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An index to rate the quality of An index to rate the quality of no-till systems:no-till systems:
validationvalidation
Glaucio RoloffGlaucio RoloffFederal University of Latin-American Integration (UNILA)Federal University of Latin-American Integration (UNILA)
Ramiro A. T. LutzRamiro A. T. LutzVetagro Crop ConsultantsVetagro Crop Consultants
Ivo Mello & Marie BartzIvo Mello & Marie BartzBrazilian No-Till Federation (FEBRAPDP)Brazilian No-Till Federation (FEBRAPDP)
55thth WCCA & 3 WCCA & 3rdrd FSD FSD Brisbane 2011 Brisbane 2011
Cooperation FEBRAPDP – ITAIPU BinacionalCooperation FEBRAPDP – ITAIPU Binacional
5th WCCA & 3rd FSD Brisbane 2011 2
NTS Quality Index (NTSQI)• A pioneer index that...
» ...requires testing and validation» ...forecasts potential impacts qualitatively» ...indicates tendencies
No-Till System (NTS) Quality Index
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Validation• Within a sustainability context:
... an index is valid if it correctly assesses factors leading to the sustainability of a given scenario
• Index validation (Bockstaller and Girardin, 2003. Agricult. Systems, 76, 639-653)» Scientific basis » Output validity → our focus» Usefulness to the end user
No-Till System (NTS) Quality Index
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Validation• Analysis must contend with:
» Cause and effect relations are difficult to establish» Agricultural systems are complex» Linear or linearisable functions should not be expected» Non-normal or unknown data distributions are to be expected
NTSQI validation
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NTSQI test• 24 voluntary farmers over 6 small river basins• NTSQI from questionnaire data
NTSQI validation M&M
NTSQI validation• Same farmers, independent parameters:
» Average terrace cross-section area (TC)» Difference between calculated and real TC (DTC)» Organic matter (OM)» Phosphorus (P)» Potassium (K)» Cation exchange capacity (CEC)» Sum of bases (SB)» Average worm population (WP)
5 subsamples per field
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NTSQI validation statistics
NTSQI validation• Statistical distribution:
» tested for normality by Shapiro-Wilk at p<0.05• Correlation strengths:
» by Spearman´s δ rank coefficient with bootstrapping
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NTSQI validation results
Basic statistics: NTSQI and its indicators
NTSQI RI RD RP TF TA CE BN AT
Average 7.17 0.81 0.71 0.67 0.86 0.63 0.68 0.66 0.61
Coef of Var % 11.7 13.6 26.8 29.9 31.4 57.1 22.1 18.2 39.3
Shapiro-Wilk p 0.20 0.03 0.00 0.19 0.00 0.00 0.00 0.00 0.01
Rotation intensity (RI)Rotation diversity (RD) Crop residue persistence (RP)Tillage frequency (TF)
Terrace adequacy (TA)Conservation evaluation (CE) Balanced nutrition (BN)NTS adoption time (AT)
Non-normal
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NTSQI validation results
Basic statistics: Independent parameters
P in mg dm-3
K, SB and CEC in cmolc dm-3
DTC in m2
WN in numbers
P OM K SB CEC DTC WN
Average 18.92 3.39 0.52 8.55 13.33 1.00 7.57
Coef of Var % 66.3 15.9 28.8 10.6 8.1 258,0 146.0
Shapiro-Wilk p 0.00 0.65 0.02 0.79 0.56 0.06 0.00
Non-normal
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NTSQI validation results
NTSQI RI RD RP TF TA CE BN ATNTSQI 1.00
RI 0.16 1.00RD -0.22 0.27 1.00RP 0.46 0.53 -0.54 1.00TF 0.56 -0.08 -0.04 -0.10 1.00 TA 0.62 -0.27 -0.45 0.21 0.49 1.00CE 0.44 -0.28 -0.18 0.04 0.05 0.29 1.00BN -0.11 0.12 -0.51 0.53 -0.45 0.00 -0.05 1.00AT 0.63 -0.03 -0.25 0.33 0.32 0.36 0.43 -0.14 1.00
Rank correlations: NTSQI and its indicators
moderate strong
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NTSQI validation results
Rank correlations: NTSQI and its indicators
• NTSQI most strongly correlated to:» tillage frequency (TF)» terrace adequacy (TA)» adoption time (AT)
• NTSQI vs rotations:» only moderately with rotation persistence (RP)» RP negatively correlated with rotation intensity (RI):
– second summer crop (corn) negates winter cover crop
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NTSQI validation results
Rank correlations: NTSQI + indicators vs independent
moderate strong
NTSQI RI RD RP TF TA CE BN AT
P 0.34 -0.17 -0.34 0.15 0.19 0.32 0.31 0.14 0.24OM 0.55 -0.12 -0.37 0.30 0.43 0.64 0.09 -0.11 0.57K -0.78 -0.10 0.23 -0.35 -0.56 -0.44 -0.41 0.05 -0.55
DTC -0.30 -0.08 0.03 -0.06 -0.38 -0.32 0.14 0.31 -0.38WN 0.21 0.45 -0.10 0.49 0.03 -0.04 -0.19 0.31 0.04
CEC and SB were not correlated to any NTSBI indicator:...withdrawn from further analysis
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NTSQI validation results
Rank correlations: NTSQI + indicators vs independent
• NTSQI correlated to most independent parameters:» exception - worm numbers (WN)» potassium content (K) is an oddball
• Organic matter (OM) correlations:» strongly with NTSQI, terrace adequacy (TA) and
adoption time (AT)» moderately with rotation diversity (RD), rotation
persistence (RP) and tillage frequency (TF)
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NTSQI validation results
Conclusions:
• NTSQI is a valid index from an output point of view.…. at this preliminary stage
• NTSQI methodology:» can pinpoint practices that need to be targeted» hence will improve NTS's environmental services
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Thank youThank you
[email protected]@unila.edu.br
55thth WCCA & 3 WCCA & 3rdrd FSD FSD Brisbane 2011 Brisbane 2011