Short-term effect of heavy precipitation on nutrient leaching from arable sandy loam soil amended with fertiliser and biochar

Abstract

The purpose of this study was to assess the effect of biochar application on the leaching of the main nutrients from the topsoil of the arable sandy loam soil (Albic Luvisol) of North-Western Russia after application of mineral fertiliser in the conditions of heavy precipitation. A short-term laboratory experiment included 6 treatments: (1) without fertiliser and biochar (control), (2–3) soil + biochar (10 and 20 t ha-1), (4) soil + fertiliser, and (5–6) soil + biochar (10 and 20 t ha-1) + fertiliser. During the experiment, the soil in the cylinders was watered three times with high rates (345 cm3) of distilled water, corresponding to the maximum amount of daily precipitation (44 mm) observed in the natural conditions of the area. The leachate was collected (on the 1st, 2nd and 5th day of the experiment) and tested for pHH2O, available nitrogen (N-NO3 −, N-NH4 +), phosphorus (P2O5) and potassium (K2O). At the end of the experiment, separate soil samples were formed of the upper 8-cm and lower 4-cm soil layers in the cylinders. The pHH2O values, concentrations of N-NO3 −, N-NH4 +, P2O5 and K2O were determined in the samples. The results showed that the effect of biochar on the movement and accumulation of the main available nutrients in the soil after fertiliser application and under the effect of heavy precipitation was more pronounced at the higher biochar application rate of 20 t ha-1. Biochar application reduced the acidity of the leachate and the soil not only in the layer, where the biochar had been applied, but also in the lower layer affected by the leachate. Available NNH4 +, P2O5, and K2O were retained in the soil through biochar application for a short period of time, while N-NO3 − leaching was not affected. Overall, biochar can be used as a soil ameliorant, as even a short delay in the nutrient leaching is potentially beneficial to nutrient utilization of crops.