Risk of nitrogen losses from cultivated soils: effect of biochar amendment


1Department of Science of Agriculture, Food and Environment, University of Foggia, Via Napoli, 25-71122, Foggia, Italy.

2Department of Agro-Environment and Ecology, Faculty of Agriculture and Environment, Agriculture University of Tirana, St. “Pajsi Vodica”, Kodër-Kamëz, Tirana, Albania.

*Corresponding author  e-mail: angela.libutti@unifg.it        

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Field experiments were carried out in Southern Italy (Apulia Region) to evaluate the effect of biochar amendment on nitrogen (N) potential losses from the soil. Three vegetable crops were grown in close succession on a clay loam soil: chicory (Chicorium intybus, L.), processing tomato (Lycopersicon esculentum, L.) and lettuce (Lactuca sativa, L.). N fertilization was performed according to the local standard practices. Biochar obtained from wood chips was mixed within the upper 0.20 m soil layer. Seven treatments were compared: B0, no biochar addition (control); B10, and B20, a single and a double biochar dose (10 and 20 t ha-1, respectively), both applied only once; B10+ and B20+, similar to the previous treatments but with biochar applied twice; B0-N1/2 and B20-N1/2, like B0, and B20, respectively, but providing half of the N supply. The apparent soil N balance was estimated considering the topsoil (0.20 m). N balance was affected by N fertilization and biochar application. When N fertilization rate was halved (N1/2), the  apparent deficit was significantly reduced, particularly in tomato (119 kg ha-1 of N), but also in chicory and lettuce crops (55 and 64 kg ha-1 of N, respectively). Similarly, biochar application (both B10 and B20) significantly reduced  apparent deficit in the three crops, as compared to B0. Considering the highest biochar rate (B20), again a higher effect was detected in tomato (84 kg ha-1 of N), than in chicory and lettuce crops (39 and 41 kg ha-1 of N, respectively). The experimental outcomes showed that biochar application to cultivated soils could be an effective option in mitigating N losses, particularly in highly risky conditions of unbalanced N supply.

Keywords: biochar, N fertilization, N uptake, soil N balance, soil N loss, vegetable crops.




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