Estimation of the Optimal Nitrogen Dose in a \u3ci\u3eBrachiaria humidicola\u3c/i\u3e-Corn Rotation System in the Colombian Eastern Plains

Improving nitrogen (N) use efficiency by optimizing the N fertilizer application dose is one way to reduce greenhouse gas (GHG) emissions in agriculture and livestock production, especially in higher demanding crops such as corn. Taking a Brachiaria humidicola (Bh)-corn rotation system in the Colombian Eastern Plains, we seek to determine both the optimal economic dose (OED) and the optimal technical dose (OTD) of N, which allow to maximize income at producer level and minimize environmental impacts. This particular rotation system was chosen as research subject given the presence of the residual effect of Biological Nitrogen Inhibition (BNI) in permanent lots of Bh, which has positive impacts on corn production such as increased yields and better N efficiency. The data for this study was obtained from trials conducted between 2013 and 2017, where corn production in a Bh-corn rotation system (with residual BNI effect) was compared with conventional corn production (without residual BNI effect). For determining the OED and OTD of N, three response models were applied: a pseudo-quadratic model (PQM), a quadratic model (QM) and a discontinuous-rectilinear model (DRM). The results show that the PQM and DRM models turn out to be the most suitable for estimating the OTD producing a better fit for the data, thus the required N doses are not overestimated. Bh-corn treatments require lower OTD and OED compared to the control scenario, which results from the residual BNI effect. The OED is lower than the OTD in the QM and PQM models for the three treatments. Thus, for maximizing profits a lower N dose is required. Both N input and corn sales price variables determine the optimum dose for maximizing the producer\u27s profits. In general, estimating the correct doses of N in a Bh-corn rotation system contributes to improving both efficiency in production and profitability, helping to avoid excessive application of N fertilizers and its associated negative effects on the environment

Spatio-Temporal Dynamics of the Dual-Purpose Cattle Value Chain in the Colombian Amazonas

The cattle sector plays an important role in the economy of the Caquetá department, located in the Colombian Amazon. However, the predominantly extensive production system is associated with low productivity and negative environmental impacts, such as land degradation, greenhouse gas emissions, and deforestation. Efforts to introduce improved practices (e.g., improved forages or silvopastoral systems) have been made over the last decades, but adoption rates remain low. Though several studies have analyzed the cattle value chain (VC) to enhance the understanding of adoption barriers, the heterogeneity of farmers has been considered only marginally when trying to explain their adoption behavior. To narrow this knowledge gap, a VC analysis was carried out in March 2022, using semi-structured interviews with key informants. Four types of cattle farmers were identified to operate along a gradient reaching from the Andean foothill in the department’s northwest to the deforestation frontier in the southeast. While specialized and dual-purpose milk farms are located close to the foothill, dual-purpose cheese and cattle fattening farms operate closer to the deforestation frontier. The associated spatio-temporal dynamics seem to be associated with differences in infrastructure, access to inputs and services, and the presence of armed groups. The observed enabling environment gradient is important for a more context-specific design of policies and interventions aimed at supporting the adoption of sustainably intensified cattle production systems, while needs and preferences of the heterogenous farmer groups should be further researched

Public policies for the Development of a Sustainable, Forage-Based Cattle Sector in Colombia, Argentina, and Costa Rica: A Comparative Analysis

Projected increases in global food demand highlight the importance of Latin America as one of the major future food suppliers, particularly regarding animal-source foods such as beef or milk. Despite the importance of the cattle sector for the region, its negative environmental impacts are numerous and the shift towards sustainability is perceived as slow and uncoordinated. This study aims to identify achievements and difficulties in the implementation of public policies for a sustainable cattle sector in Colombia, Argentina, and Costa Rica, for which policies focused on the use of silvo-pastoral systems and forage-based solutions are prioritized. Based on the review of scientific articles, government reports, and publications of international organizations, a comparative qualitative analysis was carried out, documenting the policy developments between 2010-2020. For the three countries, the findings highlight a large number of public policies focused on the implementation of silvo-pastoral systems, both at the local and national levels. At the same time, the efforts of the governments to include such strategies in the National Development Plans and stimulate legislative advances are evident. However, they also coincide in difficulties, such as the disconnection and lack of continuity between policies, unclear budgets for their financing, and little socialization within the communities. Another obstacle to the success of public policies is the way in which they are perceived by producers, who on many occasions refuse to make the transition from conventional to sustainable methods, considering that it implies the availability of economic resources, knowledge, and training that are difficult to access. The results also indicate that, despite the initiatives developed over the last ten years, problems such as deforestation and increasing greenhouse gas emissions persist in the three countries, although to different extents and at different levels. It is concluded that the policy efforts for the implementation of silvo-pastoral systems should be seen as initial steps in a long-term process towards achieving a sustainable cattle sector. Recommendations are provided that could help increase the success of these and new policies at different stages, from the identification of the problem to their evaluation, particularly given the difficulties of financing, disconnection, and participation of citizens and producers

What and Who Has Determined Adoption? A Study on Improved Forage Technologies in Colombia from an Agricultural Innovation System (AIS) Perspective

The complex process behind the adoption of improved forages in Colombia remains largely unexplored. Despite governmental and scientific efforts to promote and disseminate the implementation of improved forages for the sake of sustainable livestock production, local livestock producers continue to extensively use native species and adoption rates of more efficient forages remain low. This study explores the dynamics behind the development and diffusion of improved forage technologies in Colombia, from the 1960\u27s to the present through an Agricultural Innovation Systems (AIS) perspective. Here we map the agents involved, classify the roles they exerted over time and reconstruct the historical context in which the creation and dissemination of forage technologies in the country took form. Through the use of qualitative research tools such as in-depth interviews, and extensive archival work, we were able to identify various factors determining the course of improved forage adoption processes. First, a gradual decline on public and private investment destined to agricultural research hindered national scientific agendas and affected the continuity of ongoing projects. Second, the primacy of interpersonal relationships further complicates this panorama as it can either interfere with or promote the use of improved forages, subjecting technology dissemination to a non-institutional realm. Thirdly, released technological packages remain incomplete and impede rising adoption rates, mainly due to both Colombia’s low-latitude (and its restrictions for national seed production) and ineffective processes of training and support aimed at local livestock producers. Aside from the identification of key actors and historical trends, the study concludes by suggesting the implementation of a systematic (AIS) approach that gives account of the complex and ever-changing process of forage adoption, its agents, roles, strengths and limitations so that a comprehensive diagnosis can serve as a guideline for future adoption policies in the subject

From Theory to Practice: What Should We Have in Mind When Building Effective and Sustainable Payments for Ecosystem Services (PES) Schemes for Silvo-Pastoral Systems? Evidence from Colombia

In most Latin American countries, payment for ecosystem services (PES) can be a useful strategy for restoration and conservation of the environment, increasing productivity and promoting sustainable development in rural areas. Despite these plausible benefits, PES implementation can be challenging due to the contextual framework in which it takes place (e.g. institutional weakness in the implementation and monitoring stages, limited connectivity among stakeholders, low adoption levels of agricultural technology). This study aims at evaluating PES schemes for silvo-pastoral systems in Colombia by considering six dimensions based on an extensive literature review: policy and governance; social context; environmental context; risks and challenges; dynamics; and monitoring and evaluation approaches. A literature meta-analysis and semi-structured interviews with decision makers were carried out. The results suggest that: 1) It is necessary to restructure PES schemes given their limited scope in developing countries; 2) A new approach towards successful PES schemes should be adopted, transitioning from temporary conservation-oriented PES to schemes focused on the articulation of value chains and thus, transmitting costs to the final consumers; 3) Although policies regarding PES have been increasing, governance systems and responsibility assignments remain unclear; and 4) PES are more likely to be efficient when accompanied by complementary strategies (e.g. technical assistance, mechanisms for market inclusion) and conservation strategies that last in time. This study revealed the difficulties in monitoring territories as well as the underlying dynamics of implementing PES schemes in farms with nettle aptitude to receive them (despite the willingness of the producers). It also highlights the importance of analyzing the cultural and economic dimensions of the producers to assess the assigned importance of nature conservation. This work enriches the debate and informs the dialogue among PES experiences in order to guide public and private strategies in developing countries

Environmental Co-Benefits of Improved Forages in Smallholder Dairy Systems of Kenya

Livestock play a major role across Kenya, especially in smallholder mixed farms through provision of household nutrition and income through milk and meat. Equally, fertilization of cropland benefits from livestock manure, and livestock often act as insurance and saving. Despite the opportunities and benefits livestock production presents, livestock systems are also key drivers of environmental degradation, including increased nutrient loads, GHG emissions, water use, grassland degradation and land-use conversion. Low livestock productivity, largely due to use of low-quality crop residues and natural grasses often not endowed with nutrients key for animal performance, limits the potential positive contributions of livestock and at the same time reduces the efficiency of natural resource use. In response to this and with smallholder dairy farmers’ participation, we undertook an evaluation of 5 selected improved cultivated forages from Urochloa and Megathyrsus genus as an alternative to the Napier grass commonly grown by farmers. We evaluated impact on livestock productivity, farmers’ income, land and water requirement, soil erosion, soil health and greenhouse gas emissions. We observed more efficient use of farmers’ lands and financial resources through integrating improved forages and optimization of feeding strategies. We have also shown that the production and use of improved forages can act as a good climate change mitigation option

Ambulatory scintigraphic assessment of transient changes in left ventricular function: a new method for detection of silent myocardial ischaemia

Demonstration of ischaemic left ventricular dysfunction in the absence of chest pain should provide important confirmation of silent myocardial ischaemia in patients with asymptomatic ST segment changes. For this purpose, a new portable scintillation probe (VEST) similar to a miniaturized nuclear stethoscope combined with a Hotter ECG was evaluated. After standard equilibrium radionuclide angiocardiography with technetium-99m labelled red blood cells, the VEST was positioned under gamma-camera control and data were recorded from 1-12 h in 61 unselected patients. Ejection fraction (LVEF), relative changes in volumes, heart rate and ST segment changes were determined. Reproducibility of LVEF at rest (r = 0.91; variability 3.8 ± 3%, N = 19) and during exercise (r = 0.98; variability 3.2 ± 2%, N = 19) was good. In 15 asymptomatic exercise tests four different patterns of LVEF and ST segment responses were identified: (1) decrease in LVEF followed by significant ST depression (five times); (2) ST depression followed by decrease in LVEF (three times); (3) decrease in LVEF without significant ST changes (three times); and (4) ST depression without significant LVEF change (four times). In this still small series, patterns (1) to (3) corresponded to patients with documented coronary artery disease, which was not the case for pattern (4). For detection of silent ischaemia at rest, a decrease in LVEF of >5% lasting for >1 min was defined as ischaemic LV dysfunction. Using this definition, four spontaneous episodes of silent LV dysfunction could be demonstrated in two of three CCU patients with unstable angina during 160-680 min of data recordings without simultaneous ST changes. Based on this initial experience, we conclude that VEST is a reproducible method to detect transient global LV dysfunction and will be useful to confirm silent ischaemia in otherwise uncertain ST segment change

Can captive orangutans (Pongo pygmaeus abelii) be coaxed into cumulative build-up of techniques?

While striking cultural variation in behavior from one site to another has been described in chimpanzees and orangutans, cumulative culture might be unique to humans. Captive chimpanzees were recently found to be rather conservative, sticking to the technique they had mastered, even after more effective alternatives were demonstrated. Behavioral flexibility in problem solving, in the sense of acquiring new solutions after having learned another one earlier, is a vital prerequisite for cumulative build-up of techniques. Here, we experimentally investigate whether captive orangutans show such flexibility, and if so, whether they show techniques that cumulatively build up (ratchet) on previous ones after conditions of the task are changed. We provided nine Sumatran orangutans (Pongo pygmaeus abelii) with two types of transparent tubes partly filled with syrup, along with potential tools such as sticks, twigs, wood wool and paper. In the first phase, the orangutans could reach inside the tubes with their hands (Regular Condition), but in the following phase, tubes had been made too narrow for their hands to fit in (Restricted Condition 1), or in addition the setup lacked their favorite materials (Restricted Condition 2). The orangutans showed high behavioral flexibility, applying nine different techniques under the regular condition in total. Individuals abandoned preferred techniques and switched to different techniques under restricted conditions when this was advantageous. We show for two of these techniques how they cumulatively built up on earlier ones. This suggests that the near-absence of cumulative culture in wild orangutans is not due to a lack of flexibility when existing solutions to tasks are made impossible

Differences of disease progression in congestive heart failure due to alcoholic as compared to idiopathic dilated cardiomyopathy

In patients with alcoholic cardiomyopathy there is evidence that mild heart failure is reversible if patients abstain from alcohol, but there is no consensus whether the disease is progressive once structural myocardial dilatation has evolved. The aim of the present study was to compare the long-term course of congestive heart failure due to alcoholic and idiopathic dilated cardiomyopathy. Of 75 patients with overt congestive heart failure, 23 had alcoholic cardiomyopathy and were compared to 52 patients with idiopathic cardiomyopathy. The mean age was 48 ± 12 years. Despite medical therapy, heart failure class New York Heart Association III-IV was present in 52% of patients with alcoholic and 47% of patients with idiopathic cardiomyopathy (not significant). Their mean left ventricular ejection fraction was 30 ± l2% vs 28 ± 12% and left ventricular end-diastolic volumes were 264 ± 125 ml and 254 ± 100 ml respectively (not significant). Overall survival at 1, 5 and 10 years was l00%, 81% and 81% for the group with alcoholic dilated cardiomyopathy and 89%, 48% and 30% for the group with idiopathic cardiomyopathy, respectively (P=0·041 and the difference was even greater for transplant-free survival P=0·005 Clinical and invasive signs of left and right heart failure as well as left ventricular dimensions were predictive of a fatal outcome; however, symptom duration and left ventricular volumes were only predictive in patients with idiopathic cardiomyopathy, suggesting that in the two patient groups different mechanisms may lead to death. Mortality in patients with severe congestive heart failure and left ventricular dilatation due to alcoholic cardiomyopathy is significantly lower than that in patients with idiopathic cardiomyopathy and similar degrees of heart failure. Thus, despite structural changes mherent in marked left ventricular dilatation, disease progression in alcoholic dilated cardiomyopathy is different from that in idiopathic cardiomyopathy and thus may have implications for the choice of therap

Economic Benefits of Sustainable, Forage-Based Cattle Systems in Colombia and Nicaragua

Forage-based cattle systems play a key role in rural economies of developing countries in terms of food security and poverty alleviation, particularly in tropical Latin America. However, they are often related to being a major cause of negative environmental impacts by contributing to increased greenhouse gas emissions, land degradation, and the reduction of biodiversity. Significant resources have been allocated to research and development in forage material improvement, including selection and breeding. A broad range of improved materials were released by private and public sector actors showing superior characteristics in terms of productivity and environmental impacts compared to native or naturalized materials. Profitability is a fundamental attribute to incentivize or generate adoption of new systems by cattle producers, but this information is often not available to the livestock producer or the extension agents supporting decision-making processes. This research provides an overview on the economic viability of integrating different improved forage varieties in sustainably intensified cattle production systems in Colombia and Nicaragua. Our evaluations show that, despite higher establishment and management costs, integrating improved forage technologies (and management practices) in sustainably intensified cattle systems, either as monoculture, grass-legume associations, silvo-pastoral systems, or in combination with improved management strategies (e.g., intensive, or rotational grazing), not only make sense from the environmental and productive perspectives but also in terms of economic viability. In nearly all evaluated scenarios, the economic indicators improve by integrating improved forage technologies. Strong increases were observed for the following indicators: a) net income, b) unit profit margin, c) Net Present Value, d) Internal Rate of Return, and f) benefit-cost ratio. Strong decreases were observed for the following indicators: a) unit production cost, b) risk of obtaining economic loss, c) payback time, d) minimum area required for a profitable system, and e) sensitivity of the system to external shocks. This information will help cattle producers, extensionists and policymakers to make more holistic and informed land-use decisions that include productive, environmental, economic, and social benefits, and by this contributes to the broader adoption of more sustainable production systems