Managing crop nutrients to achieve water quality goals

Excerpt

Managing agricultural nutrients to achieve water quality goals involves complexities best organized around source and transport processes, as captured in site assessment tools used for nutrient management decision support. Source is governed by nutrient use efficiency (NUE) by crops and land management, while transport is governed by landscape and hydrologic controls. These concepts are useful for strategic and operational decisions around nutrient management in the field. However, experience shows us that nutrient management outcomes are influenced by several factors across many scales, most uncontrollable, which must be considered when transferring science into policy and when establishing realistic public expectations. Key factors influencing these nutrient management concepts, complexities, inherent tradeoffs, and outcomes are summarized in table 1 and are discussed in more detail in this article.

Nutrient use efficiency for both nitrogen (N) and phosphorus (P) has increased steadily over the last two decades, with advances in crop breeding, soil and crop tissue testing, variable rate application of fertilizer, precise fertilizer applications, and precision conservation. The increase in NUE and adoption of nutrient management and conservation practices (CPs) has led to a reduction in nutrient loss. While adoption of these practices to address so-called “low hanging fruit” can be relatively easy…