Key soil health indicators under humid grazing lands

Abstract

Background

Soil health describes critical soil functions influenced by land management. Although some key soil characteristics are inherent (such as texture, mineralogy, and landscape position), there are other soil properties and processes that are altered by land management (such as soil organic matter, nutrient concentrations, and the capacity to infiltrate and store water) to form the basis of soil health evaluation.

Methods

This perspective overview of soil health in humid grazing lands focused on key soil health attributes that should be considered to evaluate the sustainability of forage and grazing lands. Soil compaction, nutrient concentrations, and organic matter, along with their biological fractions, were emphasized.

Results

Soil bulk density is commonly measured to assess soil compaction. Density often increases with stocking rate, but it can be moderated by the accumulation of surface-soil organic C and N. Many soil nutrients are concentrated near the soil surface, but soil type and management can influence these distributions. Soil-test biological activity increases with time in forage management systems and is often greater with grazing than haying due to livestock excretal return to soil. Root-zone enrichment of soil organic C was enhanced under grasslands compared with croplands but lower than under woodlands. However, root-zone enrichment of total soil N was greater under grasslands than under other land uses, suggesting that the quality of organic matter under grasslands was greater than under woodlands, an essential feature that supports agricultural production.

Conclusions

This perspective overview of soil health in humid grazing lands illustrates the positive soil health benefits achievable with balanced agroecological farming approaches using forages.