Four experiments were conducted to facilitate the improvement of degraded grasslands in north Syria. The first examined the survival of legume seeds fed to penned Awassi wethers. The second and third observed the germination and establishment of legumes from faecal pellets in the field and in a glasshouse respectively. The fourth explored the possibility of transporting seeds from legume-rich (source) to legume-poor (target) grasslands using commercial flocks on communally-owned land. Seeds of small-seeded clovers passed through sheep in greater numbers (58–72%) than did seeds of larger-seeded species (10–40%). Of the clover seeds Trifolium campestre (seed size 0.45 mg) disintegrated least (72% passage) and T. haussknechtii (seed size 2.68 mg) disintegrated most (10% passage). Recoveries of Medicago noeana and Scorpiurus muricatus seeds were larger than expected on the basis of their seed sizes. Maximum rate of recovery was at 36 h after the seed meal for all species, all seeds were recovered by 120 h and 90% of the recovered seeds were passed in 72 h. Ingestion had little effect on the hardness and viability of most seeds. Experiments 2 and 3 suggested that seeds in pellets germinated and established as successfully as naked seeds. Burial increased establishment, whether in the field or under conditions of low moisture stress in the glasshouse. The small-seeded clovers, T. tomentosum and T. campestre, established most successfully whether from pellets or from naked seeds. About 500 seeds m−2 were successfully transported from the source to the target grassland. About half were Trigonella monspeliaca, a naturally-occurring legume found on both the source and target grasslands. Of the species sown on the source grassland, 115 seeds m−2 of Trifolium campestre (33% of the source seed bank), 62 seeds m−2 of T. tomentosum (27%) and 78 seeds m−2 of T. purpureum (21%) were detected in the target. Few medics were transported (for example, <2% of M. noeana). Apart from Trigonella monspeliaca, Trifolium tomentosum (16 plants m−2) was the most frequent species found in the target grassland in the following April. The results suggest that using sheep is a cheap and practical way of dispersing the seeds of pasture legumes and thereby improving the degraded grasslands of north Syria. They clearly demonstrate the role of small-seeded legumes (<1 mg) in grassland improvement, especially the small-seeded clovers.

Erosion changes soil properties, removes nutrients and alters crop yields. A knowledge of these impacts on soil productivity is needed for economic analyses of erosion and conservation. Based on a United Nations Food and Agriculture Organization experimental design to monitor these changes, results are reported from four research sites in southern Brazil on Ferralsols and Cambisols, enabling the construction of erosion–yield–time and nutrient loss relationships. Plot experiments ran for up to seven years of natural erosion, followed by one or two years of maize cropping. A remarkably consistent composite erosion–yield relationship in logarithmic form was found, showing a sharp yield decline with initial soil loss. Soil ‘resilience’ was identified through erosion–time relationships, ‘sensitivity’ through erosion–yield equations. As erosion progressed, losses of nutrients, especially of organic carbon and calcium, were significant. In situ changes in soil properties were far less marked. Together with measured yield reductions caused by cumulative erosion, these results enabled the modelling of changes in soil productivity over time with respect to both soil quality and impact on yields. A production ‘half-life’ of between one and 39 years according to soil type and level of erosion was also identified.

Several methods of measuring and estimating the available-water capacity of soils with varying degrees of accuracy are described. The errors associated with the use of the different techniques on a wide range of soils have been calculated and suggestions are made regarding the choice of method for particular circumstances.

The results of two tea irrigation experiments conducted independently in southern Tanzania and Malawi, where severe annual droughts of similar duration occur, were compared. There were marked differences in the dry season yield distributions between the two sites. These could be attributed to the adverse effects of large saturation deficits on plant water status and rates of shoot extension in Malawi. The implications for tea irrigation in particular and for irrigation agronomy experiments in general are discussed. The need to include detailed descriptions of the environment in which experiments are conducted is stressed.

This paper follows the progress made in India for research and farmer adoption of conservation agriculture (CA) since the publication of Erenstein (2012), who contested the idea that zero-till (ZT) establishment of wheat in rice–wheat systems could be further developed into full CA systems. Data presented in this paper show that research has successfully found solutions for both the wheat and rice phases of the rice–wheat systems of the Indo-Gangetic Plains (IGP) in the past 8 years. It shows that by finding solutions in both the rice and wheat phases, yields, water use efficiency and profits increased, while labour needs reduced. Indian scientists have also confirmed these benefits in participatory on-farm research in various locations, both east and west regions of the IGP. Farmers see for themselves through experimentation that they get higher yields with less cost and with more efficient use of inputs and water. A key factor has been the development of improved seed drills with the help of Indian private sector manufacturers of agricultural equipment. Indian scientists have also successfully conducted CA research on several other crops and in other regions besides the IGP. The paper shows that it is better to introduce parts of the CA management practices in a step-wise fashion first, rather than introducing the entire package at once since farmers first have to test and evaluate a new technology to understand how it benefits them personally before they will adopt it. The paper concludes that in the rice–wheat systems of South Asia, adoption of CA is indeed possible to achieve although it is still a work in progress. CA is a complex technology package and it takes time to overcome all of the contested issues mentioned in Erenstein (2012).

The residual effects of subsoil compaction (below 0.15 m depth) on soil properties, growth, yields and nutrient uptake by irrigated wheat (Triticum aestivum) and cotton (Gossipium hirsutum) are reported. The study was initiated during 1997 on a sandy clay loam soil in a semiarid region of Pakistan. Results showed that the adverse effects of subsoil compaction on bulk density, penetration resistance, total porosity and air-filled porosity of soil persisted for at least four years. In the third and fourth years after the imposition of treatments, compaction decreased yields of wheat by 12–18% and by 7% for cotton. The corresponding reductions in nutrient uptake by wheat were 11–16% for N, 11–15% for P and 5–10% for K. For cotton, the values were 9% for N, 3% for P and 7% for K. Subsoil compaction decreased nutrient use efficiency by 16% in wheat and 5% in cotton. The reductions in water use efficiency were estimated to be 11% in wheat and 7% in cotton. Wheat root length density was also decreased in the subsoil.

One consequence of climate change is change in the phenology and distribution of plants, including the date palm (Phoenix dactylifera L.). Date palm, as a crop specifically adapted to arid conditions in desert oases and to very high temperatures, may be dramatically affected by climate changes. Some areas that are climatically suitable for date palm growth at the present time will become climatically unsuitable in the future, while other areas that are unsuitable under current climate will become suitable in the future. This study used CLIMEX to estimate potential date palm distribution under current and future climate scenarios using one emission scenario (A2) with two different global climate models (GCMs), CSIRO-Mk3.0 (CS) and MIROC-H (MR). The results of this study indicated that Saudi Arabia, Iraq and Iran are most affected countries as a result of climate change. In Saudi Arabia, 129 million ha (68%) of currently suitable area is projected to become unsuitable by 2100. However, this is based on climate modelling alone. The actual decrease in area may be much smaller when abiotic and other factors are taken into account. On the other hand, 13 million ha (33%) of currently unsuitable area is projected to become suitable by 2100 in Iran. Additionally, by 2050, Israel, Jordan and western Syria will become climatically more suitable. Cold and heat stresses will play a significant role in date palm distribution in the future. These results can inform strategic planning by government and agricultural organizations to identify areas for cultivation of this profitable crop in the future, and to address those areas that will need greater attention because they are becoming marginal regions for date palm cultivation.

This paper seeks to establish the concept that the analysis of high temporal resolution meteorological data adds value to the investigation of the effect of climatic variability on the prevalence and severity of agricultural pests and diseases. Specifically we attempt to improve disease potential maps of root rots in common beans, based on a combination of inherent susceptibility and the risk of exposure to critical weather events. We achieve this using simulated datasets of daily rainfall to assess the probability of heavy rainfall events at particular times during the cropping season. We then validate these simulated events with observations from meteorological stations in East Africa. We also assess the utility of remotely sensed daily rainfall estimates in near real time for the purposes of updating the risks of these events over large areas and for providing warnings of potential disease outbreaks. We find that simulated rainfall data provide the means to assess risk over large areas, but there are too few datasets of observed rainfall to definitively validate the probabilities of heavy rainfall events generated using rainfall simulations such as those generated by MarkSim. We also find that selected satellite rainfall estimates are unable to predict observed rainfall events with any power, but data from a sufficiently dense network of rain gauges are not available in the region. Despite these problems we show that remotely sensed rainfall estimates may provide a more realistic assessment of rainfall over large areas where rainfall observations are not available, and alternative satellite estimates should be explored.

Yield and growth records from an oil palm planting density experiment, comparing 56, 110, 148 and 186 palms ha−1, and a progeny experiment, planted at 115 and 143 palms ha−1, were used to estimate the partitioning of assimilates into those used for structural dry matter (DM) production, and those used for growth and maintenance respiration.

Gross photosynthetic assimilation (A) for closed canopies was estimated from absorbed photosynthetically active radiation (PAR), derived from actual sunshine hours, and the assimilation-light response curve, to be 128 t CH2O ha−1 year−1. A for non-closed canopies was calculated by correcting for the degree of light transmission, which in turn was estimated from recorded leaf area index values (L), i.e. the total leaf area per unit ground area.

Forty-eight percent of gross assimilation was used for DM production, about half of this being lost in growth respiration. The remaining 52% was lost in maintenance respiration. These losses appeared to level off before crown expansion was completed, and since trunk biomass continued to increase, maintenance respiration per unit biomass (R) decreased with age.

An increase in planting density reduced the assimilates available for bunch DM, had little effect on those for vegetative growth, but strongly reduced maintenance respiration and, since biomass was little affected, reduced R. Assimilates for bunch DM ha−1 reached a maximum at L = 5.6.

The observed trends in R as a function of palm age and planting density merit further study.

The water use of clonal tea (Clone 6/8) in a line-source irrigation × nitrogen experiment in the Southern Highlands of Tanzania was monitored with a neutron probe during 1987 and 1988 to a depth of 3 m and 1989 to a depth of 5 m. The results for 1989 were used to calibrate a single layer water balance model which was then used to estimate water use for the preceding 1986, 1987 and 1988 dry seasons. In the model evapotranspiration was reduced linearly when the soil water deficit exceeded a critical value of 60 mm. The model predicted water use well for unirrigated, partially irrigated and fully irrigated treatments. Total extractable water was 330 to 350 mm in the 5.5 m deep root zone and estimated annual water use in 1988/89 ranged from 800 mm for unirrigated to 1200 mm for fully irrigated plots, of which about 400 mm was used in the wet season from December to April. Water use efficiencies were between 1 to 4 kg of made tea ha−1 mm−1, increasing with improving water and nutrient status. The slope (b) of the relation between the relative yield loss and the relative reduction in water use was very steep (b = 1.3) reflecting the sensitivity of shoot growth and yield of this clone to water stress.

Effectively nodulated plants of 3 cultivars of chickpea, classified as early, mid-late and late-maturing, were grown to reproductive maturity in 12 factorial combinations of simulated tropical environments in growth cabinets. Cultivars varied in sensitivity but all responded as quantitative long-day plants and flowered earlier in longer photoperiods. Differences in temperature had important consequences, especially on the duration of the reproductive phase and overall crop longevity; they also induced plants to flower at the same time in different photo-periods. Early flowering plants did not necessarily mature early; others taking twice as long to come into flower had short reproductive periods and came to maturity at the same time. Relations between phenology, morphology and seed yield are described and compared with similar data for field-grown plants. Screening for ‘adaptation to environment’ in chickpeas is discussed.

Greater cultivation of the underutilised Gac fruit, Momordica cochinchinensis, by poorly resourced householders and farmers would potentially improve livelihoods, and, on a larger scale, meet the increasing demand for Gac as a health product. Cultivation methods need to be developed to suit small- and large-scale production and must consider the unpredictable ratio of male to female plants grown from seed, and slow growth induced by cool temperatures. In this study, we examined the responses of Gac to propagation and protected cropping techniques to identify potential methods for increasing production. Plants germinated from seed in seed-raising mix under warm and humid conditions were grown hydroponically to maturity in a climate-controlled greenhouse during a temperate winter, producing fruits that were harvested ripe, from 44 weeks after sowing. Cuttings taken from female plants were dipped in indole-3-butyric rooting hormone powder or gel, or were left untreated, and then placed in rock wool, potting mix, water or closed media sachet. All treatment combinations, with the exception of the untreated potting mix, permitted the development of healthy plants in a second greenhouse crop. Growing plants from seed, then vegetatively increasing the number of productive female plants by cuttings is a means to increase Gac production with limited resources. Gac production using greenhouse technology, as described here for the first time, is relevant to other temperate regions. The finding that larger fruits have a higher percentage of edible aril than smaller fruits provides a new area of investigation towards enhancing production.

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.

Intercropping of pearl millet (Pennisetum glaucum) with clusterbean (Cyamopsis tetragonoloba) is a common practice in the arid zone of northwestern India. Field experiments were conducted for two years to examine the performance of two contrasting genotypes of each of these crops grown both as sole crops and as intercrops using all possible genotypic combinations of the pearl millet with the clusterbean. The seed yields of both crops were always lower in intercropping than in sole cropping, though the degree of reduction in the seed yield of each intercrop component was influenced greatly by the genotype of its companion crop. The seed yield of both clusterbean genotypes was reduced more when intercropped with the tall and late-maturing pearl millet, MH 179, than with the medium-statured and early-maturing HHB 67. On the other hand, the two clusterbean cultivars had similar effects on intercropped pearl millet. As a result, the highest land equivalent ratios (LERs) were obtained with intercrops containing pearl millet HHB 67 rather than MH 179, while the genotype of clusterbean had little overall effect on LER. The results obtained are discussed in the context of developing cultivars for intercropping.

Maize plants (Sweetcorn cv. Earliking) were grown in plots where four types of soil surface coverings were used to induce soil temperature differences During the vegetative stage of growth measurements were made of total leaf area per plant on a daily basis, and relative rates of leaf area increase were found to be closely correlated with mean daily soil temperatures at 5 cm. depth. The results were consistent with evidence that the temperature of the apical meristem strongly influences rates of leaf expansion in maize seedlings.

Glasshouse studies have shown that nodulation and dinitrogen fixation in groundnuts grown in a sand/vermiculite mixture increased with an increase in Rhizobium numbers inoculated onto each seed. Cultivars Robut 33-1 and TMV 2 required 106 rhizobia seed−1 for maximum nodulation and dinitrogen fixation, while cv. Kadiri 71-1 required larger numbers.

Maize grain yields were significantly higher following one to three years of Stylosanthes than after natural fallow or repeated cropping. This demonstrates an important benefit of the forage legume in addition to its value as a ruminant feed supplement. The implications for the development of traditional agro-pastoral production systems are discussed.

Reduced soil fertility and damage from pests and diseases have contributed to a decline in productivity of cocoa (Theobroma cacao L.) smallholdings in Sulawesi, Indonesia over the last decade. In a trial on a marginal, acidic soil in South Sulawesi, young PBC123 cocoa trees were supplied with compost, mineral fertiliser (NPK fertiliser and urea) or dolomite, alone and in combination. After 20 months, the trees supplied with compost were taller, flowered more profusely and had a five-fold higher dry bean yield than other treatments. Treatments had no impact on incidence of cocoa pod borer, Phytophthora pod rot and vascular streak dieback. All of the trees supplied with compost survived, while the control, mineral-fertiliser- and dolomite-treated trees had a mortality rate of 22–45% and symptoms of interveinal necrosis. Leaf concentrations of N, P and K were within the normal range in all treatments. In the control and mineral fertiliser treatments, leaf concentrations of Ca (0.28–0.30%) and Mg (0.11–0.15%) were deficient, but were higher in trees supplied with compost (0.78–1.21% and 0.26–0.29%, respectively). The Mg/K ratio in soil-exchangeable cations and leaves was increased three-fold by the combined compost/dolomite treatment. Supplying mineral fertiliser alone resulted in 3.3 cmol kg−1 exchangeable Al, compared to 2.2 cmol kg−1 in control soils. Since 10 kg tree−1 year−1 compost was supplied, a rate that is not practical on most cocoa smallholder farms, further investigation of cost-effective applications of organic matter in conjunction with appropriate formulations of inorganic fertilisers is recommended.

Seasonal drought stresses as a result of changes in global climate and local weather conditions are among the major factors adversely affecting growth and productivity of Robusta coffee (Coffea canephora pierre ex froehner) in many areas producing the crop. It is believed that there exists a wide range of genetic variability among Robusta coffee clones for traits associated with drought tolerance. Therefore, in an attempt to determine differences among Robusta coffee clones for some growth, physiological and biochemical parameters and identify drought-tolerant materials, 12 months old seedlings of six clones (IC-2, IC-3, IC-4, IC-6, IC-8 and R-4) were subjected to two treatments: well-watered control and drought-stressed (soil drying) by withholding irrigation for three weeks in a rain shelter at University Putra Malaysia, Malaysia. The rate of stress development, expressed as extent of wilting and damage to leaves, was considerably higher for clones IC-8, IC-4, R-4 and IC-2 than for IC-3 and IC-6 during the stress period. Leaf water potential (LWP), stomatal conductance (gs) and rate of net photosynthesis (PN) progressively decreased but leaf proline (LP) concentration substantially increased with time of exposure of the plants to soil drying. There was a considerable difference between coffee clones for the rate of change in these parameters. All the clones except IC-6 and IC-8 showed a negative carbon balance with the most negative value for R-4 at the end of the stress period. Six days after rewatering, LWP, gs and PN increased rapidly while LP concentration decreased and reached a level equivalent to those of well-watered plants, especially for clones IC-3 and IC-6. Among the drought-stressed plants, IC-6 and IC-3 had still significantly higher shoot growth, total dry matter yield and root to shoot ratio than did IC-2, IC-4, IC-8 and R-4. In general, clones IC-6 and IC-3 exhibited quite a better performance in almost all the parameters considered in this study and seemed to be less sensitive to drought stress. Hence, drought tolerance attributes in these clones could be linked to a more effective osmotic adjustment due to more rapid accumulation of LP and probably some morphological parameters, such as increased root-to-shoot ratio. However, further analyses at molecular level, detail biochemical studies and observations under diverse field conditions are required to come up with more conclusive recommendations.

Recent studies have reported the benefits of fertilizer microdosing in increasing crop yields in low input cropping systems. Little information is however available on the mechanisms underlying this effect. The objective of this study was therefore to explore the root-based mechanisms governing the growth enhancing phenomena of the fertilizer microdosing technology. A two-year experiment was conducted at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Research Station in Niger. Four treatments comprising (i) 2 g hill−1 of diammonuim phosphate (DAP), (ii) 6 g hill−1 of compound fertilizer NPK, (iii) broadcasting of 200 kg ha−1 of compound fertilizer NPK (recommended rate) and (iv) unfertilized control was arranged in a randomized complete block design with four replications. On average, fertilizer microdosing treatments (2-g DAP hill−1 and 6-g NPK hill−1) achieved 86% and 79% of the grain yields recorded from broadcasting of 200-kg NPK ha−1, respectively, in 2013 and 2014. The leaf area index and leaf chlorophyll content significantly increased with fertilizer microdosing at the early stage of millet growth. At the same stage, fertilizer microdosing enhanced the lateral root length density in the topsoil (0–20 cm) by 72% and 40% at respective lateral distances of 25 cm and 50 cm from the centre of the hill compared with broadcast of 200-kg NPK ha−1. Fertilizer microdosing did not significantly change soil pH in the root zone. It is concluded that the positive effect of fertilizer microdosing in increasing millet yield results from the better exploitation of soil nutrients due to early lateral roots proliferation within the topsoil.