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Crop and Soil Management Issues Related to
Forage Cation Levels
J.B. Peters, K.A. Kelling,
Soil Science Department
University of Wisconsin - Madison
Influence of pH on Alfalfa,
Marshfield 2000
Treatments
• Four K20 levels – 0, 100, 200, 400 lbs K2O/a/year*
• Target pH levels– Marshfield: six levels – 4.8 - 7.3– Spooner: five levels – 4.7 - 6.7– Hancock: eight levels – 4.5 - 7.0
* Applied after first cutting
Average Tissue P Levels
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
Tis
sue
P %
Marshfield Spooner Hancock
0 lb/a K2O100 lb/a K2O200 lb/a K2O400 lb/a K2O
Average Tissue K Levels
0
0.5
1
1.5
2
2.5
3
3.5
Tis
sue
K %
Marshfield Spooner Hancock
0 lb/a K2O100 lb/a K2O200 lb/a K2O400 lb/a K2O
3rd cut, 1999
Average Tissue Ca Levels
0
0.2
0.4
0.6
0.8
1
1.2
Tis
sue
Ca
%
Marshfield Spooner Hancock
0 lb/a K2O100 lb/a K2O200 lb/a K2O400 lb/a K2O
Average Tissue Mg Levels
0
0.1
0.2
0.3
0.4
0.5
0.6
Tis
sue
Mg
%
Marshfield Spooner Hancock
0 lb/a K2O100 lb/a K2O200 lb/a K2O400 lb/a K2O
Effect of crushed wallboard and gypsum fertilizer on soil Ca and K
levels. Arlington, WI.1
Ca (ppm) Exchangeable K (ppm)
Treatment 1995 1997 1995 1997
Control 1875 1650 341 285
4 t/acre WB 2075 1913 388 284
16 t/acre WB 3313 3125 330 213
50 lb S/acre gypsum 1900 1700 320 240
LSD.05 415 526 NS 48gypsum = 65 lbs Ca/acre WB = 320 lbs Ca / ton1 Treatments applied ppi, Spring 1995.
Effect of crushed wallboard and gypsum fertilizer on alfalfa tissue
cation levels. Arlington, WI, 1995.1st Cut
Treatment K Ca Mg---------- % ----------
Control 4.31 1.53 0.504 t/acre WB 4.38 1.66 0.4816 t/acre WB 3.46 1.55 0.4650 lb S/acre gypsum 3.70 1.55 0.41
Pr > F 0.12 0.83 0.17gypsum = 65 lbs Ca/acre WB = 320 lbs Ca / ton
Effect of crushed wallboard and gypsum fertilizer on soil Ca and K
levels. Lancaster, WI.1
Ca (ppm) Exchangeable K (ppm)
Treatment 1995 1997 1995 1997
Control 1450 1325 138 196
4 t/acre WB 1613 1462 106 175
16 t/acre WB 2075 2225 99 151
50 lb S/acre gypsum 1438 1400 105 176
LSD.05 184 289 NS NSgypsum = 65 lbs Ca/acre WB = 320 lbs Ca / ton1 Treatments applied ppi, Spring 1995.
Effect of crushed wallboard and gypsum fertilizer on alfalfa tissue
cation levels. Lancaster, WI, 1995.1st Cut
Treatment K Ca Mg---------- % ----------
Control 4.16 1.39 0.394 t/acre WB 4.32 1.52 0.4216 t/acre WB 3.90 1.49 0.4150 lb S/acre gypsum 3.82 1.44 0.39
Pr > F 0.34 0.01 0.47gypsum = 65 lbs Ca/acre WB = 320 lbs Ca / ton
Effect of crushed wallboard and gypsum fertilizer on soil Ca and K
levels. Spooner, WI.1
Ca (ppm) Exchangeable K (ppm)
Treatment 1995 1997 1995 1997
Control 888 788 171 235
4 t/acre WB 1150 938 144 269
16 t/acre WB 2512 1563 141 213
50 lb S/acre gypsum 936 800 156 223
LSD.05 601 191 23 NSgypsum = 65 lbs Ca/acre WB = 320 lbs Ca / ton1 Treatments applied ppi, Spring 1995.
Effect of crushed wallboard and gypsum fertilizer on alfalfa tissue cation levels. Spooner, WI, 1996.
1st CutTreatment K Ca Mg
---------- % ----------Control 3.77 1.29 0.284 t/acre WB 3.57 1.37 0.2216 t/acre WB 3.49 1.45 0.1950 lb S/acre gypsum 3.57 1.27 0.28
Pr > F 0.11 0.01 0.01gypsum = 65 lbs Ca/acre WB = 320 lbs Ca / ton
1000 2400 Wavelength (nanometers)
Ref
lect
ance
Light absorption
NIRS Concepts
Diagnostics of Forage K
K --- Cl H N -- C
2
NIRS Physics
Inorganic (Salt) Organic (Protein)
Nutrient R SEC
CP .96 .79ADF .92 1.6NDF .93 2.3
UIP .87 1.5SOLCP .81 4.4CA .81 .18
ADF-CP .77 .24NDF-CP .72 .71P .58 .04K .54 .45MG .50 .05ASH ? ?LIGNIN ? ?
2
?NIR
UN
PL
UG
GE
DForages
Fair
Good
Wet chemistry mineral analysis compared to NIR estimation. 3rd
cut, Hancock, 1999.
Regression Equation R2
PNIR = 0.22 + (0.255)(PWET) 0.19
KNIR = 0.98 + (0.579)(KWET) 0.58
CaNIR = 0.55 + (0.891)(CaWET) 0.79
MgNIR = 0.16 + (0.349)(MgWET) 0.41
Wet chemistry mineral analysis compared to NIR estimation. 3rd
cut, Marshfield, 1999.
Regression Equation R2
PNIR = 0.29 + (0.056)(PWET) 0.01
KNIR = 1.46 + (0.335)(KWET) 0.60
CaNIR = 0.57 + (0.884)(CaWET) 0.67
MgNIR = 0.21 + (0.325)(MgWET) 0.68
Wet chemistry mineral analysis compared to NIR estimation. 3rd
cut, Spooner, 1999.
Regression Equation R2
PNIR = 0.26 + (0.068)(PWET) 0.01
KNIR = 1.07 + (0.581)(KWET) 0.36
CaNIR = 0.88 + (0.506)(CaWET) 0.59
MgNIR = 0.16 + (0.457)(MgWET) 0.53
Using NIRS in Forage TestingGeneral Recommendations
General Nutrients
DM yes Lignin limitedCP yes Ash limitedADF yes Ca limitedNDF yes P noStarch yes K noFat yes Mg noBypass CP yes MiroMin noSoluble CP limitedADF-CP limitedNDF-CP limited
Summary
Liming these acid soils was essential to optimize DM production, irregardless of K
• As soil K increased, tissue K increased and tissue Ca and Mg tended to decrease
• Annual applications of K resulted in a buildup of soil K and a decrease in soil test Ca and Mg
Summary, cont.
• As soil Ca increased, tissue K levels tended to decrease and tissue Ca tended to increase, especially on the lighter textured soil at Spooner
• Large applications of Ca resulted in a buildup of soil Ca and a decrease in soil test K
Summary, cont.
• Keeping soil test K levels in the optimum range appears to be the best strategy for keeping tissue K levels in acceptable ranges for use as dairy feed