ONA REPORT

published in

THE FLORIDA CATTLEMAN AND LIVESTOCK JOURNAL


March 2016

Jiggs Bermudagrasss and Limpograss Responses to Potassium and Phosphorus Fertilization

by Maria L. Silveira


For questions or comments regarding this publication contact: Dr. Maria Silveira, University of Florida, IFAS

In the southeastern United States, forage-based livestock systems rely on warm-season perennial grasses such as bermudagrass (Cynondon dactylon), bahiagrass (Paspalum notatum), and limpograss (Hemarthria altissima). More specifically in Florida, bahiagrass is the predominant cultivated grass, occupying approximately 2 million acres (Newman et al., 2011). While bahiagrass is widely used in low input systems with limited (or no) fertilizer inputs, other grasses such as hybrid bermudagrass and limpograss are important forage crops for both dairy and beef cattle producers because of their greater yield potential and better nutritive value. However, because of the greater yields, these grass species require relatively higher fertilization levels as compared to other less productive grasses such as bahiagrass.

Fertilizer recommendations for Jiggs bermudagrass and limpograss hay production in Florida consist of 80 lb N/A, and 40 lb K2O/A, and 20 lb P2O5/A (if soil tests low or medium in P) after each cutting. For grazing, recommended N application rate is 160 lb N/A and up to 80 lb K2O/A, and 40 lb P2O5/A depending on soil test results. The need for routine use of micronutrients has not been demonstrated.

Despite the University of Florida recommendations for K and P fertilization of Jiggs bermudagrass and limpograss hayfields and pastures, many forage production systems do not supply adequate K and P to replace the nutrients removed as harvested forage. Consequently, soil K (and P to a lesser extent) availability declines which may often result in poor stand persistence and greater incidence of diseases and insect damage.

The objective of this 3-yr field trial was to evaluate Jiggs bermudagrass and limpograss responses to K and P fertilization. The study was conducted on established Jiggs bermudagrass and limpograss fields at the University of Florida/IFAS, Range Cattle Research and Education Center, Ona, FL and treatments consisted of minimum fertilization regimens that could maintain optimum forage yield, nutritive value, and stand persistence. Potassium and P were applied in the spring (April) of 2012, 2013, and 2014 at annual levels of 0, 40, and 80 lb K2O/A and 0, 20, and 40 lb P2O5/A, respectively. Nitrogen was applied at an annual rate of 80 lb N/A. Forage was harvested at 6-week intervals for a total of 4 harvest events per year to determine dry matter yield and nutritive value.

Results

Jiggs bermudagrass responses
Jiggs bermudagrass dry matter yield increased linearly as annual K fertilization levels increased (Table 1). No effect of P fertilization on Jiggs responses was observed. Cumulative annual dry matter yield for the treatments receiving K increased ~ 26 to 377% relative to the control treatments (no K added). The largest differences between control and K-receiving treatments were observed in 2014. During this year, K fertilization increased Jiggs bermudagrass dry matter yield by as much as 377% (5357 lb/A for the treatment receiving 80 K2O/A compared to 1124 lb/A for the controls). Jiggs bermudagrass dry matter yield in 2013 was considerably lower than those reported in 2012 and 2014 due to unfavorable climatic conditions experienced during that year. Averaged Jiggs crude protein concentrations across the 3-yr study were greater in the controls compared to the treatments receiving K (Table 1). This occurred because of a dilution effect as a result of greater dry matter yield observed in the treatments receiving K.

Regardless of the K fertilization levels, Jiggs bermudagrass dry matter yield generally decreased over time during the study period. These data indicated that K levels being applied during the 3-yr study were not sufficient to sustain the same level of production. In addition, considerable stand losses and concomitant weed infestation occurred at the end of the 3-yr study, particularly in the treatments receiving no K (Table 1). Jiggs bermudagrass frequency and ground cover ranged from 50 to 54 % in the treatments receiving K compared to ~ 31 to 37% in the control treatments.  

Table 1. Jiggs bermudagrass dry matter yield (DMY), frequency, ground cover, and crude protein concentration as affected by K application level.


Annual K2O application level

Cumulative DRY MATTER YIELD

Frequency 1

Ground Cover1

Crude Protein2

2012

2013

2014

___________________ lb/A__________________

_____________ %_______________

0

4536

820

1124

37

31

15.2

40

5719

1815

3959

50

52

14.0

80

6517

2216

5357

54

54

13.7

Orthogonal Contrast

Linear***

Linear**

Linear***

Linear***

Linear***

Linear***

1Frequency and ground cover were measured at the end of 2014 growing season.
2Values represent the 3-yr average
** = P equal or less than 0.01; *** = P equal or less than 0.0001

Limpograss responses


Table 2. Limpograss dry matter yield (DMY), frequency, ground cover, and crude protein concentration as affected by K application level.


K2O application level

Cumulative DMY

Frequency1

Ground Cover1

Crude Protein2

2012

2013

2014

______________ lb/A ______________

______________ %______________

0

12408

4189

8779

60

65

6.7

40

11015

4921

10947

92

87

6.2

80

12135

5798

12900

94

89

6.1

Orthogonal Contrast

NS

Linear***

Linear ***

Linear **

Linear ***

Linear *

1Frequency and ground cover were measured at the end of 2014 growing season.
2Values represent the 3-yr average
NS= not significant; * = P equal or less than 0.05; ** = P equal or less than 0.01; *** = P equal or less than 0.0001

Summary
Potassium fertilization resulted in greater Jiggs bermudagrass and limpograss dry matter yields and decreased stand loss in the 3-yr study. Despite the positive effect of K, Jiggs bermudagrass dry matter yield observed in 2014 was significantly lower than those obtained in the first year of study and considerable stand losses and concomitant weed infestation occurred at the end of the study. Although the amounts of K exported via above-ground biomass were, in general, similar or less than those applied as fertilizer, K fertilization at the levels tested in this study were likely not sufficient to sustain the same level of production during the 3-yr study. Data also indicated that limpograss may require relatively lower levels of K fertilization than Jiggs bermudagrass to sustain production and stand persistence. No effect of P on Jiggs bermudagrass and limpograss responses were observed. Results from this study suggested that continuous above-ground removal without proper K fertilization may result in decreased forage performance, stand loss, and increased weed infestation. Adequate K supply is essential to sustain Jiggs bermudagrass and limpograss productivity and long-term persistence.


Back to the Range Cattle Research and Education Center Home Page