Reducing Soil Phosphorus
Buildup From Animal
Manure Applications
Gerald W. Evers
Texas A&M University
Agricultural Research and Extension Center
Overton
Benefits of Animal Manure on
Agricultural Land

Complete fertilizer – contains all plant nutrients

Organic matter improves soil quality

Slow release of soluble nutrients (N, S, B)

Usually more economical than commercial fertilizer
Soil Phosphorus Buildup –
A Major Problem

Difference in nitrogen:phosphorus (P2O5) ratio in
mature (1:1) and plant requirements (4:1)

Only about 20 to 30% of the phosphorus is taken
up by the agricultural crop

Excess soil phosphorus can move into surface
water through runoff and soil erosion

Elevated water phosphorus levels result in
eutrophication and blue-green algae blooms.
Theory

If moderate levels of animal manure are applied
(to meet 60 to 70% of N requirements of the crop),
nitrogen becomes the most limiting nutrient.

If additional nitrogen is applied, plant growth and
uptake of excess phosphorus should be enhanced
and residual soil phosphorus reduced.
Study Outline

A Coastal bermudagrass hay meadow was
overseeded in October of 1998-2001 with annual
ryegrass or crimson clover.

Broiler litter was applied at 9.0 Mg/ha in 1998 and
1999 and 4.5 Mg/ha in 2000 and 2001.

Broiler litter was applied to the ryegrass –
bermudagrass system in October and to the clover
– bermudagrass system in April.
Study Outline

In the ryegrass – bermudagrass system, 56 kg
N/ha was applied 1 to 4 times/year in December,
March, May, and/or July.

In the clover – bermudagrass system, 56 kg N/ha
was applied 1 to 3 times/year in April, June,
and/or July.

After 4 years, soil samples from 0-15, 15-30, and
30-60 cm depths were analyzed for P.
Annual Ryegrass – Coastal Bermudagrass System
Year 1
Year 2
Year 3
Year 4
Broiler Litter Application, Ryegrass Planting, and Harvest Dates
Oct. 15, 1998
Oct. 21, 1999
Oct. 20, 2000
Oct. 1, 2001
Oct. 23, 1998
Oct. 22, 1999
Oct. 25, 2000
Oct. 31, 2001
Jan. 19, 1999
Mar. 17, 1999
Apr. 19, 1999
June 7, 1999
July 1, 1999
Aug. 10, 1999
Oct. 13, 1999
Nov. 30, 1999
Mar. 14, 2000
Apr. 21, 2000
May 31, 2000
June 28, 2000
Aug. 15, 2000
Oct. 9, 2000
Apr. 3, 2001
Apr. 30, 2001
June 19, 2001
July 18, 2001
Sept. 26, 2001
Mar. 22, 2002
Apr. 19, 2002
June 19, 2002
Aug. 15, 2002
Oct. 14, 2002
Nutrients applied to ryegrass-bermudagrass
9.0 Mg/ha
Year 1
N
P2O5
K2O
Ca
Mg
Na
Zn
Fe
Cu
Mn
Year 2
4.5 Mg/ha
Year 3
Year 4
------------------------------ kg / ha -----------------------------259
314
139
132
384
491
90
247
331
418
151
186
182
212
106
102
48.9
48.0
39.4
29.0
108.3
70.4
40.8
52.9
5.52
4.26
2.29
2.29
4.65
4.99
1.84
1.26
8.08
8.06
1.05
2.48
6.03
4.81
2.02
2.67
Yield of Ryegrass-Bermudagrass (Mg/ha)
a
Years 1 and 2
cd
cd
d
b
c
Dec, Mar, May, July
Mar, May, July
Mar, May
Dec, Mar
July
May
Mar
5
cd
a
e
Dec
10
No Nitrogen
Yield (Mg/ha)
b
May, July
15
0
Ryegrass-bermudagrass yield when fertilized with
broiler litter and N fertilizer.
Yield of Ryegrass-Bermudagrass (Mg/ha)
0
July
b,c
a,b
Mar, May, July
Mar, May
May, July
Dec, Mar
Dec
e
a
Dec, Mar, May, July
c
a,b
a
d
No nitrogen
5
c
May
10
cd cd
Mar
Year 3
No BL or N
Yield (Mg/ha)
15
Ryegrass-bermudagrass yield when fertilized with
broiler litter and N fertilizer.
Dec, Mar, May, July
Dec, Mar
b
a
Mar, May, July
May
b
Mar, May
b-d c-e
bc
a
July
5
No nitrogen
f
g
0
de
Mar
10
e
Dec
Year 4
No BL or N
Yield (Mg/ha)
15
May, July
Yield of Ryegrass-Bermudagrass (Mg/ha)
Ryegrass-bermudagrass yield when fertilized with
broiler litter and N fertilizer.
Phosphorus Uptake of Ryegrass-Bermudagrass (kg/ha)
b
ed
a
bc
c-e
a
a
10
e
Mar, May, July
Mar, May
May, July
Dec, Mar
July
May
Mar
20
Dec
30
a
b-d
40
No nitrogen
P uptake (kg/ha)
50
Years 1 and 2
Dec, Mar, May, July
60
0
Ryegrass-bermudagrass P uptake when fertilized
with broiler litter and N fertilizer.
Phosphorus Uptake of Ryegrass-Bermudagrass (kg/ha)
60
Year 3
ab
ab
a
ab
0
Mar, May, July
Mar, May
May, July
Dec, Mar
10
c
Dec
20
No nitrogen
30
a
Dec, Mar, May, July
ab
July
ab
ab
May
b
a
Mar
40
No BL or N
P uptake (kg/ha)
50
Ryegrass-bermudagrass P uptake when fertilized
with broiler litter and N fertilizer.
Year 4
ef
c-e
de
de
Dec
Mar
May
July
40
bc
c-e
cd
0
Mar, May
May, July
g
Dec, Mar
20
No nitrogen
30
10
a
f
No BL or N
P uptake (kg/ha)
50
ab
Dec, Mar, May, July
60
Mar, May, July
Phosphorus Uptake of Ryegrass-Bermudagrass (kg/ha)
Ryegrass-bermudagrass P uptake when fertilized
with broiler litter and N fertilizer.
Soil P levels after applying broiler litter and N
fertilizer for 4 years to annual ryegrassbermudagrass.
0-15 cm
56 kg N/ha
No BL or N
No N
Dec
Mar
May
July
Dec, Mar
May, July
Mar, May
Mar, May, July
Dec, Mar, May, July
15-30 cm
30-60 cm
--------------------P (ppm)----------------6.8e
44.3a
21.1cd
19.9cd
32.2b
21.3cd
34.1b
21.9cd
23.7c
22.7cd
19.0d
2.3d
11.0a
7.4b
5.7bc
7.4b
5.5bc
4.9c
5.5bc
5.1c
7.4b
5.6bc
2.5c
5.2a
3.4bc
2.7c
2.9bc
2.4c
2.3c
3.3bc
4.5ab
3.8a-c
3.3bc
SUMMARY
Ryegrass-Bermudagrass
 Maximum yield was reached with 168 kg N/ha
three years and 112 kg N/ha one year.
 Maximum phosphorus uptake occurred at 56 kg
N one year, 112 kg N two years, and 168 kg N
one year.
 After four years, combining N fertilizer with
broiler litter resulted in lower residual soil P than
broiler litter alone.
Crimson Clover – Coastal Bermudagrass System
Year 1
Year 2
Year 3
Year 4
Broiler Litter Application, Clover Planting, and Harvest Dates
April 22, 1999
April 24, 2000
May 4, 2001
May 10, 2002
June 7, 1999
May 31, 2000
June 19, 2001
June 19, 2002
June 30, 1999
June 28, 2000
July 18, 2001
Aug. 15, 2002
Aug. 10, 1999
Aug. 15, 2000
Sept. 26, 2001
Oct. 14, 2002
Oct. 13, 1999
Oct. 9, 2000
Oct. 1, 2001
Oct. 17, 2002
Oct. 21, 1999
Oct. 20, 2000
Apr. 30, 2002
Apr. 25, 2003
Nov. 30, 1999
Apr. 3, 2001
Mar. 20, 2000
Apr. 30, 2001
Apr. 21, 2000
Nutrients applied to clover-bermudagrass
9.0 Mg/ha
Year 1
Year 2
4.5 Mg/ha
Year 3
Year 4
------------------------------ kg / ha -----------------------------N
P2O5
K2O
Ca
Mg
Na
Zn
Fe
Cu
Mn
259
384
331
182
48.9
108.3
5.52
4.65
8.08
6.03
314
491
418
212
48.0
70.4
4.26
4.99
8.06
4.81
140
192
176
85
32.7
39.3
2.25
1.53
2.20
2.38
100
175
164
71
29.9
50.4
2.40
1.13
1.91
2.23
Yield of Crimson-Bermudagrass (Mg/ha)
Years 1 and 2
bc
ab
Apr, June, July
a-c
June, July
ab
Apr, July
bc
Apr, June
4
No nitrogen
Yield (Mg/ha)
8
Apr
c
12
bc
July
a
June
16
0
Crimson clover-bermudagrass yield when fertilized
with broiler litter and N fertilizer.
Yield of Crimson-Bermudagrass (Mg/ha)
16
Years 3
and 4
c
bc
c
c
a-c
a
ab
a
0
June, July
Apr, July
Apr, June
July
June
Apr, June, July
4
Apr
d
No nitrogen
8
No BL or N
Yield (Mg/ha)
12
Crimson clover-bermudagrass yield when fertilized
with broiler litter and N fertilizer.
a
a
a
a
June, July
Apr, June, July
June
a
Apr, July
a
a
Apr
Years a1 and 2
20
10
July
30
No nitrogen
P Uptake (kg/ha)
40
Apr, June
Phosphorus Uptake of Crimson-Bermudagrass (kg/ha)
0
Crimson clover-bermudagrass P uptake when
fertilized with broiler litter and N fertilizer.
Phosphorus Uptake of Crimson-Bermudagrass (kg/ha)
a
40
c
c
ab
a-c
a-c
Apr, June, July
Apr, July
Apr, June
July
June
June, July
10
Apr
20
No Nitrogen
30
No BL or Nitrogen
P Uptake (kg/ha)
Years 3
and 4
bc
a-c
d
0
Crimson clover-bermudagrass P uptake when
fertilized with broiler litter and N fertilizer.
Soil P levels after applying broiler litter and N
fertilizer for 4 years to crimson clover-bermudagrass.
0-15 cm
56 kg N/ha
No BL or N
No N
April
June
July
Apr, June
Apr, July
June, July
Apr, June, July
15-30 cm
30-60 cm
------------------------P (ppm)-------------------9.2 c
26.7 ab
23.5 ab
25.9 ab
19.3 b
31.4 a
23.3 ab
26.7 ab
29.8 a
3.0 d
10.5 a
9.1 ab
9.8 a
6.2 c
10.2 a
8.4 a-c
9.7 a
6.7 bc
2.4 a
3.3 a
3.8 a
3.4 a
4.1 a
3.8 a
2.7 a
3.6 a
3.5 a
SUMMARY
Crimson Clover-Bermudagrass
 When 9 Mg/ha of broiler litter was applied, there was
no yield response to N fertilizer. When 4.5 Mg/ha of
broiler litter was applied, there was a yield increase up
to 112 kg N/ha.
 Combining N fertilizer with broiler litter do not
increased P uptake and seldom decreased residual soil P.
 The crimson clover-bermudagrass system was as
effective as applying N fertilizer to the annual ryegrassbermudagrass system for reducing residual soil P.