Eastern Washington is unique in that diverse environment, soil, and topography result in variations in crop yield across the region as well as across farms and individual fields within farms. Due to the inherent variability associated with eastern Washington dryland crop production, a one-size-fits-all recommendation for the management of any one nutrient is of little value. Recommendations must be based on individual grower practices, achievable yields, and current soil test data. This document presents guidelines for managing major nutrients in eastern Washington dryland winter wheat and emphasizes how producers can tailor recommendations to their own production systems. It also identifies opportunities where information such as crop yield and protein and soil test nutrient levels can help refine and improve nutrient management practices.
Nutrient uptake and removal by dryland wheat
High-yielding wheat absorbs large quantities of nutrients from soil. Box A shows average values for nutrient uptake and removal in the grain and straw of wheat. This table can be used as a guide to forecast nutrient removal from the field with the grain and straw portions of the crop. Note that the majority of nitrogen and sulfur in straw is lost if a field is burned; other nutrients generally remain in the ash.
Nitrogen (N) recommendations
Nitrogen recommendations are based on the potential yield for a site, the amount of N required to achieve yield and protein goals for a desired wheat class, and an inventory of soil N contributions. A worksheet is included in this guide to aid in developing an N recommendation and as a record-keeping tool. The following paragraphs refer to specific sections of the worksheet. A separate Microsoft Excel® spreadsheet is also available to make these calculations electronically.