Before an innovation can be judged as superior to existing technology, its relevance should be jointly evaluated by researchers and farmers by testing the proposed practice in a farm environment. Using a proposed maize technology as an example, it is demonstrated how site-related and management variables can be used to quantify the factors influencing actual yields on farmers' fields. Similarly, economic and management analysis of the practice provides an estimate of the probability of the farmer being better off by using the technology. The integrated analysis of the practice provide insights for the design of problem-oriented research projects.

Yield of swamp rice on acid sulphur soil was increased by liming and could be related to soil pH but was unaffected by drainage and differences in H2S in the soil. The seedling stage was most sensitive to acid and yield could be dramatically improved by planting mature vigorous seedlings. Survival of seedlings, tillering and panicle formation were the most important yield components affected by liming and acidity. Liming also increased spikelet number and grain size to a lesser degree. The optimal economic lime level for 3-week seedlings was around 4 t/ha but could be lower with 5-week seedlings.

Root development of maize (Zea mays), soyabean (Glycine max), cowpea (Vigna unguiculata), and pigeonpea (Cajanus cajan) was investigated with and without tillage. Observations were made at different growth stages by digging trenches normal to the rows, by core sampling, and by observing growth of roots against glass windows. There were more maize roots in the surface layer (0–10 cm) with no-tillage than in conventionally ploughed plots, but at 10–40 cm maize roots were more abundant and soyabean and pigeonpea roots less so in the no-tillage plots.

An investigation was made at the Mwea Irrigation Settlement, Kenya, to discover the reason why rice units which were transplanted earlier gave higher yields. Yields over an 11-year period were examined in relation to meteorological data and cultivation activities. It was found that the period during which the units were flooded prior to transplanting correlated with the date of transplanting, with longer preflooding periods causing higher yields and not the transplanting date. A yield/temperature relationship was also established.

Increasing plant density in maize from 8 to 32 plants/m2, without irrigation, had little effect on the time of ear primordia differentiation but delayed the time of silking (by up to 16 days), reduced the potential grain sites available for pollination and the number of grains pollinated, and increased grain abortion during the grain fill period. In cv LG11 sufficient fertile ears were retained to maintain grain yield throughout the wide range in density, whereas yield fell in Anjou 210 due to barrenness after silking, which was the major factor responsible for the intolerance of this variety to high density. However, in a variety such as Anjou 210, which has a tendency to barrenness under stress, the grain content of the end product would not be affected at the plant densities normally used for maize silage.

A field experiment to study weed and fertility management in rain-fed maize was undertaken at the Palampur Experimental Farm during the wet seasons of 1977 and 1978. Intercropping soya-bean in maize did not impose undue competition and significantly increased net profit per ha. Yields and net returns were significantly higher when weeds were controlled and 80 kg N/ha was applied. Increased application of fertilizer without weed control did not alter the yield of maize, and there was no response to phosphorus. Various yield attributes of maize were significantly affected by weeding and nitrogen treatments through their effects on grain and stover.

Trials were made of the performance of batches of forage sorghum and maize, sown at different times of year. The optimum sowing periods of sorghum variety Abu Sabeen and maize variety 113 were found to be February to October and November to January respectively. Of the various climatic factors considered in this study, mean daily temperature was of greatest importance in affecting yield. The overall performance of sorghum was superior to that of maize, probably because of its relatively higher salt tolerance.

Cowpea cvs Ife Brown and New Era were sown at a wide range of densities in 1976 and 1977 (early season) at Ibadan in the rainforest zone of Nigeria. In 1977 (late season), the experiment was modified and Ife Brown and Vita 5 were used. All the cultivars were indeterminate. Grain yields were higher at lower densities, especially in 1977 (late season). Numbers of leaves, branches and pods were also inversely related to density, but there were differences between varieties in flowering, branching and leaf and pod production.

An experiment at the University of Queensland studied the response of Crotalaria juncea to a single cut above node 4 or 10 at 6, 8 or 10 weeks after planting under long or short (inductive) daylengths. Initial deleterious effects of cutting on plant parts were in the sequence nodules > roots > shoots. Subsequent greater regrowth from plants cut earliest and at the higher node was associated with higher residual leaf area and negative growth rates were inferred below 90 cm2 pot−1. Redistribution of assimilate from stem to leaf production followed cutting; in inductive daylengths of 11.4 hours, flowering was delayed and the proportion of leaf increased from 21.0 to 32.4%. The high nitrogen content of leaf (3.5–5.3%) compared to stem (0.6–1.7%) indicated that early cutting was important in producing good quality hay.