Fix meat production constraint

GAMS/IntExtOpt.gms

@@ -100,6 +100,7 @@ $gdxin
        MAX_NET_IMPORT_CONSTRAINT(import_crop)           constraint on max net imports
        MIN_NET_IMPORT_CONSTRAINT(import_crop)           constraint on min net imports
        PASTURE_IMPORT_CONSTRAINT                        constraint to not import pasture
+       PASTURE_EXPORT_CONSTRAINT
        MIN_FEED_CONSTRAINT                              constraint on min feed rate
        IRRIGATION_CONSTRAINT(location)                  constraint no water usage
        NET_SUPPLY_EQ(crop)                              calc net supply for crops
@@ -138,7 +139,7 @@ $gdxin
   
  TOTAL_CEREAL_DEMAND_CONSTRAINT .. sum(cereal_crop, net_supply(cereal_crop)) =G= demand('cereals');
  
- MEAT_DEMAND_CONSTRAINT .. meatEfficency*sum(feed_crop, feedDM(feed_crop) * feedAmount(feed_crop)) =G= demand('meat') - importAmount('meat') - exportAmount('meat');
+ MEAT_DEMAND_CONSTRAINT .. meatEfficency*sum(feed_crop, feedDM(feed_crop) * feedAmount(feed_crop)) =G= demand('meat') - importAmount('meat') + exportAmount('meat');
     
  MAX_FERT_INTENSITY_CONSTRAINT(crop, location) .. fertI(crop, location) =L= 1;
  MAX_IRRIG_INTENSITY_CONSTRAINT(crop, location) .. irrigI(crop, location) =L= 1;
@@ -150,7 +151,8 @@ $gdxin
  
  MAX_NET_IMPORT_CONSTRAINT(import_crop) .. importAmount(import_crop) - exportAmount(import_crop) =L= maxNetImport(import_crop);
  MIN_NET_IMPORT_CONSTRAINT(import_crop) .. importAmount(import_crop) - exportAmount(import_crop) =G= minNetImport(import_crop);
- PASTURE_IMPORT_CONSTRAINT .. importAmount('pasture') - exportAmount('pasture') =E= 0;
+ PASTURE_IMPORT_CONSTRAINT .. importAmount('pasture') =E= 0;
+ PASTURE_EXPORT_CONSTRAINT ..  exportAmount('pasture') =E= 0;
  
  MIN_FEED_CONSTRAINT .. sum(feed_crop_less_pasture, feedDM(feed_crop_less_pasture) * feedAmount(feed_crop_less_pasture)) =G= minFeedRate * (demand('meat') - importAmount('meat') + exportAmount('meat'));
  
@@ -190,7 +192,7 @@ $gdxin
  SOLVE LAND_USE USING NLP MINIMIZING energy;
       
 
-* display agriLandExpansion.l, previousArea, area.l, net_supply.l, demand, feedAmount.l, yield.l, netImportAmount.l;
+ display agriLandExpansion.l, previousArea, area.l, net_supply.l, demand, feedAmount.l, yield.l, importAmount.l, exportAmount.l;
 
  area.l(crop_less_pasture, location) = area.l(crop_less_pasture, location) / (1.0 - unhandledCropArea);