Soil Management (Agriculture)

The quality of your soil is paramount to plant and therefore stock productivity. 

Learn how to improve your soils and benefit from them.  This course examines:

• The properties of soil
• Testing
• How to manage and improve soil
• Soil problems
• Sustainability of soils and much  more.

Lesson Structure

There are 8 lessons in this course:

1. Introduction: Soils And Soil Classification
   • Soil health and Agricultural soils
   • What is soil health?
   • Soil Composition and Formation
   • Classifying Soil Groups and Soil Landscapes
   • Soil Profiles
   • Soil Horizons
   • Key Properties of Selected Soil Groups
   • Parent Materials
   • Classifying Soils According to Hydrological Properties
   • Soil hydrology Groups: Uniform Coarse-textured Soils, Permeability Contrast Soils; Cracking Clays; Medium to Fine Textured soils
2. Properties of Soils and Plant Nutrition
   • Understanding Soils
   • Mineral and Rock
   • How Soils Develop Naturally
   • Mechanical Weathering
   • Chemical Weathering
   • Geo-chemical Weathering Processes
   • Pedo-chemical Weathering
   • Soil Fertility and Plant Nutrition
   • Organic Carbon
   • Soil Colour
   • Texture and its Effect on Plant Growth
   • Structure and its Effect on Plant Growth
   • Consistence and its Effect on Plant Growth
   • Depth of Profile and how it Relates to Plant Growth
   • PH and Plant Growth
   • Porosity and Plant Growth
   • Plant Nutrition and Nutrient Toxicity
3. Soil Testing Methods
   • Tilth and Organic Matter
   • Soil Sampling for Chemical Analysis
   • General Principles of Soil Analysis
   • Tools for Field Sampling and Soil Investigation
   • Digging a Sample Pit or Hole
   • Finding Out about your Soil
   • Settlement Activity
   • Soil Structure Activity
   • Recording Soil Colour
   • Testing Consistence
   • Describing Texture
   • Test for Free Carbonates
   • Soil pH Testing
   • Stability of Clods to Wetting (Slaking and Dispersion)
   • Bulk Density Testing
   • Measurement of Organic Matter Content of Soil
   • Measuring Salinity
   • Measuring Water Content
   • Fertiliser Solubility
   • Affect of Lime on Soil
   • Laboratory Testing of Soils
4. Land Degradation and Other Soil Problems
   • Soil Structure Decline
   • Water Repellence
   • Erosion
   • Hard-Layers in Soils
   • Transient Bonding; Compaction; Cementation; and Natural Rigidity
   • Sub-Soil Compaction: Compression, shearing and smearing
   • Soil Acidification
   • Alkalinity and Sodicity
   • Water-logging
   • Salinity
   • Chemical Residues
5. Soil Management on Farms
   • Conservation Farming
   • No-Tillage (Zero tillage)
   • Minimum Tillage
   • Trap Cropping
   • Cover Crops and Green Manure Cropping
   • Alley Farming (AF)
   • Contour Farming and Strip Farming
   • Controlled Traffic Farming
   • Stubble Management
   • Establishing Water and Nutrient Management Plans
   • Soil Conservation Earthworks
   • Integrated Pest Management
   • Direct Drilling in Pasture Establishment
   • Soil Management in Orchards
   • Soil Management in Market Gardens
6. Crops: Soil and Nutrient Requirements (Part A)
   • Wheat
   • Oat
   • Barley
7. Crops: Soil and Nutrient Requirements (Part B)
   • Narrow-Leafed Lupins
   • Canola
   • Faba Beans
   • Grapes
8. PBL Soil project - Soil Investigation and Report
   • Aim is to:
   • evaluate a range of soils for a given situation
   • determine soil problems or limitations that exist for a given land use
   • decide on suitable soil management strategies for the selected land
   • prepare and present a report

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

• Develop a broad understanding of the physical and chemical properties of soils.
• Develop skills in sampling and field testing soils for basic physical and chemical properties
• Understand the principles, methods and techniques of sustainable soils management.
• Understand the principles and practices of earthworks.
• Understand causes and remediation methods of land degradation and soil problems.
• Develop a broad knowledge in the use of growing containers for agriculture.
• Develop strong understanding of soil science and its impact on plant growth.
• Develop practical knowledge about managing soil for particular cropping uses.

What You Will Do

• Define terms related to the production and management of agricultural soil, such as: manure, micorrhyzae, ameliorant, pore space, micro-nutrient, denitrification, ammonium fixation, chemo autrophic organisms, colloids, buffering capacity, leaching, compaction
• Create a compost heap
• Discuss ways that human activity can destroy soil structure
• Explain how pH affects nutrient availability
• Explain the function of different nutrients in soils/growing media, such at nitrogen and phosphorus
• Analyse a soil test report in order to evaluate the soil for horticultural or agricultural use
• Describe appropriate soil testing methods for different situations
• Compare the use of organic and inorganic fertilisers in different situations
• Develop a detailed nutritional management plan for a particular crop, following organic principles
• Identify suitable earth moving equipment for different tasks, and the conditions of use
• Explain various methods for assessing drainage at a site
• Evaluate the use of earthworks to refurbish or improve a specific site
• Research Environmental Protection Agency (or equivalent) recommendations for cleaning up chemical spills and for disposing of old household chemicals and their containers
• Discuss advantages and problems of importing soil from elsewhere for crop production
• Explain appropriate methods of stabiliising an unstable or erosion-prone slope
• Remove a soil profile, describe the different soil layers, and compare the effects of different soil treatments on the soil profile
• Report on prevention and control methods for soil degradation, and development of sustainable soil management practices in a case study

Why Study Soils?

The reason we investigate soils and their characteristics is to understand them in relation to plant growth and how to use them under man's management for his own manipulation. Man's management - ploughing feasibility, what type of implements will be required, and how to improve soil for the growing of a particular crop. To gain this understanding, it is necessary to integrate the combining affects of the different soil properties as they interdependently act as a medium for plant growth.

In the field, we record soil properties that are simple to measure without elaborate equipment. Attributes which can be seen directly (colour, structure) or measured directly (depth of horizons, structure form, size of structural units) or felt directly (texture, resistance to penetration) require little equipment. Presence of carbonate and pH are simple chemical tests using solutions that can be handled in the field.

Nutrient levels, pH, salinity, depth of soil, texture (properties of sand and clay), structure (form and arrangement), porosity (air space), consistence (ability of soil to withstand rupture) and even colour can all affect plant growth independently and interdependently.

NATURAL FERTILSERS AND SOIL CONDITIONERS

Seaweed Extracts

Seaweed contains a lot of micronutrients, plant growth hormones, sugars, alcohols, vitamins, alginates, proteins and biostimulants which improve the ability of plants to resist stresses caused by insects, the environment and disease. Pure seaweed may provide a source of nitrogen when used in bulk, but in the main it is better viewed as a plant "tonic" or an animal feed supplement. For plants, seaweed extracts provide micronutrients, stimulate root growth, improve disease resistance, and encourage beneficial microbial development in the soil. Unless large amounts of macronutrients are added, seaweed extracts are not normally seen as a "main fertiliser".

For animals seaweed extracts can be added to licks, feed supplements or used as a drench to provide mineral nutrients, improve general resistance to health problems and, in turn, reduce the need to use agricultural chemicals.

Research from the U.S.A. has shown that extracts of kelp (a type of seaweed) can:

•  Increase hardiness (ie. to drought and other stresses)
•  Reduce some pest problems including nematodes and mites
•  Increase flowering and fruit set on some fruits
•  Increase yields in a range of crops including wheat, soybeans, sweet potatoes and okra
•  Improve cold hardiness of some horticultural crops
•  Increase fruit spurs on apples

(Ref: UC Cooperative Extension, 2604 Ventura Ave, Rm 100, Santa Rosa, California)

Other research has shown seaweed to reduce the occurrence of various pests and diseases, including damping off, verticillium wilt, mildew, mites, aphids, soil nematodes and cattle parasites. In addition it has been shown to improve the effectiveness of pesticides.

Fish Fertilisers

Like seaweed extracts, liquid fish extracts also contain a large variety of minerals and trace elements. Fish extracts do not contain all of the other components of seaweed (eg. growth hormones), but unlike seaweed, they contain fish oil, and have a greater general effect on the inhibition of fungal and bacterial growth. Research from the U.S.A. has shown that fish emulsion can:

•  Promote plant growth in strawberries, soybeans, and various vegetables
•  Retard aging (senescence) in lettuce and peas
•  Delay flowering and fruiting
•  reduce stress during transplanting, when used as a foliar spray
•  reduce some fungal diseases by 50%

(Ref: UC Cooperative Extension, 2604 Ventura Ave, Rm 100, Santa Rosa, California)

Rock Dusts

Rock dust is a generic term (ie. it embraces a wide variety of different things that have different effects). Rock dusts are simply rocks ground into dust. Various types of rock dust are from time to time claimed to be dramatic solutions to soil problems. These products vary in their characteristics, depending on where they come from. Some rock dusts do contain plant nutrients and are valuable as fertilisers (eg. rock phosphate). Others contain certain micro-nutrients. Some rock dusts simply increase the availability of nutrients to plants. Not all rock dusts are the same!

In the home garden mineral rock dust, including its granulated form, can be broadcast over the soil before or after planting. If changing to mineral dust as a fertiliser, remember it is slow releasing, so gradually phase out the use of other fertilisers.

If handling any of these materials always wear a face mask to prevent inhalation of fine material which can cause symptoms like asbestosis. And always wear gloves - this is particularly important when handling perlite, vermiculite and zeolite.

Zeolites

These are the group of minerals classified as hydrated alumino silicates. There are more than 40 different types of naturally occurring zeolites, and a lot more synthetic variants. Zeolites occur naturally in Australia, where they are mined from Mt Gipps in NSW. These zeolites are predominantly clinoptilolite (which contains calcium, magnesium, sodium, potassium, auminium, silicon, oxygen and hydrogen. Zeolites from other places may be different!

Plant nutrients, such as ammonium nitrogen, potassium, magnesium, calcium and other elements have a positive electrical charge. This means that these nutrients are attracted to negatively charged surfaces in the soil profile. When there are too few negatively charged particles in the soil, nutrients are lost due to leaching. Zeolites have a honeycomb structure and strong negative charges – thus they are able to attract and hold the positively charged nutrient cations for future use by plants. This makes better use of any added fertiliser meaning less can be applied. In cases where too much fertiliser has been applied, zeolites act as a buffer (works particularly well with sulphate of ammonia or animal manures). It is also claimed that water retention and availability is improved.

Eco-Min

Another Australian product, Eco-Min contains important soil nutrients including calcium, magnesium, iron, zinc, manganese, copper, cobolt, molybdenum, boron, iron and selenium. It also contains some potassium and phosphorus; but does not contain nitrogen. The producers of this product claim that it stimulates microbial activity in the soil and overcomes certain nutrient shortages. In addition, it is claimed that Eco-min improves water retention and nutrient availability in a similar way to zeolites.

Under "normal" conditions it is recommended that Eco-Min be applied at the rate of 200kg/hectare. Due to improvements in soil conditions, when using Eco-Min it is expected that only 50 to 75% of normal fertiliser application is required.

ALROC Fertiliser

ALROC fertiliser is an Australian product which basically consists of 40% granite, 40% basalt, 10% dolomite and 10% bentonite. It is an organic fertiliser which can be less expensive than other conventional fertilisers. There are a number of new products now available that combine 70% ALROC fertiliser with 30% conventional fertiliser, so that conventional farmers can reduce their dependency on artificial fertilisers.

Earthcare CLC

"Earthcare CLC" is a soil conditioner described by its manufacturers as a "complex organic formulation based on naturally occurring humates, growth activators, amino acids, chelating agents and trace elements". The main benefits of CLC are:

• Nutrients which exist in the soil but are unavailable to the plant are made more accessible for the plant to use (including phosphorus).
• pH fluctuations are dampened
• Lime penetrates deeper into soils
• Air, water and root penetration are improved
• Soil micro-organisms are stimulated
• Rate of decomposition of organic material is accelerated
• Soil moisture is retained.

Vitall Fertiliser

This fertiliser was developed in the mid 1990s by chemists to minimise residues which are a problem with many other chemical fertilisers. It is produced in Australia, and its manufacturers claim that it not only increases nutrient availability to plants by reducing leaching, but it also buffers the pH of the soil. It contains nitrogen (9.4%), phosphorus (2.8%), potassium (4.1%), with smaller amounts of sulphur, magnesium, calcium, boron, iron, copper, manganese and zinc.

WHO SHOULD STUDY THIS COURSE?

Soils are the foundation of all agriculture. If the soil is poor, crops and pastures don't grow. Farm animals have less to eat. There are less crops to harvest. At the end of the day; bad soils result in unproductive farms.

• If you work in agriculture; or desire to work or invest in agriculture; this course could be the best 100 hours of study you ever do.
• If you don't already have a good understanding of soil structure, soil chemistry and plant nutrition; this course will teach you all of these things, and in doing so raise your awareness of what is possible through better soil management.
• Graduates will never look at soils in the same way after doing this course.