The whole experiment was carriedoutin agreenhouse attheexperimentalbaseof Jilin AgriculturalUniversity.Typical20-cm-deepblacksoilwasused,andthebasicsoilcharacteristicsareshowninTable 1. All soils were air-dried and passed through a 2-mm sieve beforetheexperiment.Sevenexperimentalgroupswereestablished,namelyCK (untreated soil), F (Nfertilizer only
The whole experiment was carriedoutin agreenhouse attheexperimentalbaseof Jilin AgriculturalUniversity.Typical20-cm-deepblacksoilwasused,andthebasicsoilcharacteristicsareshowninTable 1. All soils were air-dried and passed through a 2-mm sieve beforetheexperiment.Sevenexperimentalgroupswereestablished,namelyCK (untreated soil), F (Nfertilizer only