How to improve soil fertility

How to improve soil fertility
  • Soil fertility is the ability of soil to support plant growth and optimize crop yields. It can be improved by applying organic and inorganic fertilizers to the soil. Nuclear techniques provide data to improve soil fertility and crop production while minimizing environmental impacts.

Increasing food security and environmental sustainability in agricultural systems requires an integrated approach to soil fertility management that maximizes crop production while minimizing depletion of nutrient reserves and degradation of soil physical and chemical properties that can lead to land degradation, including soil erosion. Such soil fertility management practices include the use of fertilizers, organic inputs, crop rotation with legumes, and the use of improved germplasm, coupled with the knowledge needed to adapt these practices to local conditions.

The Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture assists Member Countries in the development and adoption of nuclear-based technologies to optimize soil fertility practices, thereby supporting crop production intensification and natural resource conservation.

Different approaches to effective soil fertility management

Integrated soil fertility management aims to optimize the efficiency of nutrient use for agronomic purposes and to increase crop productivity. This can be achieved through grain legumes, which improve soil fertility through biological nitrogen fixation, and the application of chemical fertilizers.

Whether planted for seed or green manure, or as pasture or woody crops in agroforestry systems, legumes are particularly important because of their ability to fix atmospheric nitrogen, which helps reduce the use of commercial nitrogen fertilizers and improve soil fertility. They form the basis of sustainable agricultural systems involving integrated nutrient management. The use of nitrogen 15 provides an understanding of the dynamics of different components of agricultural systems and their interactions, including nitrogen fixation by legumes and the use of soil nitrogen and fertilizer by crops, both in single-crop systems and in crop association systems.

Soil fertility can be further improved not only by the introduction of cover crops, which add organic matter to the soil, improving its structure and condition and fertility, but also by the addition of green manures or legume crops, which fix atmospheric nitrogen through the process of biological nitrogen fixation, the application of micro-doses of fertilizers to compensate for losses due to plant consumption and other processes, and on the other hand by drastically reducing leaching losses below the plant rooting zone through improved water and nutrient use.

Contribution of nuclear and isotopic techniques

The isotope technique involving nitrogen 15 and phosphorus 32 is used to track the movement of nitrogen and phosphorus labeled fertilizers in soils, crops, and water, providing quantitative data on the efficiency of the use of these fertilizers, as well as their movement, residual effects and transformation. This information is valuable for the development of improved fertilizer application strategies. The N-15 isotope technique is also used to determine the amount of nitrogen fixed from the atmosphere by biological nitrogen fixation by legumes.

The carbon-13 isotope signature can be used to determine the amount of crop residue incorporated into the soil to stabilize it and improve its fertility. This technique can also be used to assess the effects of conservation measures, such as the incorporation of crop residues, on soil moisture and soil quality. This information can be used to determine the origin and contribution of different types of crops to soil organic matter.

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