phosphorus indices: an understanding of upper mississippi strategies john a. lory, ph.d. division of...
TRANSCRIPT
Phosphorus Indices:
an Understanding of
Upper Mississippi Strategies
John A. Lory, Ph.D.
Division of Plant Sciences
University of Missouri
Outline
Overview Phosphorus indexes: why do we need
them? Does it make sense that every state is
different? Missouri P index
Our objectives. What you need to make it work.
Many streams and lakes are phosphorus limited.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0 25 50 75 100 125 150 175 200
Total Phosphorus (ppb)
Ozark HighlandsOthers
Jones and Knowlton 1993
Wat e
r C
lari
ty a
s m
easu
r ed
by
Secch
i d
ep
th (
m) Missouri reservoirs
Challenge:
Where,
when,
and how to apply manure
to minimize P loss to surface
water.
Runoff volume Method of application Time since application Application rate Soil test P Soil type Cultivation Vegetative cover
Factors affecting runoff of P
Nutrient planners are required to assess phosphorus loss on all fields receiving manure.
You choose the method
Agronomic soil test recommendation Objective: does the crop need P?
Phosphorus threshold
Phosphorus Index Objective: will applied P be vulnerable to
losses?
Low N-based Applications
MediumN-based Applications
High P-based Applications
VeryHigh
No Manure Applications
Phosphorus Assessment
Assessment tools are state specific.Index Target:
- Runoff- Irrigation
- Runoff- Irrigation Long-term
Runoff
- Runoff- Leaching
Assessment tools are state specific.Approach:
Multiplicative tabular factors
Simplified model
Additive tabular factors Simplified
model
Do Differences Between StatesMake Sense?
Missouri’s approach: 2 choices
Agronomic soil test recommendation Objective: does the crop need P?
Phosphorus threshold
Phosphorus Index Objective: will applied P be vulnerable to
losses?
Missouri P index objectives
Strategic planning tool for use in writing a 5-year nutrient management plan.
Identify fields where field characteristics are likely to result in high P loss in runoff.
Simple to use with readily available information for people with an NRCS conservation plan.
6 Factors in the Missouri P index Soil test result
include units and sampling depth Tillage
Tilled vs. notill and forages RUSLE estimate of erosion Land cover Soil hydrologic group
A, B, C or D Distance from water feature
Simple model approach
Sediment P Function of RUSLE-2 erosion, soil test P
and sediment delivery ratio.
Soluble P Function of runoff volume (curve number
approach and soil test P).
Higher standard in the clear-water region of the state.
P index rating system
Rating Clear-water region Other
Low <1 <3
Medium >1 and <5 >3 and <7
High >5 and <10 >7 and <12
Very High >10 >12
6 Factors in the Missouri P index Soil test result
include units and sampling depth Tillage
Tilled vs. notill and forages RUSLE estimate of erosion Land cover Soil hydrologic group
A, B, C or D Distance from water feature
Surface applications require a tactical tool. Educational tools being developed to identify
times of year runoff least likely
Inputs: Ground cover - County Soil hydrologic group - Soil condition Soil moisture
Output Evaluation of runoff risk (low, medium, high) Predicted rainfall amount needed to initiate
runoff
P index developed cooperatively by MU and NRCS.
Based on best professional judgment.
Available as a spreadsheet at: http://nmplanner.missouri.edu/
Future
P index integrated into RUSLE 2
Email notification system to help evaluate timing of manure applications.