The effective scaling out of livelihood improvement activities is crucial for agricultural development, yet achieving sustainable change at scale remains elusive in low-income countries. The objective of our study was to analyse the livelihoods of 1,001 agricultural households in three rural districts on the East India Plateau to inform the scaling out of livelihood strategies developed during previous participatory action research. Our descriptive analysis of cross-sectional data from a primary household survey in the year 2012-2013 examined the heterogeneity in livelihood assets (natural, human, social, physical, and financial capital) and household activities. We focused on two projects. In the same rural districts, the first project included a participatory action research process, and the second project collected data on agricultural household livelihoods. We showed large inter- and intra-district heterogeneity in assets, livelihood strategies, and women's empowerment. Our study suggests that households with different assets tend to pursue different livelihood activities, such as intensifying and diversifying crop production using land and water resources documented in earlier participatory action research. These insights could inform the scaling out of livelihood improvement strategies that support stepping up. While stepping up offered potential pathways to improvements in livelihoods, these strategies had trade-offs, including increased exposure to weather variability. Our findings suggest that formative assessments of assets and livelihoods can help tailor participatory action research to specific communities.

Despite more than 50 years of research, no robust evidence suggests that inoculation of cereals and other non-legumes with free-living and/or endophytic bacteria leads to fixation of agronomically significant quantities of dinitrogen gas (N2) from the atmosphere. A plethora of new products claims to increase the growth and yields of major cereals and other crops through stimulating N2-fixation by inoculating with bacteria. We review the literature on N2-fixation by bacteria in the rhizosphere and as endophytes in non-legume plants. We find no unequivocal evidence that these bacteria fix agriculturally significant amounts of N2 from the atmosphere in non-legumes. Research since the 1930s has followed repeated, overlapping cycles that have concluded that plant-growth-promoting hormones were the primary reason for crop response to microbial inoculants. We contend that regulations are required to prevent the sale of inoculant products with unsubstantiated and spurious claims. Such regulations should require that unequivocal evidence is provided and independently verified, that: (i) the inoculant bacterium can fix N2 from the atmosphere (i.e. that it possesses all the genes required to make nitrogenase), (ii) it has a clear mechanism to protect nitrogenase from poisoning by free oxygen, (iii) the bacterium is present in sufficient numbers throughout the growth cycle of the plant, (iv) that enhanced respiration can be detected from the putative N2-fixing tissues, (v) that inoculation of the non-legume growing in an N-free medium leads to prolific growth and accumulation of nitrogen, and (vi) more than one method is used to confirm quantitatively significant inputs from N2-fixation in the field.

Background and aims Below-ground (BG) N of N 2 fixing grain legumes is an important N input to farming systems, likely underestimated as N solely in coarse roots. 15 N methodology can improve measures of BG N accumulation. Our objective was to identify a 15 N method for potential use at remote field sites. We hypothesised that method and frequency of 15 N feeding may result in different estimates of BG N. Methods Glasshouse-grown grain legumes, leaf or stem fed 15 N once or twice, were sampled three weeks after feed and at physiological maturity. Three BG fractions were isolated using 2 mm sieving; recovered cleaned roots>2 mm, unrecovered roots >2 mm remaining on sieve with adhering soil, and bulk soil that passed through sieve along with fine roots <2 mm. Fractions were measured for N/ 15 N to estimate BGN. Inorganic, total soluble organic and microbial N/ 15 N were also assessed for bulk soil. Results Estimates of BG N were not influenced by method or frequency of 15 N feeding. Recovered root N was 33–55% of estimated plant BG N at physiological maturity. Low amounts of fed 15 N detected as inorganic or soluble organic N (0.1–0.7%) and microbial biomass N (0.2–2.5%) were attributed to rhizodeposition. A large proportion of fed 15 N in bulk soil (51–67%) was present as ‘insoluble’ N attributed to fine roots. Conclusions A single 15 N stem-feeding at remote field sites should suffice to provide a measure of BG N larger than that N measured in recovered roots on a 2 mm sieve. Little evidence for direct leakage into soil labile N pools of highly labelled 15 N post-feed.

High soil strength is a problem in grain production systems worldwide. It is most severe in deep sands where the high strength occurs at greater depth, and is therefore more difficult to remedy. High strength is not an intrinsic soil physical property but the outcome of abiotic, biotic, climatic and management factors. Consequently, soil strength needs to be measured in situ with a penetrometer which, despite imperfections, provides approximate benchmarks. Following examination of laboratory, glasshouse and field literature, we hypothesise that the primary effect of high soil strength on crops is a reduction in tillering or branching, resulting in reduced radiation interception, crop transpiration and grain density (grains m − 2 ). This effect appears to be manifest via strigolactone hormones. While deep tillage allows deeper root growth and access to more water in deep soil layers, we contend that it is the direct effects of hormones on shoot development which has the largest effect on yield. The development of high soil strength cropping environments is not simply a function of soil properties and increased machinery mass and traffic frequency, it arises from a confluence of these with the farming system, the climate and perhaps plant breeding activities. An improved understanding of the relative importance of the unintended consequences of breeding, the effects of changes in fallowing practices, crop rotation, soil fertility, climate and traffic, along with a better understanding of the possible importance of bio- and macropores types provide avenues for improved management of high soil strength in grain crop production systems.

There are more than nine million ha of sandy soils (<5% clay content in the surface layer) in southern Australia. These soils can have a compacted or hard layer preventing root proliferation, a water repellent surface layer causing poor crop establishment and an adverse soil pH and low nutrient supply. Measurements of soil penetration resistance and the severity of repellency have been combined to identify which strategic deep tillage techniques should be developed to ameliorate the soil physical constraints. With the support of a collaborating team of engineers, the design features of ripping tynes and inclusion plates have been tested or modified to suit the specific constraints of these sandy soils. The objectives of this paper are to use two case study sites to describe the primary soil constraints that limit crop production across deep sandy soil environments in the Southern Australian low- to medium-rainfall environment and to demonstrate which management options provide a long-term increase in crop production. It was found that tillage techniques could overcome the adverse effects of high soil strength and water repellency on grain crop production generating significant crop production benefits on sands across multiple growing seasons, and extra benefits could be derived from nutrient-containing amendments.

Failure of the rice crop, or low rice yield has dire consequences for rice-dependent households, including food insecurity and malnutrition, for India’s poorest farmers in the East Indian Plateau region. Crop diversification could reduce the risks of rice production from the vagaries of rainfall and provide cash income which is not generated from subsistence rice. Being the primary household laborers women bear the brunt of these difficult conditions in patriarchal societies. For this reason we engaged with the women farmers in Bokaro and West Singhbhum in the State of Jharkhand, and Purulia in West Bengal who participated in experiments conducted with vegetable crops and legumes in the upland and medium uplands where the traditional crop is broadcasted paddy rice. We explored four different vegetable systems, (i) cucurbits (rainy/ kharif ) (season—June to September), (ii) growing tomatoes in the “off season” (rainy season—July to October), (iii) growing legume crops in rotation with direct sown rice (dry/rabi season—November to January), and (iv) intercropping beans with maize (rainy season—June to September). The results showed that all the above crops proved much better in terms of income to the farmers, return per person day, although the input cost varied it was higher with the new systems explored. The research with the small-holding women farmers enabled them to try new options and make informed decisions about these opportunities. This study showed that farmers can increase crop diversity and expand the area sown to non-paddy crops. The farmers are now looking for new crops where the demand exceeds the supply. Importantly this study has demonstrated that the direct involvement of communities’ in research enables the farmers to sustainability explore solutions to the future problems with limited support from the external agencies.

Grain production is a key pillar in Australia's economy but it operates within challenging climatic and edaphic environments, with unreliable and often low rainfall. Moreover many of the production landscapes have soils which have limited capacity to store water or have a range of physical, chemical or biological constraints. High soil strength has emerged as an increasing problem. Strategic deep tillage approaches (>= 30 cm) are being deployed by many farmers with significant (>50%) yield responses. However the specific mechanisms under-pinning the yield responses to deep tillage are not yet clear. Our hypothesis was that the primary response by cereal crops to deep tillage is an increase in soil water use (evapotranspiration), leading to increased grain yield. Secondly, we postulated that improved access to deep soil water following deep tillage would be reflected through an increase in grain size. Five field experiments were established across four sandy soil sites in a strongly water limited environment, with a range of tillage interventions and nutrition supplements. Measurements of crop water use, grain yield and yield components were made for three or four years post treatment. Crops responded much more to deep tillage (-15 to 100%, mean 50%) than to crop nutrition interventions (0 - 62%, mean 7%). Increases in crop water use (evapotranspiration) were modest or not evident and generally insuffi-cient to explain the magnitude of yield responses. Increased crop transpiration, ear density (n/m2) and grain number per ear contributed most to yield increases. Increased crop water use does not appear to be the main driver of grain yield responses to deep tillage in this environment, rather pre-anthesis effects on crop develop-ment, radiation interception and transpiration appear to result from direct effects of soil strength on crop tillering caused by hormonal responses, which are now beginning to be understood.

Background and Aims To sustainably manage N in oil palm systems quantities of N fixed by cover legumes need to be understood. Current values are scarce, based on shoot N measures and do not include litter which releases nitrate as it decomposes. We aimed to quantify N 2 fixed by legumes under oil palm systems in PNG and to determine if soil nitrate influenced dependence on N 2 fixation (Ndfa). Methods The ureide technique for estimating tropical legume Ndfa was calibrated for Calapogonium mucunoides and Pueraria phaseoloides using 15 N isotope dilution, and then used to assess Ndfa for legume cover under oil palms (2 to 25 years old) in Papua New Guinea. Amounts of fixed N in above-ground legume biomass (shoot plus litter) were calculated incorporating % groundcover. Soil nitrate under the legume litter was also measured. Results Legume Ndfa was highly negatively correlated with soil nitrate concentration but independent of palm age. Legume groundcover, shoot and litter dry matter, and quantity of fixed N were greater under oil palms less than 5 years old, decreasing under older plantations where solely C. caeruleum was present. DM and N content of litter were similar to shoots for legumes in plantations less than 6 years old. Conclusion The calibrated ureide technique can be used, together with estimates of annual legume N accumulation, to quantify N input from legume groundcover during the life cycle of oil palm plantations and other tropical ecosystems, in order to support more sustainable management of N.

BACKGROUND:The use of common vetch in grassland-livestock systems has expanded greatly within recent years, partly because of its value as a high-quality forage crop but also to improve the soil nitrogen availability. In-field estimation of forage yield potential and nutritional characteristics is required for providing management decision to farmers on how to optimize the management and use of common vetch forages. The aim of this work was to study changes in forage partitioning and nutritive value responses of a late-maturing and an early maturing cultivar of common vetch in a two-year study on the Tibetan Plateau. RESULTS:This study provided evidence for differential patterns of forage accumulation for common vetch with contrasting maturity over 2 years. The late-maturing cultivar exhibited greater forage yield and a lower proportion of pods, compared to the early maturing cultivar. There was a tendency towards lower forage nutritive value with the late-maturing cultivar. Regressions of nutritive value parameters of common vetch forages on growing degree days were explained by the cubic (P < 0.001) models, all with high coefficients of determination (R2  ≥ 0.792). CONCLUSION:This study shows that the late-maturing cultivar harvested at end of the pod-filling stage produces high forage yield, increasing the availability of high-quality forage for ruminants, thereby improving the self-sufficiency of farmers, in terms of forage yield and high-concentration protein. For early maturing cultivars, it may be better to harvest at the early flowering stage for better nutritive value and in part to enable a subsequent double crop of oat. © 2020 Society of Chemical Industry.

Sandy soils make up a substantial fraction of cropping land in low rainfall (<450 mm p.a.) south and south-eastern Australia. In this paper we review the possible soil constraints to increased production on these soils in this region. Many of these soils have a very low (<3%) clay content and suffer from severe water repellency, making crop establishment and weed control problematic. Crops which do emerge are faced with uneven soil wetting and poor access to nutrients, with crop nutrition constraints exacerbated by low fertility (soil organic matter < 1%) and low cation exchange capacity. Zones of high penetration resistance appear common and have multiple causes (natural settling, cementation and traffic induced) which restrict root growth to <40 cm. Crop water use and grain yield are therefore likely to be well below the water-limited potential. Water repellency is readily diagnosed and where apparent should be the primary management target. Repellency can be mitigated through the use of furrow and other sowing technologies, along with soil wetting agents. These techniques appear to be affected by site and soil nuances and need to be refined for local soils and conditions. Once crop establishment on water repellent soils has been optimised, attention could be turned to opportunities for improving crop rooting depth through the use of deep tillage or deep ripping techniques. The required ripping depth, and how long the effects may last, are unclear and need further research, as do the most effective and efficient machinery requirements to achieve sustained deeper root growth. Crop nutrition matched to the water-limited crop yield potential is the third pillar of crop production that needs to be addressed. Low soil organic matter, low cation exchange capacity, low biological activity and limited nutrient cycling perhaps make this a greater challenge than in higher rainfall regions with finer textured soils. Interactions between nutrients in soils and fertilisers are likely to occur and make nutrient management more difficult. While amelioration (elimination) of water repellency is possible through the addition of clay to the soil surface, the opportunities for this may be restricted to the ~30% of the sandy soils of the region where clay is readily at hand. The amounts of clay required to eliminate repellency (~5%) are insufficient to significantly improve soil fertility or soil water holding capacity. More revolutionary soil amelioration treatments, involving additions and incorporation of clay and organic matter to soils offer the possibility of a more elevated crop yield plateau. Considerable research would be required to provide predictive capacity with respect to where and when these practices are effective.

Nitrogen (N) supply can limit the yields of soybean [Glycine max (L.) Merr.] in highly productive environments. To explore the physiological mechanisms underlying this limitation, seasonal changes in N dynamics, aboveground dry matter (ADM) accumulation, leaf area index (LAI) and fraction of absorbed radiation (fAPAR) were compared in crops relying only on biological N2 fixation and available soil N (zero-N treatment) versus crops receiving N fertilizer (full-N treatment). Experiments were conducted in seven high-yield environments without water limitation, where crops received optimal management. In the zero-N treatment, biological N2 fixation was not sufficient to meet the N demand of the growing crop from early in the season up to beginning of seed filling. As a result, crop LAI, growth, N accumulation, radiation-use efficiency and fAPAR were consistently higher in the full-N than in the zero-N treatment, leading to improved seed set and yield. Similarly, plants in the full-N treatment had heavier seeds with higher N concentration because of greater N mobilization from vegetative organs to seeds. Future yield gains in high-yield soybean production systems will require an increase in biological N2 fixation, greater supply of N from soil or fertilizer, or alleviation of the trade-off between these two sources of N in order to meet the plant demand.

•We review components of the water balance for Australian grain crops.•For wheat, on average 38% of evapotranspiration was lost to direct soil evaporation.•No evidence for increased transpiration at the expense of soil evaporation.•Transpiration efficiencies vary within crops after accounting for vapour pressure deficit.•More robust seasonal estimates of crop transpiration efficiency are required.

This paper reviews the interactions between water and nitrogen from physiological, agronomic, economic, breeding and modelling perspectives. Our primary focus is wheat; we consider forage crops, sorghum and legumes where relevant aspects of water–nitrogen interactions have been advanced. From a physiological perspective, we ask: How does nitrogen deficit influence the water economy of the crop? How does water deficit influence the nitrogen economy of the crop? How do combined water and nitrogen deficit affect crop growth and yield? We emphasise synergies, and the nitrogen-driven trade-off between the efficiency in the use of water and nitrogen. The concept of nitrogen–water co-limitation is discussed briefly. From agronomic and economic perspectives, the need to match supply of nitrogen and water is recognised, but this remains a challenge in dryland systems with uncertain rainfall. Under-fertilisation commonly causes gaps between actual and water-limited potential yield. We discuss risk aversion and the role of seasonal rainfall forecasts to manage risk. From a breeding perspective, we ask how selection for yield has changed crop traits relating to water and nitrogen. Changes in nitrogen traits are more common and profound than changes in water-related traits. Comparison of shifts in the wheat phenotype in Australia, UK, Argentina and Italy suggests that improving yield per unit nitrogen uptake is straightforward; it requires selection for yield and allowing grain protein concentration to drift unchecked. A more interesting proposition is to increase nitrogen uptake to match yield gains and conserve protein in grain. Increased stomatal conductance is a conspicuous response to selection for yield which partially conflicts with the perception that reduced conductance at high vapour pressure deficit is required to increase water- use efficiency; but high stomatal conductance at high vapour pressure deficit may be adaptive for thermal stress. From a modelling perspective, water and nitrogen are linked in multiple ways. In crops where water limits growth, reduced biomass reduces nitrogen demand. Reciprocally, nitrogen limitation during crop expansion reduces leaf area index and increases the soil evaporation : transpiration ratio. Water–nitrogen interactions are also captured in the water-driven uptake of nitrogen by mass flow and diffusion and in the water-driven processes of nitrogen in soil (e.g. mineralisation). The paper concludes with suggestions for future research on water-nitrogen interactions.

Natural variations in the stable isotope 15N are often exploited in studies of N cycling in ecosystems. Lower 15N natural abundance in non-legume plants growing in association with legumes, compared with the non-legume grown alone in pure stands have been observed in cropping, forage, and agroforestry systems. Such observations have frequently been attributed to the transfer of biologically-fixed nitrogen (N) from the legume to the companion non-legume, and various methodologies have been employed to calculate the extent of the N transfer. While some of these 15N natural abundance-based estimates of N transfer were within the range previously reported using equivalent 15N-enriched techniques (<20% of non-legume plant N and <10 kg N ha−1 derived from fixed N contributed by neighbouring legumes), many of the values obtained using natural abundance were much higher (30%–83% of the non-legume N derived from fixed N representing up to 30–40 kg N ha−1) than generally measured by 15N-enriched methods; with even greater estimates being determined where data were available to allow N transfer to be re-calculated on the basis of total legume N rather than fixed N (42% to >100%, and up to 110 kg N ha−1 per year). This review raises concerns about the assumptions behind the natural abundance approach, and provides some alternative interpretations for the observed differences in natural 15N abundance between plants grown in the presence and absence of legumes. It was concluded that simple comparative measures of non-legume δ15N alone cannot provide a quantitative estimate of N transfer between plant species if the dominant source and the isotopic identity of the transferred N cannot be validated, and if the extent of any isotopic fractionation associated with relevant N transformations occurring during transfer cannot be defined. To date this information is not forthcoming. There is a need to greatly improve our understanding of the transfer processes before the real value of the δ15N technology can be realized. In the first instance this will primarily be achieved by carefully executed experiments under controlled conditions, and in the field, employing both 15N natural abundance and enrichment approaches so estimates of transfer can be compared, and the data interrogated using modelling approaches to explore isotopic fractionation.

Brazil is a major world coffee producer, using increasing quantities of nitrogen (N) fertilizer as the monoculture expands across the savannas. The fate and efficiency of this fertilizer N were evaluated for one complete cropping cycle using 15N tracer, permitting an N balance at harvest. Annual rates of 200, 400, 600, and 800 kg N ha−1 year−1 of 15N-labeled urea and an unfertilized control were applied every 14 days via fertigation. The N concentration, percentage of N derived from fertilizer, quantity of N derived from fertilizer, and percentage of nitrogen derived from fertilizer per N rate was assessed for 8-year-old coffee trees. The most efficient N use was with 200 kg ha−1 year−1 because it presented the lowest losses and highest N recoveries in the crop. Conversely, the least sustainable rate was 800 kg ha−1 year−1, which presented the greatest losses and the lowest N recovery in the whole plant.

An agricultural research for development project on the East India Plateau provides the context for reflecting on the conduct of research, the creation of learning opportunities, scaling out of research results, and monitoring research impact. What appears at one level as research into rice agronomy actually has profound implications for climate resilient agriculture, nutrition security and the empowerment of women. It is clear the most important outcome of our research is the development of human beings rather than the development of agricultural technology or agricultural systems. Despite often extreme disadvantage, our women research farmers have frequently demonstrated individually and collectively that they have the capacity to transform their lives. The process of engaging them in research appears to hold the key to unlocking their latent capacity for independent innovation. Our research practice continues to evolve in light of this new understanding.

Methodologies based on 15N-enrichment for estimating the transfer of nitrogen (N) between legumes and companion non-legume species in agro-ecosystems are critically reviewed and classified according to whether they (i) are direct or indirect (ii) are dependent or independent of the measurement of yield and (iii) are estimating transfer of legume N, biologically-fixed legume N, or non-legume N. The two most commonly used methods are the indirect 15N isotope dilution method and the direct 15N shoot-labelling method. Published estimates both within and between agro-ecosystems are very variable, ranging from 0 to >50% of the N present in a companion species estimated to have been derived from a companion legume. The transfer of N also occurs from companion species to legumes, but is generally much less than the opposite flux. Factors conducive to N transfer include inter alia species proximity (i.e. intimacy of root contact), legume pruning, defoliation or death and the length of the transfer period. It was concluded that two methodologies (15N2 exposure and the split-root technique) lack field applicability. New insights into the various mechanisms of N transfer in agro-ecosystems may assist in the selection or development of more appropriate methodologies for estimating N transfer by both above- and below-ground pathways.