Four experiments were conducted in southern Taiwan to evaluate the yield and economic benefits of management practices aimed at alleviating the effects of high temperature and heavy rain on tomato production. Following tropical storms, waterlogging caused wilting which was more evident in tomatoes grown in beds 20 cm in height than in those grown in raised beds 40 cm in height. This indication of crop water stress induced by flooding was quantified by measurement of the difference between canopy surface and air temperature at a specified saturation vapour pressure deficit. Canopy heating was less on the raised beds, especially when straddled by rain shelters. Nevertheless, waterlogging stress for the low-bed treatment did not result in loss of stand. In crops which experienced heavy rain, application of a synthetic fruit-set hormone enhanced fruit numbers as did the simple transparent polyethylene rain shelters. While planting on raised beds was without yield benefit the use of fruit-set hormone improved yield by at least 10 t ha−1. A further 4–6 t ha−1 yield was gained through the additional use of rain shelters. Partial budget analysis showed positive returns to the use of fruit-set hormone (US$6600 ha−1) but, unless rain shelters could be constructed with cheaper frame material or used for two tomato crops throughout the summer, their use would be uneconomical. Using existing frame material, net returns to rainshelters reached US$8000 ha−1. The likelihood of high temperatures, tropical storms and typhoons will influence economic returns to summer tomato production. Data from this study may be subjected to economic analyses using values for inputs and tomato prices from other countries with similar climatic conditions.

Shoot dry matter yield, shoot nitrogen yield and amount of nitrogen derived from fixation are collated for chickpea (Cicer arietinum L.) cv. ILC482 and lentil (Lens culinaris Medic.) cv. ILL8 grown at the ICARDA research station Tel Hadya, Syria over a period of 17 years. Regression analyses of shoot nitrogen yield on shoot dry matter and of the amount of nitrogen fixed on shoot nitrogen yield were undertaken for both species. The intercepts for both analyses with lentil were not significantly different from zero, so the slopes of the lines represented the concentration of nitrogen in the plant tissue (20.6 g kg−1 dry matter) and the proportion of nitrogen derived from fixation 0.75. Data for other cultivars of lentil grown at Tel Hadya and at four other locations in Syria fell within the 95% confidence limits of the original analyses. The intercept of the regression of shoot nitrogen yield on shoot dry matter yield for chickpea grown at Tel Hadya was not significantly different from zero, so the concentration of nitrogen in the plant tissue was constant (17.8 g kg−1 dry matter). The proportion of nitrogen derived from fixation increased asymptotically as the shoot nitrogen yield increased. Data for other cultivars of chickpea grown in different locations were generally similar to those for cv. ILC482 grown at Tel Hadya. It is proposed that generalized relationships between shoot nitrogen yield and shoot dry matter yield, and between amount of nitrogen fixed and shoot nitrogen yield can be established for lentil and chickpea grown in the West Asia–North Africa region. Consequently the amounts of nitrogen fixed by the two crops could be predicted from a knowledge of dry matter production alone.

Two shrub species, Atriplex halimus L. and Salsola vermiculata L., are considered useful for rehabilitation of degraded rangelands in west Asia and north Africa. They can be established from direct seeding and are capable of self-sowing. In this study, seed storage at different temperatures and the influence of fruiting bracts on seed germination were examined for the two species during two seasons. Fruits (utricles) were stored at 20–22°C (room temperature), 0°C or −22°C. Germination tests were carried out after 33, 56, 90, 152, 272 and 397 d in storage in the first season and after 44, 76, 104, 170, 288 and 412 d in the second season. Seeds were germinated in their fruiting bracts or after bract removal. Bract removal significantly improved seed germination of both shrubs regardless of storage temperature. For S. vermiculata the increase in germination was in the range of 1.3- to 14.7-fold compared with values for the intact fruit in Season 1 and 0.5 to 3.8 in Season 2. Similarly the ranges for A. halimus were 0.5- to 4.2-fold and 0.7- to 5.3-fold in the two seasons respectively. The effect of cold storage was greater on Salsola than on Atriplex. The reduction of the storage temperature from 21°C to 0°C and −22°C increased the longevity of S. vermiculata seeds by 2.8–46.6 times in Season 1 and by 2.9–2.6 times in Season 2. There was little or no effect on the longevity of A. halimus. A leachate prepared by soaking fruiting bracts from S. vermiculata significantly depressed germination (p < 0.01), the effect being greater on Salsola seeds (20% reduction) than on Atriplex seeds (8% reduction). A leachate from A. halimus produced a slight but non-significant reduction in germination.

The agroclimatic potential of the forest–savanna transition zone of Nigeria for the cultivation of sorghum (Sorghum bicolor) was investigated. Five phenological stages of the crop formed the basic unit of time for the investigation. Selected agroclimatological thermal and moisture indices were measured daily and processed into ten-day (decadal) averages for the 1993 and 1994 cropping seasons. The thermal indices, temperature and photoperiods were optimal for sorghum growth but, on the basis of the distribution of rainfall and actual water availability in relation to the crop's water consumption, the moisture indices were above optimum. However by relating effective water availability to the indices of moisture adequacy for the growth of the crop, it was found that the agroclimatological moisture indices were optimum during the moisture sensitive stages. A comparison of the vegetative growth and grain yield of sorghum in the study area and elsewhere in the savanna region confirmed the agroclimatic potential of the forest–savanna transition zone for sorghum production.

Four weeding systems were evaluated for three seasons on sandy soils in a semi-arid area of Zimbabwe. Inter-row weeding with a plough with body (mouldboard breast) attached, produced a ridge and furrow landform. This confers the advantage of increased water retention associated with ridging without the additional investment in labour and equipment needed when ridges are made pre-planting with a ridging plough. Mid-season ridging by plough with body attached achieved more efficient weed control than the common farmer practices of using a cultivator or plough without the body. In terms of crop water use efficiency and grain yield, weeding with the plough and body performed at least as well as any existing farmer practices. Productivity, in terms of grain yield per hour worked, was considerably higher following weeding with the plough and body compared with alternative systems.

An on-farm study was carried out at 17 different sites within the Western Hills of Nepal during the spring and summer seasons of 1993 and 1994 in order to monitor the plant population density dynamics of the maize (Zea mays L.) crop under farmers' management. Five farmers were selected randomly at each site and a 20-m2 plot was demarcated just after maize sowing. The maize stands within the 20-m2 plots were first recorded 20 d after sowing, and then at 10-d intervals until harvest. Farmers were allowed to perform all cultural practices on their own. On average, the initial plant stand across all locations and over two seasons was 69 100 ± 1800 plants ha−1, which resulted in 37 300 ± 1700 plants ha−1 at harvest, a 46% reduction from the initial stand. At most locations, the population declined by 30–40 × 103 plants ha−1 between emergence and harvesting and in no cases were the recommended plant populations achieved at harvest. Populations varied across sites and seasons. The rate of population decline was higher in the low and mid hills compared to high-altitude areas. Thinning which is carried out between 30 and 60 d after sowing at most sites was the major cause of population reduction, and delay in thinning was intended to increase fodder production from the thinned maize. In addition, the removal of barren plants at the silking stage and of smutted, lodged and damaged plants attributed to about 12% of total reduction in plant population. The larger the initial stand, the larger was the proportion of barren plants to be removed. No clear relationships were observed between soil fertility and final plant stand at harvest.

The biophysical performance of hedgerow intercropping for soil fertility inprovement was assessed in a farmer-participatory trial in western Kenya over three years. Farmers successfully established dense hedgerows (median 6680 trees ha−1 on plots of 790 m2, but annual yields of hedgerow prunings of Leucaena leucocephala and Calliandra calothyrsus (1–4 t ha−1), were low compared to potentials in the region (4–8 t ha−1). The hedgerows reduced slopes from 7.2 to 4.5% within alleys (p < 0.01) but had no effect on grain yield over five seasons. Little of the variation in grain yield between hedgerow plots and control plots without hedgerows (adjusted r2 = 11%) and among control plots (adjusted r2 = 29%) could be accounted for by linear regression with measured agronomic and socio-economic variables. Fully researcher-managed trials are recommended for agronomic evaluation of complex agroforestry technologies.

Hedgerow intercropping is evaluated both economically and from the farmers' viewpoint, based on four years of experience of 45 farmers in western Kenya. Farmers were able to establish and prune the hedges; however, both activities considerably increased labour use during the busiest period of the year. Women did not generally prune the hedges. The average extra maize yield required each year, beginning in the second year, to cover the added cost of hedgerow intercropping was 10.5% (s.d. 5.5) when based on returns to land and 17.5% (s.d. 6.5) based on returns to labour. Although about half the farmers claimed that hedges improved crop yields, after three years of experimentation only about one-fifth planted additional hedges and only 14% did so to improve soil fertility. It thus appears that the potential for its adoption as a soil fertility practice in this area is low. Control plots were of little use as farmers were more interested in contrasting test-plot yields with past yields than comparing the test and control plots. Different types of trials may be required to obtain reliable biophysical data on yield response and socio-economic data on farmer assessment of complex agroforestry technologies.

In researcher-designed, farmer-managed experiments with cabbage and hot pepper, ground seashells (GSS) were compared with low-grade phosphate lime (LGP) at rates of 0, 2.5, 5, 7.5 or 10 t ha−1. A randomized complete block design, with replicates spread over different farms, was used. Liming with GSS or LGP at 10 t ha−1 increased cabbage yield from 0.5 t ha−1 without liming to 15.0 and 5.3 t ha−1 respectively. Hot pepper yield was increased from 2.1 t ha−1 without liming to 3.2 t ha−1 at the three highest rates of GSS and LGP. Application of GSS increased the pH, reduced exchangeable acidity and increased the extractable Ca content of the soil. Partial budget analyses revealed that cabbage and pepper growers obtained highest returns with GSS at 10 and 5 t ha−1 respectively.

A field experiment was conducted from 1992 to 1994 to study the effect of supplying micronutrients to wheat (Triticum aestivum L., cv. Yecora rojo) grown on calcareous soil. Chelated and/or non-chelated forms of Fe, Mn, Zn and Cu were administered through a wide range of foliar applications, sprayed either individually or in combination. All the chelated micronutrients were applied in the form of EDTA with the exception of Fe (EDDHA). However, all the non-chelated elements were in the form of sulphate. The grain yield was significantly increased by the application of individual micronutrients either in the form of sulphate or chelate, but much higher amounts of sulphates were required. Application of micronutrient combinations either in chelated or non-chelated forms gave greater biological and grain yields than individual applications of the micronutrients. Wheat response to micronutrient applications followed in rank order: combined elements > Fe > Cu = Zn > Mn. Application of the micronutrients in sulphate form generally resulted in higher concentrations of these elements in grain than when the chelated forms were applied. Foliar application of the micronutrients in the form of sulphates at higher application rates may be more effective than the chelates due to lower cost despite the higher application rates.