow for rapidly growing crops but may be adequate for perennial crops.

Such factors limit the use of rock phosphates for direct application, so that much greater knowledge of the characteristics of the phosphates, soils and crops, and their interactions, is necessary for their successful use than for the soluble phosphates. Economic considerations are important also. Because the phosphate content is less than that of concentrated soluble fertilizers, the cost of transporting rock phosphates, per unit of phosphorus, may not be economic. However, for acid and calcium deficient soils the larger amounts of calcium that rock phosphates supply may be an advantage and may lessen or eliminate the need for lime, especially for crops that require relatively large amounts of calcium.

Fosfatos de roca en la agricultura

Ground-based radiometric measurements in the red and infrared bands were used to monitor the growth and development of wheat under irrigated and stressed conditions throughout the 1987–88 and 1988–89 growth cycles. Spectral data were correlated with plant height, leaf area index, total fresh and total dry biomass, plant water content and grain yield. The radiance ratio (R) and normalized difference vegetation index (NDVI) were highly and linearly correlated with yield, establishing the potential which remote sensing has for predicting grain yield. The correlation for R and NDVI was at a maximum between 75 and 104 days after sowing, corresponding with maximum green crop canopy cover. The differences in spectral response over time between irrigated and unirrigated crops allowed detection of water stress effects on the crop, indicating that a hand-held radiometer can be used to collect spectral data which can supply information on wheat growth and development.

Efectos de lafalta de agua en el trigo

The functional distribution of root activity was determined by selective placement of 32P at fixed positions from the base of the plant in five- and six-year-old acid lime (Kagzi Kalan) on Kama Khatta rootstock. Maximum recovery of radioactivity was observed within a 40 cm radius of the plant base and at depths of 24 cm in 1988 and 16 cm in 1989. Most root activity (75–80%) was confined within a radius of 80 cm and a depth of 16–24 cm. Application of fertilizer within this zone is therefore recommended for maximum utilization by the crop.

Actividad de las raíces en la lima acida

Physiomorphological differences between crops in binary mixtures can influence grain yield. A two year field study considered intra-row mixtures of two sorghum varieties, one short (KSV4) and one tall (Yarwasha), with cowpea at Maiduguri in Nigeria. The performance of the component crops depended largely on the relative proportion of cowpea and sorghum in the mixtures. Comparison of actual and expected land equivalent ratios suggested that mutual compensation and cooperation prevailed within mixtures in most instances. The system productivity index of mixtures where the proportion of sorghum: cowpea was 1:3 showed that their yield stability was greater than that of other sorghum-cowpea mixtures.

Combination de sorgol caupi en la Sabana del Sudan