Programación del socket

From the simulation runs of crop growth under potential conditions the mean and SD of the following outcomes as simulated over 17 years for Lelystad, Flevoland, are available and also the outcomes per year are available as Excel files on request:

1) Dates of sowing, emergence, flowering (or tuber initiation), and maturity 2) Growth durations

3) Weights at harvest of total roots, leaves, stems, grains /tubers/ bulbs, and total above-ground biomass

4) Maximum leaf area index and harvest index 5) Transpiration coefficient

6) Total gross assimilation and total maintenance respiration 7) Total soil evaporation and total crop transpiration.

From the simulation runs of crop growth under water limited conditions the mean and SD of the following outcomes as simulated over 17 years, and also the outcomes per year are available as Excel files on request:

1) Dates of sowing and emergence, and the growth duration

2) Weights at harvest of total leaves, stems, grains /tubers/ bulbs, and total above-ground biomass

3) Maximum leaf area index and harvest index 4) Transpiration coefficient

5) Components of the water balance during the simulated period, such as cumulative rainfall, change in soil water in maximally rooted zone, cumulative crop transpiration and soil evaporation, and total water losses by downward flow and by surface runoff

6) Fractions of yield and total above ground biomass compared to the yield and total biomass under potential conditions.

Assuming that for regions with high groundwater levels and deep alluvial soils as Flevoland, the water supply will generally not be limiting for growth of the main crops during the summers and that some valuable crops with a limited rooting depth as onion and potato will be irrigated, we will use the simulated potential yields to calculate actual yields in Flevoland in Chapter 5. Hence, we focus in the following on the yield results of the crop growth simulations under potential conditions, as given in Table 4.1. For the reasons described in Section 4.2, we combine the high emission scenario A1FI with the W and W+ scenarios of KNMI, resulting in the A1-W and A1-W+ scenarios, and the low emission scenario B2 with the G and G+ scenarios of KNMI, resulting in B2-G and B2-G+ scenarios.

Results for winter wheat compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 6-11% and 3-11% due to mainly the positive effect of CO₂ increase which is larger than the negative effect of temperature rise (being strongest for the W+ scenario and smallest for the G scenario), (b) additional yield increases of 3-4% for the A1-W/W+ scenarios by management adaptation due to the longer growth period.

Results for spring wheat compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 11-14% and 9-18% due to mainly the positive effect of CO₂ increase, (b) additional yield increases of 6-8% for the A1-W/W+ scenarios by management adaptation due to the longer growth period and the earlier sowing date.

Results for spring barley compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 11-14% and 10-18% due to mainly the positive effect of CO₂ increase, (b) additional yield increases of 7-9% for the

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W/W+ scenarios by management adaptation due to the longer growth period and the earlier sowing date.

Results for potato ware compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 4-8% and 2-11% due to mainly the positive effect of CO₂ increase, (b) additional yield increases of 8% for the A1-W/W+ scenarios by management adaptation due to the longer growth period and the earlier planting date.

Table 4.1 Mean of crop yields (in ton dry matter per ha) for potential conditions as simulated with the WOFOST model for current weather conditions (period 1992-2008;

Base) in Lelystad, Flevoland and for future weather conditions (also 17 years) around year 2050, and the dry matter fractions in air dry yields. The calculations for future conditions have been done for the four KNMI Climate change scenarios for 2050 ( G, G+, W, and W+), first, the W and W+ scenarios being combined with a high CO2

concentration of 567 µmol CO2/mol from the ISAM model for 2050 for the high emission scenario A1FI (A1-W, A1-W+), second, the same high emission scenario but with management adaptation (A1-W-Ad, A1-W+-Ad, i.e. sowing date 15 days earlier except for winter wheat and rape seed, and 10% higher temperature sums required for phenological development) and third, the G and G+ scenarios being combined with a lower CO2 concentration of of 478 µmol CO2/mol from the ISAM model for 2050 for the low emission scenario B2 (B2-G, B2-G+)

Crop Base B2-G B2-G+ A1-W A1-W+

A1-W-Ad

A1-W+-Ad

DM fr.

in yield Winter wheat 10.35 11.44 10.99 11.46 10.63 11.97 10.99 0.84 Spring wheat 9.07 10.36 10.04 10.68 9.86 11.34 10.68 0.84 Spring barley 8.68 9.91 9.63 10.22 9.51 10.94 10.34 0.84 Potato ware 15.61 16.93 16.28 17.31 15.96 18.74 17.31 0.22 Potato seed 11.02 12.12 11.69 12.32 11.33 13.66 12.60 0.22 Sugar beet 16.91 20.17 20.20 22.11 21.75 22.46 22.56 0.20 Maize fodder 22.47 24.57 24.22 24.25 23.17 26.30 25.22 0.33 Maize grain 10.01 11.38 11.24 11.34 10.84 11.78 11.32 0.87 Winter

rapeseed 4.72 5.71 5.53 6.01 5.58 6.66 6.19 0.91

Sunflower 3.83 4.24 4.15 4.48 4.26 4.63 4.41 0.94

Peas 5.86 6.51 6.35 6.74 6.39 7.34 6.99 0.87

Onion 13.63 16.39 15.54 17.17 15.56 19.29 17.84 0.20

Tulip 6.76 7.840 7.53 8.17 7.48 8.88 8.15 0.20

Results for potato seed compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 6-10% and 3-12% due to mainly the positive effect of CO₂ increase, (b) additional yield increases of 11% for the A1-W/W+ scenarios by management adaptation due to the longer growth period and the earlier planting date.

Results for sugar beet compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 19% and 29-31% due to the positive effect of CO₂ increase and the longer growth period, (b) additional yield increases of 2-4% for the A1-W/W+ scenarios by management adaptation due to the longer growth period and the earlier sowing date.

Results for maize fodder compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 8-9% and 3-8% due to mainly the positive effect of temperature rise, (b) additional yield increases of 8-9% for the A1-W/W+ scenarios by management adaptation due to the longer growth period and the earlier sowing date.

Results for maize grain compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 12-14% and 8-13% due to mainly the positive effect of temperaturerise, (b) additional yield increases of 4% for the A1-W/W+ scenarios by management adaptation due to the longer growth period and the earlier sowing date.

Results for winter rapeseed compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 17-21% and 18-27% due to mainly the positive effect of CO₂ increase, (b) additional yield increases of 11% for the A1-W/W+ scenarios by management adaptation due to the longer growth period.

Results for sunflower compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 9-11% and 11-17% due to the positive effects of CO₂ increase and temperature rise, (b) additional yield increases of 3-4%

for the A1-W/W+ scenarios by management adaptation due to the longer growth period and the earlier sowing date.

Results for peas compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 8-11% and 9-15% due to mainly the positive effect of CO₂ increase, (b) additional yield increases of 9% for the A1-W/W+ scenarios by management adaptation due to the longer growth period and the earlier sowing date.

Results for onion compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 14-20% and 14-26% due to mainly the positive effect of CO₂ increase, (b) additional yield increases of 12-15% for the A1-W/W+ scenarios by management adaptation due to the longer growth period and the earlier sowing date.

Results for tulip compared to the current situation: (a) yield increases for the B2-G/G+ and A1-W/W+ scenarios by resp. 11-16% and 11-21% due to mainly the positive effect of CO₂ increase, (b) additional yield increases of 9% for the A1-W/W+ scenarios by management adaptation due to the longer growth period.

4.4 Evaluation of the results

Effects of climate change and increase in atmospheric CO₂ for different scenarios in 2050 on the growth and yields of the main crop types cultivated in Flevoland can be easily

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calculated with the WOFOST model. The main assumption required to use these simulated yields for 2050 to derive the actual yields for 2050 (Chapter 5), is that the simulated yields and yield changes towards 2050 under optimal growing conditions are practically similar to those under actual farming conditions. As the actual management is almost optimal and the yield levels are high in Flevoland (i.e. actual yields of the main crop types are almost 80% of the simulated yields under potential conditions, see Table 5.1), this assumption is justified.

Changes in climate and increases in atmospheric CO₂ towards year 2050 for the four scenarios result in simulated yield increases for all crop types in Flevoland. These yield increases for 2050 are mainly caused by the increase in atmospheric CO₂, being higher for the A1 emission scenario than for the B2 scenario. The four different Climate change scenarios for 2050 from KNMI result in simulated yields for the different crop types that in general change from highest to lowest yield for the scenarios in following order: G → G+ → W → W+ ; this yield order can be explained from the fact that the G scenario has the coolest summer with an increase in rainfall and the W+ scenario has the warmest summer with a considerable decrease in rainfall (hence, this scenario leads to yield reduction by shortened periods for e.g. grain and tuber filling at warmer temperatures), and the other scenarios have in-between changes.

The positive CO₂ effect on yield is partly counteracted by the negative effect of temperature rise due to the shortened growth duration. Hence, the yield increases for the A1-W/W+ scenarios appear often to be only slightly higher than those for the B2-G/G+

scenarios (Table 4.1),. This is due to the fact that the A1-W/W+ scenarios have both a higher atmospheric CO₂ concentration and a stronger temperature rise than the B2-G/G+

scenarios, with both effects compensating each other.

The simulated yield changes due to Climate change and increase in atmospheric CO₂ appear to be reliable. This is in particular the case, because the main part of these yield changes are caused by the increase in atmospheric CO₂, being a stable and simple relationship.

For changed Climate change conditions the crop simulations have been done for both current and adapted crop management. The applied adaptations are: earlier sowing or planting date and a variety adapted to warmer climate. Note that for the crop growth simulations practically optimal management is assumed and that the effects of most options to optimize the crop management (e.g. improved nutrient application and crop protection methods, change in soil tillage and in timing of field operations, and/or use of more disease-resistant crop varieties) cannot be studied in these growth simulations. The applied management adaptations result here for all crop types in Flevoland in slightly to moderately higher yields under potential growing conditions. The reason that the effects of management adaptations are often limited, is due to the fact that the warmer conditions under changed climate lead also under current crop management to an increased rate of phenological development of the crop and hence, automatically advance the growth period to the cooler periods in spring. This partly counterbalances the negative effects on yield of warmer temperatures under Climate change and limits the positive effects of management adaptation on yields.

Main conclusions are:

- Change in climate and increase in atmospheric CO₂ in year 2050 result in yield increases for all crop types in Flevoland and all Climate change scenarios.

- The four different Climate change scenarios for 2050 from KNMI result in simulated yields for the different crop types that in general differ from highest to lowest yield for the scenarios in following order: G → G+ → W → W+ ; this yield order can be explained from: G scenario has the coolest summer and the W+

scenario has the warmest summer, and the other scenarios have in-between changes.

- Increases in yields in 2050 compared to the current yields are mainly caused by the positive effect of the increase in atmospheric CO₂, whereas this effect is partly counteracted by the negative effect of temperature rise. Hence, the yield increases for the A1-W/W+ scenarios with a higher CO₂ concentration appear to be only slightly higher than those for the B2-G/G+ scenarios (Table 4.1).

- Management adaptation results in slightly to moderately higher yields for the main crop types in Flevoland.

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