Scores of assessments of the impacts of agricultural research have been carried out over the years. However, few appear to have been used to improve decision making and the effectiveness of research programmes. The Institutional Learning and Change (ILAC) Initiative emerged within the Consultative Group on International Agricultural Research (CGIAR), with the goal of strengthening learning from experience and using lessons to improve pro-poor innovation. It is testing approaches for expanding the contributions of impact assessment and evaluation to learning, decision making and improvement.

In Kenya, coffee growing east of the Great Rift Valley has its main flowering either in February–March or in October–November. These flowerings are mainly initiated from approximately August to December and June to September, respectively. Changes from an early to a late flowering rhythm and vice versa can be caused by (a) pruning, (b) the condition of the tree, and (c) the weather pattern, but more information is needed for a complete understanding of this problem.

Applying stochastic frontier Cobb–Douglas production function, the study assessed the efficiency of sweet potato (Ipomoea batatas) producers in the Southern region of Ethiopia. The study revealed the existence of fairly large technical inefficiency in sweet potato production. The technical efficiency ranged from 12.6 to 93.7%, with more than half of the producers above the mean efficiency level (66.1%). This suggests that there is room for output gains through technical efficiency improvement. If the average producers in the study region are to achieve the technical efficiency level of the most efficient producer in the sample (93.7%), they can realize nearly 30% output gains. The analysis of allocative efficiency also revealed that sweet potato producers were producing sweet potato with sub-optimal utilization of production inputs, suggesting that potential for output gains remains to be exploited through reconfiguration of the existing resource use. They can make more value out of their sweet potato production by reconfiguring their current utilization of production inputs in favour of more land and manure but less seed rate. Furthermore, age and education are important determinants of the efficiency of sweet potato production. In view of these findings, it is advisable to put in place appropriate extension intervention programmes that enable sweet potato producers to exploit the potential gains in sweet potato output through technical and allocative efficiency improvement.

The poor quality of the natural vegetation in the dry season affects both animal productivity and the lives of the pastoral community in the Adamawa Plateau of Cameroon but may be improved by introduction of the forage legume Stylosanthes guianensis. When used in a ‘fodder bank’ system, Stylosanthes grew to an average plant height of 1.41 m, had a dry matter productivity of 5.5 t ha−1 and comprised 93.4% of the pasture's botanical composition at the end of the growing season, indicating that fodder banks have considerable potential to enhance animal and crop production in Cameroon. Complementary studies conducted in Nigeria on the yield benefits of cropping leguminous pastures support the feasibility of using fodder banks as a means of improving the livelihoods of small scale farmers.

The effects of intercropping young plants of the compact arabica coffee hybrid cultivar Ruiru 11 with potatoes, tomatoes, maize and Phaseolus (dry) beans were studied between 1987 and 1989 at Ruiru in Kenya. Yields of clean (hulled) coffee were reduced by the maize intercrop by 59–100%. Coffee bean size, and raw, roast and liquor quality were not significantly affected by the potato, tomato and bean intercrops, which gave positive net economic benefits. Potatoes planted between all the coffee rows gave the largest marginal rate of economic return, followed by tomatoes in combination with beans. The technically and economically viable intercrops for coffee were potatoes, tomatoes, beans, and tomatoes in combination with beans.

Siembra simultánea de café Araébica y cultivos para la alimentatión

The principal contribution that the farming systems perspective brings to agricultural research is a farmer and problem-solving orientation. Development of this orientation helps strengthen linkages in national research systems between commodity programmes and between disciplines for both applied and adaptive research. It can also strengthen linkages between research and extension and between research and policy analysis. Issues in strengthening each of these linkages are briefly reviewed with particular emphasis on the socio-economic dimensions and the potential role of social scientists. It is argued that the farming systems perspective in agricultural research should be seen as performing an integrative role in research systems. This can often be developed without significant institutional reorganization.

Strontium was used as a tracer to detect root activity of yam (Dioscorea alata) at distances from 0.5 to 5.5 m from the plant's crown, and at depths of 7, 15, 25 and 40 cm, in field plantings separated by plastic root barriers. Tracer bands were installed at planting, and leaves were sampled at intervals throughout the growing season. Background Sr concentrations in leaves were found to be closely related to leaf Ca concentrations, allowing the expected background Sr to be calculated from the Ca concentration in each sample. The ratio of observed to expected Sr did not alter significantly with time of sampling or leaf age for control plants providing a robust parameter for comparison across harvests. Plants at all horizontal distances from the Sr placement up to 5.5 m showed significant elevation of leaf Sr by 13 weeks after planting (WAP). The depth placement at 15 cm showed earliest Sr elevation, followed by the 7 cm placement. However, both 25 cm and 40 cm placements resulted in significant leaf Sr elevation by 13 WAP, and their final Sr concentrations at 27 WAP did not differ significantly from those of shallower placements. Three fertilizer placement options were compared with respect to Sr uptake by the treated plants and by those in adjacent rows. Placement in a ring around the crown of the seed sett resulted in high leaf Sr concentration at 5 WAP, declining considerably at subsequent samplings. Placement underneath the seed sett produced a similar pattern but at lower concentrations. Banding midway between the plant rows, 0.5 m from plants, yielded a small increase at 5 WAP increasing to 13 WAP, and ultimately attaining similar concentrations to the other two placements. Plants in adjacent rows significantly accessed all three placements by 13 WAP. The results indicate greater reach of yam roots, both horizontally and vertically, than has been previously reported, and raise concerns about the adequacy of treatment separation in previously published fertilizer experiments with yams.

The effects of spacing and lopping on a mesquite (Prosopis juliflora) and Karnal grass (Leptochloa fusca) agroforestry system on an alkaline soil at Karnal in India was examined over a three year period from planting. There were no significant differences in the height and diameter of the mesquite or in the number of branches at different spacings, but growth was significantly improved by lopping. The oven dried biomass obtained from lopped branches over a 40 month period was greatest at a 2 × 2 m spacing. The green forage yield of Karnal grass was greatest under mesquite spaced 4 × 4 m apart and was markedly improved under lopped mesquite. The inorganic composition of the Karnal grass, including trace elements, made it a valuable fodder in an area with an adverse alkaline soil environment. The calcium and potassium content of the grass increased and the sodium content decreased in successive cuttings. Mesquite and Karnal grass grown together reduced soil pH and EC and improved the organic carbon and available nitrogen content of the soil.

The extent to which the number and weight components of oil palm fruit yield are affected by the total weight of fruit bunches on the palm (fruiting activity) was investigated by multiple regression analysis, with plant available water and sunshine hours as additional covariates. Fruiting activity significantly increased the percentage of aborted inflorescences six months after leaf opening, and reduced the ratio of female to total inflorescences (sex ratio) seven to eight months prior to leaf opening. Mean weight of bunches was negatively affected by fruiting activity ten to eleven months before harvest, the number of flowers per spikelet and the mean single fruit weight being the only components to show a clear response. Fruiting activity significantly reduced the petiole cross sectional area of leaves six months before opening.

Simulation models for oil palm yield forecasting must take account of the endogenous yield cycles resulting from these effects of fruiting activity.

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

This paper explores changes in the organization of seed supply in China over the last decade by means of a multi-level institutional analysis. At the landscape level, the implications for China of the regulation of plant genetic resources through various international treaties and conventions are reviewed in the light of the evolution of the global seed industry. At the regime level, the transition in the Chinese context to market-based seed supply and the development of commercial and public seed sectors are examined. The study then analyses trends in seed supply at the niche level, with reference to participatory maize (Zea mays L.) breeding in three provinces in southwest China where high rural poverty persists. This work offers radical novelty in variety development and seed provision on behalf of smallholder farmers. However, a series of technical, organizational and market ‘mismatches’ are demonstrated within the existing seed regime. The participatory work emphasizes breeding for diverse cultivars adapted to specific ecosystems but these are prevented from reaching commercial markets by existing varietal testing procedures. Participatory breeding has potential to address farmers’ varietal needs as agriculture modernises and to support the public function of research institutes, but within mainstream intellectual property regimes the public value of participatory breeding cannot be accommodated adequately. Yet, when coupled to institutional innovations for recognising intellectual property and sharing benefit among all those who contribute, participatory breeding may initiate a powerful dynamics for change within seed regimes and a sui generis seed system suited to the Chinese context.

Trends over time in annual crop yields potentially provide measures of the likely long-term sustainability of cropping systems. However, where large annual variability in the growth environment is responsible for most of the large year-to-year yield differences, appropriate analytical techniques must be developed to distinguish real long-term trends from the ‘background noise’. This paper presents models for the estimation of time trends in the yield data from crop rotation systems and discusses the results of applying these models to yield values from two types of long-term trial involving barley, each conducted at two sites in northern Syria.

The models used were linear with respect to time (years) and allowed for seasonal effects by means of a quadratic relationship on total rainfall and a linear relationship on planting date. A more complex model might account for more of the variance, but restrictions were imposed by the limited number of degrees of freedom (number of years of data less one) and the choice of meaningful single-valued parameters of growth-season conditions. For many experimental treatments the model accounted for less of the total variance at the wetter site. This may be due to seasonal bufferring by soil moisture stored at depth from one year to the next, and future iterations of the analysis will try to allow for this. The appropriateness of the linear time function is also questioned, and alternative functions will be tested along with alternative structures for plot errors over time.

Little is known about the economics of urban and peri-urban agriculture in Kabul, Afghanistan. This study therefore aimed to investigate the profitability of 15 mixed cropping farms with a total of 42 farm plots that were selected from a survey of 100 households (HHs). The sample represented the three dominant farm types: cereal producers (15 plots), vegetable farmers (15 plots) and grape producers (12 plots). A cost-revenue analysis of all inputs and outputs (costs of tillage, seed where applicable, weeding, harvesting, casual labour, machinery use, pruning, pesticides and of revenue from produce sold) over two years showed major differences in net HH income. Differences were largely due to production type and crops grown and reflected differences in market prices for produce. Cereal production yielded a total bi-annual revenue of 9630 US$ ha−1, and a gross margin and a net profit of 8770 US$ ha−1. Vegetable farming gave an average bi-annual revenue of 27 900 US$ ha−1, a gross margin of 26 330 US$ ha−1 and a net profit of 25 530 US$ ha−1. Surprisingly, vineyards generated the lowest returns with a revenue of 5400 US$ ha−1, and a gross margin and a net profit of 4480 US$ ha−1. The results suggest that among the production systems studied vegetable cultivation was most profitable given its direct linkage to city market demands, rather stable prices and much shorter growing season than for cereals and grapes. In addition, the inflow of wheat and grapes from rural areas into the city negatively affects local producer revenues. If vineyards are to be maintained in the city surroundings, incentives such as subsidized credit may need to be made available to producers.

Three irrigation regimes (250, 450, 650 mm year−1) were applied to guayule (Parthenium argentatum), a rubber-producing plant, in such a way as to provide periods of good soil water status alternating with periods of water stress. The relative water content and transpiration rate of the plants decreased only when the available soil water was depleted to about 40%. Very low values (< 30%) were measured for the relative water content. Water-stressed plants recovered as soon as irrigation was resumed. Growth and biomass accumulation, as well as the yields of rubber and resins, were directly related to the irrigation rates. The water regimes applied and the use of the drip irrigation method resulted in a relatively high water use efficiency.

The distribution of dry matter among the fractions of cotton boll (the bur, the fibre and the seed) may have significant impact on fibre biomass per boll, and consequently on lint yield. Little is known on how cotton boll allocates available photosynthetic assimilates to its components. A two-year field study was conducted to ascertain the difference in boll dry matter production and partitioning among three cotton genotypes differing in boll size and lint percentage. The dynamics of dry matter production in all fractions of cotton boll against boll age followed a logistic pattern. The final dry weights of all components were largely due to the duration of dry matter exponential accumulation, and less correlated with the maximal rate of exponential accumulation. Partitioning biomass to the bur differed significantly among these genotypes at 10 days post-anthesis (DPA). The genotypic difference in partitioning biomass to the fibre was originally observed at 24 DPA in 2009, while in 2010, this was observed at 17 DPA. The genotypic difference emerged rather late for the seed ratio compared with the fibre ratio and the bur ratio, which was first observed at 45 DPA in 2009 and at 31 DPA in 2010. These results indicate that management practices may need to be applied to cotton plants prior to 31 DPA to ensure optimal boll size and partitioning. Large boll genotype MM-2 consistently maintained higher seed ratio and lower fibre ratio than two other genotypes (2870 and AX) due to more developing ovules in its boll. These differences contributed to significant difference in lint percentage and less difference in fibre mass per boll between MM-2 and 2870 and AX.

Field experiments were carried out to study the effects of elemental sulphur on irrigated groundnut. The sulphur was applied at rates of 50, 100 or 150 kg ha−1, either at sowing, at flowering or in two equal splits at sowing and flowering. Shoot dry weight, total sulphur content of leaves, nodule number per plant and pod yield were all significantly increased by sulphur treatment, but nodule dry weight was unaffected. The greatest response lay at or below 50 kg ha−1 applied at sowing. There were no further increases in response above this level.

The main nutrient deficiency in Malawi is a chronic lack of nitrogen, which is found on all but a few soils. Phosphorus also becomes limiting quite rapidly on certain soil types as a result of permanent cultivation, but there has so far been little response to potash or lime. Incipient sulphur shortage is automatically corrected by the use of sulphate of ammonia and single superphosphate to correct the major deficiencies. Trace elements have not been widely tested. Samples of organic manure vary widely in moisture and nutrient content, and their nitrogen status is frequently low, so it is safest to consider manure as primarily a source of P, K and minor nutrients, and to supplement it with fertilizer nitrogen. It should be possible, with good cultivation of synthetic varieties and improved selections, to obtain maize yields of 15–20 bags/acre with fertilizer dressings of up to 80 lb/acre of the limiting nutrients.

The parasitic weed striga had significantly greater effects on sorghum yield components than non-parasitic weeds. Grain reduction caused by striga amounted to 65% compared with 32% reduction caused by non-parasitic weeds. Comparable reductions were also manifest in straw yield, grains/head and plant height of sorghum. Early removal of striga (a week after its emergence), and thereafter at regular weekly intervals, may help to improve crop yields.

The concept of water productivity (WP) or ‘more crop per drop’ has been revived recently in international water debates. Its application has notably been extended from single crops to mixed farming systems, integrating both crops and livestock, with the wider objective of reducing poverty. Using evidence from the Ganga Basin, India, we discuss the relevance of this concept as a tool to guide interventions for livelihood improvement and poverty alleviation. We argue that WP studies would benefit from greater attention to the role of capitals, inequities and institutions. Firstly, it is crucial to acknowledge the heterogeneity of capitals and capabilities of farmers to make changes in their farming systems and practices and avoid one-fix-all interventions. Identifying pre-existing inequities in water access within and among communities will support better targeting of poor communities. WP interventions can either reinforce or reduce inter-household inequities within communities. We stress the need for assessment of institutional impacts of WP interventions on water access and development.