Effects of organic mulching on moisture and temperature of soil in greenhouse production of tomato under unheated greenhouse cultivation in the cold zone of China

In the cold zone of China, winter is cold and long and has a short duration of sunshine. Unheated earthen‐wall solar greenhouses are used for tomato production in winter in this region. This was an experimental investigation of different organic mulching materials (newspaper, bran, and grass) on the soil temperature, soil moisture, tomato yield, fruit quality, and water use efficiency. Organic mulching variously improved soil temperature, soil moisture, water use efficiency, and tomato yield, which is very important for greenhouse winter cultivation in this cold zone. Organic mulching regulated the soil temperature, with daily soil temperature ranges of bran, newspaper, and grass treatments being 1.6, 1.9, and 2.1°C lower than for bare land, respectively. Compared to bare land, newspaper mulching had little effect on soil temperature and fruit quality, but increased soil moisture (14.1%) and water use efficiency (WUE: WUE( b ), 31.3%; WUE( y ), 30.6%), and greatly increased yield (81.8%) and biomass (82.7%); bran mulching greatly increased soil temperature, moisture (16%), and WUE (WUE( b ), 60.1%; WUE( y ), 44.3%) and increased biomass (30.2%) and yield (17.3%); grass mulching greatly increased soil temperature and moisture (20.9%) and increased biomass (17.9%), yield (11.2%), and WUE (WUE( b ), 20.5%; WUE( y ), 13.6%). In addition, organic mulching had a good water retention effect on soil layer above 30 cm. The total soil water consumption during tomato growth was in the following order: newspaper (103 mm) > bare (74 mm) > grass (73 mm) > bran (60 mm). Soil water consumption mainly occurred in the 0‐ to 10‐cm soil layers.