Treatments

Main crop and green manure

Treatment Year2019 Year2020&2021 Year2022
Main Spring wheat Spring Barley Potato
Mixture annual mixture Peronnial mixture (until end of 2021) -
Fibrous roots sudan grass Tall fescue & english ryegrass (until end of 2021) -
Taproots fodder radish Lucerne (until end of 2021) -

Mechanical treatment

Mechanical treatment
SS Subsoiling
SB Small boreholes
LB Large boreholes
Ref Untreated

The experimental design

The field is divided into four blocks. Every block is divided into three subplots. Every treatment occurs once in each subplot. We make the assumption that the treatments are divided randomly in each subplot. The mechanical treatments are divided over the blocks. The mechanical treatment will not be analysed, since we can not know if the variety between the mechanical treatments is explained by the treatment or by differences between the fields.

The data

Bulk density (g/cm^3)

##         1 2 3 4 5 6 7 8 9
##                          
## 2020 1  2 2 2 2 2 2 2 2 2
##      2  2 2 2 2 2 2 2 2 2
##      3  2 2 2 2 2 2 2 2 2
##      4  2 2 2 2 2 2 2 2 2
## 2021 1  0 0 0 2 2 2 2 2 2
##      2  0 0 0 2 2 2 2 2 2
##      3  0 0 0 2 2 2 2 2 2
##      4  0 0 0 2 2 2 2 2 2
## 2022 1  2 2 2 2 2 2 2 2 2
##      2  2 2 2 2 2 2 2 2 2
##      3  2 2 2 2 2 2 2 2 2
##      4  2 2 2 2 2 2 2 2 2

There are missing values in year 2021 in subplot III of every block. The bulk density was lowest in 2020 and highest in 2021. There are no obvious differences in variety between different depths or between blocks or subplots.

The results

Dry bulk density 15cm

There are no significant effects between the different green manure treatments on bulk density in 2022.

## Analysis of Variance Table
## 
## Response: bulkdensity2022[, var]
##              Df   Sum Sq   Mean Sq F value Pr(>F)
## treatment     2 0.000614 0.0003068  0.0424 0.9586
## blok          3 0.007716 0.0025719  0.3555 0.7857
## blok:subplot  8 0.073842 0.0092303  1.2757 0.3055
## Residuals    22 0.159181 0.0072355               
## 
##  Shapiro-Wilk normality test
## 
## data:  model$residuals
## W = 0.9651, p-value = 0.3072
## 
## $emmeans
##  contrast                 estimate     SE df t.ratio p.value
##  Fibrous roots - Mixture  0.008533 0.0347 22   0.246  0.9673
##  Fibrous roots - Taproots 0.008967 0.0347 22   0.258  0.9640
##  Mixture - Taproots       0.000433 0.0347 22   0.012  0.9999
## 
## Results are averaged over the levels of: subplot, blok 
## Note: contrasts are still on the [ scale 
## P value adjustment: tukey method for comparing a family of 3 estimates 
## 
## $contrasts
##  contrast                                                estimate     SE df
##  (Fibrous roots - Mixture) - (Fibrous roots - Taproots) -0.000433 0.0347 22
##  (Fibrous roots - Mixture) - (Mixture - Taproots)        0.008100 0.0601 22
##  (Fibrous roots - Taproots) - (Mixture - Taproots)       0.008533 0.0347 22
##  t.ratio p.value
##   -0.012  0.9999
##    0.135  0.9901
##    0.246  0.9673
## 
## Results are averaged over the levels of: subplot, blok 
## P value adjustment: tukey method for comparing a family of 3 estimates

Bulk density 30cm

There are no significant effects between the different green manure treatments on bulk density in 2022.

## Analysis of Variance Table
## 
## Response: bulkdensity2022[, var]
##              Df   Sum Sq   Mean Sq F value Pr(>F)
## treatment     2 0.009664 0.0048321  0.6130 0.5507
## blok          3 0.006740 0.0022466  0.2850 0.8357
## blok:subplot  8 0.045643 0.0057053  0.7238 0.6691
## Residuals    22 0.173410 0.0078823               
## 
##  Shapiro-Wilk normality test
## 
## data:  model$residuals
## W = 0.97048, p-value = 0.4388
## 
## $emmeans
##  contrast                 estimate     SE df t.ratio p.value
##  Fibrous roots - Mixture  -0.00182 0.0362 22  -0.050  0.9986
##  Fibrous roots - Taproots -0.03563 0.0362 22  -0.983  0.5949
##  Mixture - Taproots       -0.03381 0.0362 22  -0.933  0.6258
## 
## Results are averaged over the levels of: subplot, blok 
## Note: contrasts are still on the [ scale 
## P value adjustment: tukey method for comparing a family of 3 estimates 
## 
## $contrasts
##  contrast                                               estimate     SE df
##  (Fibrous roots - Mixture) - (Fibrous roots - Taproots)  0.03381 0.0362 22
##  (Fibrous roots - Mixture) - (Mixture - Taproots)        0.03198 0.0628 22
##  (Fibrous roots - Taproots) - (Mixture - Taproots)      -0.00182 0.0362 22
##  t.ratio p.value
##    0.933  0.6258
##    0.509  0.8675
##   -0.050  0.9986
## 
## Results are averaged over the levels of: subplot, blok 
## P value adjustment: tukey method for comparing a family of 3 estimates

Fresh weight depth 0-15

There are no significant effects between the different green manure treatments on fresh weight in 2022.

## Analysis of Variance Table
## 
## Response: bulkdensity2022[, var]
##              Df  Sum Sq Mean Sq F value Pr(>F)
## treatment     2   20.11  10.053  0.1058 0.9001
## blok          3   56.65  18.883  0.1987 0.8961
## blok:subplot  8  994.94 124.368  1.3087 0.2901
## Residuals    22 2090.74  95.034               
## 
##  Shapiro-Wilk normality test
## 
## data:  model$residuals
## W = 0.96283, p-value = 0.2624
## 
## $emmeans
##  contrast                 estimate   SE df t.ratio p.value
##  Fibrous roots - Mixture     1.677 3.98 22   0.422  0.9071
##  Fibrous roots - Taproots    1.473 3.98 22   0.370  0.9275
##  Mixture - Taproots         -0.204 3.98 22  -0.051  0.9986
## 
## Results are averaged over the levels of: subplot, blok 
## Note: contrasts are still on the [ scale 
## P value adjustment: tukey method for comparing a family of 3 estimates 
## 
## $contrasts
##  contrast                                               estimate   SE df
##  (Fibrous roots - Mixture) - (Fibrous roots - Taproots)    0.204 3.98 22
##  (Fibrous roots - Mixture) - (Mixture - Taproots)          1.882 6.89 22
##  (Fibrous roots - Taproots) - (Mixture - Taproots)         1.677 3.98 22
##  t.ratio p.value
##    0.051  0.9986
##    0.273  0.9598
##    0.422  0.9071
## 
## Results are averaged over the levels of: subplot, blok 
## P value adjustment: tukey method for comparing a family of 3 estimates

Fresh weight depth 15-30

There are no significant effects between the different green manure treatments on fresh weight in 2022.

## Analysis of Variance Table
## 
## Response: bulkdensity2022[, var]
##              Df  Sum Sq Mean Sq F value Pr(>F)
## treatment     2   64.03  32.013  0.4619 0.6360
## blok          3  161.15  53.717  0.7751 0.5204
## blok:subplot  8  588.33  73.541  1.0612 0.4239
## Residuals    22 1524.67  69.303               
## 
##  Shapiro-Wilk normality test
## 
## data:  model$residuals
## W = 0.98245, p-value = 0.8245
## 
## $emmeans
##  contrast                 estimate  SE df t.ratio p.value
##  Fibrous roots - Mixture    -0.844 3.4 22  -0.248  0.9666
##  Fibrous roots - Taproots   -3.155 3.4 22  -0.928  0.6286
##  Mixture - Taproots         -2.311 3.4 22  -0.680  0.7775
## 
## Results are averaged over the levels of: subplot, blok 
## Note: contrasts are still on the [ scale 
## P value adjustment: tukey method for comparing a family of 3 estimates 
## 
## $contrasts
##  contrast                                               estimate   SE df
##  (Fibrous roots - Mixture) - (Fibrous roots - Taproots)    2.311 3.40 22
##  (Fibrous roots - Mixture) - (Mixture - Taproots)          1.467 5.89 22
##  (Fibrous roots - Taproots) - (Mixture - Taproots)        -0.844 3.40 22
##  t.ratio p.value
##    0.680  0.7775
##    0.249  0.9664
##   -0.248  0.9666
## 
## Results are averaged over the levels of: subplot, blok 
## P value adjustment: tukey method for comparing a family of 3 estimates

Dry weight depth 0-15

There are no significant effects between the different green manure treatments on fresh weight in 2022.

## Analysis of Variance Table
## 
## Response: bulkdensity2022[, var]
##              Df  Sum Sq Mean Sq F value Pr(>F)
## treatment     2    6.14   3.068  0.0424 0.9586
## blok          3   77.16  25.719  0.3555 0.7857
## blok:subplot  8  738.42  92.303  1.2757 0.3055
## Residuals    22 1591.81  72.355               
## 
##  Shapiro-Wilk normality test
## 
## data:  model$residuals
## W = 0.9651, p-value = 0.3072
## 
## $emmeans
##  contrast                 estimate   SE df t.ratio p.value
##  Fibrous roots - Mixture    0.8533 3.47 22   0.246  0.9673
##  Fibrous roots - Taproots   0.8967 3.47 22   0.258  0.9640
##  Mixture - Taproots         0.0433 3.47 22   0.012  0.9999
## 
## Results are averaged over the levels of: subplot, blok 
## Note: contrasts are still on the [ scale 
## P value adjustment: tukey method for comparing a family of 3 estimates 
## 
## $contrasts
##  contrast                                               estimate   SE df
##  (Fibrous roots - Mixture) - (Fibrous roots - Taproots)  -0.0433 3.47 22
##  (Fibrous roots - Mixture) - (Mixture - Taproots)         0.8100 6.01 22
##  (Fibrous roots - Taproots) - (Mixture - Taproots)        0.8533 3.47 22
##  t.ratio p.value
##   -0.012  0.9999
##    0.135  0.9901
##    0.246  0.9673
## 
## Results are averaged over the levels of: subplot, blok 
## P value adjustment: tukey method for comparing a family of 3 estimates

Dry weight depth 15-30

There are no significant effects between the different green manure treatments on fresh weight in 2022.

## Analysis of Variance Table
## 
## Response: bulkdensity2022[, var]
##              Df  Sum Sq Mean Sq F value Pr(>F)
## treatment     2   96.64  48.321  0.6130 0.5507
## blok          3   67.40  22.466  0.2850 0.8357
## blok:subplot  8  456.43  57.053  0.7238 0.6691
## Residuals    22 1734.10  78.823               
## 
##  Shapiro-Wilk normality test
## 
## data:  model$residuals
## W = 0.97048, p-value = 0.4388
## 
## $emmeans
##  contrast                 estimate   SE df t.ratio p.value
##  Fibrous roots - Mixture    -0.182 3.62 22  -0.050  0.9986
##  Fibrous roots - Taproots   -3.563 3.62 22  -0.983  0.5949
##  Mixture - Taproots         -3.381 3.62 22  -0.933  0.6258
## 
## Results are averaged over the levels of: subplot, blok 
## Note: contrasts are still on the [ scale 
## P value adjustment: tukey method for comparing a family of 3 estimates 
## 
## $contrasts
##  contrast                                               estimate   SE df
##  (Fibrous roots - Mixture) - (Fibrous roots - Taproots)    3.381 3.62 22
##  (Fibrous roots - Mixture) - (Mixture - Taproots)          3.198 6.28 22
##  (Fibrous roots - Taproots) - (Mixture - Taproots)        -0.182 3.62 22
##  t.ratio p.value
##    0.933  0.6258
##    0.509  0.8675
##   -0.050  0.9986
## 
## Results are averaged over the levels of: subplot, blok 
## P value adjustment: tukey method for comparing a family of 3 estimates

Moisture percentage depth 0-15

There are no significant effects between the different green manure treatments on fresh weight in 2022.

## Analysis of Variance Table
## 
## Response: bulkdensity2022[, var]
##              Df  Sum Sq Mean Sq F value  Pr(>F)  
## treatment     2  0.3758 0.18792  0.3593 0.70216  
## blok          3  4.3605 1.45350  2.7794 0.06511 .
## blok:subplot  8  6.3367 0.79209  1.5146 0.20877  
## Residuals    22 11.5050 0.52296                  
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
##  Shapiro-Wilk normality test
## 
## data:  model$residuals
## W = 0.97705, p-value = 0.6451
## 
## $emmeans
##  contrast                 estimate    SE df t.ratio p.value
##  Fibrous roots - Mixture     0.250 0.295 22   0.848  0.6780
##  Fibrous roots - Taproots    0.124 0.295 22   0.422  0.9071
##  Mixture - Taproots         -0.126 0.295 22  -0.426  0.9052
## 
## Results are averaged over the levels of: subplot, blok 
## Note: contrasts are still on the [ scale 
## P value adjustment: tukey method for comparing a family of 3 estimates 
## 
## $contrasts
##  contrast                                               estimate    SE df
##  (Fibrous roots - Mixture) - (Fibrous roots - Taproots)    0.126 0.295 22
##  (Fibrous roots - Mixture) - (Mixture - Taproots)          0.376 0.511 22
##  (Fibrous roots - Taproots) - (Mixture - Taproots)         0.250 0.295 22
##  t.ratio p.value
##    0.426  0.9052
##    0.736  0.7453
##    0.848  0.6780
## 
## Results are averaged over the levels of: subplot, blok 
## P value adjustment: tukey method for comparing a family of 3 estimates

Moisture percentage depth 15-30

There are no significant effects between the different green manure treatments on fresh weight in 2022.

## Analysis of Variance Table
## 
## Response: bulkdensity2022[, var]
##              Df Sum Sq Mean Sq F value Pr(>F)
## treatment     2  4.247  2.1237  0.6033 0.5558
## blok          3  1.667  0.5557  0.1579 0.9235
## blok:subplot  8 20.194  2.5243  0.7171 0.6746
## Residuals    22 77.447  3.5203               
## 
##  Shapiro-Wilk normality test
## 
## data:  model$residuals
## W = 0.97904, p-value = 0.7131
## 
## $emmeans
##  contrast                 estimate    SE df t.ratio p.value
##  Fibrous roots - Mixture    -0.240 0.766 22  -0.313  0.9476
##  Fibrous roots - Taproots    0.579 0.766 22   0.755  0.7336
##  Mixture - Taproots          0.818 0.766 22   1.068  0.5431
## 
## Results are averaged over the levels of: subplot, blok 
## Note: contrasts are still on the [ scale 
## P value adjustment: tukey method for comparing a family of 3 estimates 
## 
## $contrasts
##  contrast                                               estimate    SE df
##  (Fibrous roots - Mixture) - (Fibrous roots - Taproots)   -0.818 0.766 22
##  (Fibrous roots - Mixture) - (Mixture - Taproots)         -1.058 1.327 22
##  (Fibrous roots - Taproots) - (Mixture - Taproots)        -0.240 0.766 22
##  t.ratio p.value
##   -1.068  0.5431
##   -0.797  0.7084
##   -0.313  0.9476
## 
## Results are averaged over the levels of: subplot, blok 
## P value adjustment: tukey method for comparing a family of 3 estimates

Results

Soil depth Mechanical treatment Cover crop treatment Dry bulk density Fresh weight Dry weight Soil moisture
15 LB Fibrous roots 1.402300 178.5700 140.2300 21.47089
15 LB Mixture 1.409000 178.3900 140.9000 21.03378
15 LB Taproots 1.346833 170.7067 134.6833 21.09880
15 Ref Fibrous roots 1.338000 169.6967 133.8000 21.17462
15 Ref Mixture 1.410600 177.2333 141.0600 20.43852
15 Ref Taproots 1.399700 176.5633 139.9700 20.76464
15 SB Fibrous roots 1.414900 178.3633 141.4900 20.67227
15 SB Mixture 1.347600 170.6600 134.7600 21.04228
15 SB Taproots 1.452600 181.3200 145.2600 19.89314
15 SS Fibrous roots 1.405733 178.2567 140.5733 21.14279
15 SS Mixture 1.359600 171.8933 135.9600 20.94489
15 SS Taproots 1.325933 170.4033 132.5933 22.20618
30 LB Fibrous roots 1.420867 182.4133 142.0867 22.13804
30 LB Mixture 1.415633 181.1800 141.5633 21.81909
30 LB Taproots 1.378467 176.6367 137.8467 21.98856
30 Ref Fibrous roots 1.372900 174.9200 137.2900 21.50882
30 Ref Mixture 1.377700 177.6900 137.7700 22.50797
30 Ref Taproots 1.425400 179.6033 142.5400 20.67545
30 SB Fibrous roots 1.372600 173.6600 137.2600 21.03769
30 SB Mixture 1.398633 177.4500 139.8633 21.18245
30 SB Taproots 1.409000 180.9400 140.9000 22.19237
30 SS Fibrous roots 1.400267 180.9533 140.0267 22.67877
30 SS Mixture 1.381967 179.0033 138.1967 22.81267
30 SS Taproots 1.496300 187.3867 149.6300 20.19256
x15_30_cm jaar LB Ref SB SS LB.R SB.R SS.R
15 2020 1.343556 1.264100 1.338456 1.362811 106.2855 105.8821 107.80881
15 2021 1.462300 1.458717 1.486050 1.450867 100.2456 101.8738 99.46186
15 2022 1.386044 1.382767 1.405033 1.363756 100.2370 101.6103 98.62514
30 2020 1.330433 1.283833 1.361067 1.284744 103.6298 106.0158 100.07097
30 2021 1.472417 1.456850 1.488817 1.427117 101.0685 102.1942 97.95907
30 2022 1.404989 1.392000 1.393411 1.426178 100.9331 100.1014 102.45530
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