Willamette Valley

Introduction

Introduction

Introduction

Phosphorus pollution of the Willamette River and its tributaries is a problem affecting agriculture in western Oregon. Many of our soils are high in available (soluble) P, as measured by the tests commonly used to determine plant-availability of P. Consequently, many streams have background levels of P that are conducive to algal blooms and poor water quality for fisheries and recreational use. Agriculture may also contribute to P pollution of streams through the use of large amounts of phosphate fertilizers and is under pressure to reduce P applications.

Introduction

Introduction

Introduction

Although we have established that cauliflower is more efficient that sweet corn or snapbeans in taking up fertilizer N, the large amounts of N applied to this crop (up to 300 pounds/acre) make it a candidate for improvements in N use efficiency. As with sweet corn, a predictive test of the need for late-season N applications could enable growers to cut back on wasteful and environmentally sensitive overapplication of N fertilizer.

Methods

Introduction

Introduction

Vegetable growers in the Willamette Valley use high rates of nitrogen fertilizers, often exceeding 250 to 300 pounds actual N/acre per season. While growers believe that these rates are necessary to achieve maximum yields and quality, a considerable portion of the applied fertilizer is not taken up by the crop. This has raised concerns that the remaining N may be contributing to nitrate pollution of groundwater. Improved efficiency of nitrogen management may be possible if the fertilizer could be placed for maximum contact with the root system.

Research report from OSU's North Willamette Research and Extension Center

Delbert Hemphill
OSU Dept of Horticulture

Mary Powelson
OSU Dept of Botany and Plant Pathology

Introduction

Introduction