Nitrogen prediction model in smallholder farming system integrating pig and fish farming in the urban and rural areas of Kinshasa

The modelling of nitrogen flow within integrated farms in aquaculture allows monitoring of the nitrogen evolution, which is one of the limiting elements in the farm production. This is one of the important ways to improve production in small integrated agricultural farms in rural and peri-urban areas of Kinshasa with limited financial resources. The model is built in order to use the nitrogen produced by the pig for fertilizing fish farming ponds. The pig module was calibrated, validated and ready to be used, contrary to the fish module which is not validated due to the lack of appropriate experience data. Result of pig module prediction, gives the cumulative N amount of the fattening period to 861.85 gN/pig for fecal nitrogen and 765.39 for urinary production very close to the measured value of 988.68 gN/pig and 887.55 gN/pig for N fecal and N urinary. The model shows that the variation in feed content leads to the variation in the N fecal and urinary production to the farm. Combined to the N from pig, N water in the fish pond is sensitive to N from pig addition and fish biomass. Change in factors that affect pig consumption and pig growing performance lead a variation in both N production by a pig and N water evolution in the pond water column.