河西畦田春小麦不同生育期灌水对土壤水氮空间分布的影响

试验采用规格为30m×3m条田,分别沿畦长中心位置布设了5个测点(每个测点距畦首依次为3、9、15、21、27 m)用于定点测定不同生育期春小麦0~100 cm土层深度内灌前2 d和灌后2 d土壤含水量和硝态氮的含量,评价了土壤水氮空间分布的变异性、土壤水氮贮存效率和土壤水氮沿畦长空间分布均匀性。结果表明:不同生育期内不同处理间灌前2 d和灌后2 d土壤水分空间分布均为中等变异性,灌后2 d的变差系数小于灌前2 d的变差系数;土壤硝态氮空间分布状况除拔节期灌前2 d灌水量90mm和灌水量60mm为强变异性外其余均为中等变异性;不同生育期灌水对不同处理间的土壤水贮存效率无显著影响,成熟期春小麦不灌水处理的土壤水贮存率明显低于灌水处理;不同生育期灌水对不同处理间土壤硝态氮贮存率有显著影响,其中成熟期不灌水处理能使土壤硝态氮的贮存率增加,灌水减少了根系层内土壤硝态氮的贮存率;不同生育期灌水对不同处理间土壤水分和土壤硝态氮含量沿畦长的空间分布均匀性均无显著影响,其中成熟期不灌水处理对土壤水分沿畦长的空间分布均匀性的影响显著小于成熟期灌水处理,而对土壤硝态氮的空间分布均匀性无显著影响。

Effect of irrigation at different growth stages on soil water and nitrogen spatial distribution in Hexi spring wheat border field

The experimental study on spatial distribution and uniformity of soil water and nitrogen was conducted in Hexi spring wheat border field from April to July 2011.Border irrigation,30 m×3 m,was designed and five points along border length center used for fixed observation were arranged in parts respectively 3 m,9 m, 15 m,21 m and 27 m from the head of border.The contents of soil water and nitrate 2 d before and after irrigation were investigated in 0～100 cm soil depths. Meanwhile the spatial variabilities,the storage efficiency in the crop root zone and the uniformity along basin length for soil water and nitrate were evaluated.The results show that,spatial variabilities of the soil water content 2 d before and after irrigation in all treatments at different growing stages are medium.The value of coefficient of variation 2 d before irrigation are higher than that 2 d after irrigation.The spatial variabilities of the soil nitrate(NO3-N) content 2 d before and after irrigation are also medium except those in the treatments of irrigation water consumption of 90 mm and 60 mm at jointing stage are strong.The soil water storage efficiency are not significantly different at various growing stages.There is significant difference between no irrigation and irrigation at mature stage.While the soil nitrate content storage efficiency is significantly different and increases under no irrigation and adverse under irrigation at mature stage.For the uniformity of soil water and nitrate along basin length,the results show no significant difference among all irrigation treatments at different stages.The uniformity of soil water in no irrigation treatment is significantly lower than that in irrigation treatment at mature stage,while the uniformity of soil nitrate has no significant difference in the two treatments at the same stage.