nitrogen – Western Cover Crops Council

Monitoring Soil Nitrate to Estimate Cover Crop Nitrogen Contribution in Organic Vegetable Production Fields

Authors: Nick Andrews, Dan M. Sullivan, and Kristin Pool, Oregon State University

Organic vegetable growers rely on legume cover crops as an economical source of plant-available N. This research evaluated N contributions to summer vegetable crops by cover crops (CC) residues by monitoring soil nitrate (NO3-N) concentrations during the summer crop growing season. Replicated field plots were established with three CC mixes: solo common vetch (V), phacelia + V (PV), and cereal rye + V (RV), plus a winter fallow (F) control in grower fields in the north Willamette Valley OR. Soil textures were … Read the rest

Soil Nitrate Testing for Willamette Valley Vegetable Production (2019) EM9221

Link: https://catalog.extension.oregonstate.edu/em9221

This publication describes how to use in-season soil nitrate testing to adjust sidedress N fertilizer application rate to match crop N requirements. Data to support our recommendations comes from field trials conducted in the Willamette Valley for vegetable crops produced during summer months.… Read the rest

Legume Cover in Orchard Drive Alleys

This publication evaluates a broad spectrum of legume species and cultivars for their ability to thrive in an orchard environment and provide a significant nitrogen contribution.

Link: https://www.nrcs.usda.gov/Internet/FSE_PLANTMATERIALS/publications/wapmcsr12864.pdf… Read the rest

Estimating Plant-Available Nitrogen Release from Cover Crops

This publication assists western Oregon farmers and agricultural professionals in determining the nitrogen fertilizer replacement value of winter cover crops. Includes information on plant-available nitrogen (PAN) basics; a site-specific, step-by-step method to estimate PAN; Willamette Valley case studies; and appendices summarizing Willamette Valley cover crop research that supports these PAN estimates.

Link: https://catalog.extension.oregonstate.edu/pnw636

… Read the rest

Baseline Soil Nitrogen Mineralization: Measurement and Interpretation (2020) EM9281

This Extension publication reviews baseline N mineralization which refers to plant-available nitrogen release that accompanies the decomposition of soil organic matter. The rate of baseline soil N mineralization is governed by the quantity and quality of soil organic matter, as modified by soil moisture and temperature. Baseline soil N mineralization typically supplies about half of crop N uptake. Soils that have been heavily manured for many years or are naturally very high in soil organic matter can supply most of the N required for crop production. Several laboratory tests for N mineralization are available, but most are useful only as … Read the rest