河套灌区覆盖对盐渍土壤养分迁移与分布的影响

Effect of Mulching on Transfer and Distribution of Salinizated Soil Nutrient in Hetao Irrigation District

在河套灌区对盐渍土壤覆盖后进行秋浇田间试验,研究不同覆盖下秋浇、冻融及玉米生育期3个阶段的土壤养分含量变化规律。试验设7个处理,分别为秸秆覆盖量1.2(F1.2)、0.9(F0.9)、0.6(F0.6)、0.3 kg/m2(F0.3)、玉米整秆覆盖(YZ)、地膜覆盖(DM)、未覆盖(CK)。结果表明,秋浇后地下水位较高,秋浇至冻融期间土壤水分与地下水具有补排关系,土壤养分的转化、迁移同时发生,秋浇后至冻融期内土壤养分的变化规律复杂;地表覆盖改变了土壤的水土环境,不同处理间养分含量存在差异,在试验期内全效养分的变化幅度较小,速效养分变化幅度较大;分析玉米播前耕层土壤供肥能力,秸秆覆盖处理的全氮、全磷含量小但供应强度大,春播时需补充氮肥、磷肥,以保证作物的生长。秸秆覆盖处理的全钾含量与钾素供应强度均高于CK,与CK相比较,秸秆覆盖使耕层土壤较好地满足了玉米播种及后续生长过程中的钾肥需求;相同施肥条件下,经过一年试验后,对于土壤耕层,处理DM的全氮含量较试验前降低了0.10 g/kg,其余处理变化幅度较小。各处理的全磷含量较试验前增加。处理CK、DM的全钾含量较试验前增加,处理F1.2、F0.9降低了全钾含量。处理YZ、F1.2和DM的碱解氮含量升高,其余处理则降低。各处理的速效钾、速效磷含量均较试验前升高。处理F1.2、F0.9和CK的有机质含量较试验前增加,其余处理则降低。

Field scale autumn irrigation experiments were conducted on the salinity soil in Hetao Irrigation District to study the variation of soil nutrient in autumn irrigation,freeze thawing and growth periods of maize with different mulching approaches. Seven treatments were contained as follows： mixed chopped maize straw mulching amount of 1. 2（ F1. 2）,0. 9（ F0. 9）,0. 6（ F0. 6） and 0. 3 kg / m2（ F0. 3）,as well as the whole maize straw（ YZ） mulching,plastic film（ DM） mulching,and no mulching（ CK）. Results showed that water table was high after autumn irrigation,soil water had a recharge and discharge relationship with groundwater during the autumn irrigation and freeze-thawing periods. The transfer and migration of soil nutrient occurred simultaneously. The changing law of soil nutrient was complex during the autumn irrigation and freeze-thawing periods. The soil surface mulching altered the water-soil environment of soil. The nutrient content had differences between treatments. The rangeability of whole effect nutrient was small during the experiment period. But the rangeability of available nutrient was large. Analyzing the feeder capability of surface soil before seeding stage of maize,it was showed that the treatment of straw mulching had small soil total N content but got huge supply intensity. It required nitrogen when the spring sowing happened. The treatment of straw mulching had small soil total P content but owned huge supply intensity. It needed phosphorus fertilizer for the spring sowing,which could ensure the growth of crops. Generally,the soil total K content and the potassium supply intensity of straw mulching treatments were higher than those of CK. Compared with CK,straw mulching made the surface soil be capable of satisfying the potassium fertilizer demand during the growth period. After the experiment period,the whole soil N content of DM in surface soil was decreased by0. 10 g / kg under the same fertilizer condition. The rangeability of other treatments was small. The soil total P content of each treatment was increased after experiment,and the soil total K contents of CK and DM were also increased,but the soil total K contents of F1. 2 and F0. 9 were decreased. The available N contents of YZ,F1. 2 and DM were increased. The available K and P contents for each treatment were increased after experiment. The soil organic matter contents of F1. 2,F0. 9 and CK were increased after experiment,however,it was decreased for other treatments.