不同深蓄储水灌溉量对冬小麦磷素利用和磷素下渗流失风险的影响

庞耀悦; 胡笑涛; 王芳; 查晴; 范晓懂; 王文娥

doi:10.11674/zwyf.2023424

不同深蓄储水灌溉量对冬小麦磷素利用和磷素下渗流失风险的影响

Effect of deep storage water irrigation amount on the phosphorus utilization of winter wheat and loss risk down to deep soil

摘要

摘要:
目的汛前储水灌溉是陕西关中地区雨洪资源高效利用的重要方式。研究不同深蓄储水灌溉量对农田土壤磷素利用、累积与流失状况的影响，以实现农田的“高”磷吸收和“低”磷淋溶。
方法在陕西宝鸡峡灌区进行了小麦田间试验，供试小麦品种为“小偃22”。设置储水灌溉量0、80、120、140、160和180 cm 6个处理，分别记为CK、D80、D120、D140、D160、D180。在小麦拔节期、开花期、成熟期，测定冬小麦植株各营养器官生物量、磷素含量及农田0—200 cm土层土壤速效磷含量，计算冬小麦吸磷量、磷肥利用效率和磷素盈亏。
结果与CK处理相比，D80、D120、D140、D160、D180处理冬小麦产量分别提高了8.85%、24.71%、30.99%、17.91%、9.90%，成熟期籽粒磷素积累量分别提高了37.55%、46.34%、38.09%、28.23%、22.11%，小麦植株磷素吸收效率分别增加10.10%、12.47%、10.25%、7.59%、5.95%，有效磷表观盈余量分别降低了13.82%、17.05%、14.02%、10.39%、8.13%。随着储水灌溉量的增加，成熟期小麦植株磷素累积量呈先增加后降低的趋势，以D120处理磷素积累量最高，显著高于D160、D180处理，因此其磷素表观盈余量最低(79.83 kg/hm²)，显著低于D160、D180处理。D80和D120处理促进了小麦花前磷素转运和花后磷素同化，且成熟期0—200 cm土层速效磷浓度小于土壤速效磷淋溶的环境阈值(39.9 mg/kg)，速效磷淋洗风险较低；而储水灌溉量大于140 cm时，小麦植株磷素吸收量显著降低，花前磷素转运降低，土壤速效磷存在向下迁移的趋势，磷盈余量显著增加。
结论在西北地区，适宜的储水灌溉量为土层深度范围不大于140 cm，既可以显著提高小麦磷素吸收和转运效率，又可以控制土壤中有效磷含量处于适宜范围，降低土壤磷素盈余，使成熟期土壤各土层速效磷浓度低于土壤速效磷淋溶的环境阈值(39.9 mg/kg)，从而获得较低的土壤磷素环境风险。

Abstract:
Objective Deep storage water irrigation before rain season is an efficient utilization way of rainwater and flood resources in central Shanxi province. As the potential risks of nutrient leaching, and reduced fertilizer utilization efficiency due to large irrigation water volume, we studied the effect of storage water irrigation volumes on wheat P utilization, apparent P balance, and leaching risks down to deep soil.
Methods A field experiment on wheat was conducted in the Baojixia Irrigation Area of the Guanzhong Plain (Caoxinzhuang Farm, Yangling Demonstration Zone),.with winter wheat cultivar "Xiaoyan 22" as the test material. The treated storage irrigation water volumes were 0, 80, 120, 140, 160, and 180 cm, denoted as CK, D80, D120, D140, D160, and D180, respectively. The biomass and P contents in various organs of winter wheat were analyzed for the calculation of wheat phosphorus uptake, phosphorus fertilizer utilization efficiency, and apparent P surplus. The available phosphorus content in 0−200 cm soil layers were measured for the assessment of P leaching down to deep soil.
Result Compared with CK, D80, D120, D140, D160, and D180 water storage irrigation increased winter wheat yield by 8.85%, 24.71%, 30.99%, 17.91%, and 9.90%, respectively. The phosphorus accumulation at maturity stage grains increased by 37.55%, 20.91%, 46.34%, 38.09%, 28.23%, and 22.11%, respectively. The phosphorus absorption efficiency of wheat plants increased by 10.10%, 12.47%, 10.25%, 7.59%, 5.95%, 12.46%, and the phosphorus apparent surplus decreased by 13.82%, 17.05%, 14.02%, and 10.39%, 8.13%, and 17.05%, respectively.With the increase of water storage irrigation volume, the P accumulation in wheat showed a trend of first increasing and then decreasing, reaching the highest at D120; The apparent P surplus reached lowest (79.83 kg/hm²) at D120, which was significantly lower than at D160 and D180 treatments. Within volume of 80−140 cm, the storage water irrigation promoted pre-anthesis P export and post-anthesis P assimilation, and the resulted available P in 0−200 cm soil layer during the mature period was lower than the environmental threshold for leaching (39.9 mg/kg), indicating a lower risk of available phosphorus leaching; When the storage water irrigation volume was greater than 140 cm, the wheat P absorption significantly decreased, and the pre-anthesis P export decreased, and the soil available P showed obvious downward migration trend, with a significant increased P surplus.
Conclusions Appropriate storage water irrigation volume significantly improves the efficiency of wheat phosphorus absorption and utilization, and controls the soil available phosphorus content within threshold of P leaching, and reduces phosphorus surplus in soil. The suitable irrigation volume for water storage is not more than 140 cm in the Northwest area.

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