Effect of straw and plastic film mulching on warming and insulation of tea plantation in winter

Three forms of mulching (plastic film mulching, two forms of straw mulching and CK) of tea plantation were compared to learn the role of mulching in warming and insulation in winter. The continuous investigation in 23 days on the lowest and highest temperatures on the mulching materials surface and the corresponding soil surface was conducted. The lowest correlation coefficient for the lowest temperature among measuring points is 0.889 and that for the highest temperature is 0.813 - both are at 0.01 level of significance. This indicates that temperature field is highly correlated. Compared with CK, straw mulching increases the lowest temperature by 1.2 ℃, while plastic film mulching by 0.2 ℃. The insulation effect of straw mulching is more significant compared with plastic film mulching, and is independent on the straw depth in sunny days. In cloudy and rainy or snow days, insulation effect of both the straw and plastic film mulching decreases, however, the straw mulching causes less decrease which is negatively correlated with straw depth. In sunny, the plastic film mulching increases the soil surface temperature, but, in cloudy days, not significant warming effect is observed. The warming effect of straw mulching is more obvious than that of plastic film mulching, and dependent on the type of straw, which is divided into four types, dry straw in sunny day, wet straw in sunny day, dry straw in cloudy day, and wet straw in cloudy day. In summation, compared with plastic film mulching, straw mulching has a better warming and insulation effect, zero pollution and a rich origin. Straw mulching is therefore more suitable for use as a cold-resistance material in the winter.