The results of research into the water relations and irrigation requirements of lychee are collated and reviewed. The stages of plant development are summarised, with an emphasis on factors influencing the flowering process. This is followed by reviews of plant water relations, water requirements, water productivity and, finally, irrigation systems. The lychee tree is native to the rainforests of southern China and northern Vietnam, and the main centres of production remain close to this area. In contrast, much of the research on the water relations of this crop has been conducted in South Africa, Australia and Israel where the tree is relatively new. Vegetative growth occurs in a series of flushes. Terminal inflorescences are borne on current shoot growth under cool (<15 °C), dry conditions. Trees generally do not produce fruit in the tropics at altitudes below 300 m. Poor and erratic flowering results in low and irregular fruit yields. Drought can enhance flowering in locations with dry winters. Roots can extract water from depths greater than 2 m. Diurnal trends in stomatal conductance closely match those of leaf water status. Both variables mirror changes in the saturation deficit of the air. Very little research on crop water requirements has been reported. Crop responses to irrigation are complex. In areas with low rainfall after harvest, a moderate water deficit before floral initiation can increase flowering and yield. In contrast, fruit set and yield can be reduced by a severe water deficit after flowering, and the risk of fruit splitting increased. Water productivity has not been quantified. Supplementary irrigation in South-east Asia is limited by topography and competition for water from the summer rice crop, but irrigation is practised in Israel, South Africa, Australia and some other places. Research is needed to determine the benefits of irrigation in different growing areas.

The results of research on the water relations and irrigation requirements of the mango fruit tree are collated. The stages of development (including roots) are summarised, followed by reviews of plant water relations, water requirements, water productivity and water management. This long-lived tree is well adapted to a wide range of tropical and subtropical environments. In the low-latitude tropics, flowering is initiated after a period of water stress (at least six weeks duration) and is ended by rain or irrigation. In the high-latitude tropics and subtropics, flower buds are initiated during the cool winter months (<15 °C). Less than 1% of the flowers that set fruit reach maturity. Roots can reach depths of 5 m. Stomata occur mainly on the lower (abaxial) leaf surface. They are sensitive to dry air, closing as the saturation deficit increases (from 0.5 to 4.0 kPa). In humid tropical areas, the mean seasonal potential evapotranspiration rates (ETc) average 4–5 mm d−1, with peak rates of 5–6 mm d−1. The crop coefficient (Kc) varies between 0.65 and 1.05. Water productivities are in the range 3–6 kg (fresh fruit) m−3 (irrigation). Micro-sprinklers and drip irrigation are the preferred methods of irrigation. The trend towards greater intensification of production will impact on the water relations and irrigation needs of mango and provide a focus for future research.

Globally, a range of agronomic factors have been reported to have an impact on the performance of conservation agriculture (CA) and often determine its performance in relation to conventional agriculture (CONV). To assess this performance in Zimbabwe, 48 CA experiments were conducted by the International Crops Research Institute for the Semi-Arid Tropics in the semi-arid areas of southern Zimbabwe from 2004 to 2010, to calculate the weighted mean difference (WMD) through meta-analytical methods. The two CA practices, planting basins (Basins) and ripper tillage (Ripper), were compared with CONV. It was hypothesised that CA results improved yield compared with CONV and that the effect of CA practices on yield is affected by soil type, rainfall amount and distribution and selected management practices, which included rates of inorganic fertilisers and manures and mulching. Basins were superior to CONV in 59% of the experiments and the overall effect was significant (p < 0.001). The effect of Ripper was non-significant. The hypothesis that CA practices result in improved maize grain yield over CONV was accepted for Basins. The WMD for experiments conducted on sandy soils was 0.365 t ha−1 for Basins and 0.184 t ha−1 for Ripper, and in both cases was significant (p < 0.05). For clay soils, only the WMD for Basins was significant. A higher rainfall regime (500–830 mm) resulted in a lower WMD for Basins (0.095 t ha−1) and Ripper (0.105 t ha−1) compared with 0.151 t ha−1 for Basins and 0.110 t ha−1 for Ripper under lower rainfall (320–500 mm). The overall effect of Basins under the higher rainfall regime was not significant. There was better yield performance for Basins when the rainfall was well distributed; the reverse was noted for the Ripper. The application of 10–30 kg ha−1 of N (micro-dose range) resulted in a higher WMD for Basins than zero N application. Without N application, the WMD of Basins was not significant. For zero manure application in Basins, the WMD was 0.043 t ha−1 compared with 0.159 t ha−1 when manure was applied. The application of mulch depressed the WMD in Basins by 44% and Ripper by 89%. The hypothesis that yield performance under CA is influenced by soil type, rainfall amount and distribution, inorganic fertiliser and manure application was accepted.

Soil quality integrates the effects of soil physical, chemical and biological attributes. Some of them are dynamic in nature and behave differentially in various agro-ecosystems (AESs) and are quantified in terms of a soil quality index (SQI). An attempt has been made in this paper to develop an SQI based on a minimum data set (MDS), which could be used to evaluate the sustainability of the crop production in three varying AESs in India, namely sub-humid, semi-arid and arid. Thirteen indicators were utilized to develop the SQI from the properties measured from the surface soil layer (0–15 cm). Each indicator of the MDS was transformed into a dimensionless score based on scoring functions (linear and non-linear) and integrated into four SQIs. The weighted non-linear index (WNLI) was identified as the most sensitive for all the AESs and was recommended as an index for future assessments. Based on this index, the quantification of soil quality under several cropping systems was carried out for sub-humid, semi-arid and arid AESs and the most suitable cropping system was identified. WLNI was positively and significantly correlated (R2 = 0.79, p < 0.01) with wheat equivalent yield for all the cropping systems. This clearly indicated that the index may be used satisfactorily for quantifying soil quality.

The objective of this study was to determine whether salicylic acid, nitric oxide (NO) and/or feeding by nymphs of the spittlebug Mahanarva spectabilis affect the concentration of total phenolic compounds and the dry matter content of different genotypes of elephant grass (Pennisetum purpureum). Four genotypes of elephant grass with varying levels of resistance to insect attack were treated with 4 mL of salicylic acid (1%) or 2 mL of NO per plant in the presence and the absence of nymphs. We determined the concentration of total phenolic compounds and the percentage dry matter of shoots and roots in the plants. We found that salicylic acid, NO and attack by M. spectabilis did not change significantly the total phenolic compounds concentration in any of the genotypes of elephant grass tested. However, we observed variations in the concentration of phenolic compounds produced between the resistant and susceptible genotypes, both in the shoot, when subjected to salicylic acid or nymphs, and in the roots in the presence of nymphs. Furthermore, the inducers resulted in variation in the dry matter content of the shoots and roots for most of the genotypes tested. Therefore, we conclude that chemical inducers and feeding by M. spectabilis nymphs cannot be used to elicit a resistance response in elephant grass by stimulating the production of phenolic compounds.

The centre of origin of cashew is believed to be Brazil, from where it has spread since the 16th century throughout the tropics. In recent years, Vietnam has surpassed India to become the world's largest producer of cashew nut. Most of the research on the water relations of cashew has been done in Brazil, where it is both a large-scale commercial and a smallholder crop, and in Australia, where cashew is a possible emerging new crop. There are two ‘types’ of cashew: ‘talls’ and ‘dwarfs’. Both are evergreen trees in which vegetative growth occurs in a series of flushes. Flowers form annually on the end of branches in the dry season, and flowering continues for two to four months. It then takes about two months from pollination for the nut to mature. Roots can extend to great depths (>5 m), while cashew's wide-spreading rooting habit is critical to its successful adaptation to semi-arid/dry conditions. The optimum temperature for CO2 assimilation is in the range 25–35 °C. Progressive closure of the stomata occurs at saturation deficits of the air >1.5 kPa. In the field, differences in rates of gas exchange between irrigated and unirrigated cashew trees only become apparent three or four months after the end of the rains, the stomata playing an important role in maintaining a favourable leaf water status in dry conditions. Sap flow measurements indicate transpiration rates of 20–28 L d−1 tree−1. Irrigation can be beneficial during the period from flowering to the start of harvest, but reliable estimates of water productivity have yet to be established. The best/only estimate is 0.26 kg (nut in shell) m−3 (irrigation water). There is a continuing need to develop a method to estimate the water requirements of cashew, to identify where and when irrigation of cashew is likely to be justified and to develop a practical irrigation schedule.

Common bean (Phaseolus vulgaris L.) is a dominant grain legume in eastern and southern Africa, where it constitutes a major source of protein and microminerals in peoples’ diet. The current studies aimed at determining how initially promising genotypes of bean responded in terms of yield and grain element composition under farmers’ cropping conditions. It was found that variations between genotypes in the proportions of elements in the grain dry matter across a wide range of conditions could be linear with an additional 20% iron (Fe) or zinc (Zn) for some genotypes. However, this linearity was only identifiable under relatively favourable conditions. Further, a favourable season could enhance the proportion of Fe in the grains of the same genotypes by up to 20%, whereas Zn did not respond. Fe and Zn correlated only to some degree with P (r2 > 0.35). It is concluded that the supply of elements in the diet may best be secured by selecting for high-yielding cultivars as the amounts of phosphorus (P), Fe and Zn in the grains correlated strongly (r2 > 0.93) to the dry matter grain yield.

We aimed to evaluate aluminium (Al) effects on the photosynthetic apparatus of two rice cultivars with contrasting tolerances to Al. Nine-days-old seedlings were exposed to 0 or 1 mM Al for 10 days, and then dry mass, Al and chloroplastidic pigment contents and photosynthetic parameters were determined. Al accumulated mainly in the roots of the Al-treated plants. In the leaves, Al increased only in the sensitive cultivar, but there was no difference between the cultivars in Al-treated plants. The root and leaf dry mass, the net carbon assimilation rate, stomatal conductance and internal CO2 concentration were all reduced in response to Al application, but only in the sensitive cultivar. Both the initial fluorescence and potential photochemical efficiency of photosystem II were unresponsive to the Al treatments, regardless of the cultivar. In the Al-sensitive cultivar, Al provoked significant decreases in the photochemical quenching coefficient, quantum yield of photosystem II electron transport and apparent electron transport rate, in parallel to an unaltered non-photochemical quenching coefficient. All of these parameters remained at the control levels in the tolerant cultivar. The chloroplastidic pigment content increased only in the Al-tolerant cultivar, whereas it remained unaltered after Al treatment in the sensitive cultivar. In conclusion, Al induced stomatal and (most likely) photochemical constraints on photosynthesis but with no apparent signs of photoinhibition in the Al-sensitive cultivar. Despite the similar Al levels of the cultivars, unchanging biomass accumulation or photosynthetic performance in the tolerant cultivar challenged with Al highlights its higher intrinsic ability to cope with Al stress.

The risks of flooding in rice production include losses that can affect some 13 million ha of rice lands in Southeast Asia. This study integrated social and gender perspectives into the varietal evaluation process to contribute to planned faster uptake of submergence-tolerant rice (Sub1) varieties. In this study, the participatory varietal selection (PVS) process was used in eliciting male and female farmers' opinions with respect to selecting popular varieties with the SUB1 gene introgressed, for added tolerance of flash floods of up to two weeks. Fifteen Sub1 varieties and the farmers' local check were tested under the PVS researcher-managed (PVS-RM) trials, which involved farmers' preference analysis (PA). The farmers tested the pre-selected lines with the SUB1 gene in their own fields to further evaluate their performance under varying conditions. During flooding, farmers experienced lower production depending on water depth, timing with respect to rice growth stage, duration, frequency of occurrence and quality. On-farm PA results showed wide variability in the performance of the Sub1 varieties compared with local popular varieties. This implies the need for further testing of pre-released lines in terms of adaptability and the continuous development of rice genotypes for varying flood-prone rice ecosystems. Women are as knowledgeable as men because of the significant roles they play in rice production and food preparation. Moreover, farmers and breeders have almost the same criteria in choosing the best performing rice lines. Sensory tests revealed the eating and cooking qualities important to farmers. The findings of this study can provide feedback to breeding programmes to ensure a greater likelihood of adoption and ultimately increasing rice productivity in submergence-prone rice areas.

In addition to latex and timber, the rubber tree is useful in the alleviation of rural poverty and also in the mitigation of climate change through fixing atmospheric CO2 as biomass. For developing any rubber-based carbon projects, protocols for quantifying biomass and carbon fixed are required. In this context, the present study was aimed at building up allometric models using simple growth indicators (i.e. tree diameter and total height) to assess the timber, biomass and carbon in rubber trees and also to quantify their ontogenetic variation under average growth conditions in two major climatic regimes (i.e. wet and intermediate) of Sri Lanka. All models developed were in the accuracy level of over 88%. The mean absolute percentage error in the validation of allometric models was only 12.9% for timber and less than 5% for biomass and carbon. Under average growth conditions, 1 ha of rubber could produce 208 m3 timber, 191 MT biomass and fix 78 MT carbon during its 30-year lifespan in the wet zone and ca. 16% lesser values in the intermediate zone. The applicability of the findings in carbon trading is discussed.

Rice is the major staple food crop in the North Eastern Region of India (26.2 million hectare geographical area) and the region has a deficit of 1.40 million tones of rice, mainly due to low productivity (1.72 t ha−1). Field experiments were conducted for the first time to evaluate the new techniques of rice cultivation, viz. the system of rice intensification (SRI) and integrated crop management (ICM) along with conventional rice culture (CRC) for improving productivity, water and energy use efficiency during the rainy seasons of 2004–07 at the ICAR Research Complex for North Eastern Hill Region, Umiam, Meghalaya (950 m msl), India. Three stand establishment methods, viz. SRI, ICM and CRC in main plots, and five nutrient management practices, viz. recommended dose of fertilizers (RDF = 80:26:33 kg NPK ha−1), farmyard manure (FYM) 10 t ha−1, RDF + FYM 5 t ha−1, 50% RDF + FYM 10 t ha−1, and a control (no fertilizer and manure) in sub-plots, were tested in a split-plot design; only few meaningful interactions were found. Results showed a higher number of panicles per square metre under CRC and ICM compared with SRI. However, the number of panicles per hill, grains per panicle and the test weight remained higher in the SRI method. In terms of mean grain yield, ICM (4.86 t ha−1) and SRI (4.72 t ha) produced 12.8 and 9.6%, respectively, higher grain yield over CRC (4.3 t ha−1). Among the nutrient management practices, the application of RDF + FYM 5 t ha−1 (5.0 t ha−1) and 50% RDF + FYM 10 t ha−1 (4.87 t ha−1) not only produced higher grain yield of rice (23.8 and 20.5%, respectively, higher yield over control) but also maintained higher soil available N, P and organic carbon at harvest compared with other nutrient management practices. Photosynthesis rate and water use efficiency were found to be significantly (p < 0.05) higher under SRI, whereas the transpiration rate was higher under CRC. The ICM method recorded maximum net return and energy output to input ratio, which was followed by SRI and CRC. Therefore, the ICM method of rice cultivation would be the preferred option for the sub-tropical mid-hills of eastern Indian Himalayas.

Cultivation of less productive soils such as closed landfills has become convenient because European subsidies covered part of the risk to obtain production. Aim of the research was to evaluate grain yields of maize hybrids belonging to different maturity classes (FAO 200, 300 and 400) (Gretzmacher, R. (1979). Die Bodenkultur 30:256--280) grown on closed landfills by the adoption of two minimum tillage methods (chisel plowing at 0.35 m plus disk harrowing at 0.20 m, or only disk harrowing at 0.20 m). Maize cultivation inserted in a winter cereal rotation had a grain production ranging from 4.6 t ha−1 (FAO 200, disk harrowing only) to 8.3 t ha−1 (FAO class 400, chisel plowing plus disk harrowing) in the two considered years (2011 and 2012). The adoption of chisel plowing coupled with disk harrowing reduced yield fluctuation between years, and furnished higher yield performance if compared with the single disk harrowing passage. The best growing hybrid cycles were those belonging to FAO class 300 with production similar to that of the longest maturity class, and with moisture content equal to the shortest maturity class.

Red skin disease seriously limits the production and quality of Panax ginseng (ginseng) in the Changbai Mountains of Northeast China, which is the main origin of ginseng. To cultivate ginseng, the albic and humus horizons of albic luvisols are artificially mixed to produce ginseng bed soils. To clarify the relationship between red skin disease and soil characteristics, red skin disease indices were calculated from six plots located on a ginseng farm. Ginseng roots were analysed for aluminium (Al) content. Soils from the ginseng beds were sampled at three depths for the evaluation of physico-chemical parameters. Al fractionation from the soil solid fraction was analysed using atomic absorption spectrophotometry. Ginseng plants exhibiting larger red skin areas accumulated higher concentrations of Al in the epidermis and in the fibrous roots. Ginseng bed soils in the six plots were acidic with pHH2O values ranging from 4.0 to 5.0. Plots exhibiting higher red skin disease indices also had higher bulk densities, moisture contents and nitrate concentrations. They also contained higher concentrations of exchangeable Al, NaOH-extracted Al and ammonium oxalate-oxalic-extracted Al in the bed soils. The Al saturation and molar ratio of base cations to Al were above 20% and below 10, respectively, in the two plots with the highest disease indices. Compact soils with higher moisture, nitrate concentrations and active Al species may increase the incidence of ginseng red skin disease.

The complex dynamics of the sulphur (S) cycle has prompted several questions concerning its bioavailability and evaluation by different extraction methods, and few studies under field conditions have been performed to elucidate available S on Brazilian soils under no-till (NT) cropping systems. A field experiment examined the effects of phosphogypsum (PG) applications on nutrient uptake and availability of S to maize and wheat crops under an NT system aiming to establish critic levels of S on an Oxisol (clay, kaolinitic, Rhodic Hapludox) in Parana state, Brazil. PG at the rates of 0, 3, 6 and 9 t ha−1 was applied on the surface of the plots in 1998 upon conversion from pasture to an NT cropping system, and in 2004 subplots received either 0 or 6 t ha−1 of PG on the surface. Effects of PG applications on nutrient uptake and available soil SO4-S to the maize and wheat crops were evaluated in 2004–2005. Increasing the surface-applied PG rate in 1998 increased Mg uptake by maize, and N, K, Ca and Mg uptake by wheat plants. Reapplication of PG in 2004 increased the uptake of N and P by maize, and the uptake of N, K, Ca and Mg by wheat plants. The PG rates surface-applied in 1998 have resulted in a long-term residual effect on soil by increasing SO4-S in surface and subsoil layers 6.5 and 7.5 years after application, affecting aboveground biomass, S uptake and S content in the leaves of the wheat crop. The reapplication of PG in 2004 increased maize S uptake, S content in leaves and grains and S exported by maize harvest, and increased wheat aboveground biomass, S uptake and S content in leaves. These effects were due to increasing available soil SO4-S from different depths extracted by 0.5 M ammonium acetate (NH4OAc) along with 0.25 M acetic acid (HOAc) and 0.01 M calcium phosphate (Ca(H2PO4)2). Both extractants were very similar in their ability to assess available soil S in these crops, and the 0–0.20-m layer is shown to be adequate for evaluating the concentration of available SO4-S in maize and wheat cultivated under NT.

Best management practices in agriculture have the potential to sequester carbon and improve soil aggregation. Hence, in the present investigation, different levels of irrigation and nitrogen (inorganic and organic) were used in the maize–wheat cropping system to study their effect on soil organic carbon (SOC) accumulation and aggregation. The treatments consisted of three levels of water regimes (namely W1, W2 and W3 referring to limited, medium and maximum irrigation) and five nitrogen levels (T1, 0% N; T2, 75% N; T3, 100% N; T4, 150% N; T5, 100% N from organic source), with three replications taken in a split plot design. Positive and significant correlation between SOC and mean weight diameter (MWD) was observed, implying that increasing SOC improved soil structure and increased the MWD. The quantification of water and nitrogen interaction on SOC was done by developing a multiple regression equation, which, when validated with SOC of the subsequent year, resulted in significant correlation. Irrigation and N was found to have a significant effect on soil aggregation and organic carbon build-up. Two N treatments (T4: 150% N and T5: 100% N from organic source) improved soil aggregation (macro-aggregates) and SOC when accompanied with W3 water regime (maximum amount of irrigation). Across N treatments, the W3 regime registered significantly higher SOC by more than 30% over control in the 0–15-cm soil depth.

Capturing agricultural heterogeneity through the analysis of farm typologies is key with regard to the design of sustainable policies and to the adoptability of new technologies. An optimal balance needs to be found between, on the one hand, the requirement to consider local stakeholder and expert knowledge for typology identification, and on the other hand, the need to identify typologies that transcend the local boundaries of single studies and can be used for comparisons. In this paper, we propose a method that supports expert-driven identification of farm typologies, while at the same time keeping the characteristics of objectivity and reproducibility of statistical tools. The method uses a range of multivariate analysis techniques and it is based on a protocol that favours the use of stakeholder and expert knowledge in the process of typology identification by means of visualization of farm groups and relevant statistics. Results of two studies in Zimbabwe and Kenya are shown. Findings obtained with the method proposed are contrasted with those obtained through a parametric method based on latent class analysis. The method is compared to alternative approaches with regard to stakeholder-orientation and statistical reliability.

Modern maize varieties have been bred for drought tolerance and early maturity, to assist farmers in avoiding or escaping the effects of moisture stress in drought-prone areas. This study evaluates the prospects for widespread adoption of these modern maize varieties as a climate change adaptation strategy for smallholder farmers. Data are from a detailed household survey completed in four rural villages in Southern Malawi between May and July 2010. The empirical analysis involves estimation of an ordered logit regression model because the dependent variable is categorical, with one category for nonadoption (has never grown modern maize varieties) and three categories for the duration of growing a modern maize variety among adopters (this year only, 2 to 5 years and 6 years or more). The empirical findings indicate a positive association between a farmer's perception of drought risk and the adoption and continued use of modern maize. Regression results also show that farmers that value the traits of early maturity and drought tolerance are more likely to adopt modern maize varieties. There is evidence of some disadoption among farmers dissatisfied with maize genotype performance, in terms of poor storability and yield under drought conditions. Finally, the study highlights the urgent need for maize breeders interested in sustained use of modern varieties to simultaneously address robust drought tolerance, early maturity and storability. This underscores the importance of cognizance of local farmer preferences in crop breeding efforts.

The effect of drought and temperature on the growth and development of bambara groundnut (Vigna subterranea (L.) Verdc.) was studied in controlled environment glasshouses in the United Kingdom. There were two landraces, S19-3 (from a hot, dry environment; Namibia) and Uniswa Red (from a cool, wet environment; Swaziland), two temperature regimes (23 °C and 33 °C) and three watering regimes (2006; fully irrigated), 2007 (drought imposed at 77 days after sowing (DAS)) and 2008 (drought imposed at 30 DAS)). Bambara groundnut responded to drought by slowing the rate of leaf area expansion and reducing final canopy size and total dry matter (TDM). Drought also caused significant reductions in pod dry matter, pod numbers and harvest index (HI), leading to a decrease in final yield that was different between landraces. Throughout the three growing seasons, landraces grown at 33 °C produced more TDM than the landraces grown at 23 °C. The two landraces differed in their phenology; S19-3 exhibited a reduced phenology where leaf numbers started to decrease before Uniswa Red at both temperatures, while Uniswa Red maintained the longest life cycle. The lowest pod yield was produced by Uniswa Red in 2008 at 33 °C (maximum of 35.5 gm−2), while S19-3 produced a minimum pod yield of 56.6 gm−2 at 33 °C, also in 2008. However, both landraces produced considerably more pod yield at 23 °C throughout the three growing seasons (minimum of 151 gm−2 and 162 gm−2 for Uniswa Red and S19-3, respectively). Under moderate drought, S19-3 at 33 °C gave the highest pod yield (365 gm−2) among the treatments throughout the three growing seasons and maintained HI better under drought. Despite being from a hot, dry environment, S19-3 also performed well at low temperature, which indicates the adaptation of S19-3 to low temperature that it also experiences in the country of origin.

Climate change characterized by global warming is expected to have an incidence on fruit trees’ development and production. The severity of these effects depends on lack of chilling. The current study focused on the research of an optimal dose of hydrogen cyanamide (Dormex®) treatment which can advance the bud break of female pistachio trees (Pistacia vera L.) to ensure better blooming synchronization with pollinators. A field experiment was conducted in northern Tunisia (36°49′N, 9°48′E) on mature pistachio trees. Two hydrogen cyanamide treatments at 2% and 4% Dormex® were applied with reference to the control untreated trees. The flowering time, vegetative growth, starch content, productivity and nut characters were followed. Results show that 4% Dormex® advanced the normal bud break by 15 days and flowering by 11 days and improved natural pollination by synchronization of male and female flowers. Consequently, fresh yield and nut quality as split and blank rates and nut weight were improved. However, shoot growth, leaf area and starch content in current shoot seemed unaffected by hydrogen cyanamide applications. In conclusion, hydrogen cyanamide could be used as 4% Dormex® and sprayed 45 days before bud break to improve pistachio productivity and prevent anomalies of lack of chilling due to global warming that could be more frequent in the Mediterranean areas.

Mineral fertiliser is a scarce input for smallholder maize farmers in Malawi. A recent provision of small amounts of subsidised fertilisers by government programmes to farmers throughout Malawi has increased fertiliser access and raised maize production, but fertiliser management and yield responses frequently remain poor. To seek ways to use the fertiliser more efficiently, we analysed the effects of low rates of N (15 or 30 kg N ha−1) and P (9 kg P ha−1) fertiliser in combination with improved weed management on maize yields in experiments on 12 smallholder farms in Chisepo, central Malawi. Several indices of N and P use efficiency were computed from the above-ground crop components and nutrient contents. Maize yield simulations were conducted using long-term rainfall records in the APSIM crop-soil system model. NP fertiliser significantly (p < 0.001) raised maize grain yield from 0.65 to 1.5 t ha−1, and twice-weeding fertilised maize significantly (p < 0.001) raised maize yields by 0.4 t ha−1 compared with weeding once (0.9 t ha−1). The agronomic efficiency of applied fertiliser N (AEN) averaged 19.3 kg grain kg N−1 with one weeding but doubled to 38.7 kg with the additional weeding. The physiological efficiency of applied N (PEN) was 40.7 kg grain kg−1 N uptake. APSIM predicted that similar or larger maize yield responses to 15 or 30 kg N ha−1 can be expected in 8 out of 10 years in areas with similar rainfall patterns to Chisepo. A financial analysis showed that the application of these small amounts of fertiliser was economic even when fertiliser was purchased from the open market, provided the crop was adequately weeded. Participatory assessments helped farmers understand the increased efficiency of fertiliser use possible with additional weeding, although some farmers reported difficulty implementing this recommendation due to competing demands for labour. We conclude that to raise the productivity and sustainability of fertiliser support programmes in Malawi, initiatives should be introduced to help identify and educate farmers on the major drivers of productivity in their systems.