Grassland Crops as Drivers for the Improvement of Soil Fertility

The management of soil fertility is a fundamental aspect of agriculture. Modern agriculture is deeply dependent on the overuse of mineral fertilizers to support increased crop production, reducing framer’s profits, lessening farm sustainability and endangering the surrounding ecosystems. Resorting to grassland crops to strengthen soil fertility offers many advantages in comparison to mineral fertilization. Grasslands are extensive natural or agricultural lands, mainly composed of Poaceae and Fabaceae, but may also include woody species. Pastures and forages are the most important feed resources for many livestock species and mixed farming systems worldwide, contributing to minimize farmers' economic risks and preserving natural resources. The decrease in soil health imposed by fertilizer-based agricultural practices may be overcome by implementing permanent grassland crops or in rotation. Soils from grassland crops show higher amounts of nitrogen, potassium, and organic matter, when compared to croplands. Additionally, phosphorus inputs from mineral fertilizers are reduced, which lessens farmers expenses. The improvement of soil fertility assessed by its physical and biological components has been reported after the implementation of grassland crops, suggesting the potential role of pastures and forages as promoters of land restoration by limiting erosion and boosting biological diversity in agricultural soils. The present report reviews published work on the benefits of using grassland crops, with special emphasis on the characteristic agrosilvopastoral systems of the Iberian Peninsula, the Montado and Dehesas, providing a comprehensive summary on soil fertility and restoration of soil quality. Ultimately, the potential of implementing grassland crops is discussed.