Leaching of soil organic carbon and nutrients in organic farming

Abstract

Organic farming (OF) could decrease the leaching of nutrients and protect the content of soil organic carbon (SOC). However, a lack of the OF data comparison with the data obtained in the adjacent forests has been observed. The aim of this study was to compare the leaching of SOC and plant nutrients in Luvisols in OF and Scots pine stands (ecological control). This study was carried out at the end of a long-term (2006-2017) ecological crop rotation (ECR) in the plots of the OF at the Perloja Experimental Station of LAMMC and adjacent Scots pine stands. It was found that the SOC content did not essentially differ in the examined OF and forest sites. However, in ECR, in comparison with Scots pine stands, the ploughed Ap horizon was significantly less acidic and contained more plant nutrients. According to the amount and chemical composition of soil water collected at the depth of 40 cm in zero-tension lysimeters, it was calculated that the leaching of nitrate + nitrite nitrogen (NO3-N + NO2-N), potassium (K+) and calcium (Ca2+) cations was more intensive in the cropping plots of the OF. Thus, the leaching of dissolved organic carbon (DOC) in Scots pine stands was from 30-40% to 2-3-fold higher than in the OF. In comparison with forests, long-term OF has increased the leaching of nutrients. Due to the mineralisation of the forest floor, the DOC leaching is more intensive in forest stands.