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Yield gaps in banana-based production systems have increased in the past two decades due to declining soil fertility, drought and biotic stresses. Sustainable, environmentally sound and economically viable strategies for intensification in these systems are urgently needed. Agroecological practices, such as the integration of shade- and drought-tolerant crops, nitrogen-fixing and cover crops could potentially improve soil fertility and moisture retention, reduce the weed burden, narrow yield gaps and increase overall plot/farm productivity in these systems. In Malaysia, leguminous crops like Pueraria phaseoloides, Calopogonium caeruleum and Centrosema pubescens are often cultivated as cover crops (to suppress weeds, and reduce moisture loss and soil erosion) in young rubber and oil palm plantations with low shade levels. Even in mature oil palm plantations with less than 30% light intensity, various shade-tolerant crops are grown, e.g., elephant foot yam, turmeric and arrow root. In humid tropical Africa, Colocasia (taro) and Xanthosoma (cocoyam) are reported to tolerate shade conditions and hence often planted under perennial banana/plantain plantations. Drought tolerance is a less common feature of most annual crops grown in the humid tropics. A few root and tuber crops (e.g., cassava, taro, yam and sweetpotato) remain in the field during the dry season in Central Africa and are then harvested according to household needs. This paper also reports on crops (Mucuna, lablab and chickpea) with potential for integration into banana-based systems during the dry season, if planted during the last month of the rainy season. These crops are reported to use the residual soil moisture content for continued growth during the dry season months. The paper concludes with detailed descriptions (from a literature review) on drought- and shade-tolerance characteristics of various crops which have long been integrated in Central African banana-based cropping systems, crops with a more recent cultivation history and crops with potential for system integration.

Agroecology is increasingly promoted by scientists, non-governmental organisations (NGO&rsquo, s), international organisations and peasant movements as an approach to foster the transition to sustainable and equitable food systems. The challenges to agroecological transitions are not the same for all farmers, as they can face different social and bio-physical conditions. We developed a farm typology combining participatory and quantitative methodologies to assess and categorise farm diversity and its implications for developing strategies to promote agroecological transitions. The participatory typology was developed during workshops to acquire insights on local farmers&rsquo, perceptions and knowledge, and to generate hypotheses on family farm diversity. The participatory-based hypotheses were tested in the quantitative farm characterisation, which provided information on household characteristics, production strategies, land use, participation in public policies and extension services. Farms were located in Zona da Mata, Minas Gerais, Brazil, which harbour a wide diversity of farmers and where different actors have been engaged in agroecological transitions for the past 30 years. Our main findings were: (i) In the face of agroecological transitions, farmers differ in their management strategies, practices and principles, (ii) farmers identified as agroecological typically had stronger engagements in a network composed of farmers&rsquo, organisations, universities and NGO&rsquo, s, (iii) agroecological farms showed great potential to provide a wide range of ecosystem services as they featured a higher crop diversity and a higher number of crops for self-consumption, (iv) to promote agroecology, it is crucial to recognise peasant knowledge, to change the dominant discourse on agriculture through social movement dynamics, and to generate support from public policies and funds, and (v) participatory and quantitative methodologies can be combined for more precise and relevant assessments of agroecological transitions.

Alternative host plants are important in the survival and perpetuation of several crop pathogens and have been suspected to play a role in the survival of Xanthomonas campestris pv. musacearum (Xcm) and perpetuation of Xanthomonas wilt (XW) disease of banana and enset. This study determined the potential risk posed by two weeds (Canna spp. and wild sorghum) and common banana intercrops (maize, millet, sorghum, taro, and sugarcane) as alternative hosts to Xcm. The study employed screenhouse experiments, laboratory procedures and diagnosis of banana fields in XW-affected landscapes. Typical XW symptoms were only observed in artificially inoculated Canna sp., with an incidence of 96%. Leaf lesions characteristic of xanthomonads occurred on millet (50%) and sorghum (35%), though the plants recovered. No symptoms occurred in maize, sugarcane, taro or wild sorghum. However, Xcm was recovered from all these plant species, with higher recoveries in Canna sp. (47%), millet (27%), sugarcane (27%), and wild sorghum (25%). Only isolates recovered from Canna sp., millet, sorghum and wild sorghum caused disease in banana plantlets. The presence and incidence of XW on-farm was positively associated with the presence of susceptible ABB Musa genotypes and negatively with number of banana cultivars on farm and household access to training on XW management. Only 0.02% of field sampled Canna spp. plants had Xcm. Risk posed by Canna spp. on-farm could be limited to tool transmission as it has persistent floral bracts that prevent insect-mediated infections. Given the high susceptibility, perennial nature and propagation through rhizomes of Canna sp., it could pose a moderate-high risk, thus warranting some attention in the management of XW disease. Sugarcane could offer a low-moderate risk due to its perennial nature and propagation through rhizomes while risk from maize, millet, and sorghum was deemed zero-low due to their annual nature, wind-mediated mode of pollination and propagation through seed. Understanding the interactions of a crop pathogen with other plants is thus important when diversifying agroecosystems. The study findings also suggest other factors such as cultivar composition and management of the disease at farm and landscape level to be important in the perpetuation of XW disease.

Western Kenya is one of Africa's most densely populated rural areas, characterised by intensive smallholder crop-livestock systems on degraded lands managed with small inputs of mineral fertiliser and animal manure. Competing uses for crop residues and other organic resources often results in poor nutrient cycling efficiencies at farm scale. Modifying livestock feeding, retaining more crop residues in the field, and improving manure management can help conserving considerable amount of nutrients on-farm. To examine to what extent such strategies would be feasible, we analysed whole-farm nutrient cycling efficiencies (NCE) of a range of farms differing in resource-endowment and production orientation, identifying the most efficient farmer strategies considering labour and financial constraints. Nutrient concentration in excreted cattle manure was relatively small (i.e., N

The use of time series of Normalized Difference Vegetation Index (NDVI), obtained from satellite sensors has become frequent in studies for land degradation assessment and monitoring. Linear trends of NDVI are usually considered as indicators of vegetation dynamics and widely used as proxies for land degradation. Yet, long-term trends of NDVI often exhibit unidirectional (monotonic) but also cyclic (non-monotonic) dynamics, including mid-term oscillations, both of which are poorly captured by linear trends. Trend-cycle is a time series analysis that represents a smoothed version of a seasonally adjusted time series, which provides information on long-term movements while including changes in direction underlying the series. We assessed NDVI trend-cycles in Patagonia (Argentina) as proxies for land dynamics, integrating trend and medium-term cycles (>4 years). We used MODIS images between years 2000 and mid-2018; trend-cycles were analysed using the Basis Pursuit method. We observed that trend-cycles explained a significant portion of total temporal variability (reaching almost 20%), from which most patterns were explained by non-monotonic behaviour. We identified five major patterns in vegetation dynamics: decreasing (0.1% of area), increasing (0.6%), recovery (48.8%), relapsing (36.8%) and no trend-cycle (13.8%). Contrary to what is generally seen in the literature, monotonic patterns and particularly decreasing trend-cycles were marginally recorded in the last 18 years of NDVI records in Patagonia. Instead, the greater proportion of the area was classified as initial or advanced recovery and initial relapsing patterns, which refer to phases of a cyclic behaviour. We call for the need to revisit the conceptualization of land degradation assessment by means of remote sensing, and to critically review the ability of linear trends to reflect vegetation dynamics. Finally, we discuss the potential use of trend-cycle as a tool to monitor land dynamics and progress towards land degradation neutrality. Fil: Easdale, Marcos Horacio. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Fariña, Clara María. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Hara, Sofía María. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Pérez León, Natalia. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Umaña, Fernando Javier. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche; Argentina Fil: Tittonell, Pablo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina Fil: Bruzzone, Octavio Augusto. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Patagonia Norte. Estación Experimental Agropecuaria San Carlos de Bariloche. Instituto de Investigaciones Forestales y Agropecuarias Bariloche. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones Forestales y Agropecuarias Bariloche; Argentina

The unprecedented impacts of humans on the Earth (e.g. Rockström et al., 2009; Sachs et al., 2010; Foley, 2011) have prompted a debate on the future of land use and, with agriculture as the major anthropogenic use, on new models of agricultural production. In addition to concerns about the eects of current agricultural land use, the debate is fuelled by the predicted growth of the human population, at least until 2050, and the associated need to nourish an extra 3 billion people in the face of a limited unused area of agriculturally exploitable land (e.g. Godfray et al., 2010). Leadley et al. (2014) predict rapid shifts in the state of ecosystems at regional scales within the next decades that it will be dicult to reverse. Assuming business-as-usual socioeconomic development pathways, these shifts will drive coupled human-environment systems to highly degraded states in terms of biodiversity, ecosystem services, and human well-being. Steen et al. (2015) describe how planetary boundaries that delimit a ‘safe space’ for global societal development have been exceeded in the domains of climate change and land-system change and are reaching well into high-risk zones for biosphere integrity (operationalized as genetic diversity) and biogeochemical ows of P and N. For various indicators, it is not the absolute global levels that are a cause for concern, but the speed at which current levels are being reached, which is unprecedented in the Anthropocene (Kidwell, 2015).

Vulnerability and resilience are two crucial attributes of social-ecological systems that are used for analyzing the response to disturbances. We assess these properties in relation to agroecosystem buffer capacity and adaptive capacity, which depend on the 'window of opportunities' of possible changes in terms of selected performance indicators, i.e., the solution space. The vulnerability of the system was quantified as the distance of performance indicators between original and disturbed systems. The buffer capacity was derived from the size of the solution space that could be obtained after reconfiguration of farm components (crops, animals, fertilizers, etc.) that were present on the original farm, whereas the assessment of adaptive capacity was derived in a similar way, but after allowing innovation by introducing new components to the farm. To illustrate the approach, we applied these concepts to two dairy farms in Northwest Michoacán, Mexico. After a disturbance resulting in a fodder maize yield decline, both economic profitability and soil organic matter inputs were reduced. The scope for recovery was different between the farms, but the projected improvements in profitability and organic matter inputs would require considerable changes in the farm configurations, and thus flexibility in farm management. High resilience requires a farmer with the managerial ability to make the required changes to move through the proposed solution space. The approach we present here offers a generic quantitative assessment of vulnerability and resilience concepts, based on a combined assessment of the social and ecological dimensions of agroecosystems..

New livestock production models need to simultaneously meet the increasing global demand for meat and preserve biodiversity and ecosystem services. Since the 16th century beef cattle has been produced on the Pampas and Campos native grasslands in southern South America, with only small amounts of external inputs. We synthesised 242 references from peer-reviewed and grey literature published between 1945 and mid-2015 and analysed secondary data to examine the evidence on the ecosystem services provided by this grassland biodiversity hotspot and the way they are affected by land use changes and their drivers. The analysis followed the requirements of systematic review from the PRISMA statement (Moher et al 2009 Acad. Clin. Ann. Intern. Med. 151 264–9). The Pampas and Campos provide feed for 43 million heads of cattle and 14 million sheep. The biome is habitat of 4000 native plant species, 300 species of birds, 29 species of mammals, 49 species of reptiles and 35 species of amphibians. The soils of the region stock 5% of the soil organic carbon of Latin America on 3% of its area. Driven by high prices of soybean, the soybean area increased by 210% between 2000 and 2010, at the expense of 2 million ha (5%) of native grassland, mostly in the Pampas. Intensification of livestock production was apparent in two spatially distinct forms. In subregions where cropping increased, intensification of livestock production was reflected in an increased use of grains for feed as part of feedlots. In subregions dominated by native grasslands, stocking rates increased. The review showed that land use change and grazing regimes with low forage allowances were predominantly associated with negative effects on ecosystem service provision by reducing soil organic carbon stocks and the diversity of plants, birds and mammals, and by increasing soil erosion. We found little quantitative information on changes in the ecosystem services water provision, nutrient cycling and erosion control. We discuss how changing grazing regimes to higher forage allowance can contribute to greater meat production and enhancing ecosystem services from native grasslands. This would require working with farmers on changing their management strategies and creating enabling economic conditions. (Resume d'auteur)

In this forum paper we discuss how soil scientists can help to reach the recently adopted UN Sustainable Development Goals (SDGs) in the most effective manner. Soil science, as a land-related discipline, has important links to several of the SDGs, which are demonstrated through the functions of soils and the ecosystem services that are linked to those functions (see graphical abstract in the Supplement). We explore and discuss how soil scientists can rise to the challenge both internally, in terms of our procedures and practices, and externally, in terms of our relations with colleague scientists in other disciplines, diverse groups of stakeholders and the policy arena. To meet these goals we recommend the following steps to be taken by the soil science community as a whole: (i) embrace the UN SDGs, as they provide a platform that allows soil science to demonstrate its relevance for realizing a sustainable society by 2030; (ii) show the specific value of soil science: research should explicitly show how using modern soil information can improve the results of inter- and transdisciplinary studies on SDGs related to food security, water scarcity, climate change, biodiversity loss and health threats; (iii) take leadership in overarching system analysis of ecosystems, as soils and soil scientists have an integrated nature and this places soil scientists in a unique position; (iii) raise awareness of soil organic matter as a key attribute of soils to illustrate its importance for soil functions and ecosystem services; (iv) improve the transfer of knowledge through knowledge brokers with a soil background; (v) start at the basis: educational programmes are needed at all levels, starting in primary schools, and emphasizing practical, down-to-earth examples; (vi) facilitate communication with the policy arena by framing research in terms that resonate with politicians in terms of the policy cycle or by considering drivers, pressures and responses affecting impacts of land use change; and finally (vii) all this is only possible if researchers, with soil scientists in the front lines, look over the hedge towards other disciplines, to the world at large and to the policy arena, reaching over to listen first, as a basis for genuine collaboration.