Starter P, K and Zinc Fertilizer: 3 Takeaways From a Long-Term Study in Southwest Minnesota

Aug 04, 2025

By Dan Kaiser

With low corn and soybean prices, I have been looking at some of our long-term data to figure out how growers can reduce fertilizer costs. One study I have not spoken much about is a long-term trial that was started in 2011 at the Southwest Research and Outreach Center in Lamberton, Minnesota. Data from this study show some interesting insights on starter fertilizer containing phosphorus (P), potassium (K), and zinc.

About the study

Initially, the study was established to look at fertilizer additives used in combination with starter fertilizer, and one thing that is unique about this site is that the soil pH is very acid, testing below 5.0.

I have maintained the study over time to look at reduced rates of P and K with and without a P and K starter fertilizer in a three-year corn-corn-soybean rotation. The broadcast treatments for the first six years were similar, focused on application of removal rates of P and K for the corn crop, which resulted in a buildup of soil P from 20 to 30 ppm according to the Bray-P1 test and an increase from 150 to 200 ppm in extractable soil test K.

Source : umn.edu

Video: A chain harrow is a game changer

Utilizing a rotational grazing method on our farmstead with our sheep helps to let the pasture/paddocks rest. We also just invested in a chain harrow to allow us to drag the paddocks our sheep just left to break up and spread their manure around, dethatch thicker grass areas, and to rough up bare dirt areas to all for a better seed to soil contact if we overseed that paddock. This was our first time really using the chain harrow besides initially testing it out. We are very impressed with the work it did and how and area that was majority dirt, could be roughed up before reseeding.

Did you know we also operate a small business on the homestead. We make homemade, handcrafted soaps, shampoo bars, hair and beard products in addition to offering our pasture raised pork, lamb, and 100% raw honey. You can find out more about our products and ingredients by visiting our website at www.mimiandpoppysplace.com. There you can shop our products and sign up for our monthly newsletter that highlights a soap or ingredient, gives monthly updates about the homestead, and also lists the markets, festivals, and events we’ll be attending that month.