季节性冻融期不同水氮量组合下土壤水分的时空变化特征

以季节性冻融期系列田间试验资料为基础,探求不同水肥耦合下非饱和冻融土壤介质中含水率的时空变化特征。结果表明:封冻前N_0W_0含水率较灌水地块低。快速冻结阶段水分运移主要受冻结作用形成的附加基质势驱动,土壤聚墒区为20~50 cm,N_(500)W_(750)和N_(300)W_(375)处理峰值聚墒量高于其他处理。稳定冻结期土壤聚墒区范围延伸至60 cm处,含水率峰值下移至50 cm,由大到小为:N_(300)W_(750)、N_(300)W_(375)、N_(500)W_(750)、N_0W_0、N_(500)W_(375)、N_(100)W_(750)、N_(100)W_(375)。解冻后N_(300)和N_(500)地块0~60 cm土层略高于自然储水量;封冻前后表土层(0~20 cm)灌溉效应衰减随深度增加而延迟。N_(500)W_(750)和N_(300)W_(375)地块10~20 cm冻结含水峰值呈现时间比N_0W_0提前7 d。灌水后30~40 cm含水率峰值高于N_0W_0,冻结聚墒峰值出现时间随肥量的增加而缩短,消融期N_(500)W_(750)和N_(300)W_(375)处理对水分的吸持作用更强。N_(300)W_(750)和N_(300)W_(375)处理50~60 cm的含水率峰值较高,消融期增幅最为明显,分别为2.00%和0.9%。冻融期各处理土壤含水率与N_0W_0绝对关联度整体随深度增加而减小,说明水氮量组合对冻融期0~60 cm含水率时程动态的影响随深度增加而递减。

The Spatiotemporal Variation of Soil Water Content under Different Irrigation Nitrogen Modes during Seasonal Freeze thaw Period

Based on series of field test data during seasonal freezing thawing period,the spatiotemporal variation of unsaturated soil water content under water and fertilizer coupling conditions is explored.The results show that water content of N-0W-0 is low irrigation plots before freezing;in the fast freezing stage,the water movement is mainly driven by the additional matric potential formed by the freezing action,the higher moisture content area occurs at 20~50 cm depth;the peak of water content of N-{500}W-{750} and N-{300}W-{375} are higher than other treatments;the soil moisture accumulation area extends to 60cm and the moisture content peaks downs to 50 cm,the values in descending order is N-{300}W-{750},N-{300}W-{375},N-{500}W-{750},N-0W-0,N-{500}W-{375},N-{100}W-{750},N-{100}W-{375} in stably freezing phase;N-{300} and N-{500} are higher than the natural water storage of 0~60 cm in post thaw;the disappearance of irrigation effect delays as the depth increases in the epipedon;the peak of water content of N-{500}W-{750} and N-{300}W-{375} occurs 7 days earlier than N-0W-0,the water content of 30~40 cm after irrigation is higher than N-0W-0,and the occurrence time of the peak water content decreases with the increase of fertilizer amount,N-{500}W-{750} and N-{300}W-{375} enhance the soil retention capability in the ablation period;the peak water content of N-{300}W-{750}and N-{300}W-{375} at 50~60 cm depth are higher and the increase amplitude are 2.00% and 0.9%,respectively,in the ablation period.The absolute correlation degree between the treatments and N-0W-0 decreases with the increase of depth,which indicates that the effect of irrigation and fertilization treatments on the dynamic of water content of 0~60 cm also decreases with the increase of depth during freezing and thawing period.