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: How American Farmers Harvest 1.15 Billion Pounds of Sunflowers

Across the open plains of North Dakota and South Dakota, sunflower fields turn the American landscape into a sea of gold. In this farming documentary, we go inside modern sunflower farming to see how farmers plant, grow, harvest, clean, dry, process, and transform sunflower seeds into valuable products used every day.

In 2024, American farmers harvested about 1.15 billion pounds of sunflowers. This video follows the full journey from warm spring planting to combine harvesting, seed cleaning, storage, oil extraction, refining, roasting, packaging, and animal feed production.

You will see how sunflower seeds are processed into cooking oil, roasted snacks, bakery ingredients, birdseed, livestock feed, and useful byproducts. From golden fields to modern processing plants, this is the story of how a beautiful flower becomes one of America’s important oilseed crops.

Watch until the end to discover how sunflower farming connects farmers, machines, factories, food production, and sustainable agriculture.