Why Study Soils
Soil is more than just dirt; it’s a dynamic, living system that supports life on Earth. It’s where plants anchor their roots and find the nutrients they need to grow. Soil exists at the vital interface between the atmosphere, lithosphere, hydrosphere, and biosphere, playing a crucial role in the interactions between air, water, rock, and living organisms. It’s the medium through which water and nutrients cycle, sustaining ecosystems and human life alike. Understanding soil means understanding one of the most essential and interconnected resources on our planet.
Soil is a complex mixture of minerals, organic matter, water, air, and a vast diversity of living organisms. The mineral portion comes from weathered rock and gives soil its texture, ranging from sand to silt to clay. Organic matter, such as decaying plants and animals, enriches the soil with nutrients. Water and air fill the spaces between soil particles, creating an environment where roots can grow, and organisms can thrive.
Within this intricate blend, the soil is teeming with life—home to a vast diversity of microorganisms and micro and macro fauna, all of which play vital roles in nutrient cycling and soil health. This makes soil a unique and essential component of the environment, supporting life above and below the ground.
Soil formation is a slow and fascinating process that takes place over thousands of years. It is shaped by six critical factors, which Vasily Vasilyevich Dokuchaev described in the 1880s and Hans Jenny refined in the 1940s. These factors include:
Climate
Climate influences the rate of weathering and organic matter decomposition, determining how quickly soil forms.
Organisms
Organisms, including plants, animals, and microbes, contribute organic matter and help break down minerals, enriching the soil.
Relief
Relief, or the landscape’s shape, affects water drainage and erosion, leading to soil depth and composition variations.
Parent material
Parent material, the underlying geological material, provides the mineral content and initial structure of the soil.
Time
Over time, these factors interact, creating distinct soil layers, each with its characteristics, and continuously shaping the soil’s ability to support life.
Human Activity
We as humans as a species have a disproportionate effect on our environment, which of course includes soils. For thousands of years, the human practices of foraging, hunting, farming and fire use has changed the landscape and the soils within them.
Not all soils are the same; in fact, they vary widely depending on where they are found. From rich, dark soils in fertile valleys to sandy, dry soils in deserts, each type has its own properties and functions. These differences affect everything from how plants grow to how water is absorbed and stored. Understanding the diversity of soils helps us manage land resources more effectively and appreciate the unique qualities of different environments.
Soils can be grouped into Orders, Suborders, Great Groups, Subgroups, Families and Series. Order is the broadest of these collections, and Series is the narrowest. Due to global soil variation, most countries and regions will have their own classification.
The soils of Australia can be described as extremely old and weathered. In Europe and America, the movement of glaciers receding during the last ice age carved through the landscape, wearing down a significant amount of bedrock. This widescale physical weathering has contributed to the relatively deep, nutrient-rich soils of these regions.
Australia received very little glaciation, contributing to our thinner, nutrient-poor soils. Australia’s arid environment is caused by low rainfall and high temperatures, significantly contributing to their small organic matter content. While a challenge for agriculture, these soil constraints significantly contribute to the evolution of our unique flora and high biodiversity.
The Australian Soil Classification consists of 15 unique soil Orders.
Soil plays a crucial role in supporting biodiversity and regulating environmental processes in natural ecosystems. It provides a habitat for countless organisms, from tiny microbes to burrowing animals, and acts as a reservoir for water and nutrients.
Healthy soils contribute to the stability of ecosystems, helping to filter water, store carbon, and cycle nutrients. Preserving these natural soils is essential for maintaining the balance and resilience of our planet’s ecosystems.
In agroecosystems, soil is the foundation of food production, providing the nutrients and structure needed for crops to grow. Farmers rely on healthy soils to produce the food, fibre, and fuel that sustain human life.
However, intensive agriculture can deplete soil nutrients and degrade its structure, leading to challenges like erosion and reduced fertility. Understanding soil’s role in agriculture is key to developing sustainable farming practices that protect this vital resource for future generations.
Numerous initiatives are underway to protect and enhance soil health globally and in Australia. The United Nations Food and Agriculture Organisation (FAO) has recognized the importance of soil by establishing World Soil Day (5th of December) and the Global Soil Partnership, which promotes sustainable soil management practices worldwide.
In Australia, the National Soil Strategy ensures that soil is valued and sustainably managed, supporting agricultural productivity and environmental resilience. Programs like the National Soil Carbon Research and Development, the Australian Government’s Smart Farms Program and the National Landcare Program provide funding and support for farmers and communities to adopt best practices in soil conservation and regeneration. All are focused on developing innovative solutions to improve soil performance, ensuring that soils remain a vital resource for future generations