BIOCHAR USE IN THE NITROGEN BALANCE IN ALUVIAL SOILS OF SAN RAMON / CHANCHAMAYO / PERU

Abstract

In the last decades, the intensive use of nitrogen fertilizers in annual and perennial crops has increased in Peru. These fertilizers are quickly available to plants by converting to nitrates, increasing crop yields. However, nitrogen fertilizers are very volatile and are also lost easily by leaching. This lost nitrogen (N) implies economic costs and leads to environmental problems such as eutrophication. Biochar, a new soil amendment, has been suggested as a solution to these problems; however, there has been little research on the subject in Peru. The objective of this study was to evaluate the effect of biochar application on corn yield and nitrogen balance in soils (Entisols with alluvial deposition) in San Ramon (Peru). Biochar was produced from green waste and pig manure. The research design considered five treatments: Control (T1), 7 t·ha^-1 of pig manure (T2), 17.5 t·ha^-1 of biochar (T3), 23 t·ha^-1 of biochar with pH adjustment (T4), and 17.5 t·ha^-1 of biochar with pH and C/N ratio adjustment (T5). The results showed that treatments T1 and T2 obtained the lowest corn yields, with an average production of 0.41 t·ha^-1 and 2.45 t·ha^-1, respectively. Treatment T5 produced the highest corn yield, reaching a production of 5.71 t·ha^-1. A significant difference was only found in the yield of treatments T1 and T5 (p = 0.011). Nitrogen use efficiency percentages (NUE), defined as the percentage of applied N that was available to be absorbed by the crop or retained in the soil, were higher for treatments T3, T4, and T5 with 28, 28, and 56% efficiency, respectively, in comparison to treatments T1 and T2. Likewise, biochar treatments T3, T4, and T5 produced lower nitrogen losses compared to treatments T1 and T2. This research concluded that biochar-based amendments have positive effects on corn crop yield while limiting nitrogen loss.