In Minnesota, potatoes are typically grown under irrigated conditions on sandy, low organic matter soils, Prof Rosen writes. Because of a high nutrient requirement and a relatively shallow root system (most roots are within the top foot), the crop is often responsive to applied nutrients, particularly the three primary macronutrients (nitrogen, phosphorus, and potassium).
Nutrient management research over the years has provided some insight into optimizing nutrient inputs to enhance yields and minimize losses to the environment. More recently, improving soil health in potato cropping systems has also been a focus.
Below is a summary of the five things Prof Rosen and his team have learned so far:
1. Strategies to Boost Nitrogen Efficiency: Potatoes, grown predominantly on sandy soils in Minnesota, have a high nutrient requirement. Nitrogen (N) is often the limiting factor. To enhance nitrogen use, it’s crucial to select a realistic target nitrogen rate and split applications to align with the crop’s demands. Enhanced efficiency fertilizers, like polymer-coated urea, can extend nitrogen availability. Moreover, petiole nitrate analysis is a sensitive tool to determine nitrogen needs during the growth phase. Current research is also exploring the potential of drones for remote sensing to schedule nitrogen applications.
2. Fumigation’s Role in Nitrogen Efficiency: Soil-borne diseases can hinder potato root health. Fumigation can enhance nitrogen use efficiency, but it doesn’t alter the optimal N rate. While fumigation can boost N uptake, its effects are temporary. Current studies are examining alternatives like cover crops, composted manure, and biofumigation.
3. The Challenge of Improving Soil Health: Enhancing soil health in potato cropping systems is challenging due to significant soil disturbance and the need for fumigation. However, a nationwide Potato Soil Health Project found that a three-year rotation yielded better results than a two-year one. The study suggests that extended rotations, combined with biofumigation, cover crops, and composted manure, might offer long-term benefits.
4. Factors Influencing Phosphorus Uptake: Phosphorus (P) is vital for potato growth. While P recommendations are often based on soil test P and yield goals, potatoes can still respond to phosphorus even in high P conditions. Factors like soil pH, soil-borne diseases, and varietal differences can influence P uptake. Research indicates that banding P might reduce the need for higher application rates.
5. The Impact of Potassium on Yield and Quality: Potassium (K) is essential for potato production. Both deficiency and excess of K can affect potato yield and quality. Current research is delving into how chloride affects yield and quality and exploring split applications to reduce its leaching potential.
Prof. Rosen will be presenting further on this topic at the ASA-CSSA-SSSA International Annual Meeting in St. Louis, Missouri, on October 31, 2023. The topic of the lecture will be “Keeping Nutrients in Place: A Journey of Challenges, Benefits, and Tradeoffs” and will include much of his research on potato cropping systems.
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