New MontGuide Available on Nutrient Uptake Timing by Crops
A new MontGuide is available to assist producers with fertilizing decisions. The guide was written by Clain Jones, Extension Soil Fertility Specialist and Professor, Kathrin Olson-Rutz, former Research Associate, and Pariera Dinkins, former Research Associate.
Timing the application of nutrients so that they are available before peak crop nutrient demand is critical. Adequate nutrients early in the growing season are necessary to maximize yield and ensure nitrogen (N) and phosphorus (P) are available for good grain or seed fill. A large portion of N and P used for grain fill comes from the stem, leaves, and head, rather than directly from the soil. If these nutrients are not available for early plant growth, then yield and efficiency of fertilizer use are reduced. Maximum nutrient uptake varies among crops, and generally occurs prior to maximum growth rates. The objective of this document is to present nutrient uptake curves for selected Montana crops (small grains, oilseeds, corn and sugar beet) to help growers and their advisers optimally time fertilizer applications. The focus is on N because it is more commonly topdressed than P or potassium (K)
All plants require the same mineral elements; however, the quantity, rate and timing of uptake vary with crop, crop variety, climate, soil characteristics and management. These combined factors influence the nutritional need, nutrient content, and overall yield of a crop. When fertilizer prices represent a large portion of a producer’s costs, it is very important to maximize fertilizer nutrient use efficiency (the percentage of applied nutrient removed by the crop). Timing fertilizer applications so that nutrients are available when plants need them should increase nutrient use efficiency and reduce potential adverse environmental effects.
Plants require a balanced supply of nutrients throughout their development. Generally, they accumulate most of their nutrients by sometime between the flowering and ripening stages. Approximately 50 to 90 percent of N and P in the plant moves from the leaves and stem to the developing seed during flowering (1). Therefore, low nutrient uptake early in a plant’s growth lowers nutrient quantity for the seed, affecting both yield and quality.
Knowing how nutrient needs change during the growing season is essential for matching nutrient supply with plant needs, especially for producers who can apply nutrients in-season or for those considering controlled- and slow-release fertilizers. Because nutrient uptake varies among regions and growing seasons, the results presented in this guide should be considered as general guidelines only.
The guide is available at the Chouteau County Extension office in the green building behind the courthouse or online at MSU Extension publications.
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