Discussion on Afforestaion Techniques in Salt-Alkaline Soil in Northern Ningxia

Abstract

based on the investigation of afforestation project in 2007 in Pingluo city of Ningxa province, this paper analyzed the change of salt concentration of soil and the planting survival rate, and then proposed the afforestation techniques system for saline-alkaline soil in northern Ningxia. The result showed that: (1) Under application of organic fertilizer and irrigation water to reduce salt concentration in the soil, the salt concentration of the soil depths of 10 cm to 30 cm and 30 cm to 50 cm were (1.37 g/l), and the planting surviving rates for Tamarix chinensis, Amorpha fruticosa, Elaeagnus angustifolia, and Populus euphratica were 75%, 75.4%, 96.8% and 92.6% respectively. But with the film covering on the bottom of the planting hole and irrigating water to reducing salt, the salt concentrations for the two soil depths were all 1.28g/l, and the planting surviving rate of D was only 11.4%. (2) Under elevating the planting surface and increasing the soil depth by 80 cm to 100 cm with the soil from trench, and application of organic fertilizer and irrigation water to reducing salt, the salt concentrations for two depth layers were around 0.36g/l, and the planting surviving rates of Elaeagnus angustifolia, Sophora japonica, Tamarix chinensis, and Amorpha fruticosa were 84/1%, 91.1％, 99.5%, and 82.5% respectively. But when soil depth was increased by 40cm to 60cm, the salt concentrations were between 0.65g/l to 0.71g/l, and the planting surviving rates for Amorpha fruticosa, Tamarix chinensis, Elaeagnus angustifolia, Sophora japonica, Euonymus bungeanus were 81.2%, 64.3%, 93.6%, 83.8%, and 100% respectively. (3) Afforestation is a kind of systemic project, if planting is based on selecting some salt resistance tree species such as Amorpha fruticosa, Tamarix chinensis, Elaeagnus angustifolia, Populus euphratica, Atriplex canescens, Nitraria sibirica, Hippophae rhamnoides, Lycium chinense, Sophora japonica, Euonymus bungeanus etc. with the techniques of elevating the planting surface and increasing the soil depth, covering film on the bottom of planting hole, ground surface covering and seedling treatment with chemicals, and application of organic fertilizer, soil amending chemicals and irrigation water to reduce salt, the planting survival rates will be increased in salt-alkaline soil in northern Ningxia.