| In order to analyse the influence of full plastic film mulching over double ridges and sowing on soil temperature,three similar plots were set up according to annual precipitation and average annual accumulated temperature in the regions below 1 700 m altitude on the dry plateau of Longdong.Using maize as planting object,five different experiments were made,such as full plastic film mulching on double ridges and sowing in catchment furrows in fall,in early spring,before sowing,half flat-mulching and non-mulching,and the temperature in each treatment in five different soil layers(surface, 5 cm,10 cm,15 cm,20 cm) was measured separately.The results show that soil temperature and effective accumulated temperature in different soil depths at each growth period follows the principles: 1) full mulching on double ridges in fall and sowing in catchment furrows > 2) full mulching on double ridges and sowing in catchment furrows in early spring > 3) full mulching on double ridges before sowing in catchment furrows > 4) half flat-mulching > 5) non-mulching.In the regions below 1700m altitude,almost all mulching approaches mentioned above,except non-mulching,could provide accumulated temperature needed for the normal growth of maize. |