垄作免耕影响冷浸田水稻产量及土壤温度和团聚体分布

Influences of combing ridge and no-tillage on rice yield and soil temperature and distribution of aggregate in cold waterlogged field

研究垄作免耕对冷浸田水稻产量及其构成因子的影响，同时，观察其耕层土壤温度和土壤团聚体结构的变化，旨在为冷浸田的综合治理技术提供科学依据。该研究以湖北省冷泉烂泥型冷浸田为对象，采用垄作免耕栽培田间定位试验方法，设计垄高10（LG10）、15（LG15）、20 cm（LG20）和平作（CK）4个处理种植中稻。研究结果表明，起垄（垄高10和15 cm）能显著（P〈0.05）提高冷浸田水稻产量，2011年和2012年垄高15 cm较CK分别增产10.95%和18.51%；与CK处理相比，垄作土壤平均增温范围为0.4～1.2℃，在0～5 cm土层内，垄作处理的土壤大团聚体（〉1 mm）含量明显提高；在〉5～25 cm土层内，土壤大团聚体含量LG15最高、CK最低、而LG20和LG10处于两者之间。垄高15 cm对大团聚体形成的影响大于垄高10和20 cm。垄作对冷浸田表层（0～5 cm）和下层（〉5～25 cm）土壤团聚体形成的影响存在差异，起垄后表层土壤大团聚体数量高于下层。但是，不同起垄高度与土壤温度和土壤大团聚体的变化不存在对应的数学正相关。综上所述，冷浸田合适的免耕起垄高度为15 cm。

Cold waterlogged paddy field refers to the paddy field submerged under water for extensive period of time in a year. It has the characteristics of“cold in temperature, slush in tillage, rich in plant toxicants, and low in productivity”. There are 267 to 400 million hectares of the cold-waterlogged field in China, accounting for 15.07%of the total paddy field area and 44.20%of low-yield paddy field area. Since the waterlogged paddy field has such a large acreage it has become a focus of study in order to make full use of it by increasing rice production. This study aimed to apply ridges and no-tillage together to improve cold spring mud type of cold waterlogged paddy field for rice production in field experiment in 2011 and 2012. Rice was planted by using techniques of conventional till and no till combined with ridging with heights of 10 （LG10）, 15 （LG15） and 20 cm （LG20）. Soil temperature was monitored throughout the growing season. Rice yields and its component were measured and aggregate distribution was determined from soil samples taken at 0-20 cm depth at the end of the experiment. The results showed that the ridge culture could increase rice yield markedly in cold water-logged paddy field. The rice yield in the LG15 treatment was 10.95%and 18.51%higher （P1 mm） in the ridging treatments increased greatly in 0-5 cm depth, but highest in LG15 and lowest in conventional till treatment in 5-25 cm. Effect of ridging on soil aggregate distribution on formation of soil aggregate was obvious in 0-5 cm than 5-25 cm. After ridging, the content of large soil aggregate at 0-5 cm soil depth was higher than that at 5-25 cm. However, there was no positive correlation between ridge height and soil temperature and large soil aggregate. In summary, the ridge height under no-tillage of the cold water-logged paddy field was best at 15 cm for rice production.