施用PAM防治松散土风蚀的机理及其抵御风沙流能力研究

采用室内风洞试验方法,研究了内蒙古西部干旱半干旱地区荒漠沙地松散土风蚀规律、风沙流对风蚀量的影响和施用PAM防治松散土壤风蚀的机理及其抗风沙流的能力。风沙流对风蚀量的影响试验,采用试样接续放置的方法,前一试样为后一试样提供风沙流;施用PAM试样抗风沙流的能力试验,采用PAM使用量为1g/m2,2 g/m2和4 g/m2等3个处理水平和0,17.6%,36.4%,7.7%等4个吹角水平。试验结果表明,相同的风速条件下风沙流对土壤的侵蚀程度比净风侵蚀程度高得多,侵蚀量显著不同;PAM用量为1 g/m2时,在7~8m/s风速的风沙流作用下只能经历5~10 min的吹蚀试样即破坏;PAM用量为2 g/m2时可以抵御8~10 m/s风速的风沙流历时30 min的吹蚀;PAM用量达4 g/m2时,可以抵御10 m/s风速的风沙流历时30 min的吹蚀试样仍未破坏,几乎可以防止自然界99%的各级风速所引起的土壤风蚀。从经济方面考虑,推荐PAM用量为2g/m2可以防止自然界中大部分风力(约97%~99%)造成的风蚀,经济上是可行的。经PAM处理的试样破坏过程和切片分析得出,在松散土表面喷施PAM之所以能够有效地防止风蚀,最根本的原因是施用PAM溶液后松散土表面可形成较厚的结皮。

Study on Mechanism by Use of PAM to Keep From Wind Erosion of Loosing Soil and Its Capability to Withstand Wind Flow with Sand

It have been studied with wind tunnel experiments that the wind erosion rule of loosing soil on the hungriness sand land of western Inner-Mengolia,the impact of wind flow with sand on the wind erosion amount,the mechanism by use of PAM to keep from wind erosion of loosing soil and its capability to withstand wind flow with sand.The samples were taken in sequences about the impact of wind flow with sand on the wind erosion amount and anterior sample applied wind flow with sand for posterior one.The 3 levels of PAM dosage(1 g/m2,2 g/m2 and 4 g/m2) and 4 wind degrees(0,17.6%,36.4% and 57.7%) was contained in the tests for PAM sample capability to withstand wind flow with sand.The results showed that the erosion ability of wind flow with sand was much more than the ability of pure wind when the wind velocity was equal and the wind erosion amounts of them were evidently different.The samples just only withstood wind flow with sand for 5 to 10 minutes with a wind velocity of 7~8 m/s when PAM dosage was 1 g/m2.However the samples would withstand wind flow with sand for 30 minutes with a wind velocity of 8~10 m/s when PAM dosage was 2 g/m2.It would withstand wind flow with sand for more than 30 minutes with exceeding 10 m/s wind velocity when PAM dosage was 4 g/m2 and the sample almost could prevent 99% of all soil erosion caused by natural winds.The dosage of 2 g/m2 PAM was recommended normally and economically in the paper for most of wind erosion(about 97%~99%) could be prevented.The surface could form a crack when PAM solution was sprayed on loosing soils surface so that it could effectually prevent from wind erosions.