玉米秸秆生物炭对滇池流域大棚土壤磷素利用和小白菜生长的影响

Effect of Straw Biochar on Utilization of Soil Phosphorus and Growth of Bok Choi in Greenhouse in Dianchi Lake Basin

滇池是中国水体富营养化最严重的湖泊之一,滇池流域大棚种植中大部分磷素最终汇入滇池,是滇池富营养化的重要原因。生物炭作为一种土壤改良剂,可以改良土壤的理化及生物性状,吸附土壤中的磷肥,减少磷素迁移流失。通过室内模拟结合实际农业生产的方法,研究了生物炭对滇池流域大棚土壤中磷素利用和小白菜生长及产量的影响。结果表明:施用生物炭能提高大棚土壤中小白菜磷肥利用率,当生物炭添加量为8%(质量百分比)且减半施肥(33 kg hm^(-2),P_2O_5)时,小白菜磷肥利用率由14.77%提高至31.21%,提高了1.11倍,大棚土壤的磷流失量降低43.83%。生物炭可促进大棚小白菜的生长,小白菜出苗率提高7%~9%,子叶展平率提高10%~12%。株高提高69.51%,株重提高71.75%,产量提高31.87%。总之,施用比例8%的玉米秸秆生物炭可提高大棚土壤有效磷含量,减少磷素流失,改善小白菜生长状况,可作为大棚土壤的优良改良剂。

【Objective】Lake Dianchi is a lake the most serious in eutrophication in China.Most of the phosphorus applied in farmlands in the Dianchi Lake watershed is finally imported into the Lake,which is an important reason for eutrophication of the Lake.Biochar as a soil amendment can be used to improve soil physical and chemical properties,adsorb soil phosphate,and hence reduce phosphorus loss from the soil.In order to improve bio-availability of soil phosphorus,increase yield of crops,reduce phosphorus pollution of the soil and the environment,and provide a theoretical basis for management and application of biochar in the soil environment,this study was carried out.【Method】In this study,an indoor simulation and greenhouse pot experiments were conducted to explore effects of biochar on loss and utilization of phosphorus in the production of bok choi and yield of the crop.The experiment was designed to have a gradient of five levels of biochar application rate,and four levels of phosphate application rate,thus making up 20 treatments and three replicates for each.Bok choi was planted in single-compartment planting boxes in a greenhouse.Each box contained 5 kg of soil and had 8 bok choi plants.After the application of biochar,the soils in the boxes were analyzed for total phosphorus and available phosphorus,separately and ratio of the two calculated.After the plants were harvested,the soils in the boxes were analyzed again for fertilizer utilization efficiency and phosphorus loss and effects of the biochar.On D3（Three days after sowing）,germination rate and cotyledon flattening rate of the plants were measured.On D10,D20,D30 and D40,plant height and plant weight was checked of the plants harvested,and effects of the biochar on growth of bok choi were analyzed.After harvesting of the crop,effect of the biochar on yield of bok choi analyzed,calculated and converted into yield per hectare.【Result】Application of biochar may improve P utilization efficiency of bok choi in greenhouse.In the treatment,8%in biochar application rate and 33 kg hm^（-2）,（1/2of the conventional rate）in P_2O_（5 ）application rate,P fertilizer utilization efficiency increased from 14.77%up to 31.21%or by 111.3%,thus reducing P loss by 43.83%,and germination rate of the crop increased by7%-9%,cotyledons flattening rate by 10%-12%,plant height by 69.51%,plant weight by 71.75%and yield by 31.87%.The effect of biochar on plant height appeared the most significantly during the period of D20-D40 and that on plant weight did during the period of D30-D40.【Conclusion】The application of 8%corn stalk-derived biochar can increase the content of soil available phosphorus in greenhouse,reduce the loss of phosphorus,improve the growth of bok chai Therefore,it can be used as a good soil amendment in greenhouse.