Measuring the Nutrient Accumulation Rates of High-Yielding Potatoes and Sugar Beets

One of the fundamental components of 4R Nutrient Stewardship is applying nutrients at the "Right Time." However, for many important crops, there is a lack of understanding of when nutrients are actually taken up during the season. A study was conducted to evaluate the amount, rate, and the partitioning of dry matter and nutrient accumulation by sugar beet during the growing season.

Sugar beets, growing on an adequately fertilized and irrigated field in Southern Idaho (a major sugar beet-growing area), were harvested at 10-day intervals and separated into tops and roots, weighed, dried, and analyzed for nutrient composition. Total accumulation at harvest was 50 t/ha dry matter, 270 kg N/ha, 70 kg P/ha, 530 kg K/ha, 200 kg Na/ha, 122 kg Ca/ha, 108 kg Mg/ha, 28 kg S/ha, 13 kg Fe/ha, 1.9 kg Mn/ha, 0.6 kg Zn/ha, 0.15 kg/Cu/ha, and 0.7 kg B/ha. The distribution of nutrients between the plant tops and the roots exhibited large differences depending on the specific nutrient. For example, nitrogen (N) accumulation rates in the plant tops peaked at 4 kg N/ha/day and 0.6 kg N/ha/day in the roots, approximately 45 days after planting. During the sugar development stage, there was a net transport of N from the leaves to the roots as sugar production dominates the physiological processes. Phosphorus (P) was partitioned with 20% of the total P in the tops and 80% in the roots. Maximum P uptake of 1.4 kg P/ha/day occurred during the root bulking stage. Potassium (K) accumulation was approximately equal between the tops and the roots. The maximum K accumulation rate was 8 kg K/ha/day during the root bulking stage of growth.

Better knowledge of when plants require nutrients to support their growth pattern will allow more precise application of 4R principles.