Applying the right nutrient source, at the right rate, at the right time, in the right place is essential to nutrient stewardship and is the core of the 4Rs. To achieve this goal, a team of experts has created the following learning modules.  An essential component of these learning modules is to provide information about the basic components of soil fertility and nutrient best management practices. Topics include an explanation of the key components of plant nutrition in relation to selection of fertilizer best management practices addressing the 4Rs. The modules address the macro- and micronutrients as well as soil sampling and integrated economic and environmental issues relative to nutrient management.

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The materials inlcuded in these modules were authored by Agustin Pagani, John Sawyer, and Antonio Mallarino; Iowa State University Department of Agronomy. Materials inlcude a chapter and an automated presentation for each topic.

INTRODUCTION TO THE 4RS AND THE EDUCATIONAL MODULES

4R nutrient stewardship for fertilizer best management practices is an approach that considers economic, social, and environmental dimensions of nutrient management and is essential to sustainability of agricultural systems. While the concept is simple, implementation requires knowledge-intensive and site-specific nutrient management. Providing educational materials to stakeholders will help increase the adoption and implementation of the best management practices that are right for crop production systems.

Before diving into the educational modules, take a few minutes to read the introduction to 4Rs to better understand how fertilizer best management practices fit within this framework.

Read the introduction chapter >>

This module will provide an overview of important concepts for soil fertility, plant nutrition, and nutrient management in agronomic systems for profitable and environmentally safe crop production. General concepts and management practices will be presented.

Nitrogen is an essential nutrient for crop growth and production. However, unneeded application or poor efficiency results in increased production cost and lost economic return. In addition, nitrogen management has environmental importance since losses from agricultural systems have been identified as likely contributors to elevated surface or groundwater nitrate concentrations, impairment of freshwater bodies, and hypoxia of coastal waters. This module will cover important concepts of nitrogen management in agronomic systems for profitable and environmentally safe crop production.

Phosphorus is an essential element for plant growth and is needed in adequate supply for profitable crop production. However, phosphorus application to soils in excess of crop needs reduces profitability and may increase phosphorus loss to water resources. Proper management of phosphorus applications is a key for optimizing yield, profitability, and water quality. This module will cover important concepts of phosphorus management in agricultural systems for profitable and environmentally safe crop production.

Potassium is an essential element for plant growth and is needed in adequate supply for profitable crop production. Potassium is not a water quality concern, but wastes a natural resource and reduces farm profitability if not properly managed. In this module, important concepts of potassium management in agricultural systems for profitable crop production will be discussed.

Sulfur is often classified as a secondary plant essential element, mainly due to a smaller plant requirement, but also because it is less frequently applied as a fertilizer and applied in smaller amounts compared to other nutrients like nitrogen, phosphorus, and potassium macronutrients. However, if deficient, sulfur can have a dramatic effect on plant growth and crop productivity. This module will cover important concepts of sulfur management in agricultural systems for profitable crop production.

Calcium and magnesium are considered secondary nutrients because they are less commonly yield limiting than the macronutrients, yet are required by crops in relatively large amounts. This module will cover important concepts of calcium and magnesium management in agricultural systems to provide for profitable crop production.

Micronutrients are those essential elements required in very small quantities for plant growth and reproduction, or often supplied at adequate levels naturally from soils, and when applied fertilization rates are low. Seven essential elements are considered micronutrients, and include boron, copper, chlorine, iron, manganese, molybdenum, and zinc. This module will cover the principal concepts of micronutrient management in agricultural systems to provide for profitable crop production.

Soil pH is one of the most important chemical properties of soils in terms of biological activity, chemical reactions, and crop production capacity. Soil pH should be properly managed through soil testing and limestone application so acidic pH does not limit crop productivity and economic return. This module will discuss important concepts of soil pH and lime management in agronomic systems for profitable crop production.

Soil testing is one of the most useful and commonly used tools to estimate crop availability for many plant nutrients. The accuracy of a nutrient recommendation depends on how well soil samples represent a field or areas within a field. This module will cover important concepts and practices regarding soil sampling for nutrient management in agronomic systems to attain profitable and environmentally safe crop production.

The objective of nutrient management is to select the proper nutrient rate, placement, source, and timing for profitable and most environmentally safe crop production. Unneeded nutrient application or poor efficiency results in increased production cost and lost economic return to the producer, and adds to potential for water quality degradation. This module will cover important economic aspects of nutrient management and environmental issues in agronomic systems.