IPI K Centre - Nutrient Removal and Nutrient Balance

Studies of soil nutrient balances confirm that unbalanced fertilization is still a widespread phenomenon. It is well known that farmers are often forced to take decisions about their fertilizer strategy that reflect economic rather than agronomic pressure. However, in the long run, with the aim to keep soil fertility at a sustainable level, a precise calculation of removal rates of nutrients by harvested crops is vital.

Moreover, it is not only the question of the harvested part of the crop. "More than half of all absolutely dry matter in the global harvest is in cereal and legume straws; in tops, stalks, leaves and shoots of tuber, oil, sugar and vegetable crops..." (Smil 1999). This global bulk of dry matter contains nutrients; the removal of the produce by harvest and the dry matter for other purposes (e.g. heating, animal feed, biofuels) means large removals of nutrients. Globally, the annual crop phytomass contains 75, 14 and 60 million tonnes of nitrogen (N), phosphorous (P) and potassium (K), respectively. With nutrient applications of N and P at similar levels to total nutrient content in crop phytomass removal (80 and 14 million tonnes, respectively; data for 1999), K is applied at a much lower level, to replenish only 35% of the K removed (Smil, 1999).

The issue of potassium removal, cycling and balance of potassium is hence of utmost importance.

The following items found on our web describe the methodologies for calculating nutrient balance under different agro climatic zones and the evidence for fertility losses as a consequent of unbalanced fertilization practices.

Smil, V. 1999. Crop residues: Agriculture's largest harvest. BioScience, 49:4, 299-308.

Projects & Demonstrations

Evaluation of Root Stock Efficiency in Nutrient Uptake and Utilzation with Special Regard to Potassium

Mapping Spatial and Temporal Potassium Balances in Brazilian Soils of South-West Goias

Establishment of Criteria for K Fertilization in Sandy and Medium Texture Soils

Crop Response to NPK, Using Missing Element Design Experiment.

Potassium Use in High Yield Crop System in Various Soil Types

Study on Potassium Strategy to Maintain Crop Yield and the Balance of Potassium in Cropland

Validation and Refining of K Fertilization Recommendations in Different Crops and Regions in China

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Publications

Papers and presentations

K in the literature