Chemical changes in the soil and leachate after the application of coffee wastewater

Abstract

Coffee wastewater (CWW) is rich in organic mater and nutrients, but if applied in high doses, CWW may affect the soil sorptive complex balance and contaminate water tables through leaching process. This paper aims to evaluate the leachate composition and the chemical changes of the soil after application of increasing CWW doses. Therefore, CWW was applied in 12 PVC columns with 100 mm diameter and 800 mm height filled up with Yellow Latosolic Argisoil at doses of 1070 (control, dose 1), 214 (dose 2), 642 (dose 3) and, 1070 mL (dose 4), corresponding to 1, 3 and 5 times the necessity of K (80g K₂O plants^-1) required by coffee tree in production. After CWW application, two leaching depths were applied, at 60 (sheet 1) and 75 days (sheet 2), using water and collecting leachate for further analysis of OCD, EC and soluble K, Na, Ca and Mg. After the incubation period, soil samples were collected 0-15; 15-30; 30-45 and 45-60 cm deep for electric conductivity of saturate paste extract (ECs ) and pH in water (1:2,5) determination, along with K, Na, Ca e Mg analysis. CWW application in the soil changed the chemical characteristics of pH, ECs , K and Na. In leachate, there was variation in CE, K, Na, Ca and Mg related to incubation time.