Visual Assessment of Soil Structure as an Early Indicator of Soil Quality in Response to Intensive Rotational Grazing

Grasslands can play a crucial role in mitigation of global warming by serving as carbon sink. Nevertheless, to achieve the grasslands’ potential, sustainable management is of the utmost importance as it determines system’s productivity and ecosystem services. Due to the increasing demand for animal products in developing countries, grazed areas increase exponentially in the tropics, mainly due to unsustainable management leading to low productivity and soil degradation. We evaluated the impact of intensive rotational grazing management (IRG) on early indicators of soil quality following land-use change based on on-farm observations of visual soil characteristics using two different widely used assessment methods: visual soil assessment-VSA and visual evaluation of soil structure-VESS. Correlation of visual methods were combined with measurements of soil macrofauna abundance and physical properties (e.g. bulk density, soil porosity). The IRG established in two study sites in Colombia was compared with traditional long-term continuous grazing with low stocking rate (1 LU ha-1). The IRG was based on rapid (1 day) cattle grazing in paddocks with high stocking rate (180 LU ha-1) followed by 60 days of recovery. In both study sites, IRG increased considerably total stocking rate to 4 LU ha-1 while improving grassland composition by enabling more valuable species, which contributed to soil quality and increased grassland productivity. Both VSA and VESS discriminated IRG-managed sites in less than one year after IRG adoption. Our results demonstrate that visual soil assessment is a useful mean for evaluation of soil quality and grassland productivity. Furthermore, VSA and VESS seemed to be more suitable in discriminating among management in early stages, when compared to commonly used soil physical properties, and were strongly correlated mainly to the abundance of earthworms. Furthermore, our study confirms the importance of grazing management in soil quality and ecosystem productivity/sustainability

Regenerative agriculture for low-carbon and resilient coffee farms: A practical guidebook. Version 1.0

For decades, global coffee consumption has grown, as tastes and offerings for consumers have increased around the world, and global demand for coffee will continue to grow in the years to come. At the same time, climate change presents coffee producers and other supply chain actors with major challenges. Its impacts are already reducing the area that is well suited for growing coffee, and this lends urgency to the adoption of farming strategies than can secure future coffee supplies and the livelihoods of coffee-producing families. Major efforts are also needed to lower the contribution of agri-food systems, including coffee, to climate change and other negative environmental impacts, such as land degradation and biodiversity loss. Regenerative agriculture provides coffee producers with a means to transform their farms by restoring and conserving soil, water and biodiversity, thus building resilience in the face of climate change. This approach also creates opportunities to reduce greenhouse gas emissions and enhance carbon storage on farms, while increasing farm income through diversification. Regenerative agriculture offers the further advantage of flexibility, based on principles that apply to both small- and large-scale production across many diverse conditions. As a result, this approach can address multiple environmental and production challenges in ways that are socially and economically viable. Designed for field agronomists and technicians in the global coffee sector, this guidebook aims to help identify the best regenerative practices and adapt them to different origins, farm types and agroecological conditions. Each region and farm type has its own requirements. For this reason, we highlight key principles and a wide array of practices that can be applied flexibly and combined to enhance the sustainability and resilience of coffee farms. In other words, this guidebook describes the “what” and “why” of regenerative agriculture but does not prescribe “how” it should be implemented. Instead, we offer tools that enable agricultural extensionists to support farmers in the transition to regenerative agriculture by selecting the practices that best match specific needs, objectives and available resources, and by adapting them to the local context

Effect of sieving on ex-situ soil respiration of soils from three land use types

This study aims to investigate the effect of sieving on ex situ soil respiration (CO2 flux) measurements from different land use types. We collected soils (0–10 cm) from arable, grassland and woodland sites, allocated them to either sieved (4-mm mesh, freshly sieved) or intact core treatments and incubated them in gas-tight jars for 40 days at 10 °C. Headspace gas was collected on days 1, 3, 17, 24, 31 and 38 and CO2 analysed. Our results showed that sieving (4 mm) did not significantly influence soil respiration measurements, probably because micro aggregates (< 0.25 mm) remain intact after sieving. However, soils collected from grassland soil released more CO2 compared with those collected from woodland and arable soils, irrespective of sieving treatments. The higher CO2 from grassland soil compared with woodland and arable soils was attributed to the differences in the water holding capacity and the quantity and stoichiometry of the organic matter between the three soils. We conclude that soils sieved prior to ex situ respiration experiments provide realistic respiration measurements. This finding lends support to soil scientists planning a sampling strategy that better represents the inhomogeneity of field conditions by pooling, homogenising and sieving samples, without fear of obtaining unrepresentative CO2 flux measurements caused by the disruption of soil architecture

Indicadores biofisicos de la Estructura Agroecological Principal (EAP) para el co-deseno de SAF cacao en dos zonas productora de Tumaco (Narino)

El co-diseño de sistemas agroforestales (SAF) implica entender la estructura y función de los sistemas, no solo a nivel productivo, sino también a nivel ecosistémico y cultural. Lo anterior, porque las decisiones que toman los agricultores, sobre cómo arreglar espacialmente los sistemas productivos, responden a motivaciones productivas y no productivas, las cuales se basan en la experiencia y evidencia empírica local. Sin embargo, estas decisiones pueden ser mejor orientadas a partir del análisis de información cartográfica, indicadores de paisaje y de aspectos socioculturales. En este trabajo, enmarcado en el programa rutas PDET para la estabilización territorial, se caracterizaron 100 unidades productivas agropecuarias (UPAs) de cacao en dos zonas productoras del municipio de Tumaco (Nariño). En el presente trabajo se exponen los resultados de cuatro indicadores biofísicos que han sido usados para el análisis de estructura agroecológica principal (EAP), como herramienta de co-diseño de los SAF cacao a nivel predial, pero también como instrumento de planificación a escala de paisaje. La conexión de las UPAs con la Estructura Ecológica Principal del Paisaje (CEEP) no muestra correlación con los diferentes parámetros de paisaje evaluados, sin embargo, si se identifica que UPAs cacaoteras con arboles de más de 10 años tienen mayor conectividad con el paisaje, en comparación con UPAs de cacao de menor edad. Además, son estás fincas en las que hay mayor porcentaje de uso del suelo (USC) con coberturas diversificadas (SAF cacao, áreas de barbecho y zonas de conservación) y mayor conectividad externa (CE) con setos y cercas vivas. La conectividad interna (CI) de las UPAs es baja, y es quizá el indicador biofísico que más impacta de manera negativa la EAP. De lo anterior se interpreta que, bajo el análisis de paisaje, si bien los componentes de los SAF de cacao por si solos contribuyen en la EAP, hay que implementar acciones que mejoren la conectividad interna y externa, además del establecimiento y ampliación de áreas de conservación, que contribuyan a mejorar la integración de las fincas cacaoteras con el paisaje

Exclusion of soil macrofauna did not affect soil quality but increased crop yields in a sub-humid tropical maize-based system

Soil macrofauna such as earthworms and termites are involved in key ecosystem functions and thus considered important for sustainable intensification of crop production. However, their contribution to tropical soil and crop performance, as well as relations with agricultural management (e.g. Conservation Agriculture), are not well understood. This study aimed to quantify soil macrofauna and its impact on soil aggregation, soil carbon and crop yields in a maize-soybean system under tropical sub-humid conditions. A field trial was established in Western Kenya in 2003 with tillage and residue retention as independent factors. A macrofauna exclusion experiment was superimposed in 2005 through regular insecticide applications, and measurements were taken from 2005 to 2012. Termites were the most abundant macrofauna group comprising 61% of total macrofauna numbers followed by ants (20%), while few earthworms were present (5%). Insecticide application significantly reduced termites (by 86 and 62%) and earthworms (by 100 and 88%) at 0-15 and 15-30 cm soil depth respectively. Termite diversity was low, with all species belonging to the family of Macrotermitinae which feed on wood, leaf litter and dead/dry grass. Seven years of macrofauna exclusion did not affect soil aggregation or carbon contents, which might be explained by the low residue retention and the nesting and feeding behavior of the dominant termites present. Macrofauna exclusion resulted in 34% higher maize grain yield and 22% higher soybean grain yield, indicating that pest damage – probably including termites - overruled any potentially beneficial impact of soil macrofauna. Results contrast with previous studies on the effects of termites on plant growth, which were mostly conducted in (semi-) arid regions. Future research should contribute to sustainable management strategies that reduce detrimental impact due to dominance of potential pest species while conserving soil macrofauna diversity and their beneficial functions in agroecosystems