Sustainable Soil Management - Conservation Agriculture

How much land is lost annually due to tillage-caused erosion?

7 million hectares

What is conservation agriculture (CA)?

A farming system that promotes minimum soil disturbance, maintenance of a permanent soil cover, and diversification of plant species (FAO, 2022).

What are the 3 principles of conservation agriculture?

1) Minimum mechanical soil disturbance (no tillage) - through direct seed and/or fertiliser placement

2) Permanent soil organic cover (at least 30%) with crop residues and/or cover crops

3) Species diversification - through varied crop sequences using at least 3 different crops.

What are the economic advantages of CA?

. Time saving (lower labour requirement)

. Reduction of costs (e.g. fuel, machine operating costs, labour costs...)

. Higher efficiency (more output for lower input)

· Potentially higher yields

· Benefits for soil health save lots of money in the long term

What are the agronomic advantages of CA?

· Organic matter increases

· Increased options for integration of production sectors (e.g. integration of crops with trees or livestock)

· Improvement of soil structure/health (better water transport/retention)

What are the environmental advantages of CA?

· Reduction in soil erosion

· Improvement of water quality (less eutrophication)

· Reduction in GHG emissions

· Increase in biodiversity

· Carbon sequestration

What are the disadvantages of CA?

. Reduced soil disturbance = more weed growth. So although external inputs are applied in quantities that do not interfere with biological processes, there is still a reliance on weed control chemicals (potential resistance). IPM can also be used

. Improvements in microporosity & water infiltration can increase leaching

. Increased management requirements

. Crop rotations must be developed.

What are the main challenges of sustainable intensification? (result of CA)

· Land degradation = a major economic, social & ecological problem. Fertility decline

· High cost of production inputs (mineral fertilisers & herbicides)

. Widespread unavailability of diverse and improved seed material -> reduced crop productivity

· Lack of machinery

· Absence of irrigation

· Farmers lack of knowledge of crop management practices

· Underdeveloped public extension service -> shortage of staff resources, facilities & funds

· Mindset of farmers is difficult to change. Farmers are used to growing a small number of crop species and are reluctant to grow different crops or change the management practices they are familiar with.

What are the advantages of tillage?

- Weed control

- Decomposition of crop residue

- Prepares the seed bed -> better germination

- Increased soil temperature

- Alleviation of compaction

What is direct drilling?

Drilling that penetrates the soil cover, opens a seeding slot and places the seed into that slot. Minimal seed slot size and movement of soil. The slot is covered by mulch after seeding.

Why are weeds a problem in CA?

No cultivation = no removal of weeds, so many farmers are reliant on chemicals (e.g. glyphosate)

- However, this is potentially subjected to a ban

- Some farmers may abandon CA if such chemicals are unavailable

However, CA offers benefits in weed control by reducing the spread of weed diseases

- Example of black grass -> evidence suggests it can be controlled by careful rotation

- Also potential for new products to emerge without harmful properties...

What is regenerative agriculture (how is it different to CA?) and what methods are used?

= use of growing practices to improve the health of land. Broader than CA (which focuses on soil). Ecosystem-wide approach.

. Increasing biodiversity

. Rotating crops

. Minimising chemical inputs

. No-till systems

. Integrating livestock

. Cover crops

What is strip tillage? why is it good?

Tillage that disturbs 30% of the surface

- It is meant to provide seed bed and increase soil temperature

- The remaining residues minimise wind & water erosion

- Allows increases in soil organic matter -> increased nutrient & water storage capacity.

What are the outcomes of conservation agriculture?

· Prevents crusting

· Reduces erosion/nutrient loss

· Increases soil organic matter

· Increased microbial activity

· Decreases evaporation from soil surface

· Reduced tillage and labor costs.