Crop Nutrition

Fall Fertilizer for Alfalfa Stands

Cristie Preston, Ph.D.

Cristie Preston

Cristie Preston, Ph.D.


Senior Agronomist

Agriculture has always been an integral part of Dr. Cristie Preston’s life. She grew up in southwest Virginia and had interest in crop and animal agriculture since an early age. Once she began college, she initially chose to study animal science but switched to soil science. Dr. Preston attributes her decision partly to an influential professor who told her, “You can’t understand animals until you understand what they eat.” She received a Bachelor of Science degree in animal science and a Master of Science degree in crop and soil environmental science from Virginia Tech. Dr. Preston holds a Ph.D. in agronomy, focusing on soil fertility from Kansas State University. While completing her advanced degrees, Dr. Preston conducted more than six years of field and lab research. Dr. Preston has experience in laboratory research measuring volatility loss from urea-based fertilizers. Her field research has focused on phosphorus availability and the interactions with tillage and placement. She also has extensive experience in working with large data sets and analysis. Her main priority is helping growers to identify yield-limiting factors and fix those issues as cost efficiently as possible.

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In the Midwest, it is time for fall alfalfa seeding. Many farmers take advantage of fall seeding due to decreased weed pressure compared to spring. To achieve high yields and high protein for the next three to five years, nutrient management for alfalfa needs extensive attention even before seeding.

A recent article from Kansas State Research and Extension stresses that the first step is to soil sample and correct soil acidity before seeding. The optimum pH for alfalfa production is between 6.2 and 6.8 due to the symbiotic relationship with rhizobia.

Kansas State recommends phosphorus fertilizer applied if soil test levels are below 25ppm and potassium fertilizer if soil test levels are below 130ppm. Even if soil test levels are above these critical levels, additional fertilizer may be required. Starter nitrogen at 15-20 pounds per acre applied this fall could aid in germination and establishment.

Double check your nutrient uptake and removal with site specific yields using the eKonomics Nutrient Removal Calculator to ensure adequate nutrient availability and maximize yields.