Native Warm-Season Grasses Show Limited Response to Phosphorus and Potassium

Data are needed to identify optimum response to potassium (K) and phosphorus (P) amendment and associated mycorrhizal colonization for native warm-season grasses (NWSGs; big bluestem [BB; <i>Andropogon gerardii</i> Vitman] and switchgrass [SG; <i>Panicum virgatum</i> L.]). To...

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Main Authors: Eric Bisangwa, Jonathan D. Richwine, Patrick D. Keyser, Amanda J. Ashworth, David M. Butler, Utsala Shrestha, Forbes R. Walker
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Agronomy
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Online Access:https://www.mdpi.com/2073-4395/15/3/669
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author Eric Bisangwa
Jonathan D. Richwine
Patrick D. Keyser
Amanda J. Ashworth
David M. Butler
Utsala Shrestha
Forbes R. Walker
author_facet Eric Bisangwa
Jonathan D. Richwine
Patrick D. Keyser
Amanda J. Ashworth
David M. Butler
Utsala Shrestha
Forbes R. Walker
author_sort Eric Bisangwa
collection DOAJ
description Data are needed to identify optimum response to potassium (K) and phosphorus (P) amendment and associated mycorrhizal colonization for native warm-season grasses (NWSGs; big bluestem [BB; <i>Andropogon gerardii</i> Vitman] and switchgrass [SG; <i>Panicum virgatum</i> L.]). To evaluate these responses, experiments were conducted in Knoxville and Springfield, Tennessee, from 2013 to 2019. In twice-annual harvests, we assessed BB and SG dry matter (DM) yield, crude protein (CP), total digestible nutrients (TDNs), P and K removed by grasses (removal), and soil test P and K in response to P (29 to 88 kg ha<sup>−1</sup>) and K (70 to 257 kg ha<sup>−1</sup>) elemental rates, and rates of root colonization by mycorrhizal fungi in response to P. Amendments had no effect (<i>p</i> > 0.05) on DM yield, CP, or TDN for either species. Yield, CP, and TDN fluctuated among years (<i>p <</i> 0.001) for both species, but no consistent temporal trends were observed. Although removal exceeded inputs at the control (no input) for P and K, and at 70 kg K ha<sup>−1</sup>, there was not an associated reduction in soil test K and P values. Phosphorus rate affected (<i>p</i> = 0.02) total mycorrhizal colonization, with an average of 62% colonization across both species and 70% at the highest P rates. Given the lack of response for yield, CP, TDN, or associated soil nutrient test levels, NWSGs appear to offer a low-input option for forage production.
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spelling doaj-art-3d8157c4b21846c0bcadf9f62593d77c2025-08-20T03:40:42ZengMDPI AGAgronomy2073-43952025-03-0115366910.3390/agronomy15030669Native Warm-Season Grasses Show Limited Response to Phosphorus and PotassiumEric Bisangwa0Jonathan D. Richwine1Patrick D. Keyser2Amanda J. Ashworth3David M. Butler4Utsala Shrestha5Forbes R. Walker6School of Natural Resources, University of Tennessee, Knoxville, TN 37996, USACollege of Agriculture, Arkansas State University, Jonesboro, AR 72467, USASchool of Natural Resources, University of Tennessee, Knoxville, TN 37996, USAPoultry Production and Product Safety Research Unit, Agricultural Research Service, U.S. Department of Agriculture, 1260 W. Maple Street, Fayetteville, AR 72701, USADepartment of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USADepartment of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USADepartment of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, TN 37996, USAData are needed to identify optimum response to potassium (K) and phosphorus (P) amendment and associated mycorrhizal colonization for native warm-season grasses (NWSGs; big bluestem [BB; <i>Andropogon gerardii</i> Vitman] and switchgrass [SG; <i>Panicum virgatum</i> L.]). To evaluate these responses, experiments were conducted in Knoxville and Springfield, Tennessee, from 2013 to 2019. In twice-annual harvests, we assessed BB and SG dry matter (DM) yield, crude protein (CP), total digestible nutrients (TDNs), P and K removed by grasses (removal), and soil test P and K in response to P (29 to 88 kg ha<sup>−1</sup>) and K (70 to 257 kg ha<sup>−1</sup>) elemental rates, and rates of root colonization by mycorrhizal fungi in response to P. Amendments had no effect (<i>p</i> > 0.05) on DM yield, CP, or TDN for either species. Yield, CP, and TDN fluctuated among years (<i>p <</i> 0.001) for both species, but no consistent temporal trends were observed. Although removal exceeded inputs at the control (no input) for P and K, and at 70 kg K ha<sup>−1</sup>, there was not an associated reduction in soil test K and P values. Phosphorus rate affected (<i>p</i> = 0.02) total mycorrhizal colonization, with an average of 62% colonization across both species and 70% at the highest P rates. Given the lack of response for yield, CP, TDN, or associated soil nutrient test levels, NWSGs appear to offer a low-input option for forage production.https://www.mdpi.com/2073-4395/15/3/669big bluestemcrude proteindry matterforage nutritive valuepotassiummycorrhizae
spellingShingle Eric Bisangwa
Jonathan D. Richwine
Patrick D. Keyser
Amanda J. Ashworth
David M. Butler
Utsala Shrestha
Forbes R. Walker
Native Warm-Season Grasses Show Limited Response to Phosphorus and Potassium
Agronomy
big bluestem
crude protein
dry matter
forage nutritive value
potassium
mycorrhizae
title Native Warm-Season Grasses Show Limited Response to Phosphorus and Potassium
title_full Native Warm-Season Grasses Show Limited Response to Phosphorus and Potassium
title_fullStr Native Warm-Season Grasses Show Limited Response to Phosphorus and Potassium
title_full_unstemmed Native Warm-Season Grasses Show Limited Response to Phosphorus and Potassium
title_short Native Warm-Season Grasses Show Limited Response to Phosphorus and Potassium
title_sort native warm season grasses show limited response to phosphorus and potassium
topic big bluestem
crude protein
dry matter
forage nutritive value
potassium
mycorrhizae
url https://www.mdpi.com/2073-4395/15/3/669
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