Revision as of 15:55, 26 January 2020

Problem definition

Crop rotation is based on growing a series of different types of crops in the same area in sequential seasons. The planned rotation may vary from a growing season to a few years or even longer periods. It is one of the most effective agricultural control strategies that is used in preventing the loss of soil fertility. It also helps in reducing soil erosion and increases crop yield. Planning an effective crop rotation requires weighing fixed and fluctuating production circumstances: market, farm size, labor supply, climate, soil type, growing practices, etc.

In this simulation I will try to find parameters which have impact on the whole process of crop rotation with goal to find model providing desired outputs (these were slightly changed from concept) - crop yields, greenhouse gas emissions (N2O, CO2, NH4), soil fertility (nitrogen levels).

I will focus on four crop rotation strategies with three different crops - corn, soybean, wheat:

CCC (continuous corn) - only corn will be farmed for the whole observed time period (40 years)

CS (corn-soybean) - rotation of corn and soybean will be used in year cycles for the whole observed time period (40 years), first year corn, second year soybean, repeat..

SSS (continuous soybean) - only soybean will be farmed for the whole observed time period (40 years)

CSW (corn-soybean-wheat) - rotation of corn, soybean and wheat will be used in year cycles for the whole observed time period (40 years), first year corn, second year soybean, third year wheat, repeat..

Goal of this simulation is to observe dynamic changes with yields, greenhouse gas emissions and soil nitrogen levels, while changing different crop rotation strategies.

Method

Vensim modelling approach was selected due to dynamic behavior of the simulated system.

Model

Variables

Number of rotated crops

Input constant variable which can be changed based on crop strategy. Range <1,3>.

=1 (in case of CCC and SSS strategies)

=2 (in case of CS strategy)

=3 (in case of CSW strategy)

Corn production

=Corn quantity*PULSE TRAIN(0, 1 , Number of rotated crops ,40)

Soybean production

Soybean quantity*PULSE TRAIN(IF THEN ELSE(Number of rotated crops=1, 0 , 1 ), 1 , Number of rotated crops , 40 )

Wheat production

Wheat quantity*PULSE TRAIN(IF THEN ELSE(Number of rotated crops=1, 0 , 2 ), 1 , Number of rotated crops , 40 )

Corn quantity

<0,100>

Soybean quantity

<0,40>

Wheat quantity

<0,80>

increase of N2O emissions

increase of CO2 emissions

increase of CH4 emissions

Cumulative N2O emissions

Cumulative CO2 emissions

Cumulative CH4 emissions

Corn N2O emission coef

Soybean N2O emission coef

Wheat N2O emission coef

Corn CO2 emission coef

Soybean CO2 emission coef

Wheat CO2 emission coef

Corn CH4 emission coef

Soybean CH4 emission coef

Wheat CH4 emission coef

Inorganic fertilizer

Soil nitrogen

increase of soil N

decrease of soil N

Soil nitrogen level

Temperature

Precipitation

Pests

Tillage

Natural disasters

increase of C yield

increase of S yield

increase of W yield

Corn yield

Soybean yield

Wheat yield

Total yield

= Corn yield + Soybean yield + Wheat yield

@@ Line 24: / Line 24: @@
 == Variables ==
-'''Number of rotated crops'''
-	''<1,3>''
+===Number of rotated crops===
-Corn production
+''Input constant variable which can be changed based on crop strategy. Range <1,3>.''
-Corn quantity*PULSE TRAIN(0, 1 , Number of rotated crops ,40)
-Soybean production
+=1 (in case of CCC and SSS strategies)
+=2 (in case of CS strategy)
+=3 (in case of CSW strategy)
+===Corn production===
+=Corn quantity*PULSE TRAIN(0, 1 , Number of rotated crops ,40)
+===Soybean production===
 	Soybean quantity*PULSE TRAIN(IF THEN ELSE(Number of rotated crops=1, 0 , 1 ), 1 , Number of rotated crops , 40 )
-Wheat production
+===Wheat production===
 	Wheat quantity*PULSE TRAIN(IF THEN ELSE(Number of rotated crops=1, 0 , 2 ), 1 , Number of rotated crops , 40 )
-Corn quantity
+===Corn quantity===
 	<0,100>
-Soybean quantity
+===Soybean quantity===
 	<0,40>
-Wheat quantity
+===Wheat quantity===
 	<0,80>
-increase of N2O emissions
+===increase of N2O emissions===
-increase of CO2 emissions
+===increase of CO2 emissions===
-increase of CH4 emissions
+===increase of CH4 emissions===
-Cumulative N2O emissions
+===Cumulative N2O emissions===
-Cumulative CO2 emissions
+===Cumulative CO2 emissions===
-Cumulative CH4 emissions
+===Cumulative CH4 emissions===
-Corn N2O emission coef
+===Corn N2O emission coef===
-Soybean N2O emission coef
+===Soybean N2O emission coef===
-Wheat N2O emission coef
+===Wheat N2O emission coef===
-Corn CO2 emission coef
+===Corn CO2 emission coef===
-Soybean CO2 emission coef
+===Soybean CO2 emission coef===
-Wheat CO2 emission coef
+===Wheat CO2 emission coef===
-Corn CH4 emission coef
+===Corn CH4 emission coef===
-Soybean CH4 emission coef
+===Soybean CH4 emission coef===
-Wheat CH4 emission coef
+===Wheat CH4 emission coef===
-Inorganic fertilizer
+===Inorganic fertilizer===
-Soil nitrogen
+===Soil nitrogen===
-increase of soil N
+===increase of soil N===
-decrease of soil N
+===decrease of soil N===
-Soil nitrogen level
+===Soil nitrogen level===
-Temperature
+===Temperature===
-Precipitation
+===Precipitation===
-Pests
+===Pests===
-Tillage
+===Tillage===
-Natural disasters
+===Natural disasters===
-increase of C yield
+===increase of C yield===
-increase of S yield
+===increase of S yield===
-increase of W yield
+===increase of W yield===
-Corn yield
+===Corn yield===
-Soybean yield
+===Soybean yield===
-Wheat yield
+===Wheat yield===
-Total yield = Corn yield + Soybean yield + Wheat yield
+===Total yield===
+= Corn yield + Soybean yield + Wheat yield
 =Results=

Difference between revisions of "Crop Rotation in sustainable farming"