{"title":"Potassium and harvest time interaction effect on alfalfa production and profitability","authors":"Michael M. Baidoo, M. Anowarul Islam","doi":"10.1002/agj2.21575","DOIUrl":null,"url":null,"abstract":"<p>Researchers have extensively studied and documented the effects of potassium (K) fertility on alfalfa (<i>Medicago sativa</i> L.). Yet, additional research is needed to determine how interactions of K, cultivar, and harvest management influence the K needs of alfalfa. To explore these interactions, we conducted 5 years of field research at the University of Wyoming James C. Hageman Sustainable Agriculture Research and Extension Center in Lingle, WY. Treatments were (a) four K rates (0, 56, 112, and 168 kg K<sub>2</sub>O ha<sup>−1</sup> year<sup>−1</sup>) applied before planting in the fall of 2016 and after the final harvest in the fall of 2017–2020, (b) two cultivars (Hi-Gest 360 and AFX 457), and (c) two harvest times (early harvest, late bud to early [10%] bloom, and late harvest, 7 days after early harvest), arranged in a 4 × 2 × 2 factorial under random complete blocks with four replications. At 168 kg K<sub>2</sub>O ha<sup>−1</sup> year<sup>−1</sup> and early harvest, a consistently significant (<i>p</i> < 0.05) higher yield response was observed. The same response was seen at 112 kg K<sub>2</sub>O ha<sup>−1</sup> year<sup>−1</sup> and late harvest. This occurred at a site with moderate-to-high soil K levels throughout the study period. There was a linear (<i>p</i> < 0.001, <i>R</i><sup>2</sup> = 0.66) and quadratic (<i>p</i> = 0.006, <i>R</i><sup>2</sup> = 0.61) response of forage accumulation to K rate at early and late harvest, respectively. Similar trends were also seen for stem count, relative water content, root uptake of K, and tissue K. Time of harvest showed immense potential for optimizing K's effect for a consistent high-yield response. However, fertilizing alfalfa with 112 kg K<sub>2</sub>O ha<sup>−1</sup> year<sup>−1</sup> gave the most profitable production under both harvest times. If K fertilizer prices drop over time, high profits could be attained with higher K fertilization rates. After 3 years of production, average forage accumulation increased under an early harvest system and decreased under a late harvest system. Growers in Wyoming and similar regions are encouraged to consider fertilizing alfalfa with moderate K rates (∼112 kg K<sub>2</sub>O ha<sup>−1</sup> year<sup>−1</sup>) on soils testing moderate-to-high in soil test K, implement a late harvest system for the first 3 years after planting, and transition to an early harvest system after the initial 3 years to maximize alfalfa profits.</p>","PeriodicalId":7522,"journal":{"name":"Agronomy Journal","volume":null,"pages":null},"PeriodicalIF":2.0000,"publicationDate":"2024-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Agronomy Journal","FirstCategoryId":"97","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/agj2.21575","RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"AGRONOMY","Score":null,"Total":0}
引用次数: 0
Abstract
Researchers have extensively studied and documented the effects of potassium (K) fertility on alfalfa (Medicago sativa L.). Yet, additional research is needed to determine how interactions of K, cultivar, and harvest management influence the K needs of alfalfa. To explore these interactions, we conducted 5 years of field research at the University of Wyoming James C. Hageman Sustainable Agriculture Research and Extension Center in Lingle, WY. Treatments were (a) four K rates (0, 56, 112, and 168 kg K2O ha−1 year−1) applied before planting in the fall of 2016 and after the final harvest in the fall of 2017–2020, (b) two cultivars (Hi-Gest 360 and AFX 457), and (c) two harvest times (early harvest, late bud to early [10%] bloom, and late harvest, 7 days after early harvest), arranged in a 4 × 2 × 2 factorial under random complete blocks with four replications. At 168 kg K2O ha−1 year−1 and early harvest, a consistently significant (p < 0.05) higher yield response was observed. The same response was seen at 112 kg K2O ha−1 year−1 and late harvest. This occurred at a site with moderate-to-high soil K levels throughout the study period. There was a linear (p < 0.001, R2 = 0.66) and quadratic (p = 0.006, R2 = 0.61) response of forage accumulation to K rate at early and late harvest, respectively. Similar trends were also seen for stem count, relative water content, root uptake of K, and tissue K. Time of harvest showed immense potential for optimizing K's effect for a consistent high-yield response. However, fertilizing alfalfa with 112 kg K2O ha−1 year−1 gave the most profitable production under both harvest times. If K fertilizer prices drop over time, high profits could be attained with higher K fertilization rates. After 3 years of production, average forage accumulation increased under an early harvest system and decreased under a late harvest system. Growers in Wyoming and similar regions are encouraged to consider fertilizing alfalfa with moderate K rates (∼112 kg K2O ha−1 year−1) on soils testing moderate-to-high in soil test K, implement a late harvest system for the first 3 years after planting, and transition to an early harvest system after the initial 3 years to maximize alfalfa profits.
期刊介绍:
After critical review and approval by the editorial board, AJ publishes articles reporting research findings in soil–plant relationships; crop science; soil science; biometry; crop, soil, pasture, and range management; crop, forage, and pasture production and utilization; turfgrass; agroclimatology; agronomic models; integrated pest management; integrated agricultural systems; and various aspects of entomology, weed science, animal science, plant pathology, and agricultural economics as applied to production agriculture.
Notes are published about apparatus, observations, and experimental techniques. Observations usually are limited to studies and reports of unrepeatable phenomena or other unique circumstances. Review and interpretation papers are also published, subject to standard review. Contributions to the Forum section deal with current agronomic issues and questions in brief, thought-provoking form. Such papers are reviewed by the editor in consultation with the editorial board.