暗管条件下牧草种植对农牧交错区盐渍土的改土效应

Effect of Forage Planting on Improvement of Saline Soil under Subsurface Pipe in Agro-pastoral Intertwined Zones

摘要:

为探究农牧交错区暗管条件下种植耐盐牧草对改良盐渍土的效应，在河套灌区红卫试验基地开展为期2年的种植不同牧草田间试验。试验设置暗管条件下种植苜蓿（TM）、甜高粱（TB）、苏丹草（TS）和无牧草（T），以空白地为对照（CK），共5种处理。结果表明，2年种植苜蓿（TM处理）0~60 cm土层平均容重最小，为1.416 g/cm3，较CK下降9.4%（P<0.05）；相比对照处理，暗管条件下种植牧草可显著提高盐渍土壤孔隙度，增幅为10.3%~24.3%（P<0.05），2年试验后苜蓿孔隙度最高，为51.6%；各处理土壤有机质（SOM）含量随土层深度增加而减少，T处理0~60 cm土层有机质流失严重，2年试验期平均降低20.3%（P<0.05），而暗管+牧草处理可有效缓解SOM流失，TM处理效果较佳，2年SOM含量平均提高5.0%（P<0.05）。2021年暗管条件下牧草鲜质量较2020年提高24.6%~49.2%（P<0.05），TM处理增产效果最大，为49.2%。综上，暗管条件下种植苜蓿改良盐渍土壤效果较佳，可实现河套灌区盐渍土结构改善与SOM含量提高，达到提高牧草产量的目标，可为农牧交错区实施暗管工程+生物改良盐渍土提供理论基础与技术支撑。

Abstract:

To explore the effects of planting salt-tolerant forage grass varieties on improving saline soil under the subsurface pipe in agro-pastoral intertwined zones, field experiments were carried out in Hongwei Experimental Base of Hetao Irrigation District in 2020 and 2021. The experiment consisted of five different treatments. It included Medicago sativa (TM treatment), Sorghum bicolor (TB treatment), Sorghum sudanense (TS treatment) and vacant land (T treatment), and the blank plot as the control (CK treatment). The results showed that the average bulk density of TM treatment was 1.416 g/cm3 in 0~60 cm soil layer in two years, which was decreased by 9.4% compared with that of CK treatment (P<0.05). It improved the salinity soil porosity under subsurface pipe for planting the three kinds of forage grass. The average porosity of 0~60 cm soil layer was increased by 10.3%~24.3% (P<0.05). And Medicago sativa treatment was the highest, 51.6%, after two years of experiment. The content of soil organic matter (SOM) in each treatment was gradually decreased with the increase of soil depth. The loss of organic matter in 0~60 cm soil layer treated by tube T alone was serious, and the average loss in two years was reduced by 20.3% (P<0.05). However, planting forage grass under subsurface pipe could effectively alleviate the loss of SOM. The treatment effect of Medicago sativa (TM treatment) was better, and the average organic matter content in soil layer was increased by 5.0% (P<0.05). The biomass fresh weight of three forage species under subsurface pipe was increased by 24.6%~49.2% in 2021 compared with that in 2020 (P<0.05). Medicago sativa had better effect on increasing fresh production. In conclusion, it had better effect on improving the saline soil under subsurface pipe for planting Medicago sativa (TM treatment). It improved the physical and chemical properties of saline soil and increased the content of SOM. It also achieved the objective of improving forage yield. The research result can provide theoretical basis and technical support for the implementation of subsurface pipe project and biological improvement of saline soil in Hetao Irrigation District.