Diversifying the Landscape with Animal Integration: An Introduction to the Environmental Sustainability of Crop–Livestock Systems

In this Special Issue of “Environmental Sustainability of Crop–Livestock Systems,” we collected eleven articles that represent a wide breadth of integrated systems around the world, including the U.S., Canada, Uruguay, Colombia, Spain, South Africa, and Portugal. In “The ‘Palo a Pique’ Long-Term Research Platform: First 25 Years of a Crop–Livestock Experiment in Uruguay” by Pablo Rovira et al. [1], we learn about a 25-year-old Long-Term Experiment (LTE) evaluating different pasture–crop rotations under livestock grazing. Results from this experiment demonstrated that the rotation of perennial pastures of grasses and legumes with crops was essential in mitigating soil carbon losses. This long-term-experiment lays the necessary groundwork to address the role of ruminants in climate change, competition for land, nutrient dynamics, and food security in today’s society and the future. The article “Estimation of Soil Loss Tolerance in Olive Groves as an Indicator of Sustainability: The Case of the Estepa Region (Andalusia, Spain)” by Antonio Alberto Rodríguez Sousa et al. [2] explores the sustainability of olive groves in Andalusia, Spain, where soil erosion is a serious impediment to optimal productivity. Because animals have been known to graze under these food-producing trees, the authors evaluated soil loss and its role in ecosystem sustainability. Two indices—the Soil Loss Tolerance Index (SLTI) for nonspecific crops and a Soil Loss Tolerance Index corresponding to the Estepa region (SLTIlog)—were utilized. Using two unique indices can inform the adoption of management measures to maintain productivity while supporting conservation and ecosystem services. The article on “Clipping Forage Sorghum Twice and Nitrogen Topdressing Offer an Option for Dual-Purpose Use for Cover Cropping and Fodder in Mixed Crop/Livestock Farming Systems” by Kudzayi Janhi et al. [3] highlights the use of sorghum as a diverse crop that can supply animal nutrition and help mitigate soil erosion as a cover crop. The experiment varied the number of sorghum clippings and supplemental nitrogen applications to determine the root biomass and crude protein changes. Results showed that clipping twice and N topdressing was the best management practice for the dual-purpose of soil cover and livestock feed. In the “Nutritional Quality of Plant Species in Pyrenean Hay Meadows of High Diversity” by Ramón Reiné et al. [4], the feed quality of 34 species of vegetation present in the Pyrenean mountain hay meadows subject to extensive management is analyzed in this article. Results showed that all species presented suitable mineral content, with the exception of phosphorus, and some species proved exceptional in their forage feed value. Soil analysis showed that most species are growing under N-limited conditions, which is sufficient for their conservation in meadows. The article “Fatty Acid Composition Dynamics of Rye (Secale cereale L.) and Wheat (Triticum aestivum L.) Forages under Cattle Grazing” by Hannah N. Phillips et al. [5] investigates the fatty acid compositions of fall-planted rye and wheat forages while rotationally grazed by steers. Results from the study show that fatty acid composition had more variation in wheat than rye over the course of the grazing interval. The fatty acid compositions varied based on the length of the grazing and the forage species, suggesting possible adjustments to grazing schedules to better manage the dietary fatty acid intake of grazing cattle.