Reduce Yield Gaps Research Articles

Unveiling the Opportunities of Unexplored Use of Cover Crop in Mediterranean Agriculture through Systematic Review and Meta-Analysis

Cover crops are multifunctional, and contribute to improving soil properties and reducing environmental impact compared to no-cover crops, thus could provide multiple soil, agricultural, and environmental benefits, and they are recognized as a valid strategy for the achievement of sustainable agriculture. However, cover crops’ impacts on subsequent cash crops and soil characteristics are dependent on several factors, such as pedoclimatic conditions, cover crop species, agricultural practices, method of termination, and irrigation management. The fact that cover crops are never applied as a single practice in the real agricultural sector, but are instead combined with other factors or agricultural practices, deeply affects their performance, but the scientific literature nevertheless keeps considering the use of cover crops alone. Moreover, the potential outcomes of cover crops that encompass other factors or agricultural practices affecting soil quality, weed control, and cash crops are still unclear. Additionally, cover crops are still poorly use in the Mediterranean type of climate. Therefore, this study reviewed the scientific literature to identify the most relevant factors or agricultural practices driving cover crops’ performance, and to outline future fields of investigation looking towards promising sustainable agriculture in Mediterranean areas with a view to minimizing the competition for soil water with the cropping systems and to reduce soil degradation. Furthermore, the investigation includes multiple factors or agricultural practices that better represent the real farming system, contributing to a comprehensive understanding of their interactions with cover crops, and suggests alternative strategies for reducing yield gap while seeking to achieve agricultural sustainability.

Early-season yield fluctuations of strawberry (Fragaria ×ananassa Duch.) follow a bimodal Gaussian model

Strawberries (Fragaria ×ananassa Duch.) are highly perishable and require intensive labor inputs for harvesting. Therefore, yield forecasting is critical for improving labor management and marketing decision-making in strawberry production. In Florida, United States, strawberry yields during winter months have a unique distribution pattern characterized by multiple waves. We hypothesized that individual yield waves can be described using Gaussian distribution, a model that represents a symmetrical bell-shaped curve. Two short-day cultivars (‘Florida Radiance’ and ‘Florida Brilliance’) and one day-neutral cultivar (‘Florida Beauty’) were grown in west-central Florida. Harvesting was performed 30 times, generally twice a week from November through February. Yield data were converted to weekly values prior to model fitting. The first two yield waves were described by a bimodal Gaussian distribution model, which was then converted into two unimodal Gaussian distribution models. The goodness of fit was very high (R2 = 0.934–0.959) for both yield waves in all tested cultivars. Different yield distribution patterns of the tested cultivars were characterized quantitatively by estimating not only the yield but also the timing and duration of each yield wave. Our modeling approach provides insights into understanding cultivar-dependent fruiting phenology, yielding capacity, and fruit earliness. Such information can help optimize yield distribution through breeding and reduce yield gaps by using different cultivars or staggered planting dates. The model developed here only applies to the first two waves of fruit production. Future research will aim to model the following yield waves to fully characterize the strawberry yield distribution.

Impactos potenciais da redução do hiato de rendimento microrregional das principais culturas alimentares no Brasil

Abstract This study aimed to measure yield gaps and the potential gains in production and revenue from mitigating these gaps for the four main food crops in Brazil and worldwide (rice, maize, soybean, and wheat). Based on the concepts of potential yield, observed yield, and yield gap, and data from the 2017 Brazilian Agricultural Census, a parameter for the potential yield of each crop was defined at the microregional level, and yield gaps and potential gains in production and revenue resulting from reducing these gaps were measured. The results showed that reducing yield gaps in Brazil for the analyzed crops may lead to an expansion in supply of these food products by almost 10% of the volume achieved in 2017, or the equivalent of 19 million tons. The greatest potential gains in yield and production were found for maize, 13.2%, valued at about US$ 1.7 billion (at 2017 prices). Soybean showed the lowest potential for gains in percentage terms (5.5%), but these gains would represent US$ 1.8 billion, the highest value among the crops analyzed.

Review of crop modelling approaches to address climate change challenges in Africa

Africa is facing an urgent need to increase food production to meet increasing demands. Targeted investments in integrated agriculture and, water management systems are required to meet this challenge. However, there is a lack of comprehensive information on the potential applications of climate-smart agriculture (CSA). This paper reviews current crop modeling technologies and their applications within the scope of climate change and the CSA framework in Africa. It evaluates current research trends in various crop simulation models and suggest advanced approaches to improve crop and environmental assessment, crop management, and decision-making. A total of 140 relevant papers were considered. Results showed that 84% of studies used process-based models, with Maize being the most studied crop. Additionally, DSSAT crop models and analysis of variance models have the highest contribution of physical and empirical crop modeling studies respectively. Over 72% of studies have contributed to adaptation strategies and reducing yield gaps, while only 8% of studies have been conducted on climate change mitigation and their trade-offs with adaptation using crop models under CSA. To ensure food security through sustainable agricultural practices in Africa, there is crucial to implement CSA models with a focus on the climate change mitigation component.

A yield gap analysis to assess vulnerability of commercial sugarcane to climatic extremes in southern Africa

Sugarcane yields have steadily declined across southern Africa for the past 25 years and, despite research into the causes, there has been limited progress in addressing these trends. This study developed a methodology of assessing yield declines and performed a yield gap analysis to assess and develop recommendations to assist in combating yield declines and offering potential safeguards for the sugarcane industry against climatic extremes. Mill areas from South Africa, eSwatini, Malawi and Tanzania were selected, providing a diversity of regional hydroclimatic conditions and sugarcane agronomic management approaches. Using the AquaCrop crop model, maximum potential yields and yield gaps were simulated based on observed climate and yield data spanning 25 years. Results show that yields are declining for the mill areas in South Africa, Malawi and Tanzania, resulting in increased yield gaps, whilst yields are stagnant in eSwatini resulting in relatively fixed yield gaps. Yield gaps remained high across all six mill areas, suggesting that they remain vulnerable and exposed to climatic extremes. Modelling results suggest that these yield trends, including yield gaps, are primarily attributed to existing crop management approaches as opposed to the climatic regimes in these areas. Recommendations include several solutions that could result in an immediate response and reduce yield gaps while increasing harvestable yields. Such measures include increasing technology transfer and agronomic management education to small-scale outgrowers, adopting drought-resistant, high-yielding sugarcane varieties, contouring and mulching, improving soil structural properties and minimizing in-field traffic. The study concludes that if sugarcane growers are to withstand the effects of extreme climatic events, they have to consider shifting crop management approaches and be proactively included in related research.

Hill-placement of manure and fertilizer for improving maize nutrient- and water-use efficiencies in the northern Benin

Optimizing the use of organic and mineral fertilizer in rain-fed maize production is crucial for sustainable food production in sub-Saharan Africa. This study investigates the effect of hill-placement of two nutrient sources (farmyard manure and synthetic fertilizer) on nutrient- and water-use efficiencies of maize crops i.e. recovery efficiency (NUEre), internal utilization efficiency (NUEie) and water use efficiency (WUE). A four-year trial was conducted in the tropical sub-humid zone of the northern Benin with a factorial combination of farmyard manure at three levels (0, 3 and 6 t ha−1, hereafter NM, 3M and 6M, respectively) and three levels of fertilizer [0% (NF), 50% (50F) and 100% (100F) of the recommended rate (76 kg N + 13.1 kg P + 24.9 kg K ha−1) by the national center for agricultural research. The NUEre decreased with increasing rate of manure and/or fertilizer, but the decreasing rate was lower under combined manure and fertilizer application. However, the NUEie increased with the increasing manure and fertilizer amounts. The WUE was significantly higher in 3M and 6M treatments than in NM treatment, and higher in 50F and in 100F than in NF treatments. The combination of 3000 kg ha−1 farmyard manure with half recommended fertilizer rate (100 kg ha−1) could be suggested as an optimal nutrient management practice for maize production in the Northern Benin. Future studies should target the other agro-ecological zones in Benin, and also consider other widely cultivated crops in the study area for reducing yield gaps and promote food security.

Foliar fungicides help maize farmers reduce yield gaps in late sown crops in a temperate region

Foliar diseases produce significant maize (Zea maize L.) yield reductions, increasing yield gaps and threatening food security. In the central temperate region of Argentina 50 % of maize cropped is grown under late sowing dates (December), where meteorological conditions are favorable to disease development, such as higher temperatures during initial stages and higher relative humidity. However, no major testing was reported to fully understand yield responses to foliar fungicides. Our objectives were to quantify the impact of foliar fungicide application on grain yield in late sown crops, and to identify genotype, management, and environmental interactions modulating the yield response. We conducted 21 on-farm trials during 6 growing seasons (2014/15 and from 2016/17 to 2020/21) with and without a fungicide, each trial having 8–20 commercial hybrids. Fungicide application was done between V8 and V12 stages (eight and twelve fully expanded leaves, respectively), using a commercial fungicide mix of azoxystrobin and cyproconazole. Average yield variation across sites ranged from 4359 to 12,101 kg ha−1, and fungicide use produced an average positive yield increase of 472 kg ha−1 (or 5.8 %). The yield increase varied from no response to 1282 kg ha−1 across sites, and was not correlated to the site yield. Fungicide application explained 1.9 % of the total yield variation, higher than its interaction with either site or genotype (1.1 and 0.1 % of total yield variance, respectively). Mean temperature from sowing to V14 (fourteen fully expanded leaves) helped explain the crop yield response variation to fungicide application across sites, increasing by 138 kg ha−1 °C−1 in response to higher mean temperature (explored temperatures from 21.9 to 26.4 °C). Our results illustrate the relevance of fungicide applications to reduce yield gaps, where described predictors can help farmer optimize this decision.

Intensive management simultaneously reduces yield gaps and improves milling and baking properties of bread wheat

AbstractGenotype (G), environment (E), management (M), and their interactions determine grain yield, biochemical composition, and quality of wheat. However, we are not aware of studies evaluating whether intensive management can simultaneously reduce yield gaps and improve wheat milling and baking attributes, which were our main objectives. A factorial experiment of five genotypes × four management intensities (farmer practice, high‐input, high‐input minus nitrogen, and high‐input minus fungicide) was conducted in six Kansas (United States) environments resulting from the combination of four locations and three seasons. Grain yield and 13 parameters characterizing the grain (test weight [TWT], thousand kernel weight [TKW], grain protein [GP]), flour (e.g., ash, protein), dough (e.g., water absorption [WA], dough stability [DS]), and baking qualities (loaf volume [LV]) were measured. For most variables, the primary contributor of the variance was E while M and G were secondary and tertiary contributors, except for LV in which G was a larger moderator. High input practices increased yield (4206 kg ha−1) compared to farmer practice (3347 kg ha−1) suggesting a yield gap of 859 kg ha−1. Management intensities receiving foliar fungicides improved grain properties related to milling characteristics (i.e., TKW and TWT), while management intensities receiving more nitrogen improved baking characteristics (e.g., WA and DS). Across sources of variation, yield response to improved management associated positively with the responses of TKW, TWT, and in some cases, GP, and WA. Our results showed the possibility of simultaneously improving grain yield and selected milling and baking attributes of bread wheat genotypes through intensive management.

Grapevine Yield Big-data for Soil and Climate Zoning. A case study in Languedoc-Roussillon, France

New winegrower and resource datasets appear to be a great opportunity to understand which are the environmental factors involved in grapevine yield spatially. Such analysis can help regional label managers and winegrowers for the conception of local adaptation strategies to climate change, reducing yield gaps. In the present study, we aggregated yield a big dataset obtained from Pays d’Oc winegrowers (n = 96677) between 2010 and 2018 at the municipality level (n = 606), located in the Languedoc-Roussillon region, in the South of France. We used a backward stepwise model selection process using linear mixed-effect models to discriminate and select significant indicators capable of estimating grapevine yield at the municipality level, these include: Soil Available Water Capacity (SAWC), soil pH, Huglin Index, the Climate Dryness Index, the number of Very Hot Days and Days of Frost. We then determined spatial zones by creating clusters of municipalities with similar soil and climate characteristics. The seven zones presented two marked yield levels. Yet, all zones had municipalities with both high yield and high yield gaps. On each zone, grapevine yield was found to be driven by a combination of climate and soil factors, rather than just by a single environmental factor. Environmental factors at this scale largely explained yield variability across the municipalities, but they were not performant in terms of annual yield prediction. Further research is required on the interactions between environmental factors, plant material and farming practices.

Genotype-dependent responses of Andean and Coastal quinoa to plant population density for yield and its physiological determinants in Northwest Argentina

Context In quinoa, similar yields are found under a wide range of plant population densities due to its phenotypic plasticity. Aims This study aimed to identify optimal plant population densities for achieving attainable yields, in relation to the most adapted genotype for a given environment. Methods Andean (RQ252 and RQ420) and Coastal (Titicaca and Puno) genotypes were tested at conventional (14 plants/m2) and low (7 plants/m2) plant population densities, in Dry Valley and Highland mega-environments for 2 years. Key results More than 64% of total variation was explained by genotype, location, and interaction effects for grain yield, biomass, and harvest index. For these variables, the genotype × location × plant population density term presented the highest percentage of variation among triple and quadruple interaction terms. In the Highlands, grain yields decreased with plant population density for Andean genotypes (30–40%), in contrast to lower reductions for Coastal genotypes (9–20%). In the Dry Valleys, no effect of plant population density was found for all genotypes. In the Highlands, reductions in biomass and harvest index explained grain yield response, in parallel with increases in small grain percentage of up to 16% when frosts came early, related to uneven maturity at low plant population density. Conclusions Attainable yields in Northwest Argentina were achieved by exploring local adaptation and response to plant population density of Andean genotypes in the Highlands, in contrast to stable yields of Coastal genotypes through locations and plant population densities. Implications Understanding genotype-dependent responses to plant population density according to Northwest Argentina mega-environments can reduce yield gaps in quinoa production and refine breeding strategies.

Applied Biotechnological Approaches for Reducing Yield Gap in Melon Grown Under Saline and Drought Stresses: an Overview

Applied Biotechnological Approaches for Reducing Yield Gap in Melon Grown Under Saline and Drought Stresses: an Overview

Impact of soil compaction on 30-year soybean yield simulated with CROPGRO-DSSAT

CONTEXTSoil compaction is a threat to crop yield, but mechanical decompaction operations increase soil degradation risk and crop costs. The decision about soil management practices that minimize yield loss depends on the impact of soil compaction on crop yield. However, the relationship between soil compaction and crop yield is affected by rainfall pattern, which changes over the years. Long-term effect of soil compaction in crop yield is wide unknown, and fill this gap is crucial for adjust soil management to improve soil conservation and increase crop yield. OBJECTIVETo evaluate the impact of soil compaction on soybean yield over 30 crop seasons using DSSAT CSM-CROPGRO-Soybean model. METHODSSoybean yield was simulated in hypothetical soil profiles of sandy loam, silty loam and clay soils and 12 scenarios of soil compaction (contrasting scenarios - from a whole compacted profile to one compacted layer). We also set two hypothetical reduced rooting depths and three levels of reduced root proliferation due to soil compaction by changing the soil root growth factor parameter to mimic the mechanical stress effect on root growth on DSSAT. Simulations were carried out with data (1990 to 2020) from a weather station located in Southern Brazil and with soybean genetic parameters calibrated for the same region. RESULTS AND CONCLUSIONSThe reduction in soybean yield due to soil compaction estimated by DSSAT was lower than 0.1 Mg ha−1 in simulations with well-distributed rainfall (every 2 weeks or shorter) but it reached 4.1 Mg ha−1 in simulations with periods without rainfall longer than 2 weeks. The simulated cumulative reduction in soybean yield over 30 years due to soil compaction reached up to 39% of the potential yield, of which 77% was associated with the decrease in rooting depth and 21% with the reduction in soil water availability. Thus, a reliable overview of the effect of soil compaction on soybean yield should consider the interactions between soil, plant and weather variables. SIGNIFICANCEThis work presents a strategy based on DSSAT simulations to assess the relation between crop yield and soil compaction, which is a worldwide demand still fed with scarce data. Researchers, farmers, technicians and decision makers can replicate and improve this strategy to simulate the negative impact of soil compaction on soybean yield and many other crops, which can assist them to adjust management practices to minimize soil degradation and reduce yield gaps.

Modulation of Wheat Yield Components in Response to Management Intensification to Reduce Yield Gaps.

Appropriate genotype selection and management can impact wheat (Triticum aestivum L.) yield in dryland environments, but their impact on yield components and their role in yield modulation are not well understood. Our objectives were to evaluate the yield response of commercial winter wheat genotypes to different management practices reflecting a stepwise increase in management intensity (including a reduction in crop density under high input), and to quantify how the different yield components modulate wheat yield. A factorial experiment evaluated six management (M) intensities [“farmer practice” (FP), “enhanced fertility” (EF), “ecological intensification” (EI), “increased foliar protection” (IFP), “water-limited yield” (Yw), and “increased plant productivity” (IPP)] and four winter wheat genotypes (G) in four Kansas environments (E). Average grain yield was 4.9 Mg ha–1 and ranged from 2.0 to 7.4 Mg ha–1, with significant two-way interactions (E × M and E × G). The EF usually maximized yields in dry environments, while EI, which consisted of EF plus one fungicide application, maximized yields in environments with greater water availability. Across all sources of variation, kernels m–2 and aboveground biomass were the strongest modulators of yield as compared to kernel weight and harvest index, while spikes m–2 and kernels spike–1 modulated yields at a similar magnitude. Foliar fungicides improved yield through increased green canopy cover duration and greater radiation intercepted during grain filling. When crop density was reduced from 2.7 to 1.1 million plants per hectare in an otherwise high-input system, plants produced more productive tillers (with genotype-specific response); however, reduced green canopy cover at anthesis and reduced cumulative solar radiation intercepted during grain filling limited wheat yield—although large differences in canopy cover or intercepted radiation were needed to cause modest changes in yield. Treatments more intensive than EI were not warranted as EF or EI maximized yields at all environments, and practices that promote biomass and kernels m–2 are to be targeted for future increases in wheat yield.

Novel Genetic Variation Through Altered zmm28 Expression Improves Maize Performance Under Abiotic Stress

We previously reported that extended and increased expression of the native maize gene zmm28 in maize resulted in transgenic events with greater grain yields under optimum field environments. Here we report additional positive impacts of altered zmm28 expression on improving yield stability of maize in the presence of the key abiotic stresses of water deficit and low nitrogen (N). Transgenic zmm28 elite hybrids were evaluated with their wild type (WT) comparators in multiple Managed Stress Environments (MSE), where a water deficit stress was imposed at flowering (FS) or during grain fill (GFS), or where N application was restricted (LN). Across 5 years of testing (2014–2018, 1600 comparisons, 80 hybrids, 43 locations), the ZmGos2-zmm28 lead event DP202216 increased yield relative to WT an average of 479 kg ha -1 (6.6%), 345 kg ha -1 (3.4%) and 166 kg ha -1 (2.0%) in FS, GFS and LN environments, respectively. Maximum observed yield response across 6–12 transgenic hybrids in a single location x year combination was 1181 kg ha -1 (13.9%), 860 kg ha -1 (9.4%) and 834 kg ha -1 (7.0%), relative to WT, for FS, GFS and LN, respectively. Another independent event, DP382118, provided similar yield improvements in the same environments, confirming overall confidence in the performance of the construct functional gene. In a separate genetic penetration study in 2018, DP202216 increased yield an average of 487 kg ha -1 (4.4%) over a combined set of GFS and FS locations, where 6 SS Bulk F3 populations were crossed with 6 diverse NSS testers (36 hybrids), confirming consistent positive yield responses across diverse germplasm under water-limited conditions. The improved yield stability of multiple elite ZmGos2-zmm28 transgenic hybrids demonstrated over multiple years of abiotic stress exposure indicates this novel transgenic variation can contribute to the sustainable intensification of maize production that will be required to address global yield gaps. • Altered expression of zmm28 increases abiotic stress performance in maize. • Zmm28 transgenic hybrids demonstrate improved maize grain yield stability. • Transcription factors may be used to reduce yield gaps in maize.

Assessing the impact of high-input management for reducing soybean yield gaps on high-productivity farms

To increase soybean actual yields (Ya), modern farmers are interested in exploring novel intensification options. We hypothesize that the inclusion of a high-input treatment in high-productivity systems may potentially reduce yield gaps (Yg), representing additional profits for farmers. Our objectives were to: (i) estimate Ya, water-limited yield potential (Ywlim), and Yg; (ii) evaluate a high-input treatment as a management option for reducing Yg; (iii) identify management and environmental factors associated to yield response to inputs and, (iv) determine the economic outcome of this high-input management on high-productivity soybean crops. We carried out 27 on-farm field experiments comparing a conventional management system versus a novel high-input treatment across the Central Pampas of Argentina. The conventional treatment was the most common management prescribed by farmers in the region. The high-input treatment included a set of inputs that were not usually applied and involved soil fertilizers with S and Zn, seeds treated with insecticides, fungicides, and inoculants, stress-reducing product, Ca and B foliar fertilizers and preventive insecticide. The Ywlim was estimated using crop simulation models. Yield gaps were calculated as the difference between Ywlim and Ya. Average Ya and Ywlim were 4571 and 5100 kg ha−1, respectively, with a Yg lower than 30%. High-input treatments promoted a yield response of 131 kg ha−1 across sites (p < 0.001), reducing Yg by 2.6%. Yield response to high-input treatment was positively correlated with Yg and soil pH, but negatively correlated with soil P. No positive economic outcomes were obtained with the high-input treatment. This study showed low benefits of the high-input treatments for reducing Yg in high-yielding soybeans managed by high-productivity farmers. Future yield increases in this type of systems would rely on genetic improvement of soybean yield potential and exploiting genotype x management x environment interactions.

“The maize is the cost of the farming, and the cassava is our profit”: smallholders’ perceptions and attitudes to poor crop patches in the eastern region of Ghana

BackgroundCrop yields are lowest in sub-Saharan Africa compared to other regions, and this is true even for such an important staple crop as maize. Persistence of patches of low crop vigour side-by-side to patches with healthier maize crops has been shown to significantly contribute to low yields on smallholdings. Farmers' perspectives on the presence of such poor patches are important as far as their on-farm investment attitudes are concerned. We analyse maize yield levels and farmers’ perspectives of their production levels in two farming communities in rural Ghana.ResultsWe find substantial potential for yield improvements; while local attainable yields (average of the yields attained by the top 10% of farmers in each village) were 4.4 t/ha and 3.6 t/ha, average crop cut yields were 2.0 t/ha and 2.4 t/ha for Asitey and Akatawia, respectively. As much as 62% of the maize fields in both study locations were unable to reach the respective average village yield level. From the photo-elicitation interviews, the general attitude of smallholders to the presence of poor patches is that of indifference. We find contradictions in farmers’ perceptions and attitudes towards low yields. While more than half (54%) perceived they were getting adequate yields relative to their expectations, an even greater proportion (88%) of farmers interviewed aver that their plots could yield much more. Similarly, a significant majority (63%) did not attempt to remedy the poor patches even though the same proportion perceive that it is worth it to invest in yield-improving inputs.ConclusionsFarmers in such contexts view investments in fertilizers on their farms as too risky. As alternatives, they would rather invest their already limited resources in non-farm ventures. Farmers opt for yield optimization rather than maximization and this has important implications for diversification off the farm. These findings have important implications for smallholder households’ ability to meet their subsistence needs and for efforts to reduce yield gaps on small farms particularly in resource-poor contexts.

Assessment of the 2006 Abuja Fertilizer Declaration With Emphasis on Nitrogen Use Efficiency to Reduce Yield Gaps in Maize Production

The Abuja Fertilizer Declaration in 2006 recommended the increase of fertilizer use from the current practice for Sub-Saharan Africa (SSA) to achieve food sufficiency and improve soil fertility status. However, the current recommended rates of fertilizer have not been evaluated for specific crops on their potential to reduce the yield gap and optimize nitrogen use efficiency (NUE). In this study, with nitrogen (N) being a significant yield-determinant nutrient, four N use scenarios were drawn from existing recommendations and were evaluated under field conditions for maize crops in two catchments of the Lake Victoria basin. The scenarios included Business as Usual (BAU, 0 kg N ha−1), 25% of the Abuja declaration (ADS 12.5 kg N ha−1), 50% of the Abuja declaration (ADS 25 kg N ha−1), and Abuja declaration–Abuja scenario (ADS, 50 kg N ha−1). The results revealed that increasing N input levels significantly influenced the growth and yield of maize crops. The ADS scenario recorded the highest grain yield increase (167.39%) in Nyando and 103.25% in Rangwe catchments compared to the BAU scenario. N deficits were observed in all the N use scenarios with a range of −66.6 to −125.7 kg N ha−1 in Nyando and −62.5 to −105.4 kg N ha−1 in Rangwe catchments with the 50% ADS scenario having the highest deficits. The deficits imply that the added N input is insufficient to create an N balance for optimal NUE with consequent high risks of soil N mining. In both catchments, all N use scenarios were within the recommended agro-physiological N efficiency (APEN) level of between 40 and 60 kg kg−1 N. The partial N balance obtained at Nyando (1.56–3.11) and Rangwe (1.10–4.64) was higher than the optimal values, a sign of insufficiency of N inputs and possible risk of soil N depletion in all the scenarios. Our findings conclude that the proposed N rates in the region are still very low for food sufficiency and optimized NUE. Therefore, there is a need to explore other sources of N such as biological N fixation and organic manure and inform policy- and decision-makers to recommend higher rates beyond the “Abuja declaration” with the prospect of reaching target yield and optimizing NUE values based on specific crop recommendations.

Weed Management Role in Meeting the Global Food and Nutrition Security Challenge

The global agricultural production must increase by around 70% to meet the food and nutrition demands of 9.9 billion people, by 2050. It was predicted that 670 million people will still be undernourished in 2030. Hence, feasible and cost-effective strategies in the global agri-food system need to be implemented for meeting nutrition security. Weed management played a key role in achieving global food and nutrition security, till to date. In this paper the role of weed management in meeting food and nutrition security is revisited in view of the changed scenario of prevailing unintended ecological imbalance, climate change, water overuse and waste, soil degradation, loss of natural resource quality, and declines in biodiversity, increased herbicide use, and chemical runoff that are decreasing crop growth yields and raising reasonable concerns about the sustainability of the current agricultural methods in meeting the future food and nutrition security. The future role of weed management is discussed in terms of: reducing the continued losses caused by weeds and improving crops productivity and production by reducing yield gap; improving resources (land, water, light, nutrients); improving farmers income; advancement of farmers livelihood; combating climate change and balancing biodiversity. The possible role of climate resilient integrated weed management in playing the intended roles in agri-food system is discussed. In order to play much more sustainable role, the weed management, as an integral part of agricultural production, needs to move away from its mono-disciplinary perspective at targeting weeds to multidisciplinary and multifaceted technological solution to serve as a component of overall technological solutions to improve agricultural production for achieving ever increasing food and nutritional security challenges.

Monitoring and Analyzing Yield Gap in Africa through Soil Attribute Best Management Using Remote Sensing Approaches: A Review

Africa has the largest population growth rate in the world and an agricultural system characterized by the predominance of smallholder farmers. Improving food security in Africa will require a good understanding of farming systems yields as well as reducing yield gaps (i.e., the difference between potential yield and actual farmer yield). To this end, crop yield gap practices in African countries need to be understood to fill this gap while decreasing the environmental impacts of agricultural systems. For instance, the variability of yields has been demonstrated to be strongly controlled by soil fertilizer use, irrigation management, soil attribute, and the climate. Consequently, the quantitative assessment and mapping information of soil attributes such as nitrogen (N), phosphorus (P), potassium (K), soil organic carbon (SOC), moisture content (MC), and soil texture (i.e., clay, sand and silt contents) on the ground are essential to potentially reducing the yield gap. However, to assess, measure, and monitor these soil yield-related parameters in the field, there is a need for rapid, accurate, and inexpensive methods. Recent advances in remote sensing technologies and high computational performances offer a unique opportunity to implement cost-effective spatiotemporal methods for estimating crop yield with important levels of scalability. However, researchers and scientists in Africa are not taking advantage of the opportunity of increasingly available geospatial remote sensing technologies and data for yield studies. The objectives of this report are to (i) conduct a review of scientific literature on the current status of African yield gap analysis research and their variation in regard to soil properties management by using remote sensing techniques; (ii) review and describe optimal yield practices in Africa; and (iii) identify gaps and limitations to higher yields in African smallholder farms and propose possible improvements. Our literature reviewed 80 publications and covered a period of 22 years (1998-2020) over many selected African countries with a potential yield improvement. Our results found that (i) the number of agriculture yield-focused remote sensing studies has gradually increased, with the largest proportion of studies published during the last 15 years; (ii) most studies were conducted exclusively using multispectral Landsat and Sentinel sensors; and (iii) over the past decade, hyperspectral imagery has contributed to a better understanding of yield gap analysis compared to multispectral imagery; (iv) soil nutrients (i.e., NPK) are not the main factor influencing the studied crop productivity in Africa, whereas clay, SOC, and soil pH were the most examined soil properties in prior papers.

Field-level factors for closing yield gaps in high-yielding rice systems of Uruguay

Yield gap assessments at the field-level are key for developing management practices to increase crop production in a sustainable manner. Although rice is an important food crop worldwide, yield gaps remain less investigated in Latin American rice systems. In this study, we evaluated field-level factors for closing yield gaps (based on attainable farm yield, defined as the mean of top 10 % of farmers) for rice production in Uruguay using crop management and yield records from 2012 to 2017, covering approximately 70,000 ha per year (40 % of total rice area). The mean annual attainable yield gap ranged from 16 % to 22 % in fields with non-hybrid cultivars (90 % of planted area) and from 14 % to 22 % in fields with hybrid rice (10 % of planted area). Early seeding was identified as the most influential factor for reducing yield gaps in both systems, followed by N rate. Stand establishment was also important for closing yield gap in non-hybrid fields, while rotation with improved pasture was important in hybrid fields. When variables were categorized as input-related, manageable, or non-manageable, on average manageable factors (e.g. early planting and stand establishment) were more important than input-related factors (e.g. seed or fertilizer rate). This study highlights a simple, self-contained method using large field-level datasets to quantify yield gaps and develop strategies for improving agricultural productivity.