摘要:地膜覆盖因能有效地增温保墒增产而在黄土丘陵区旱作农林生产中广泛应用。为明确不同薄膜覆盖的差异以及连续覆膜条件下的土壤水热盐变化特征，于2015年7月1日-2017年6月30日在陕北米脂进行野外连续覆膜定位观测，试验设裸地（CK）、白色薄膜（WF）与黑色薄膜（BF）3种处理，利用GS3仪器监测0~150 cm深度的土壤水分、温度和电导率。结果表明：1）连续覆盖两年后，两种覆膜处理平均土壤含水量为16.9%，CK为13.6%，土壤储水量分别达314.56 mm、204.44 mm，具体表现为土壤含水量BF在0~15 cm高于WF（P < 0.05），15~30 cm低于WF（P < 0.05）；0~150 cm，WF和BF总储水量差异不显著，与CK差异显著（P < 0.05）；在作物生育期覆膜平均较CK提高储水量60.8 mm。2）膜覆盖下近地面日温差WF大于BF，0~150 cm，两种覆膜周年土壤平均温度无显著差异，较CK高1.3℃（P < 0.05）；气温较高条件下WF比BF、CK缩短冻融时间分别达8 d和24 d，WF更有利于土壤解冻和早春土壤增温。3）周年土壤表层盐分高，其中0~30 cm土层电导率为BF > WF > CK，30~50 cm土层为WF > BF > CK，但土壤总体盐分较低，无土壤盐渍化趋势，50 cm以下3种处理盐分没有差异。综合而言，WF较BF更能提高表层土壤温度，BF较WF更能提高表层土壤水分，覆膜保墒增温，延长作物生长时间。研究成果可为黄土丘陵区旱作农业覆膜应用提供土壤水热盐调控依据，也为果园和林地常年连续覆膜提供参考。
关键词:薄膜覆盖/
水盐运移/
土壤温度/
连续覆膜/
水分恢复/
黄土丘陵区
Abstract:Plastic film mulching in agriculture is known as the "white revolution", which has played a decisive role in agriculture in semi-arid areas. With the wide application of black and white films in agro-forestry production, many scholars have focused on the studies of mechanisms and functions of film mulching. It was found that film mulching not only promote crop growth, but also accelerate soil moisture lose. However, previous studies were conducted on white mulch tests under condition of growing crops. In order to clarify the differences between black and white film mulching and the ecological benefits under continuous film mulching, the field experiment of continuous film mulching without crop were conducted in Mizhi, northern Shaanxi, from July 1st, 2015 to June 30th, 2017. The experiment included three treatments, white film mulching of ridge (WF), black film of ridge (BF) mulching and no mulching of ridge (CK). In the experiment, the ridge was 50 cm wide, 20 cm high with 20 cm wide furrow. Each treatment was repeated three times and soil moisture, temperature, and electrical conductivity were measured at depths of 5 cm, 15 cm, 30 cm, 50 cm, 75 cm, 100 cm, 125 cm and 150 cm using GS3 instrument. The results indicated that:1) after two consecutive years of film mulching, soil moisture contents under two film mulching treatments and CK were 16.9% in average and 13.6%, and soil water storage capacity were 314.56 mm and 204.44 mm. Soil moisture content under BF was higher at 0-15 cm (P < 0.05) and lower at 15-30 cm (P < 0.05) than that of WF. At 0-150 cm, the total water storage of WF and BF was not significantly different, but significantly different from that of CK (P < 0.05). During the crop growth period, the average soil water storage with film mulching was 60.8 mm higher than that of CK. The daily temperature difference near soil surface under WF was greater than that under BF. At 0-150 cm, there was no significant difference in the average soil temperature between WF and BF in two years, which was 1.3℃ higher than that of CK (P < 0.05). At higher temperatures, WF decreased the freeze-thaw time by 8 days and 24 days compared with BF and CK, respectively, which was more conducive for soil thawing and soil warming in early spring. Annual soil salt content was higher in shallow soil, and was in the order of BF > WF > CK at 0-30 cm soil layer, WF > BF > CK at 30-50 cm soil layer. The results also revealed that soil salt content was low and no difference among treatments below 50 cm depth. No salinization of soil was observed under CK, BF and WF treatments. Overall, WF was more beneficial for improving surface soil temperature than BF, but it was the opposite for soil water moisture. Film mulching may increase soil temperature and prolong crop growth time. The research results could provide a basis for reasonable soil water-heat-salt regulation by film mulching in semi-arid Loess Hilly Region, and also provide a reference for the continuous film mulching technique in orchard and woodland.
Key words:Film mulching/
Water-salt movement/
Soil temperature/
Continuous film mulching/
Water recovery/
Loess Hilly Region
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