Influence of organic mulches and different thickness of mulch layer on soil properties

Mulching has become increasingly common during recent decades not only in commercial horticulture. Mulching is especially important in organic farming. An organic mulch on the surface of the soil usually intercepts solar radiation, reduces soil temperature, maintains soil moisture at higher levels than bare soil, reduces losses of nitrate, sulfate, calcium, magnesium, potassium, increases soil organic C and nutrientes content, microbial biomass. A two–factor field experiment was carried out in the Pomological Garden of Lithuanian University of Agriculture in 2004–2007. The soil type – Calc(ar)i-Endohypogleyic Luvisol. Scheme of the experiment: Factor A – mulches: 1) without mulching; 2) chopped wheat straw; 3) peat; 4) sawdust; 5) grass. Factor B – thickness of mulch layer: 1) 5 cm; 2) 10 cm. The aim of this investigation was to evaluate the effect of different mulches and different thickness of mulch layer on soil properties. All examined mulches reduced soil temperature. The tendency of lower soil temperature in plots covered with 10 cm thickness mulch layer compared with plots covered with 5 cm thickness mulch layer was established. Soil moisture in mulched plots was established significantly better in comparison with soil moisture in plots without mulch. Higher soil moisture was evaluated in plots mulched with 10 cm thickness mulch layer compared with plots covered with 5 cm thickness mulch layer. All mulches increased the amount of available potassium and phosphorus in the soil. Grass mulch had the biggest positive effect on available potassium and available phosphorus in the soil. Thicker mulch layer increased content of available potassium, but decreased content of available phosphorus in the soilVytauto Didžiojo universitetasŽemės ūkio akademij