Effects of Two Chelating Agents on Availability of Calcium and Phosphorus in Black Soil of Vegetable Fields

To explore the effects of the two chelating agents on the availability of calcium and phosphorus in black soil of vegetable fields and the growth of cabbage （Brassica pekinensis Rupr.） seedlings,humic acid （F） and ethylene diamine tetraacetic acid disodium salt （EDTA） were used as experiment materials,and two factors and three levels completely randomized experiment of the nine treatments was set.The experiments were carried out by soil incubation experiment and pot experiment to investigate the effects of the two chelating agents with different ratios and their interaction on soil and cabbage.The results showed that there were very significant differences among soil pH,soil available phosphorus content,cabbage biomass,calcium and phosphorus accumulation of cabbage under the interaction of the two chelating agents.It could improve pH of the soil and reduce the electric conductivity （EC） value of soil,when applied chelating agents of different proportions.The EC value of soil fluctuated during the incubation period.There were significant differences between pH and EC in the early incubation period,but there was no significant difference in the later stage.And there were significant differences between soil available calcium and available phosphorus content;there were significant differences between cabbage biomass and the accumulation of calcium and phosphorus in cabbage,and the data of F2E2 treatment were significantly higher than those of other treatments.In summary,under the conditions of the experiment,the available phosphorus content of black soil in vegetable fields,the biomass and accumulation of calcium and phosphorus in cabbage increased significantly in F2E2 treatment (appied 675 kg·hm^-2 of lime,300 kg·hm^-2 of humic acid and 150 kg·hm^-2 of EDTA).