Non-Organic Organic C - Corn S - Soybeans W - Wheat A - Alfalfa Apply 20 X 40 ft

N

ST - Strip Till 6.096 x 12.192 m1 2 3 4 5 6 7 8 9 10 11 12 13 W1 14 15 16

A C S C S A S C C S S C C 1 A S AST ST CT ST ST CT ST ST CT ST CT CT CT 2 CT CT CTC-S-W/A-A C-S-W/A-A C-S C-S C-S-W/A-A C-S-W/A-A C-S C-S C-S C-S C-S C-S C-S-W/A-A 3 C-S-W/A-A C-S-W/A-A C-S-W/A-AYF NF YF YF NF NF YF NF YF YF NF NF NF 4 NF NF YF

17 18 19 20 21 22 23 24 25 26 27 28 29 W2 30 31 32S C C S S C A C S S C C A 1 C W WST CT CT CT CT CT CT ST CT ST ST CT ST Well 2 ST ST CTC-S-W/A-A C-S C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A 3 C-S C-S-W/A-A C-S-W/A-AYF YF NF NF YF YF YF YF YF YF YF YF NF 4 NF YF NF

33 34 35 36 37 38 39 40 41 42 43 44 45 W3 46 47 48C A W S W W S W W C S A S 1 C S WCT ST CT CT ST CT ST ST ST ST ST ST ST 2 ST CT CTC-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S 3 C-S-W/A-A C-S-W/A-A C-S-W/A-ANF NF YF NF NF NF NF YF NF YF NF YF NF 4 NF YF YF

49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 W4C A S C S A S W C C C W S S C A 1ST ST CT ST CT CT ST ST ST ST ST CT ST ST CT ST 2C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A 3NF YF YF YF NF YF YF NF NF NF YF YF NF NF NF NF 4

65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 W5W C C S A S S S C W A S W A S S 1ST ST CT ST ST CT ST CT CT ST CT CT CT CT ST ST 2C-S-W/A-A C-S-W/A-A C-S C-S C-S-W/A-A C-S C-S C-S C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A 3YF NF NF NF NF YF YF NF YF NF NF NF NF YF YF YF 4

81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 W6A S C C C W W C S C C C W S S A 1CT ST CT ST CT CT CT CT CT CT CT ST ST CT CT ST 2C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S C-S C-S-W/A-A 3NF NF YF YF NF YF NF YF YF YF NF YF YF NF YF YF 4

97 98 99 100 101 102 103 104 105 106 107 108 109 110 W7 111 112C S C S A S C S S S W A S S 1 C CCT ST CT ST ST CT ST ST ST ST ST CT CT ST 2 ST STC-S-W/A-A C-S C-S C-S-W/A-A C-S-W/A-A C-S C-S C-S C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A 3 C-S-W/A-A C-SNF YF YF NF YF NF YF NF NF YF YF NF NF YF 4 YF NF

113 114 115 116 117 118 119 120 121 122 123 124 125 126 W8 127 128W C A C A C S C A S C C C S 1 S CCT ST CT CT CT CT ST ST CT ST ST CT ST CT 2 CT CTC-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S C-S C-S-W/A-A C-S-W/A-A 3 C-S C-SNF NF NF YF YF NF YF YF YF NF YF NF NF NF 4 YF YF

129 130 131 132 133 134 135 136 137 138 139 140 141 142 W9 143 144S S W W W S C A W W W C A A 1 C SCT CT ST CT ST CT ST ST CT CT ST CT ST ST Well 2 CT CTC-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A 3 C-S-W/A-A C-S-W/A-AYF NF YF YF NF YF NF NF YF NF NF YF YF NF 4 NF YF

145 146 147 W10 148 149 150 151 152 153 154 155 156 157 158 159 160C S A 1 S C W C A W W S S A A C SST CT CT 2 ST ST CT CT CT CT ST CT ST CT CT CT CTC-S C-S C-S-W/A-A 3 C-S-W/A-A C-S C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-ANF YF NF 4 NF YF NF NF YF YF NF NF YF YF NF YF NF

161 162 163 W11 164 165 166 167 168 169 170 171 172 173 174 175 176W C C 1 C S A A W W C W S C S S CCT ST CT Tile 2 ST CT ST ST ST CT CT ST ST CT CT CT STC-S-W/A-A C-S-W/A-A C-S-W/A-A 3 C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S C-S C-S C-S-W/A-A C-SYF NF YF 4 YF YF NF YF YF NF YF YF YF NF YF YF YF

177 178 179 W12 180 181 182 183 184 185 186 187 188 189 190 191 192S S C 1 S W S C S C S C A C C S ACT ST CT 2 ST ST ST CT CT ST ST CT ST ST ST ST STC-S C-S C-S 3 C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-A C-S-W/A-A C-S C-S-W/A-A C-S-W/A-ANF YF YF 4 YF NF NF NF NF YF NF NF NF NF NF NF YF

NF - No FertilizerYF - Yes FertilizerFarming Systems 2005Date:

Initial: CT - Conventional Till

MICROBIAL DYNAMICS IN CONVENTIONAL AND ORGANIC MANAGED SYSTEMSLACHNICHT WEYERS, S.L., ARCHER, D.A., JOHNSON, J., WILTS, A., BARBOUR, N., AND EKLUND, J.

USDA ARS North Central Soil Conservation Research Laboratory, Morris MN

SITE DESCRIPTION

Swan Lake Research Farm , Morris, MN

192 experimental units (EU) 20 ft x 40 ft. established

in 2002

Management split of 4 replicate blocks

» Conventional vs. Organic management

Treatments within management split:

» Fertilization: Yes or No fertilizer (YF/NF)

» conventional inorganic

» organic animal manure

» Tillage:

» Conventional tillage (CT) vs. Strip tillage (ST)

» Crop rotation: 2 yr vs. 4 yr

» 2 yr Traditional Corn-Soybean

» 4 yr Alternative Corn-Soybean-Wheat –Alfalfa

OBJECTIVE

Determine if microbial biomass (C & N) and community composition (fatty acid methyl ester; FAME) differs between two main management systems and three sub-management treatments.

METHODS Soil Sampling:

» Spring 2002, 2003, 2004, 2005, to 15 cm depth FAME:

» Saponified with 3.75 NaOH in methanol (100ºC -30 min)» Methylated with 6 N HCl in methanol (80ºC – 10 min)» Phase extraction MTBE in hexane (v:v) (2x)» Washed w/ NaOH, re-suspended in MTBE in hexane» Varian GSMS w/ 30 m SP2330 capillary column 40 min » SAS PCA on Peak Area of 12 FAME peaks

MICROBIAL BIOMASS:» Chloroform fumigation direct extraction 0.5 M K2SO4

» MBC determined by Chemical Oxygen Demand; kEC of 0.4» MBN determined by Autoclave assisted Persulfate Oxidation

STATISTICS

Performed on a split-block basis, where h =system, e =system*block:1. Main effects: system (S) , tillage (T) , fertilizer (F) , rotation (R) y = mean + S + block + (S * block) + T + S*T + F + S*F + R + S*R + T*F + T*R + F*R + T*F*R

2. Treatment combinations ( 24 ) with LSD tested y = mean + system +block + (system * block) + treatment + treatment*system

3. Full effects model, two-way and three-way interactions

y = mean + S +block + (S * block) + T + S*T + F + S*F + R + S*R + crop + S*crop + T*F +

T*R + F*R + T*F*R + T*F*crop + F*R*crop +T*R*crop + T*F*R*crop

» The 24 treatments were significantly different for MBC and MBN only in the forth year of production, 2005.

» LSD among treatments from the 2005 spring exhibited complex dynamics. In general, significant differences occur where standard error bars do not overlap.

» On average, MBC and MBN were higher within strip-tilled crops under 4 yr rotations.

CT - NF

CT - YF

ST - NF

ST - YF

0.00

0.10

0.20

0.30

0.40

0.50

0.60

four four two four two four

A C S WCrop by Rotation

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

four four two four two four

A C S W

MBC 2005

MBN 2005

Figure 2. Average MBC and MBN in spring of 2005 of twenty four treatment combinations averaged across management system by crop of 2004 production year. A = Alfalfa, C = Corn, S = Soybean, W = Wheat. Units = mg g-1 soil ± s.e.

TREATMENT COMBINATION EFFECTS »Statistical analysis of full effects were performed to identify individual crop treatment effects.

»The crop effect was significant for only MBN in 2005; the full analysis showed a significant effect of tillage (p<0.0001), crop (p =0.04) and rotation (p = 0.02), with the effect of tillage dependent on the effect of crop (till*crop interaction, p = 0.02).

»Soil from spring 2005 samples following a wheat crop in 2004 exhibited significantly greater MBN than that following other crops but only within the conventional tillage plots (red box).

Table 2. Tillage and rotation by crop comparison for MBN (mg N g-1 soil ± s.d.) in spring 2005 samples.

2004 Crop

Tillage Rotation Corn Soybean Wheat Alfalfa

CT 4 yr 0.38 ± 0.07 0.39 ± 0.07 0.45 ± 0.05 0.36 ± 0.09

2 yr 0.38 ± 0.06 0.34 ± 0.10

Total 0.38 ± 0.06 0.36 ± 0.09 0.45 ± 0.05 0.36 ± 0.09

ST 4 yr 0.47 ± 0.07 0.45 ± 0.10 0.47 ± 0.07 0.48 ± 0.07

2 yr 0.41 ± 0.10 0.43 ± 0.09

Total 0.44 ± 0.09 0.44 ± 0.09 0.47 ± 0.07 0.48 ± 0.07

FULL EFFECTS

SUMMARY Conventional vs. Organic management systems were not

different, which is understandable because N in fertilized plots was applied at the same rate.

Significant effects ( Tillage and Rotation ) appeared by the third year.

As these management systems become better established FAME and microbial biomass C & N should more clearly reflect management differences.

» Conventional or Organic management had no effect in any production

year.» Interactions were not significant in any production year.» Strip Tillage and 4 yr Rotation significantly increased MBC in 2004,

and both MBC and MBN in 2005.» Treatment with fertilizer significantly increased MBC in 2005.

0.39 ± 0.09>0.43 ± 0.090.42 ± 0.08≤0.41 ± 0.080.45 ± 0.08<0.38 ± 0.080.42 ± 0.09≤0.41 ± 0.092005

0.50 ± 0.12≥0.53 ± 0.130.52 ± 0.13=0.52 ± 0.130.51 ± 0.13≥0.53 ± 0.130.51 ± 0.12≥0.53 ± 0.142002

MBN

0.60 ± 0.15>0.65 ± 0.190.66 ± 0.17<0.60 ± 0.190.67 ± 0.18<0.60 ± 0.170.62 ± 0.16≥0.65 ± 0.202005

0.53 ± 0.14>0.58 ± 0.130.57 ± 0.13≤0.55 ± 0.130.59 ± 0.14<0.54 ± 0.130.55 ± 0.14≥0.58 ± 0.132004

0.49 ± 0.16≥0.50 ± 0.160.52 ± 0.16≤0.48 ± 0.150.50 ± 0.15≤0.49 ± 0.160.50 ± 0.16=0.50 ± 0.152003

0.96 ± 0.20≥0.98 ± 0.190.99 ± 0.20≥0.96 ± 0.180.95 ± 0.20≥1.00 ± 0.180.94 ± 0.19≥1.01 ± 0.192002

MBC

2 yr4 yrYFNFSTCTORGCNVYear

RotationFertilizerTillageSystem

Table 1. Treatment differences for microbial biomass C (MBC; mg Cmic g-1 soil ± s.d.) and microbial biomass N (MBN, mg N g-1 soil ± s.d.) by year.

CNV – Conventional, ORG – Organic, CT – Conventional, ST – Strip, NF – No fertilizer, YF – Yes Fertilizer, Symbols: ≤ or ≥ indicate no significant difference, < or > indicate a significant difference at P < 0.05.

MAIN EFFECTSMICROBIAL BIOMASS

RESEARCH DIRECTION

Continue to analyze FAME, MBC and MBN.

Conduct additional studies on microbial community,

characterize bacterial and fungal components.

Examine enzyme dynamics.

Link microbial dynamics to trace gas production and

nitrogen mineralization.

»PCA of FAME profiles showed shifts from year one to year three under new crop management regimes (A).»Management did not have clear effect in first three years (not shown)

however, certain treatment combinations exhibit apparent crop effect (B).»Evaluation of profiles complex because of extensive treatment

combinations.

FAME

Figure 1. Plots of principle components I (y-axis) and II (x-axis) of profiles for 12 consistently recognizable FAMEs per EU. A. Profiles by year, B. Profiles for 2004 CNV 4 yr rotation.

2002 2003 2004 alfalfa wheat corn soybean A. B.