What factors affect soil fertility

Humus - humus and agriculture

Location factors and management influence the humus and its functions.

The farmer can only influence the humus content through the management measures.

The soil fertility triangle

The humus, the soil structure and the microorganisms are of great importance for soil fertility and influence each other.

Maintenance of humus through agricultural measures

Agricultural measures that preserve and promote the humus:

  • Balanced, varied crop rotation, catch crops, undersown crops.
  • Sufficient supply of the soil with organic matter, through the incorporation of plant residues or organic fertilizers.
  • Soil cultivation adapted to the location in order to avoid erosion and compaction.
  • Observance of the principles of good professional practice in fertilization measures.
  • Demand-based supply of lime: Soil microorganisms require a neutral pH value, acidic soils reduce bacterial life in the soil and thus soil fertility.
  • Grassland conservation

Attempt to influence crop rotation

Duration since 1953wheat
Crop rotation
Permanent cultivation
Silage maize
Crop rotation
Silage maize
Permanent cultivation
Aggregate stability10082775918
Infiltration rate100462230
Microbial biomass100100857029
Values ​​related to wheat crop rotation = 100 percent
Humus-consuming: silage maize, sugar beet, potato
Increasing humus: legumes, catch crops for green manure
A 60-year long-term test in Puch shows a gradual decrease in the humus content (C.org) in the permanent cultivation of wheat and silage maize compared to the wheat crop rotation.

Experiment on the influence of organic fertilization

A 20-year experiment on organic fertilization shows that the microbial biomass increases through various measures of organic fertilization.
The microbial biomass is clearly related to the humus content and is a measure of the bioactivity in the soil.

Attempt to influence the cultivation of the soil

The effect of tillage on humus content (Corg ) was investigated in a 21-year (1992-2013) test series in the test station in Puch (Fürstenfeldbruck district).

Test result

Tillage with no-till, cultivator or plow determines the depth distribution of the humus in the soil. No-till increases Corg stocks in the top 10 cm of the soil due to decreased Corgorg- Inventories balanced in lower areas.
At all sampling depths, the type of tillage hardly changes the total amount of organic carbon.
The evaluation of the 21-year long-term test on the subject of soil cultivation and humus content shows that
that the use of the plow is not humus-sapping.

Humus and microbial activity

The determination of soil microbiological parameters complements the humus analysis at the LfL. The content of microbial biomass in the soil (C.mic) is a sensitive indicator for changes in soil management. The ratio C enables a statement to be made about the C dynamics in the soilmic/ Corg, which shows the proportion of metabolically active microbial biomass in the humus content.
The microbial biomass is determined by means of the SIR method (substrate-induced respiration) after adding glucose as a readily available carbon source using the method described by Heinemeyer et al. (1989) described IR gas measuring system.