Wheat relative yield response - replicate normalisation
Jan C Greyling
24/02/2020
Prepare the data
dat <- fread("Output/wheat_data_prepped.csv")
#fix rotation
dat[!is.na(yldb), yld := yldb]
#drop all blank yields and biomass estimates
dat <- dat[!is.na(yld)]
dat[, c("wind","yldb") := NULL]
# Max yield index ---------------------------------------------------------
dat[, yld_max := max(yld,na.rm = T), by = .(year,local,rotation,rep)]
#keep original yield
dat[, yld.OR := yld]
#calculate control normalised yield
dat[, yld := yld/yld_max*100]Model results
Langgewens
Canola-Wheat
Langgewens Canola-Wheat results
| Year | ||||
| Relative yield (Max trial yield = 100) | ||||
| 2016 | 2017 | 2018 | 2019 | |
| (1) | (2) | (3) | (4) | |
| Mineral N | 0.923** | -0.300 | 1.056** | 0.538 |
| (0.405) | (0.671) | (0.504) | (0.530) | |
| Mineral N squared | -0.009* | 0.003 | -0.017** | -0.005 |
| (0.005) | (0.012) | (0.007) | (0.007) | |
| Intercept | 64.687*** | 85.340*** | 62.071*** | 69.274*** |
| (7.356) | (8.281) | (8.432) | (9.363) | |
| Observations | 60 | 61 | 61 | 55 |
| R2 | 0.158 | 0.019 | 0.115 | 0.045 |
| Adjusted R2 | 0.128 | -0.014 | 0.085 | 0.008 |
| Residual Std. Error | 8.879 (df = 57) | 11.504 (df = 58) | 11.353 (df = 58) | 11.588 (df = 52) |
| F Statistic | 5.339*** (df = 2; 57) | 0.576 (df = 2; 58) | 3.781** (df = 2; 58) | 1.217 (df = 2; 52) |
| Note: | p<0.1; p<0.05; p<0.01 | |||
And now for the plots.
| Year | ||||
| Mineral N | ||||
| 2016 | 2017 | 2018 | 2019 | |
| (1) | (2) | (3) | (4) | |
| Total Nitrogen Applied | 0.231*** | 0.158*** | 0.187*** | 0.262*** |
| (0.019) | (0.011) | (0.011) | (0.018) | |
| Intercept | 11.339*** | 5.539*** | 11.163*** | 12.288*** |
| (2.408) | (1.377) | (1.389) | (1.914) | |
| Observations | 59 | 60 | 62 | 56 |
| R2 | 0.724 | 0.781 | 0.822 | 0.805 |
| Adjusted R2 | 0.719 | 0.777 | 0.819 | 0.801 |
| Residual Std. Error | 8.886 (df = 57) | 5.117 (df = 58) | 5.331 (df = 60) | 7.384 (df = 54) |
| F Statistic | 149.593*** (df = 1; 57) | 206.777*** (df = 1; 58) | 277.548*** (df = 1; 60) | 222.494*** (df = 1; 54) |
| Note: | p<0.1; p<0.05; p<0.01 | |||
Medics-Wheat
Langgewens Medics-Wheat results
| Year | ||||
| Relative yield (Max trial yield = 100) | ||||
| 2016 | 2017 | 2018 | 2019 | |
| (1) | (2) | (3) | (4) | |
| Mineral N | 0.637 | -0.870 | 1.379 | -1.574** |
| (0.661) | (0.596) | (1.149) | (0.604) | |
| Mineral N squared | -0.011 | 0.012 | -0.021 | 0.011** |
| (0.009) | (0.008) | (0.016) | (0.005) | |
| Intercept | 78.510*** | 91.016*** | 61.635*** | 126.498*** |
| (11.473) | (11.093) | (17.572) | (15.668) | |
| Observations | 61 | 61 | 62 | 53 |
| R2 | 0.058 | 0.039 | 0.032 | 0.228 |
| Adjusted R2 | 0.026 | 0.006 | -0.001 | 0.197 |
| Residual Std. Error | 9.518 (df = 58) | 12.684 (df = 58) | 11.523 (df = 59) | 12.278 (df = 50) |
| F Statistic | 1.791 (df = 2; 58) | 1.185 (df = 2; 58) | 0.967 (df = 2; 59) | 7.375*** (df = 2; 50) |
| Note: | p<0.1; p<0.05; p<0.01 | |||
And now for the plots.
| Year | ||||
| Mineral N | ||||
| 2016 | 2017 | 2018 | 2019 | |
| (1) | (2) | (3) | (4) | |
| Total Nitrogen Applied | 0.129*** | 0.133*** | 0.123*** | 0.155*** |
| (0.016) | (0.017) | (0.023) | (0.036) | |
| Intercept | 20.785*** | 28.629*** | 18.752*** | 32.195*** |
| (2.063) | (2.209) | (2.951) | (4.068) | |
| Observations | 60 | 60 | 60 | 53 |
| R2 | 0.520 | 0.502 | 0.322 | 0.261 |
| Adjusted R2 | 0.512 | 0.494 | 0.311 | 0.247 |
| Residual Std. Error | 7.858 (df = 58) | 8.415 (df = 58) | 10.746 (df = 58) | 15.406 (df = 51) |
| F Statistic | 62.935*** (df = 1; 58) | 58.570*** (df = 1; 58) | 27.591*** (df = 1; 58) | 18.037*** (df = 1; 51) |
| Note: | p<0.1; p<0.05; p<0.01 | |||
Darling
Canola-Wheat
Darling Canola-Wheat results
| Year | |||
| Relative yield (Max trial yield = 100) | |||
| 2016 | 2017 | 2018 | |
| (1) | (2) | (3) | |
| Mineral N | 2.755*** | -8.012*** | 0.956 |
| (0.676) | (1.863) | (0.807) | |
| Mineral N squared | -0.027*** | 0.261*** | -0.014 |
| (0.009) | (0.070) | (0.019) | |
| Intercept | 17.054* | 123.694*** | 71.738*** |
| (10.184) | (11.013) | (7.506) | |
| Observations | 60 | 60 | 62 |
| R2 | 0.358 | 0.281 | 0.083 |
| Adjusted R2 | 0.335 | 0.256 | 0.052 |
| Residual Std. Error | 18.949 (df = 57) | 14.802 (df = 57) | 10.733 (df = 59) |
| F Statistic | 15.866*** (df = 2; 57) | 11.161*** (df = 2; 57) | 2.674* (df = 2; 59) |
| Note: | p<0.1; p<0.05; p<0.01 | ||
And now for the plots.
| Year | |||
| Mineral N | |||
| 2016 | 2017 | 2018 | |
| (1) | (2) | (3) | |
| Total Nitrogen Applied | 0.120*** | 0.054*** | 0.084*** |
| (0.014) | (0.004) | (0.009) | |
| Intercept | 10.460*** | 4.105*** | 6.856*** |
| (1.714) | (0.498) | (1.067) | |
| Observations | 58 | 61 | 60 |
| R2 | 0.569 | 0.759 | 0.605 |
| Adjusted R2 | 0.561 | 0.755 | 0.598 |
| Residual Std. Error | 6.430 (df = 56) | 1.939 (df = 59) | 4.024 (df = 58) |
| F Statistic | 73.918*** (df = 1; 56) | 186.207*** (df = 1; 59) | 88.852*** (df = 1; 58) |
| Note: | p<0.1; p<0.05; p<0.01 | ||
Porterville
Canola-Wheat
Porterville Canola-Wheat results
And now for the plots.
| Year | ||||
| Mineral N | ||||
| 2016 | 2017 | 2018 | 2019 | |
| (1) | (2) | (3) | (4) | |
| Total Nitrogen Applied | 0.109*** | -0.022 | 0.097*** | 0.289*** |
| (0.012) | (0.045) | (0.012) | (0.029) | |
| Intercept | 8.546*** | 56.975*** | 12.396*** | 16.986*** |
| (1.451) | (5.686) | (1.386) | (3.560) | |
| Observations | 60 | 60 | 60 | 46 |
| R2 | 0.603 | 0.004 | 0.546 | 0.687 |
| Adjusted R2 | 0.596 | -0.013 | 0.538 | 0.680 |
| Residual Std. Error | 5.627 (df = 58) | 21.348 (df = 58) | 5.226 (df = 58) | 12.656 (df = 44) |
| F Statistic | 87.915*** (df = 1; 58) | 0.250 (df = 1; 58) | 69.804*** (df = 1; 58) | 96.639*** (df = 1; 44) |
| Note: | p<0.1; p<0.05; p<0.01 | |||
Caledon
Lucern-Wheat
Caledon Lucern-Wheat results
| Year | ||
| Relative yield (Max trial yield = 100) | ||
| 2017 | 2018 | |
| (1) | (2) | |
| Mineral N | 0.033 | 0.058 |
| (0.553) | (0.226) | |
| Mineral N squared | -0.001 | -0.0001 |
| (0.008) | (0.002) | |
| Intercept | 84.323*** | 74.547*** |
| (8.380) | (5.084) | |
| Observations | 60 | 60 |
| R2 | 0.003 | 0.013 |
| Adjusted R2 | -0.032 | -0.022 |
| Residual Std. Error (df = 57) | 9.196 | 10.487 |
| F Statistic (df = 2; 57) | 0.094 | 0.362 |
| Note: | p<0.1; p<0.05; p<0.01 | |
And now for the plots.
| Year | ||
| Mineral N | ||
| 2017 | 2018 | |
| (1) | (2) | |
| Total Nitrogen Applied | 0.163*** | 0.248*** |
| (0.017) | (0.024) | |
| Intercept | 14.630*** | 9.279*** |
| (2.113) | (2.971) | |
| Observations | 62 | 59 |
| R2 | 0.602 | 0.651 |
| Adjusted R2 | 0.596 | 0.645 |
| Residual Std. Error | 8.110 (df = 60) | 11.113 (df = 57) |
| F Statistic | 90.937*** (df = 1; 60) | 106.450*** (df = 1; 57) |
| Note: | p<0.1; p<0.05; p<0.01 | |
Tygerhoek
Canola-Wheat
Tygerhoek Canola-Wheat results
| Year | ||||
| Relative yield (Max trial yield = 100) | ||||
| 2016 | 2017 | 2018 | 2019 | |
| (1) | (2) | (3) | (4) | |
| Mineral N | 2.583*** | 0.542 | 0.475 | 0.640** |
| (0.554) | (0.734) | (0.387) | (0.257) | |
| Mineral N squared | -0.028*** | -0.009 | -0.001 | -0.007*** |
| (0.007) | (0.013) | (0.003) | (0.002) | |
| Intercept | 28.898*** | 79.649*** | 58.030*** | 73.333*** |
| (9.820) | (9.964) | (9.930) | (5.931) | |
| Observations | 60 | 59 | 59 | 61 |
| R2 | 0.370 | 0.012 | 0.306 | 0.189 |
| Adjusted R2 | 0.348 | -0.023 | 0.281 | 0.161 |
| Residual Std. Error | 11.158 (df = 57) | 7.495 (df = 56) | 11.547 (df = 56) | 11.357 (df = 58) |
| F Statistic | 16.743*** (df = 2; 57) | 0.338 (df = 2; 56) | 12.352*** (df = 2; 56) | 6.769*** (df = 2; 58) |
| Note: | p<0.1; p<0.05; p<0.01 | |||
And now for the plots.
| Year | ||||
| Mineral N | ||||
| 2016 | 2017 | 2018 | 2019 | |
| (1) | (2) | (3) | (4) | |
| Total Nitrogen Applied | 0.154*** | 0.091*** | 0.220*** | 0.177*** |
| (0.016) | (0.016) | (0.034) | (0.015) | |
| Intercept | 17.105*** | 19.355*** | 27.447*** | 16.229*** |
| (2.098) | (1.925) | (4.150) | (1.760) | |
| Observations | 60 | 62 | 57 | 61 |
| R2 | 0.605 | 0.364 | 0.432 | 0.693 |
| Adjusted R2 | 0.599 | 0.353 | 0.422 | 0.687 |
| Residual Std. Error | 7.907 (df = 58) | 7.390 (df = 60) | 15.244 (df = 55) | 7.340 (df = 59) |
| F Statistic | 88.971*** (df = 1; 58) | 34.311*** (df = 1; 60) | 41.874*** (df = 1; 55) | 132.988*** (df = 1; 59) |
| Note: | p<0.1; p<0.05; p<0.01 | |||
Riversdale
Canola-Wheat
Riversdale Canola-Wheat results
| Year | ||||
| Relative yield (Max trial yield = 100) | ||||
| 2016 | 2017 | 2018 | 2019 | |
| (1) | (2) | (3) | (4) | |
| Mineral N | 0.948*** | 0.056 | -0.280** | -0.566* |
| (0.203) | (0.385) | (0.122) | (0.302) | |
| Mineral N squared | -0.006*** | -0.002 | 0.0003 | 0.003 |
| (0.002) | (0.003) | (0.0002) | (0.002) | |
| Intercept | 54.240*** | 84.336*** | 90.540*** | 94.549*** |
| (4.215) | (10.430) | (9.069) | (8.316) | |
| Observations | 50 | 44 | 46 | 41 |
| R2 | 0.599 | 0.096 | 0.181 | 0.127 |
| Adjusted R2 | 0.582 | 0.052 | 0.143 | 0.081 |
| Residual Std. Error | 6.865 (df = 47) | 11.978 (df = 41) | 22.248 (df = 43) | 14.216 (df = 38) |
| F Statistic | 35.120*** (df = 2; 47) | 2.185 (df = 2; 41) | 4.762** (df = 2; 43) | 2.764* (df = 2; 38) |
| Note: | p<0.1; p<0.05; p<0.01 | |||
And now for the plots.
| Year | ||||
| Mineral N | ||||
| 2016 | 2017 | 2018 | 2019 | |
| (1) | (2) | (3) | (4) | |
| Total Nitrogen Applied | 0.258*** | 0.209*** | -0.046 | 0.393*** |
| (0.016) | (0.035) | (0.120) | (0.048) | |
| Intercept | 11.354*** | 22.026*** | 89.334*** | 10.530* |
| (1.837) | (4.585) | (14.738) | (5.433) | |
| Observations | 50 | 44 | 46 | 41 |
| R2 | 0.842 | 0.466 | 0.003 | 0.636 |
| Adjusted R2 | 0.839 | 0.454 | -0.019 | 0.627 |
| Residual Std. Error | 6.676 (df = 48) | 13.278 (df = 42) | 46.219 (df = 44) | 18.402 (df = 39) |
| F Statistic | 255.617*** (df = 1; 48) | 36.693*** (df = 1; 42) | 0.151 (df = 1; 44) | 68.288*** (df = 1; 39) |
| Note: | p<0.1; p<0.05; p<0.01 | |||
