Effect of Sand Mulches of Different Particle Sizes on Soil Evaporation during the Freeze–Thaw Period

Huijun Feng,Yongxin Xu,Xiuqing Zheng,Junfeng Chen,Chunyan Miao,Qi Du,Jing Xue

doi:10.3390/w10050536

Huijun Feng, Yongxin Xu + Show 5 more

Open Access

https://doi.org/10.3390/w10050536

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Abstract

Reducing ineffective evaporation is a feasible means to improve water use efficiency in agriculture, especially in arid and semi-arid areas. A field experiment assessed the impact of sand mulches (1-cm thickness) with a particle size of 0.5–1.5 mm (XS) and 1.5–2.0 mm (CS) on soil evaporation during winter in Northern China. Results showed that CS and XS increased by at least 11.93% and 14.92% compared to bare soil (LD), respectively. However, the sand mulches showed significant distinctions in soil evaporation at different stages. Soil evaporation was the highest in LD, while CS evaporated the least in the unstable freezing stage (P1) and stable freezing stage (P2); in the thawing stage (P3), XS evaporated the most, while LD evaporated the least. Ten factors affecting evaporation were analyzed using the principal component analysis method to elaborate the mechanisms of soil evaporation. Mean soil moisture at depths from 0 to 15 cm was a factor that affected the evaporation of XS and CS in the test. Soil moisture was evaporated by vapor when the frost penetration was dense and the frost impeded the vapor movement. The evaporation rates were steady and weak in this period, and soil moisture had slight impact on soil evaporation, especially XS and CS treatment with higher water content at the surface. The research is significant for preventing evaporation and the improvement of water-use efficiency.

Highlights

Frozen soil is primarily distributed in the arid and semi-arid areas, at the northern latitude above 30◦, where most precipitation is lost by evaporation, especially in the Loess Plateau, China [1,2,3]
Most experiments were conducted in the non-freeze period without freezing and thawing cycles, and few studies have assessed soil evaporation during the freeze–thaw period with sand mulches
The results indicate that sand mulches with particle sizes of 0.5–1.5 mm and 1.5–2.0 mm were able to prevent soil evaporation in P2, and relatively coarse particle sizes were more effective

Summary

Introduction

Frozen soil is primarily distributed in the arid and semi-arid areas, at the northern latitude above 30◦ , where most precipitation is lost by evaporation, especially in the Loess Plateau, China [1,2,3]. The mean precipitation on the Plateau is only 388.9 mm, while the annual surface evaporation capacity is up to 1500–2000 mm [4,5]. Reducing soil evaporation to improve water-use efficiency is one of the best available means to alleviate the severe water scarcity for agriculture. Covering surfaces with mulches can prevent soil evaporation, adjust the soil temperature, and alleviate soil salinization to some extent [15,16]. Most experiments were conducted in the non-freeze period without freezing and thawing cycles, and few studies have assessed soil evaporation during the freeze–thaw period with sand mulches

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