A comprehensive understanding of the nature of organic matter and its role in the efficiency and stabilization of material cycles in the soil is a key element of ecosystem agriculture. This sustainable form of agriculture enables continuous and high-quality crop production even under unstable and challenging climate conditions.
Why is organic matter essential for crop cultivation?
Organic matter plays a fundamental role in creating and maintaining the multi-dimensional characteristics of soil fertility for several key reasons:
Improving soil structure: Organic matter enhances soil structure and porosity, increasing water retention, air flow, and root penetration. This allows plant roots to absorb oxygen, water, and nutrients more effectively.
Nutrient supply: Organic matter contains essential nutrients such as nitrogen, phosphorus, and potassium. Its gradual decomposition makes these nutrients available to plants over time.
Microbial activity: Organic matter provides a suitable environment for microbial life to thrive.
Reducing soil erosion: By stabilizing the soil, organic matter helps prevent erosion and protects the nutrient-rich topsoil.
pH regulation: Organic matter can help regulate soil pH and create better conditions for plant growth.
Increasing cation exchange capacity (CEC): Higher CEC means better ability of the soil to hold and exchange essential nutrients.
The Importance of Organic Matter Quality
Using organic matter to improve soil fertility requires attention to its quality — including its composition and rate of decomposition. Without this, the desired outcomes may not be achieved.
Methods for assessing organic matter quality:
Chemical analysis:
– Carbon-to-nitrogen ratio (C/N): Lower ratios typically indicate higher quality.
– Nutrient content: Measuring levels of elements like phosphorus, potassium, and sulfur.
Physical analysis:
– Structure and texture: Assessing the physical texture and structure helps evaluate quality.
– Moisture content: Affects decomposition and usability.
Biological analysis:
– Microbial activity: Indicates the presence and activity of beneficial microbes.
– Degradability: How easily microorganisms break down the material.
Practical tests:
– Field tests: Evaluating the effect of organic matter on plant growth and crop performance.
– Soil tests: Measuring the impact on physical and chemical soil properties.
Spectral analysis:
– Techniques such as spectroscopy can help identify compounds and assess quality.
Signs of Decomposition
Decomposition is closely tied to microbial activity and soil health. Common indicators include:
– Weight loss
– Chemical changes
– Gas production (CO₂, methane, ammonia)
– pH changes
– Color change
– Temperature increase
– Physical changes (texture, density, solubility)
Assessing Soil Microbial Activity
Different methods can be used to assess microbial activity and its impact on soil biochemistry:
– Colony counting
– Biochemical methods (enzyme activity)
– Gas measurement
– Fluorescence & spectroscopy
– Molecular methods (PCR, DNA sequencing)
– Microbial respiration
– Bioprobing
Sustainable Use Indicator: Oxidizable Carbon
One important quality metric is the level of oxidizable carbon — the portion of carbon microbes use for energy. This influences the type and abundance of microbial life (aerobic or anaerobic). More oxidizable carbon promotes the growth of beneficial aerobic bacteria and boosts microbial diversity.
Thus, one of the key criteria in selecting organic matter should be its sustainable productivity index.