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Long-Term Grazing Intensity Research in the Missouri Coteau of North Dakota

Bob Patton, Paul Nyren, Gregory Mantz, and Anne Nyren, NDSU Central Grasslands Research Extension Center

 


 

Introduction

 

In 1989, the CGREC initiated a grazing-intensity research project that is ongoing. The objectives of the project are to determine the effect of grazing intensity on livestock performance and profitability and the sustainability of forage production. Five treatments are included in the study: no grazing, light, moderate, heavy, and extreme grazing. Each treatment is replicated three times in pastures of about 30 acres each except the no-grazing treatment, which consists of six 0.3-acre exclosures placed on both overflow and silty range sites. Livestock are not rotated between pastures and each pasture receives the same treatment each year. Our goal is to stock the pastures each year so when the cattle are removed in the fall, 65%, 50%, 35%, and 20% of the forage produced in an average year remains on the light, moderate, heavy, and extreme treatments, respectively. For these pastures, that means 2034, 1625, 937, and 485 lbs./ac. of forage remaining on the light, moderate, heavy, and extreme pastures, respectively. Table 1 presents the stocking history of the study and Figure 1 shows how much forage remained at the end of the grazing season each year.

 

To attain the desired grazing intensities, adjustments in stocking pressure are made each year based on information from previous years. Changes in the vegetation are determined by monitoring permanent plots located on silty and overflow range sites in each pasture and on the six exclosures. Table 2 lists the average production on these range sites during each year of the study and the total precipitation for the year.

 

Table 1. Stocking history of the grazing intensity trial for 1989 through 2008 at Central Grasslands Research Extension Center, Streeter, ND.

Year

Class of Animal

Stocking Date

Removal Date

Length of Grazing Season (Days)

1989

Steers

May 22

August 22

92

1990

Bred Heifers

May 30

November 27

181

1991

Bred Heifers

May 29

September 25

119

1992

Bred Heifers

June 1

August 25

85

1993

Bred Heifers

May 29

September 26

120

1994

Open Heifers & Steers

May 17

November 10

177

1995

Open Heifers

May 18

October 30

165

1996

Open Heifers

May 20

September 23

126

1997

Open Heifers

May 27

November 5
(Extreme- August 27)
1

162
(Extreme- 92)

1998

Open Heifers

May 16

October 28

165

1999

Open Heifers

May 27

November 4

161

2000

Open Heifers

May 18

September 25

130

2001

Open Heifers

May 21

September 11

113

2002

Open Heifers

May 23

July 17

55

2003

Open Heifers

May 23

September 19

119

2004

Open Heifers

May 19

September 9

113

2005

Open Heifers

May 17

October 27

163

2006

Open Heifers

May 11

July 27

77

2007

Open Heifers

May 18

October 1

136

2008

Open Heifers

May 20

August 25

97

1Due to lack of forage, livestock were removed early in the extreme grazing treatment.

 

 

Above ground biomass remaining (lbs/acre) on each treatment at the end of the grazing season from 1989 to 2008.

 

Treatment

Year

Light

Moderate

Heavy

Extreme

1989

2,078

2,074

2,035

1,701

1990

2,634

2,383

2,023

1,985

1991

2,385

1,494

833

641

1992

1,915

1,353

574

406

1993

2,924

2,256

1,290

608

1994

2,017

1,728

1,393

901

1995

2,772

1,906

1,583

504

1996

2,552

1,975

1,064

513

1997

2,550

1,711

689

560

1998

2,674

1,848

686

522

1999

2,269

2,108

806

609

2000

2,387

2,246

1,130

718

2001

1,933

1,883

1,197

617

2002

1,225

1,132

701

329

2003

2,434

2,128

1,205

678

2004

1,801

1,775

1,284

518

2005

2,324

1,994

1,331

357

2006

1,443

1,284

826

378

2007

2,172

2,359

1,239

600

2008

2,002

1,527

1,320

551

Ideal Remaining

2,034

1,625

937

485

 

 

Table 2. Total crop year precipitation (October 1 to September 30) and peak total above-ground biomass production on overflow and silty range sites on the grazing intensity study from 1989 to 2008. 

Year

Precipitation

(in)

Above-Ground Biomass (lbs/acre)

Overflow

Silty

1989

18.40

3,863

2,089

1990

16.10

3,847

2,962

1991

12.89

3,142

2,629

1992

15.25

2,758

2,065

1993

26.59

3,999

3,446

1994

16.86

4,201

2,803

1995

22.60

4,773

3,134

1996

20.55

3,837

2,645

1997

18.63

3,351

2,376

1998

18.91

3,334

2,855

1999

26.91

4,338

3,152

2000

15.60

3,950

2,846

2001

18.44

3,569

2,678

2002

16.69

1,850

1,175

2003

15.39

3,128

2,730

2004

21.95

3,676

2,814

2005

15.10

4,390

3,097

2006

16.62

2,450

1,632

2007

22.05

3,948

3,114

2008

14.31

3,126

2,433

20-Year Average

17.77

3,577

2,634

 


 

Table of Contents

  Livestock Response

  Forage Production and Utilization Treatment Effects

  Plant Community Dynamics

  Recommendations

  Future Research

 


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