Failure to scale in digital agronomy: An analysis of site-specific nutrient management decision-support tools in developing countries.

While many have extolled the potential impacts of digital advisory services for smallholder agriculture, the evidence for sustained uptake of such tools remains limited. This paper utilizes a survey of tool developers and researchers, as well as a systematic meta-analysis of prior studies, to assess the extent and challenges of scaling decision support tools for site-specific soil nutrient management (SSNM-DST) across smallholder farming systems, where "scaling" is defined as a significant increase in tool usage beyond pilot levels. Our evaluation draws on relevant literature, expert opinion and apps available in different repositories. Despite their acclaimed yield benefits, we find that SSNM-DST have struggled to reach scale over the last few decades and, with strong heterogeneity in adoption among intended stakeholders and tools. For example, the log odds of a SSNM-DST reaching 5-10 % of the target farmers compared with reaching none, decreases by âˆ¼200% when a technical problem is stated as a reason for the tools' failure to be used at scale. We find a similar decrease in odds ratios when technical, socioeconomic, policy, and R&D constraints were identified as barriers to scaling by national extension and private systems. Meta-regression analysis indicates that the response ratio of using SSNM-DST over Farmer Fertilizer Practice (FFP) varies by non-tool related covariates, such as initial crop yield potential under FFP, current and past crop types, acidity class of the soil, temperature and rainfall regimes, and the amount of input under FFP. In general, the SSNM-DST have moved one step forward compared with the traditional 'blanket' fertilizer recommendation by accounting for in-field heterogeneities in soil and crop characteristics, while remaining undifferentiated in terms of demographic and socioeconomic heterogeneities among users, which potentially constrains adoption at scale. The SSNM-DSTs possess reasonable applicability and can be labeled 'ready' from purely scientific viewpoints, although their readiness for system-level uptake at scale remains limited, especially where socio-technical and institutional constraints are prevalent.

Regenerative Agriculture: An agronomic perspective.

Agriculture is in crisis. Soil health is collapsing. Biodiversity faces the sixth mass extinction. Crop yields are plateauing. Against this crisis narrative swells a clarion call for Regenerative Agriculture. But what is Regenerative Agriculture, and why is it gaining such prominence? Which problems does it solve, and how? Here we address these questions from an agronomic perspective. The term Regenerative Agriculture has actually been in use for some time, but there has been a resurgence of interest over the past 5 years. It is supported from what are often considered opposite poles of the debate on agriculture and food. Regenerative Agriculture has been promoted strongly by civil society and NGOs as well as by many of the major multi-national food companies. Many practices promoted as regenerative, including crop residue retention, cover cropping and reduced tillage are central to the canon of 'good agricultural practices', while others are contested and at best niche (e.g. permaculture, holistic grazing). Worryingly, these practices are generally promoted with little regard to context. Practices most often encouraged (such as no tillage, no pesticides or no external nutrient inputs) are unlikely to lead to the benefits claimed in all places. We argue that the resurgence of interest in Regenerative Agriculture represents a re-framing of what have been considered to be two contrasting approaches to agricultural futures, namely agroecology and sustainable intensification, under the same banner. This is more likely to confuse than to clarify the public debate. More importantly, it draws attention away from more fundamental challenges. We conclude by providing guidance for research agronomists who want to engage with Regenerative Agriculture.

Science-based decision support for formulating crop fertilizer recommendations in sub-Saharan Africa.

In sub-Saharan Africa, there is considerable spatial and temporal variability in relations between nutrient application and crop yield, due to varying inherent soil nutrients supply, soil moisture, crop management and germplasm. This variability affects fertilizer use efficiency and crop productivity. Therefore, development of decision systems that support formulation and delivery of site-specific fertilizer recommendations is important for increased crop yield and environmental protection. Nutrient Expert (NE) is a computer-based decision support system, which enables extension advisers to generate field- or area-specific fertilizer recommendations based on yield response to fertilizer and nutrient use efficiency. We calibrated NE for major maize agroecological zones in Nigeria, Ethiopia and Tanzania, with data generated from 735 on-farm nutrient omission trials conducted between 2015 and 2017. Between 2016 and 2018, 368 NE performance trials were conducted across the three countries in which recommendations generated with NE were evaluated relative to soil-test based recommendations, the current blanket fertilizer recommendations and a control with no fertilizer applied. Although maize yield response to fertilizer differed with geographic location; on average, maize yield response to nitrogen (N), phosphorus (P) and potassium (K) were respectively 2.4, 1.6 and 0.2 t ha-1 in Nigeria, 2.3, 0.9 and 0.2 t ha-1 in Ethiopia, and 1.5, 0.8 and 0.2 t ha-1 in Tanzania. Secondary and micronutrients increased maize yield only in specific areas in each country. Agronomic use efficiencies of N were 18, 22 and 13 kg grain kg-1 N, on average, in Nigeria, Ethiopia and Tanzania, respectively. In Nigeria, NE recommended lower amounts of P by 9 and 11 kg ha-1 and K by 24 and 38 kg ha-1 than soil-test based and regional fertilizer recommendations, respectively. Yet maize yield (4 t ha-1) was similar among the three methods. Agronomic use efficiencies of P and K (300 and 250 kg kg-1, respectively) were higher with NE than with the blanket recommendation (150 and 70 kg kg-1). In Ethiopia, NE and soil-test based respectively recommended lower amounts of P by 8 and 19 kg ha-1 than the blanket recommendations, but maize yield (6 t ha-1) was similar among the three methods. Overall, fertilizer recommendations generated with NE maintained high maize yield, but at a lower fertilizer input cost than conventional methods. NE was effective as a simple and cost-effective decision support tool for fine-tuning fertilizer recommendations to farm-specific conditions and offers an alternative to soil testing, which is hardly available to most smallholder farmers.

DOES SIZE MATTER? A CRITICAL REVIEW OF META-ANALYSIS IN AGRONOMY.

Intended to test broad hypotheses and arrive at unifying conclusions, meta-analysis is the process of extracting, assembling, and analyzing large quantities of data from multiple publications to increase statistical power and uncover explanatory patterns. This paper describes the ways in which meta-analysis has been applied to support claims and counter-claims regarding two topics widely debated in agricultural research, namely organic agriculture (OA) and conservation agriculture (CA). We describe the origins of debate for each topic and assess prominent meta-analyses considering data-selection criteria, research question framing, and the interpretation and extrapolation of meta-analytical results. Meta-analyses of OA and CA are also examined in the context of the political economy of development-oriented agricultural research. Does size matter? We suggest that it does, although somewhat ironically. While meta-analysis aims to pool all relevant studies and generate comprehensive databases from which broad insights can be drawn, our case studies suggest that the organization of many meta-analyses may affect the generalizability and usefulness of research results. The politicized nature of debates over OA and CA also appear to affect the divergent ways in which meta-analytical results may be interpreted and extrapolated in struggles over the legitimacy of both practices. Rather than resolving scientific contestation, these factors appear to contribute to the ongoing debate. Meta-analysis is nonetheless becoming increasingly popular with agricultural researchers attracted by the power for the statistical inference offered by large datasets. This paper consequently offers three suggestions for how scientists and readers of scientific literature can more carefully evaluate meta-analyses. First, the ways in which papers and data are collected should be critically assessed. Second, the justification of research questions, framing of farming systems, and the scales at which research results are extrapolated and discussed should be carefully evaluated. Third, when applied to strongly politicized topics situated in an arena of scientific debate, as is the case with OA and CA, more conservative interpretations of meta-analytical results that recognize the socially and politically embedded nature of agricultural research is are needed.

Capturing farm diversity with hypothesis-based typologies: An innovative methodological framework for farming system typology development.

Creating typologies is a way to summarize the large heterogeneity of smallholder farming systems into a few farm types. Various methods exist, commonly using statistical analysis, to create these typologies. We demonstrate that the methodological decisions on data collection, variable selection, data-reduction and clustering techniques can bear a large impact on the typology results. We illustrate the effects of analysing the diversity from different angles, using different typology objectives and different hypotheses, on typology creation by using an example from Zambia's Eastern Province. Five separate typologies were created with principal component analysis (PCA) and hierarchical clustering analysis (HCA), based on three different expert-informed hypotheses. The greatest overlap between typologies was observed for the larger, wealthier farm types but for the remainder of the farms there were no clear overlaps between typologies. Based on these results, we argue that the typology development should be guided by a hypothesis on the local agriculture features and the drivers and mechanisms of differentiation among farming systems, such as biophysical and socio-economic conditions. That hypothesis is based both on the typology objective and on prior expert knowledge and theories of the farm diversity in the study area. We present a methodological framework that aims to integrate participatory and statistical methods for hypothesis-based typology construction. This is an iterative process whereby the results of the statistical analysis are compared with the reality of the target population as hypothesized by the local experts. Using a well-defined hypothesis and the presented methodological framework, which consolidates the hypothesis through local expert knowledge for the creation of typologies, warrants development of less subjective and more contextualized quantitative farm typologies.

Beyond conservation agriculture.

Global support for Conservation Agriculture (CA) as a pathway to Sustainable Intensification is strong. CA revolves around three principles: no-till (or minimal soil disturbance), soil cover, and crop rotation. The benefits arising from the ease of crop management, energy/cost/time savings, and soil and water conservation led to widespread adoption of CA, particularly on large farms in the Americas and Australia, where farmers harness the tools of modern science: highly-sophisticated machines, potent agrochemicals, and biotechnology. Over the past 10 years CA has been promoted among smallholder farmers in the (sub-) tropics, often with disappointing results. Growing evidence challenges the claims that CA increases crop yields and builds-up soil carbon although increased stability of crop yields in dry climates is evident. Our analyses suggest pragmatic adoption on larger mechanized farms, and limited uptake of CA by smallholder farmers in developing countries. We propose a rigorous, context-sensitive approach based on Systems Agronomy to analyze and explore sustainable intensification options, including the potential of CA. There is an urgent need to move beyond dogma and prescriptive approaches to provide soil and crop management options for farmers to enable the Sustainable Intensification of agriculture.

Applying Parallel Factor Analysis models to HPLC diode array detector datasets reveals strain dependent regulation of polyketide biosynthesis in Fusarium graminearum, Fusarium culmorum and Fusarium pseudograminearum.

Fungal secondary metabolites confer an indiscriminate resource of bioactive compounds with both pharmaceutical and industrial relevance. Synthesis of these compounds is tightly controlled through regulatory networks. These networks act in response to the environmental conditions in which the fungus grows. One class of fungal secondary metabolites that have drawn increased attention, is the polyketides produced by a high number of fungi and bacteria. The increasing number of publicly available genomic sequences of filamentous fungi, combined with new and highly efficient DNA-cloning techniques, has allowed the use of new efficient approaches to study the regulation and synthesis of these compounds. With the availability of new molecular genetic tools, a new bottleneck has occurred in fungal molecular biology; the analytical chemical analysis of the generated transgenic mutants. In this study, a method based on PARAFAC data analysis of HPLC data is presented and shown useful for gaining overview of complex and diverse datasets. Further, the strain specific and nutrient dependent regulation of polyketide synthesis is discussed.

Efficient four fragment cloning for the construction of vectors for targeted gene replacement in filamentous fungi.

BACKGROUND: The rapid increase in whole genome fungal sequence information allows large scale functional analyses of target genes. Efficient transformation methods to obtain site-directed gene replacement, targeted over-expression by promoter replacement, in-frame epitope tagging or fusion of coding sequences with fluorescent markers such as GFP are essential for this process. Construction of vectors for these experiments depends on the directional cloning of two homologous recombination sequences on each side of a selection marker gene. RESULTS: Here, we present a USER Friendly cloning based technique that allows single step cloning of the two required homologous recombination sequences into different sites of a recipient vector. The advantages are: A simple experimental design, free choice of target sequence, few procedures and user convenience. The vectors are intented for Agrobacterium tumefaciens and protoplast based transformation technologies. The system has been tested by the construction of vectors for targeted replacement of 17 genes and overexpression of 12 genes in Fusarium graminearum. The results show that four fragment vectors can be constructed in a single cloning step with an average efficiency of 84% for gene replacement and 80% for targeted overexpression. CONCLUSION: The new vectors designed for USER Friendly cloning provided a fast reliable method to construct vectors for targeted gene manipulations in fungi.

Heme oxygenase and nitric oxide synthase in human middle ear epithelium indicates local carbon monoxide and nitric oxide production.

The gas mixture of the middle ear differs from that of the atmosphere, a fact that has been attributed to gas exchange across the middle ear mucosa. Several diseases of the middle ear seem to be related to impaired ventilation together with conjunctional changes in pressure and gas composition. Carbon monoxide (CO) and nitric oxide (NO) have recently been shown to be endogenously produced in the human lung as well as in the nasal airways. The production of CO and NO is enzymatically regulated by heme oxygenase (HO) and NO synthase (NOS), respectively. These enzymes display isoforms that are both constitutively expressed [HO-2, endothelial NOS (eNOS), neuronal NOS (nNOS)] and inducible [HO-1, inducible NOS (iNOS)] following different types of stimulation. The present study was designed to investigate the presence of HO-1, HO-2 and eNOS in the middle ear epithelium, using immunocytochemistry. Specimens from human middle ear mucosa obtained at autopsy and during surgery revealed HO-1-, HO-2- and eNOS-like immunoreactivity, indicating the possibility of local CO and NO production in the middle ear. If this assumption is true, it may affect our understanding of middle ear physiology and give new insights into the mechanisms behind middle ear pathology.

A decrease in maxillary sinus pressure, as seen in upper airway allergy or infection, results in an increase in upper airway nitric oxide levels.

The paranasal sinuses are connected to the nasal cavity via small osties. Ostial occlusion, caused by mucosal swelling, will result in a slowly increasing negative pressure inside the sinus cavity. In parallel, the oxygen content in the sinus will decrease, resulting in the development of relative hypoxia. Hypoxia is a powerful inducer of nitric oxide (NO) synthase, and inducible NO synthase has been shown to be present in considerable amounts in the upper airways, including the sinuses. The present study was designed to investigate whether a reduction in sinus pressure would affect upper airway NO production. Thirteen healthy volunteers were investigated. A pressure chamber was used to lower the ambient pressure to -4.9 kPa. NO was sampled from one nostril or via a drainage tube inserted into the maxillary sinus before, during and after the hypobaric exposure. When the pressure was decreased, NO levels increased from 256 +/- 15 to 316 +/- 19 ppb (n = 13, p < 0.001). The NO levels remained elevated (282 +/- 21 ppb; p < 0.05) when measurements were repeated 20 min after leaving the chamber. The nasal airway resistance (V2tot) also increased as a result of the chamber session (from 16 +/- 2 degrees before to 21 +/- 3 degrees after; p < 0.05). An increase in NO levels was also found when the experiments were repeated with NO sampled directly from the maxillary sinus (225 +/- 6 before and 265 +/- 9 ppb after; n = 6, p < 0.001). For control purposes the nasal analyses were repeated again, this time under hyperbaric conditions (+ 4.9 kPa). This resulted in a slight decrease in the NO levels (from 273 +/- 22 to 241 +/- 17 ppb; n = 10, p < 0.001), but there was no change in the nasal airway resistance. We conclude that a reduction in sinus pressure, as seen in upper airway allergy or infection, may result in an increase in upper airway NO production.

The paranasal sinuses as reservoirs for nitric oxide.

OBJECTIVE: Nitric oxide (NO) is an important mediator and inflammatory marker in human upper airways. Enzymes responsible for NO production have been demonstrated both in the nose and in the paranasal sinuses, but NO levels in the sinuses are reported to be several times higher than those in the nose. It has been postulated that the paranasal sinuses may be the primary sites for NO production in the upper respiratory tract. The present study was designed to compare the NO levels sampled from the nose with those found in the paranasal sinuses. MATERIAL AND METHODS: NO levels in the maxillary sinus and nose were determined using a continuous chemiluminescence measuring technique in seven healthy volunteers. RESULTS: When NO was sampled, via a drainage tube inserted into the maxillary sinus, a transient peak in NO level was recorded. The maximal NO level (5,761 +/- 1,513 ppb; n = 7) was reached within 10 s and was followed by the establishment of a lower steady-state level (304 +/- 51 ppb). When NO was continuously sampled from the nose a steady-state level, similar to that found in the sinus, was immediately established (313 +/- 52 ppb). CONCLUSION: The data presented confirm previous findings of extremely high NO levels in the paranasal sinuses and suggest that these cavities may also function as reservoirs for NO.