覆盖对盐渍土壤冻融特性与秋浇灌水质量的影响

Effect of Mulching on Salinized Soil Freezing and Thawing Characteristics and Autumn Irrigation Quality

在河套灌区进行不同覆盖措施秋浇田间冻融试验,研究其对盐渍土壤冻融特性及秋浇灌水质量的影响,试验设5个处理,分别为秸秆覆盖量0.9kg/m2（F0.9）、秸秆覆盖量0.6kg/m2（F0.6）、玉米整秆覆盖（YZ）、地膜覆盖（DM）、未覆盖（CK）。研究表明：覆盖秋浇后,不同地面覆盖的输热能力对地层的热响应有着不同的影响,不同覆盖影响了土壤冻结融化推进过程,改变了土壤冻结深度对气温负积温的响应关系,通过初步确定冻结期冻土深度与负积温变化的定量关系,可用气温负积温来判断和预测冻结期内土壤冻结深度的变化。从冻融期结束后春玉米播期的土壤水、盐、热3方面综合考虑不同地面覆盖对秋浇灌水质量的影响,各覆盖处理均较CK显著提高了春玉米播期0～10、0～40和0～120cm的土壤储水量,但覆盖使得土层0～20cm土壤含水率偏高,不利于春玉米播种及出苗。覆盖处理均较CK显著降低了表层0～10cm及耕层0～40cm土壤含盐量,整秆覆盖YZ的控盐效果最好。地膜覆盖下春玉米的适宜播期较CK提前了7d,而秸秆覆盖较CK延后了6～7d。覆盖措施显著提高了玉米的出苗率,处理YZ与F0.9出苗率显著高于F0.6和DM。

The objective of this paper is to discuss the effects of mulching methods on freezing and thawing characteristics of salinized soil and the autumn irrigation quality in cold - drought - salt irrigation district. The field freezing and thawing experiments were conducted with the mulched salinized soil in Hetao Irrigation District. The experiments included five treatments： chopped maize straw 0.9 kg/m2 （ F0.9 ） , chopped maize straw 0.6 kg/m2 （F0.6） , whole maize straw （YZ） , plastic film （DM） and no mulching （CK）. The results showed that the heat transport capability of different soil layers was affected by surface mulching after ＇autumn irrigation. Mulching affected the process of soil freezing and thawing and changed the response correlation of the soil frozen depth to the negative accumulated temperature. The soil frozen depth variability during the freezing period can be assessed and predicted by the available negative cumulative air temperature. Results revealed that all mulching treatments improved the soil water storage in the maize sowing time for following year at depth of 0 - 10, 0 ～ 40 and 0 - 120 cm significantly compared with CK. The soil salinity in the surface layer （0 - 10 cm） and plough layer （0 ～40 cm） was drastically lower than that of CK. The salt control effect of whole maize straw YZ was superior to the other treatments. The suitable sowing date of spring maize under plastic film mulching was advanced by 7 d relative to CK, while the straw mulched date was delayed by 6 -7 d. Mulching measures improved the maize seedling emergence rate significantly, the emergence rate of maize of YZ and F0.9 were considerably higher than F0.6 and DM. The results could be used to guide the research of autumn irrigation scheduling under mulching situations in Hetao Irrigation District.