Estimation of water losses volume due to waste of potato and tomato crops (Case study: Isfahan city fields)

The concept of water footprint is used to know the volume of water used in the production of various crops. Considering that the two potato and tomato crops on a Country scale, have the highest amount of waste compared to other crops, Therefore, in this study, the harvest stage losses of these two crops were studied in four fields located in Isfahan and in two irrigation methods. Finally, using water footprint, the volume of water lost due to waste of the mentioned products was calculated.

In the present study, first, the inflow of water to each field was measured and the gross irrigation volume of the crops was estimated using the irrigation program of the relevant fields. Then, using CROPWAT software and Climate data of stations close to the study area (east of Isfahan and Kabutarabad), the net irrigation requirement of crops was determined. Then, using the weighing method, the yield of products and the weight of lost crops were determined. Finally, water footprint was calculated for each crop and the volume of water lost due to their waste was estimated.

According to the results of this study, the average losses of potato and tomato crops in the harvest stage are estimated to be 4.8 ± 1.3 and 8.5 ± 0.8 percent of their total harvest, respectively. The total water footprint of potato crop in furrow and drip irrigation method is equal to 277.8 and 129.7 (m3 ton-1), respectively, while the amount of total water footprint for tomato crop is equal to 145.1 and 175.2 (m3 ton-1).

Based on the percentage of losses of potato and tomato crops and the average use of their total water footprint and also, according to the annual production of these crops in Isfahan and the country, the average volume of water lost due to waste of these two crops and only in Harvest stage is estimated to be 4.2 (minimum 2.9 and maximum 5.7) and 128 (minimum 102 and 152.9) Mm3 year-1 in Isfahan and the country, respectively. However, based on the total waste of these two crops from harvest to consumption, the average volume of water lost due to them is equal to 17.4 (minimum 11.5 and maximum 23.2) and 482 (minimum 380.3 and maximum 583.6) Mm3 year-1 is estimated, so the management of waste water from crop waste is important in the management of water resources allocated to the agricultural sector.