Department of Soil and Environmental Sciences
Dr. Marta Kohmann, Dr. Natasha Rayne, and Dr. Luiz Ferraretto presented in the first 2026 Focus on Forage webinar. Dr. Natasha Rayne explored how to unlock the full nutrient value of manure in alfalfa production. She began with an overview of key nutrient needs in alfalfa—especially nitrogen, phosphorus, potassium, sulfur, and boron—and explained how alfalfa’s …
In this article Dr. Rayne and Dr. Rebecca Larson explore: 1) approaches used to calculate plant available N (PAN) from manure; 2) research methods used to develop “book values” or availability coefficients; 3) soil test indices that might help farmers determine manure N availability from a specific manure application. Approaches to Estimating Manure Nitrogen Credits …
This video features Dr. Natasha Rayne, assistant professor and extension soil fertility specialist at UW–Madison, discussing the concept of manure nitrogen credits and their importance in agricultural nutrient management. She explains how nitrogen credits are calculated, the variability in nitrogen content across different types of manure, and the factors affecting nitrogen availability. The presentation highlights …