How Management Practices Impact the Relative Proportion of ...Extension and Outreach IOWA STATE...
Transcript of How Management Practices Impact the Relative Proportion of ...Extension and Outreach IOWA STATE...
How Management Practices Impact the Relative Proportion of Dissolved P
in Surface Runoff
Antonio MallarinoDepartment of Agronomy
Iowa State University
Extension and OutreachIOWA STATE UNIVERSITY
Phosphorus Lost from Fields
• Dissolved P in water (DRP, DTP, TRP) and particulate P (bound to soil particles)
• Particulate P and algae growth:- Slower but long-term impact- Iowa P Index: "70% of amount delivered to
Iowa mostly shallow lakes will be available for a long period of time"
• Dissolved P, large short-term impact- Mostly dissolved P in subsurface drainage- Variable proportion in surface runoff
Extension and OutreachIOWA STATE UNIVERSITY
Iowa P Index Three Components
Soil Erosion(Particulate P)
Water Runoff(Dissolved P)
Tile Drainage(Dissolved P)
Source Factors- soil P- application method,timing, and rate
Soil and water conservation practices
Extension and OutreachIOWA STATE UNIVERSITY
Tillage and P Application
• No-till reduces erosion (and corn yield)• No yield response to P placement in Iowa
even for no-till, other than starter• Incorporation/injection of manure is good
for N management and odor control• Injection/banding and incorporation by
tillage reduce runoff P loss if soil erosion and runoff are not increased
• The timing of operations and runoff events and P source are key issues
Extension and OutreachIOWA STATE UNIVERSITY
What Do we Say or Farmers Do?• No yield response to P placement or timing of
application in Iowa even for no-till• The spring is not a practical time to apply
fertilizer; wet soils, rain, little time; very little rainfall in the fall, low risk of surface runoff
• Most apply manure & P before corn of C-S; they need to empty pit or stockpiles
• We say don't till in the fall, apply manure-N in spring or as late as possible in the fall
• Most fertilizer P & solid manure are applied in the fall to soybean ground not incorporated
Extension and OutreachIOWA STATE UNIVERSITY
This Presentation
• Effects of P source, tillage, and time to a runoff event on P loss with surface runoff
• Studies conducted under natural or field simulated rainfall
• Runoff P fractions- Dissolved reactive P (DRP, filtered)- Total dissolved P (filtered, digestion or ICP)- Bioavailable P (FeO filter paper)- Total P
On-Farm Rainfall Simulations2000s National Runoff P Project Protocol
Short-Term EvaluationsP Source, Tillage, Time to Runoff
Extension and OutreachIOWA STATE UNIVERSITY
P Source, Immediate Runoff EventNo Incorporation, Broadcast 50 kg P/ha to Soybean Residue
Means of 21 Fields
Run
off P
Los
s (k
g ha
-1)
0.0
0.5
1.0
1.5
2.0
2.5
No P
BeefCattle
Manure
PoultryManure
LiquidSwine
Manure
FertilizerDissolved PTotal P
18% 29% 31%
49%
88%% Dissolved P of TP
Haq & Mallarino, ISU
Extension and OutreachIOWA STATE UNIVERSITY
Source, Short-Term Runoff TimingNo Incorporation, Broadcast 50 kg P/ha to Soybean Residue
Means of Six Fields
Dis
solv
ed R
unof
f P (k
g ha
-1)
0
1
2
3
4
Tota
l Run
off P
(kg
ha-1
)
0
1
2
3
4Fertilizer
No P
24 hours10 days10 days wet
24 hours10 days10 days wetFertilizer
LiquidSwineManure
PoultryManure
No P
81
8174
67
87
85
5266
32
80
1828
LiquidSwineManure
PoultryManure
% Dissolved P of TP
Haq, Allen, & Mallarino, ISU
Extension and OutreachIOWA STATE UNIVERSITY
Source, Runoff Timing, Incorporation
With/Without Incorporation, Broadcast 50 kg P/ha to Soybean ResidueMeans of Two Fields
Run
off P
Los
s (k
g ha
-1)
0
1
2
3
4
No P
PoultryManure
Fertilizer24-hr Event, Incorporated24-hr Event, Not Incorporated
LiquidSwine
Manure
10-day Event, Not Incorporated
No P
PoultryManure
FertilizerLiquidSwine
Manure
No P
PoultryManure
Fertilizer
LiquidSwine
Manure
21%57%
68%
52%
5% 20%
47%
52%
11%47%
69%63%
Dissolved PTotal P
Dissolved PTotal P
Dissolved PTotal P
DRP % of TP DRP % of TPDRP % of TP
Allen, Haq, & Mallarino, ISU
Extension and OutreachIOWA STATE UNIVERSITY
Tillage and Runoff Event Timing
• Let's add the P rate factor
Extension and OutreachIOWA STATE UNIVERSITY
Liquid Swine P Rate, Incorporation, Time
Allen and Mallarino, 2008
Dis
solv
ed P
(g h
a-1 )
0.0
0.1
0.2
0.3
0.4
0.5
0 10 20 30 40 50
Run
off T
otal
P (g
ha-
1 )
0.0
0.2
0.4
0.6
0.8
Not Incorporated
Incorporated
Liquid Swine Manure P Rate (kg P ha-1)0 10 20 30 40 50
24-hour Event15-day Event
24-hour Event 15-day Event
5
6 7
1632
56
62
1
Not Incorporated
Incorporated1
4 612
1 9 93
Not Incorporated
IncorporatedNot Incorporated
Incorporated
ns
6-mo Event
Not Incorporated
Incorporated
0 10 20 30 40 50
ns
15-day Event24-hour Event
6-mo Event
Not Incorporated
Incorporated
Extension and OutreachIOWA STATE UNIVERSITY
Poultry Manure Rate and Incorporation
Kaiser, Mallarino, Haq, 2009
Poultry Manure at 0, 56, or 102 kg P/ha, Averages Across Eight FieldsRunoff 24-48 hours After Application
Total P
0
1
2
3
4Dissolved Reactive P
Run
off P
Los
s (k
g P
ha-1
)
0
1
2
3
4
Incorporated
Not Incoporated
ControlLow ManureHigh Manure
ControlLow ManureHigh Manure
Incorporated
Not Incoporated
7% 17% 31%19%
49%
59%
% DRP of TP
Extension and OutreachIOWA STATE UNIVERSITY
Tillage and Runoff Event Timing
• Let's add amendments for poultry manure application
Extension and OutreachIOWA STATE UNIVERSITY
Alum or Gypsum, Tillage, Time to Runoff
Haq and Mallarino, 2013
Fall Surface Application, 50 kg P/ha, 3 years different sites
DRP % of TP10% 40% 39% 6% 13% 14% 21% 28% 30%
DRP % of TP DRP % of TP
Run
off P
Los
s (k
g ha
-1)
0.0
0.1
0.2
0.3
0.4
0.5
0.0
0.1
0.2
0.3
0.4
0.5
0.0
0.1
0.2
0.3
0.4
0.5
ManureManure+ GypsumManure
+ Alum
Manure
Manure+ Gypsum
Manure+ Alum
Manure+ Gypsum
Manure
Manure+ Alum
24 hours Event Tillage24 hours Event No-Till 10 Days Event No-TillDissolved PTotal P
Dissolved PTotal P
Dissolved PTotal P
Extension and OutreachIOWA STATE UNIVERSITY
Major Results Summary• Short-term dissolved and total P loss was
Fertilizer > Liquid manure > Solid manure- Larger differences without incorporation - % dissolved P of TP: Same overall ranking but
smaller & less consistent differences- % dissolved P increased with the P rate- Manure soluble P not a good index
• A runoff delay greatly reduced the large total P loss with fertilizer & liquid manure- No clear effect on % dissolved P of total P- With no-till it was as effective at reducing
dissolved and total P loss as tillage
Extension and OutreachIOWA STATE UNIVERSITY
The NW Iowa Runoff P StudyCorn-Soybean Rotations
Tillage, Fertilizer, Liquid Swine ManureSix Years
Extension and OutreachIOWA STATE UNIVERSITY
Site and Management Practices
• Sac series (Oxyaquic Hapludoll), slope 3.3%, optimum STP (16-20 mg kg-1, 15 cm)
• Plots 30x6 m, 6 years study• Corn-soybean rotations• Tillage: No-till or chisel-plow/disk tillage• P: 2-year rate before corn (112 kg P/ha)
- Fertilizer P always broadcast- Liquid swine manure P always injected
• The most commonly used practices in Iowa for fertilizer or liquid manure
Extension and OutreachIOWA STATE UNIVERSITY
Soil Loss
Soil
Loss
(kg
ha-1
)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5 Tillage
No-Till
Fert
Swine
Fert Swine
Haq and Mallarino, 2013
Corn-Soybean Rotation Averages
Extension and OutreachIOWA STATE UNIVERSITY
Runoff P and % Dissolved P of Total PD
RP
Loss
(kg
P ha
-1)
0
1
2
3
4
Total P
21
57
19
57
% of TP
Tillage
No-Till
Tota
l P L
oss
(kg
P h
a-1)
0
1
2
3
4Tillage
No-TillFert
SwineFert
Swine
FertSwine
Haq and Mallarino, 2013
Corn-Soybean Rotation Averages
Extension and OutreachIOWA STATE UNIVERSITY
Placement and Cover Crop for No-TillR
unof
f P L
oss
(kg
ha-1
)
0.0
0.5
1.0
1.5
2.0
2.5
3.02X Broad P
to corn 1X Band Peach crop
No P, Rye
DRP
TP
DRP
TP
DRP
TP
Optimum STP
VH STP
Natural Rainfall, Corn-Soybean Rotation, Fertilizer P, 2-Year Avgs
Haq and Mallarino, 2015
Extension and OutreachIOWA STATE UNIVERSITY
Major Results Summary
• No-tillage reduced soil loss by 70%• Highest total P loss for broadcast fertilizer
with tillage, lowest and no differences for broadcast fertilizer with no-till or injected manure with or without tillage
• Twice more dissolved P loss with no-till, and no differences between P sources
• Confirmed value of cover crop to reduce P soil and P loss- Reduced % dissolved P of total P- Not much in ongoing dedicated study
Extension and OutreachIOWA STATE UNIVERSITY
Overall Thoughts
• No-till drastically reduces soil P loss and often also total P loss
• But sometimes increased dissolved P loss- Mainly with runoff events shortly after applying
broadcast P fertilizer or liquid manure- A runoff delay drastically reduces P loss
• Surface apply fertilizer or liquid manure in periods of low probability of runoff- In the fall as early as possible after harvest- Seems to be as good as incorporation by
tillage