Table 1. Site and stand characteristics of the experiments and total amount of the applied fertilisers.
Exp. Lat.
°N 		Long.
°E 		Tempsum
d.d.
(>5 °C) 		Tree
species 		Started
at 		Stand age
at 2009 		SI a), m Prod a) ,
m3 ha–1 a–1 		N,
kg ha–1 		P,
kg ha–1 		Lime,
kg ha–1 		Soil
texture b)
25 61.817 29.329 1239 Pine 1958 84 27.9 7.4 1676 149 6000 SL
33 61.875 29.343 1234 Pine 1958 70 29.3 5.9 1908 120 6000 LS
35 62.409 28.707 1168 Spruce 1958 77 18.3 8.3 714 144 6000 SL
36 62.409 28.710 1168 Spruce 1958 77 19.9 8.5 714 144 6000 SL
37 61.415 28.545 1240 Pine 1958 75 20.0 7.4 714 109 6000 LS
38 61.416 28.542 1233 Pine 1958 75 21.5 8.2 714 109 6000 S
52 62.024 24.811 1154 Pine 1959 58 25.9 8.1 1496 149 6000 LS
55 61.662 29.304 1170 Pine 1959 65 26.1 9.8 534 69 6000 SL
56 62.927 25.607 1025 Pine 1959 76 22.8 4.5 1496 149 6000 SL
57 62.935 25.678 1020 Spruce 1959 77 19.4 5.9 1496 149 6000 SL
58 62.935 25.677 1024 Spruce 1959 77 21.5 6.9 1496 149 6000 SL
60 62.930 25.666 1020 Spruce 1959 77 23.0 7.7 1136 109 6000 SL
64 61.493 29.066 1215 Pine 1959 90 22.0 5.3 714 109 6000 LS
67 61.537 29.062 1160 Pine 1959 70 21.1 9.3 714 109 6000 SL
68 61.956 27.575 1147 Pine 1959 84 21.5 7.6 1404 149 6000 S
73 62.759 24.747 1034 Pine 1959 55 25.9 8.0 1254 160 6000 SL
75 62.913 24.571 1028 Pine 1959 54 25.3 4.9 742 109 6000 SL
76 62.912 24.570 1028 Pine 1959 54 26.3 5.2 742 109 6000 SL
77 62.911 24.568 1028 Pine 1959 54 23.3 4.1 742 109 6000 SL
82 63.300 25.340 999 Pine 1959 54 17.6 3.7 965 193 6000 SL
97 62.574 24.119 1074 Pine 1960 61 24.8 8.5 742 193 6000 LS
98 62.579 24.125 1074 Pine 1959 60 24.5 6.9 1356 69 6000 SL
103 63.215 24.624 1006 Pine 1960 58 22.2 4.2 742 109 6000 LS
106 63.389 24.300 1013 Pine 1960 73 15.0 3.0 1136 120 6000 LS
107 63.095 24.294 1013 Pine 1960 63 18.0 2.6 742 153 6000 LS
113 61.172 26.050 1251 Spruce 1961 58 28.4 12.8 1486 193 6000 SL
135 67.250 23.869 791 Pine 1961 87 17.6 4.6 1194 120 6000 SL
155 61.169 26.048 1250 Spruce 1962 59 28.2 13.4 1074 160 6000 SL
157 61.111 26.026 1229 Pine 1962 62 24.2 7.1 1317 160 5000 LS
194 66.855 27.133 754 Spruce 1964 74 19.5 1.5 1110 160 6000 SL
a) SI is H100 and Prod is the mean annual stem volume production for plots not fertilised with N (4 per experiment).
b) Soil texture classes: S = sand, LS = loamy sand and SL = sandy loam.
1

Fig. 1. Fertilisation experiments.

2

Fig. 2. Relative increase in stand production caused by nitrogen fertilisation as a function of mean annual production on unfertilised (no N) plots.

Table 2. Concentrations of elements by fertilisation treatment. Covariates in the ANOVA were effective temperature sum, tree species, i.e. pine (0//1), and mean thickness of the organic layer on plots not fertilised with N.
Variable b) Treatments a)
Cntrl N P L NP NL PL NPL F value c)
Organic layer
Ctot, g kg–1 442a 443a 428ab 362e 444a 403bc 370de 396cd 28.4
Ntot, g kg–1 12.6b 15.2a 12.1b 10.5c 15.1a 14.4a 10.9c 14.3a 60.0
C/N 35.7a 29.6b 38.1a 35.2a 29.8b 28.7b 34.9a 28.4b 66.7
Catot, mg kg–1 2823c 2960c 4261c 8246b 4378c 9420ab 10471a 10525a 87.2
K tot, mg kg–1 769a 622cd 734ab 693bc 597d 620d 738ab 641cd 13.6
Mgtot, mg kg–1 396b 502b 386b 1841a 491b 2019a 2104a 2231a 30.5
Ptot, mg kg–1 796b 757bc 946a 706c 912a 714bc 951a 966a 33.4
pHCaCl2 3.22d 3.21d 3.38bc 4.06a 3.35cd 4.07a 4.19a 4.18a 191
CaAAA, mg kg–1 1964d 2014d 2902cd 5157b 2963c 5922ab 6212a 6255a 118
KAAA, mg kg–1 784a 581c 752ab 687b 583c 583c 704b 570c 28.1
MgAAA, mg kg–1 273b 347b 252b 773a 337b 904a 782a 912a 45.3
PAAA, mg kg–1 230bc 179de 270a 184de 232bc 157e 246ab 212bcd 25.9
Mineral soil
C, g kg–1 25.9bc 30.5ab 25.3c 29.2abc 29.6abc 28.4abc 27.5abc 31.8a 4.39
Ntot g kg–1 1.03cd 1.25ab 1.02d 1.13bcd 1.20abcd 1.21abc 1.05cd 1.34a 7.80
C/N 25.9ab 24.6bc 25.1abc 26.1ab 24.8bc 23.7c 27.0a 24.4bc 5.51
pHCaCl2 3.99b 3.80b 3.92b 4.68a 3.81b 4.37a 4.71a 4.55a 74.1
CaAAA, mg kg–1 63c 78c 120c 680a 105c 474b 694a 683a 52.2
KAAA, mg kg–1 31.3a 30.2a 32.7a 33.2a 29.6a 27.8a 32.4a 30.1a 2.17
MgAAA, mg kg–1 11.1b 15.3b 12.9b 83.5a 16.3b 80.7a 81.1a 86.0a 42.5
PAAA, mg kg–1 9.6c 8.8cd 12.4a 7.1de 11.8ab 6.1e 10.0bc 9.2cd 20.3
a) Cntrl = control, N = nitrogen fertilisation, P = phosphorus fertilisation, L = liming.
b) AAA = acid ammonium acetate extraction, tot = dry combustion concentration.
c) F value from mixed model ANOVA with covariates. If F7,200 > 3.64, then p < 0.001.
Table 3. Amounts of elements by fertilisation treatment. Potential covariates in the ANOVA were effective temperature sum, tree species, i.e. pine (0/1), and mean thickness of the organic layer on plots not fertilised with N.
Variable b) Treatments a)
Cntrl N P L NP NL PL NPL F value c)
Organic layer
Ctot, Mg ha–1 16.8b 22.8a 17.5b 16.0b 22.5a 21.0a 16.4b 20.5a 25.2
Ntot, kg ha–1 488b 778a 496b 468b 764a 741a 485b 734a 58.9
Catot, kg ha–1 112d 150cd 177cd 373b 221c 488a 485a 545a 64.9
Ptot, kg ha–1 30.5e 38.2cd 38.8cd 31.7e 46.1ab 36.8d 42.2bc 49.8a 35.6
Mineral soil
Ctot, Mg ha–1 20.8bc 24.3ab 20.3c 22.6abc 23.7ab 22.7abc 22.6abc 24.5a 5.28
Ntot, kg ha–1 842d 998a 822d 883bcd 961abc 977ab 860c 1023a 9.38
Org. + min. soil
CaAAA, kg ha–1 127d 162d 214d 771bc 233d 693c 862ab 870a 88.8
PAAA, kg ha–1 16.4cd 16.1cd 21.2a 14.0de 21.5a 13.2e 19.4ab 18.5bc 33.3
a) Cntrl = control, N = nitrogen fertilisation, P = phosphorus fertilisation, L = liming.
b) AAA = acid ammonium acetate extraction, tot = dry combustion concentration.
c) F value from mixed model ANOVA with covariates. If F7,200 > 3.64, then p < 0.001.
Table 4. Regression equations for total concentrations of elements as a function of cumulative amounts of fertilisers, and site and tree-stand properties. All coefficients are statistically significant (p < 0.05).
  Dependent variables
Organic layer Mineral soil 0–10 cm
Independent
variables a) 		Ntot
g kg–1 		C/N lnCatot
mg kg–1 		Ktot
mg kg–1 		Ptot
mg kg–1 		ln(Ntot+1)
g kg–1 		C/N
Constant b) –4.61 50.9 7.16 237 316 –.278 22.3
N, Mg ha–1 3.07 –5.76   –116   .0820 –1.40
P, kg ha–1     .000849   1.47    
Lime, Mg ha–1 –.208   .167        
Ol. thickn., cm 1.22            
Stand age, a .0978   .00701 5.77 5.56    
Pine (0/1) –2.24 8.09     –129 –.278 3.10
Tempsum, d.d. .00703 –.0197       .000896  
Fines, %     .0107 3.47 4.72 .00680  
Stones, %             .0531
R2 (obs./pred.) .667 .738 .688 .441 .619 .667 .256
a) N = cumulative amount of fertilised nitrogen, P = cumulative amount of fertilised phosphorus, Lime = cumulative amount of spread lime, Ol. thickn. = mean organic layer thickness on plots not fertilised with nitrogen, Stand age = stand age at year 2009, Pine = 1, if pine, 0 if spruce, Tempsum = average effective temperature sum, Fines = sum of clay + silt, i.e. under 63 µm fraction, Stones = Volumetric percentage of stones.
b) In the logaritmic models the constant has been adjusted to yield the original arithmetic mean by adding a residual variance of the regression model, constant + sf2/2.
Table 5. Regression equations for pH and concentrations of elements extracted with acid ammonium acetate as a function of cumulative amounts of fertilisers and site and tree-stand properties. All coefficients are statistically significant.
  Dependent variables
  Organic layer Mineral soil 0–10 cm
Independent
variables a) 		pHCaCl2
 CaAAA
mg kg–1 		KAAA
mg kg–1 		PAAA
mg kg–1 		pHCaCl2
 lnCaAAA
mg kg–1 		lnKAAA
mg kg–1 		lnPAAA
mg kg–1
Constant b) 3.88 2879 932 163 3.31 4.00 2.29 1.97
N, Mg ha–1 –.0874   –135 –33.7 –.248 –.207    
P, kg ha–1       .412       .00295
Lime, Mg ha–1 .139 .562 –6.46 –4.75 .114 .360   –.0464
Ol. thickn., cm –.120         –.240 –.163 –.150
Stand age, a     5.27          
Pine (0/1) –.342 –1222     .421      
Tempsum, d.d.     –.495       .000855  
Fines, %       1.96 .0101 .0292 .0189 .0231
Stones, %             .00565  
R2 (obs./pred.) .811 .756 .442 .346 .646 .575 .583 .540
a) N = cumulative amount of fertilised nitrogen, P = cumulative amount of fertilised phosphorus, Lime = cumulative amount of spread lime, Ol. thickn. = mean organic layer thickness on plots not fertilised with nitrogen, Stand age = stand age at year 2009, Pine = 1, if pine, 0 if spruce, Tempsum = average effective temperature sum, Fines = sum of clay + silt, i.e. under 63 µm fraction, Stones = Volumetric percentage of stones.
b) In the logaritmic models the constant has been adjusted to yield the original arithmetic mean by adding a residual variance of the regression model, constant + sf2/2.
Table 6. Regression equations for total amounts of elements as a function of cumulative amounts of fertilisers, and site and tree-stand properties. All coefficients are statistically significant.
  Dependent variables
Organic layer Mineral soil 0–10 cm
Independent
variables a) 		Ctot
kg ha–1 		Ntot
kg ha–1 		lnCatot
kg ha–1 		Ktot
kg ha–1 		Ptot
kg ha–1 		lnCtot,
kg ha–1 		lnNtot,
kg ha–1
Constant b) 8898 579 5.01 35.7 39.7 8.21 5.28
N, Mg ha–1 4476 245 .139   6.31 .104 .158
P, kg ha–1     .000829   .0727    
Lime, Mg ha–1 –229 –4.10 .181 .325   .00769  
Tempsum, d.d.           .00148 .00134
Ol. thickn., cm 2562            
Fines, %           .00957 .00845
Pine (0/1)   –125 –.338 –8.01   –.278 –.405
R2 (obs./pred.) .400 .544 .593 .192 .468 .578 .641
a) N = cumulative amount of fertilised nitrogen, P = cumulative amount of fertilised phosphorus, Lime = cumulative amount of spread lime, Ol. thickn. = mean organic layer thickness on plots not fertilised with nitrogen, Pine = 1, if pine, 0 if spruce, Tempsum = average effective temperature sum, Fines = sum of clay + silt, i.e. under 63 µm fraction.
b) In the logaritmic models the constant has been adjusted to yield the original arithmetic mean by adding a residual variance of the regression model, constant + sf2/2.
Table 7. Regression equations for elemental amounts extracted with acid ammoníum acetate as a function of cumulative amounts of fertilisers and site and tree-stand properties. All coefficients are statistically significant.
  Dependent variables
Organic layer Mineral soil 0–10 cm
Independent
variables a) 		CaAAA
kg ha–1 		KAAA
kg ha–1 		PAAA
kg ha–1 		SAAA
kg ha–1 		lnCaAAA
kg ha–1 		lnKAAA
kg ha–1 		lnPAAA
kg ha–1 		SAAA
kg ha–1
Constant b) 121 23.9 –5.65 –2.34 5.78 2.43 1.649 2.823
N, Mg ha–1 19.2 1.14   .756 –.206 .0854   .201
P, kg ha–1     .0193 .00283     .00302  
Lime, Mg ha–1 29.4     –.113 .36   –.0477 –.0983
Tempsum, d.d.           .000781    
Ol. thickn., cm   3.78 2.29 .786 –.305 –.118    
Fines, %         .0246 .012 .0165  
Stones, %             –.0065 –.00832
Pine (0/1) –59.8 –8.28 –2.86          
Stand age, a     .123 .065 –.024     .0114
R2 (obs./pred.) .67 .235 .469 .348 .624 .505 .433 .380
a) N = cumulative amount of fertilised nitrogen, P = cumulative amount of fertilised phosphorus, Lime = cumulative amount of spread lime, Ol. thickn. = mean organic layer thickness on plots not fertilised with nitrogen, Stand age = stand age at year 2009, Pine = 1, if pine, 0 if spruce, Tempsum = average effective temperature sum, Fines = sum of clay + silt, i.e. under 63 µm fraction, Stones = Volumetric percentage of stones.
b) In the logaritmic models the constant has been adjusted to yield the original arithmetic mean by adding a residual variance of the regression model, constant + sf2/2.
3

Fig. 3. Relative surplus of N in the organic layer, i.e. (amount of N on the fertilised plots – amount of N on the non-fertilised plots)/amount of N in fertilisers, as a function of the C/N ratio in the organic layer on the unfertilized plots.