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Tes$ng Alfalfa for Nutrient Management
Aron A. Quist, CPAg/SS Stanworth Crop Consultants, Inc
And Michael J. OCman
University of Arizona
Santa Fe Magazine September 1916
Agronomic Laboratory
Plant Analysis Soil Analysis Feed Analysis Consul$ng for Nutrient Mgmt Programs
Alfalfa Produc$on in Desert SW USA
• Nutrient Management is about P and K • In-‐season Applica$ons – P, water run liquid fer$lizer – K, broadcast muriate of potash
1998 California Alfalfa Symposium
Soil P Tes$ng Program
• FEEDBACK SYSTEM • SAMPLE 1-‐4 TIMES PER YEAR • PREDICATE FERTILIZER RECOMMENDATIONS UPON ANALYSIS
Alfalfa produc$on per cuZng to achieve 10 ton/acre annual yield in Palo Verde Valley
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
1 2 3 4 5 6 7 8 9
Hay Yield (ton
s/acre)
CuZng
Stanworth Database Review
• 20 years and 326,000 samples analyzed • Samples were collected by SCC primarily • 86,618 soil P samples from Established Alfalfa • 47,464 Soil K samples from Established Alfalfa • Excluded preplant soil samples • Each record contained soil texture informa$on – Each field contained soil texture records (SP)
ANALYTICS
• REVIEW DATA TO IMPROVE NUTRIENT MANAGEMENT STRATEGIES
• REVIEWING EFFICIENCY, EFFICACY OF PROGRAM
• MONEYBALL OF NUTRIENT MANAGMENT – PAYDIRT OF AGRONOMY
P soil test levels Soil texture effect
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
clay loam sand
Above
At
Below
Cri$cal Zone
P soil test levels Season effect
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Fall Winter Spring
Above
At
Below
Cri$cal Zone
P soil test levels Sand soils
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Fall Winter Spring
Above
At
Below
Cri$cal Zone
P soil test levels Loam soils
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Fall Winter Spring
Above
At
Below
Cri$cal Zone
P soil test levels Clay soils
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Fall Winter Spring
Above
At
Below
Cri$cal Zone
Alfalfa produc$on per cuZng to achieve 10 ton/acre annual yield in Palo Verde Valley
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
1 2 3 4 5 6 7 8 9
Hay Yield (ton
s/acre)
CuZng
P soil test levels Trend over $me (5 yr running avg.)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100% 1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2007
2008
2009
2010
2011
Above
At
Below
Cri$cal Zone
Soil K Tes$ng Program
• Soil samples taken the same $me as P soil samples
• K is slightly mobile in the soil, so samples depth is increased
• Potassium is prone to “Luxury Consump$on”, so rates are limited to 200 lbs K20/ac per applica$on maximum
K soil test levels Soil texture effect
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
clay loam sand
Above
At
Below
Cri$cal Zone
K soil test levels Season effect
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Fall Winter Spring
Above
At
Below
Cri$cal Zone
K soil test levels Sand soils
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Fall Winter Spring
Above
At
Below
Cri$cal Zone
K soil test levels Loam soils
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Fall Winter Spring
Above
At
Below
Cri$cal Zone
K soil test levels Clay soils
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Fall Winter Spring
Above
At
Below
Cri$cal Zone
K soil test levels Trend over $me (5 yr running avg.)
0% 10% 20% 30% 40% 50% 60% 70% 80% 90%
100%
Above
At
Below
Cri$cal Zone
Database Lessons
• Analy$cs telling us we are doing a reasonable job of maintaining P and K levels
• Soil texture has a strong influence on levels • Nutrient needs are seasonal driven by yields • We may consider increasing sufficiency levels in the late spring sampling to even out the percentages of samples below the cri$cal Values
• Recent prac$ces of applica$on of compost are increasing soil potassium levels
