An Approach for Describing the Effects of Grazing on Soil Quality in Life-Cycle Assessment

Sensing and Mapping the Effects of Cow Trampling on the Soil Compaction of the Montado Mediterranean Ecosystem

The economic and environmental sustainability of extensive livestock production systems requires the optimisation of soil management, pasture production and animal grazing. Soil compaction is generally viewed as an indicator of soil degradation processes and a determinant factor in crop productivity. In the Montado silvopastoral ecosystem, characteristic of the Iberian Peninsula, animal trampling is mentioned as a variable to consider in soil compaction. This study aims: (i) to assess the spatial variation in the compaction profile of the 0-0.30 m deep soil layer over several years; (ii) to evaluate the effect of animal trampling on soil compaction; and (iii) to demonstrate the utility of combining various technological tools for sensing and mapping indicators of soil characteristics (Cone Index, CI; and apparent electrical conductivity, EC_a), of pastures' vegetative vigour (Normalised Difference Vegetation Index, NDVI) and of cows' grazing zones (Global Positioning Systems, GPS collars). The significant correlation between CI, soil moisture content (SMC) and EC_a and between EC_a and soil clay content shows the potential of using these expedient tools provided by the development of Precision Agriculture. The compaction resulting from animal trampling was significant outside the tree canopy (OTC) in the four evaluated dates and in the three soil layers considered (0-0.10 m; 0.10-0.20 m; 0.20-0.30 m). However, under the tree canopy (UTC), the effect of animal trampling was significant only in the 0-0.10 m soil layer and in three of the four dates, with a tendency for a greater CI at greater depths (0.10-0.30 m), in zones with a lower animal presence. These results suggest that this could be a dynamic process, with recovery cycles in the face of grazing management, seasonal fluctuations in soil moisture or spatial variation in specific soil characteristics (namely clay contents). The NDVI shows potential for monitoring the effect of livestock trampling during the peak spring production phase, with greater vigour in areas with less animal trampling. These results provide good perspectives for future studies that allow the calibration and validation of these tools to support the decision-making process of the agricultural manager.

Influence of Plants on the Spatial Variability of Soil Penetration Resistance

Soil penetration resistance is an informative indicator to monitor soil compaction, which affects a range of ecological processes in floodplain ecosystems. The aim of the investigation was to reveal the influence of vegetation cover on the spatial variability of penetration resistance of floodplain soils. The study was carried out in the elm oak forest in the floodplain of the Dnipro River (Dniprovsko-Orilsky Nature Reserve, Ukraine). The study of the soil profile morphology was performed in accordance with the guidelines of the field description of soils FAO. The soil penetration resistance was measured in the field using the Eijkelkamp manual penetrometer to a depth of 100 cm at 5-cm intervals within the polygon consisted of 105 sampling points. Vegetation descriptions were made in a 3×3-meter surrounding from each sampling point. The soil penetration resistance was found to regularly increase with increasing depth. The changes in resistance values were insignificant until 25–30 cm depth. After that, there was a sharp increase in penetration resistance up to the depth of 70–75 cm, after which the indicators plateaued. In the three-dimensional aspect, the spatial variation of soil penetration resistance can be fractionated into broad-scale, medium-scale, and fine-scale components. Tree vegetation induces a broad-scale component of soil penetration resistance variations, which embraces the whole soil profile. The herbaceous vegetation induces a medium-scale component, which embraces the upper and middle parts of the soil profile. The fine-scale component is influenced by pedogenic factors.

Effects of Grazing on Water Erosion, Compaction and Infiltration on Grasslands

Seventy-seven percent of all agricultural land is related to livestock, meat and dairy, including grazing land and arable fields used for animal feed production. The effect of livestock on the natural environment is well documented. Many types of research describe these effects on biodiversity. The surface runoff and soil erosion on grasslands and pastures are investigated with smaller intensity since grasslands are one of the two major land uses that are considered as natural or at least semi-natural lands. Still, mainly due to overuse, grazing on sloping pasture lands can cause severe soil damage, the trampling can cause compaction, compaction decrease infiltration and thus increase runoff and, consequently, soil loss. There are several consequences of the grazing pressure that cause water erosion and surface runoff above the acceptable limit, such as a dramatic decrease in grass densities and/or above-ground bio-mass, compaction, animal tracks, etc. Related research started as early as 1911 and continues until today. There are several methods to analyse the consequences of grazing pressure, e.g., in situ rainfall simulations, infiltration and soil resilience measurements, modelling of runoff, soil loss and infiltration, calculation of ecological costs, etc. Furthermore, most importantly, scientists are investigating the possibilities for improvement of the achieved unstable grazing system due to bad management. Numerous publications have been publishing results on positive changes with the removal of grazing livestock from the grasslands. However, since the socio-economic situation is changing on Earth, more people requiring the products of the pastures, an optimal grazing solution is greatly needed. One of the solutions can be the planning of the optimal animal unit per area, based on the expected grass yields. However, due to the big differences in yields, caused by the greatly unreliable weather, the solution for the future must be a multifunctional agriculture and a flexible land use.

CH4 and N2O Emissions From Cattle Excreta: A Review of Main Drivers and Mitigation Strategies in Grazing Systems

Cattle production systems are an important source of greenhouse gases (GHG) emitted to the atmosphere. Animal manure and managed soils are the most important sources of emissions from livestock after enteric methane. It is estimated that the N2O and CH4 produced in grasslands and manure management systems can contribute up to 25% of the emissions generated at the farm level, and therefore it is important to identify strategies to reduce the fluxes of these gases, especially in grazing systems where mitigation strategies have received less attention. This review describes the main factors that affect the emission of GHG from manure in bovine systems and the main strategies for their mitigation with emphasis on grazing production systems. The emissions of N2O and CH4 are highly variable and depend on multiple factors, which makes it difficult to use strategies that mitigate both gases simultaneously. We found that strategies such as the optimization of the diet, the implementation of silvopastoral systems and other practices with the capacity to improve soil quality and cover, and the use of nitrogen fixing plants are among the practices with more potential to reduce emissions from manure and at the same time contribute to increase carbon capture and improve food production. These strategies can be implemented to reduce the emissions of both gases and, depending on the method used and the production system, the reductions can reach up to 50% of CH4 or N2O emissions from manure according to different studies. However, many research gaps should be addressed in order to obtain such reductions at a larger scale.

Global Assessment of Agricultural Productivity Losses from Soil Compaction and Water Erosion

To guide us toward a sustainable future, the impacts of human activities on natural resources need to be understood and quantified. In this study on global agriculture, we use a Life Cycle Assessment framework to estimate potential long-term soil productivity losses caused by soil compaction and water erosion due to agricultural crop production. We combine several data sets to model spatially resolved Life Cycle Inventory information at the global level and multiply results with characterization factors from a previous publication. The global picture shows a compaction-stressed "Global North" and an erosion-stressed "Global South", with some countries and regions in between, for example, China and parts of South America. Results show that both compaction and water erosion impacts matter at the global level and that overall potential long-term productivity losses of 10-20% can be expected, with high relative impacts on low input production systems. These losses might limit long-term agricultural productivity and lead to additional land use change. Our work adds to and extends the discussion of global assessments of soil degradation. Furthermore, we prove the suggested framework to be applicable and useful for Life Cycle Assessments and other studies and provide results that can be used in such global assessments.