降水模拟下施肥对生土地玉米冠-根-土系统的影响

Effect of Fertilization under Precipitation Simulation on the Completion of Maize Crown-root-soil System in Raw Land

影响黄土高原地区生土熟化的主要限制因素是干旱和土壤贫瘠。为探索施肥和降水配合对生土地玉米冠-根-土的相互影响机制,确定不同降水模拟下施何种肥料能有效促进生土地作物冠-根-土系统建成,达到生土地熟化的目的,在前期研究(生土地玉米最佳施肥深度60~80 cm)的基础上,连续2 a将黄土作为试验土壤,采用根管法,研究肥料种类(NPK+有机肥(ORG))和降水模拟(欠水年275.9 mm、平水年482.8 mm、丰水年763.9 mm)对玉米地上部生产力(秆质量、总粒质量)、地下部根质量、根系氮磷钾养分积累量、根际土壤营养含量(速效磷、碱解氮、有机质)及根际土壤酶活性(脲酶、碱性磷酸酶、蔗糖酶)的影响。结果表明,在水分充盈的条件下,有机肥的施用对地上部干物质的积累有促进作用;通过有机肥的施用可以达到根干质量增加的目的,但对应的水分需求不大;水分需求达不到满足时,通过NPK+ORG处理可以实现玉米根系N、P、K养分积累量的提高;水分充盈的条件下,ORG处理的玉米根系NPK养分积累量远远高于NPK+ORG处理;水分充盈的条件下,ORG处理可以提高玉米根际有机质含量和蔗糖酶活性。改良生土的最佳水肥方式为丰水年模拟下施用有机肥,欠水年模拟下以施用NPK肥+有机肥更好。

Drought and poor soils are a major factor limiting the Loess Plateau adobe ripening.To explore the effect mechanism of fertilization and precipitation on crown-root-soil of raw land maize,determine which fertilizer can effectively promote the establishment of crown-root-soil system of raw land crops under different precipitation simulations and achieve the purpose of raw soil maturation,in this experiment,the loess parent native was used as the test soil for 2 consecutive years,based on the root canal method,the optimum fertilization depth 60~80 cm of the raw land maize was obtained in the previous study.The effects of fertilizer types(fertilizers NPK+organic fertilizer,organic fertilizer)and precipitation simulation(dry year 275.9 mm,normal year 482.8 mm,humid year 763.9 mm)on maize aboveground productivity(stalk quality,total grain quality),root quality,root nutrient accumulation(nitrogen,phosphorus,potassium),rhizosphere soil nutrients(available phosphorus,alkali-hydrolyzed nitrogen,organic matter)and rhizosphere soil enzymes(urease,alkaline phosphatase,invertase)activity were studied.The results showed that under the condition of sufficient water,the application of organic fertilizer was beneficial to the accumulation of aboveground substances.The application of organic fertilizer was beneficial to increase the root system quality of maize,but the water should not be too much.The treatment of NPK+ORG was beneficial to the increase of N,P and K accumulation of maize root system when water deficiency was applied.The accumulation of N,P,K in maize roots treated with ORG alone was much higher than that treated with NPK+ORG when water was sufficient.When water was sufficient,application of ORG could improve the content of organic matter and the activity of invertase in maize rhizosphere.The best way of water and fertilizer for improving raw soil is to apply ORG under water-rich simulation,while NPK+ORG is the better under water-deficient simulation.