Effect of organic mulches on the content of organic carbon in the soil.

Natural organic mulch eventually breaks down and adds organic material to the soil. The increase of the amount of soil organic carbon (SOC) is regarded as the main advantage of organic mulches. The aim of our investigation was to evaluate the effect of different organic mulches and different thicknesses of the mulch layer on the content of SOC. The field experiment was carried out in the Pomological Garden of Aleksandras Stulginskis University (54°53'N, 23°50'E) in a certified organic field. The soil was Calc(ar)i-Endohypogleyic Luvisol. The following treatments were applied: factor A - mulch: (1) without mulch, (2) straw, (3) peat, (4) sawdust, and (5) grass. Factor B - thickness of mulch layer: (1) 5 cm and (2) 10 cm. The influence of organic mulches was investigated in 2004-2009 and their residual effect in 2010-2011. In the article the data of 2008-2011 are presented. A higher content of SOC was established in all mulched experimental plots compared with the unmulched plots. A significant influence of peat mulch was observed during the whole period reported. Sawdust mulch significantly increased the content of SOC (2008-2009) but its residual effect (2010-2011) was not significant. The influence of straw mulch on the content of SOC was significant only in 2009. The thicker (10 cm) mulch layer significantly (by 0.35-0.52 percentage points) incresed the content of SOC compared with the thinner (5 cm) layer. A very strong positive linear correlation (r = 0.994, P ≤ 0.01) between the amount of organic C carried into the soil with mulch and the content of organic C in the soil was established. [ABSTRACT FROM AUTHOR]

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