How does soil fertility affect plant growth

Importance of humus for soil fertility

The importance of humus lies in the complex influencing of almost all soil properties and soil functions.

Storing nutrients

The humus represents a slowly flowing source of nutrients for the plants. Through the microbial degradation of the humus components, organically bound elements (carbon, oxygen, nitrogen, phosphorus, sulfur, hydrogen) are converted into compounds that can be absorbed by plants. The humus is also the food source for soil microorganisms and soil animals. Numerous experimental results show that there is a close relationship between the humus content of a soil and the amount of microbial biomass.
The humus creates the structure and stabilizes the structure by bonding the mineral particles to form a void-rich soil bond. It thus influences the pore system and ultimately the air and water balance of the soil. This influences the supply of water and nutrients to the plant roots, the root development, the aeration and thus the microbial activity, the water storage capacity, the water seepage and the water stability of the soil aggregates of the soil. In addition, the mechanical load-bearing capacity of the soil is increased and soil cultivation is made easier.
Risks from soil compaction and erosion can be reduced through optimal humus content.
The humus can interchangeably bind the cations (calcium, magnesium, potassium) and anions (phosphate, sulfate, nitrate) that are important for plant nutrition and thus protect against leaching, a property that is particularly important in sandy soils because of their low clay content.
The proteins, an important part of humus, act as a buffer and prevent major pH fluctuations, an important prerequisite for the biochemical processes in the soil.
The humus can store water, a property that is also important with regard to global warming. The amount of water stored can reach twenty times the weight of the humus.
The humus controls the leaching and degradation rate of pesticides and environmental chemicals through a variety of adsorption mechanisms and thus protects the environment.
The humus represents an important carbon sink. Viewed globally, the humus stores around 1600 Gt of carbon. That is about two to three times as much carbon as in the air (760 Gt) or in vegetation (600 Gt). A tiny 0.1% decrease in this carbon reservoir in Europe would be equivalent to the carbon emissions of an additional 100 million cars. The humus therefore plays an important role in climate change.
Due to these diverse effects, an orderly, site-adapted humus management in agricultural operations represents an essential basis for sustainable soil fertility and yield security.
Soil fertility characteristicsWheat crop rotationPermanent wheat cultivationSilage corn crop rotationSilage maize permanent cultivationFallow land
Aggregate stability10082775918
Infiltration rate100462230
Microbial biomass100100857029
The effects of one-sided crop rotations on the Corg-Contents and, as a result, important soil properties, determined in long-term crop rotation tests at the Puch State Estate, are shown in the table and figure.
In the one-sided crop rotation variants, the aggregate stability, as a measure of the soil's tendency to silt and thus also its susceptibility to erosion, decreased significantly. The infiltration rate, an indicator of the proportion of large coarse pores, fell almost to zero. Microbial biomass, a measure of the soil's conversion capacity, also declined.