南方设施菜地填闲苋菜筛选及其氮磷淋失阻控效果研究

Planting Amaranth as Catch Crop to Reduce Nitrogen and Phosphorus Leaching Losses from Greenhouse Vegetable Soils in Southern China

筛选经济效益高、易推广,且对夏季休闲期氮磷淋失阻控效果好的填闲作物,对减轻我国珠三角地区设施菜地土壤氮磷流失、保护水体环境具有重要意义。通过淋溶管法研究了夏季休闲期(7月至8月)种植4种苋菜(圆红苋菜、心红苋菜、青苋与南星苋)对设施菜地土壤淋溶液pH、无机氮磷浓度及收获后土壤速效养分等的影响。结果表明:苋菜作为填闲作物种植可产生2.04~2.83万元/hm^(2)的经济效益,同时降低设施菜地土壤淋溶液NO–3-N、NH4+-N与总磷浓度,对三者淋溶损失的阻控效率依次达到31.2%~49.5%、35.5%~37.5%和30.1%~43.6%。与休闲对照处理相比,苋菜种植收获后土壤碱解氮与有效磷养分并没有表现出耗竭,其中有效磷含量提升31.9%~67.8%。综合本研究结果,4种苋菜均为可优选的填闲叶菜,皆具较高的减控设施蔬菜休闲期土壤氮磷淋溶损失效率与经济效益,且不影响后茬蔬菜生产的地力基础,其中,心红苋菜在环境效益和经济效益(2.83万元/hm^(2))方面表现较为突出。

Catch crops with economic value are easy to popularize and have good effects on controlling nitrogen and phosphorus leaching losses during leisure time,thus are of great significance for reducing nitrogen and phosphorus losses from greenhouse vegetable soils in the Pearl River Delta Region in China.In this study,the leaching tube method was used to study the effects of planting four kinds of edible amaranth(round red amaranth,heart red amaranth,green amaranth and Nanxing amaranth)on pH,inorganic nitrogen and phosphorus concentrations of soil leaching solution,and the available nutrient contents in greenhouse vegetable soil after vegetable harvest during summer fallow period(from July to August).The results showed that the economic benefits of planting amaranth ranged from 20400 to 28300 yuan/hm^(2).At the same time,planting amaranth reduced the concentrations of NO–3-N,NH4+-N and total P in soil leaching solution with the average efficiencies of 31.2%–49.5%,35.5%–37.5%and 30.1%–43.6%,respectively.Compared with the fallow control treatment,no depletion was observed in the concentrations of available phosphorus and alkaline hydrolysis nitrogen in the soil after amaranth harvest,while the concentration of available phosphorus increased by 31.9%–68.1%.The results indicate that planting amaranth as catch crop is an optimal technology,which can reduce soil nitrogen and phosphorus leaching losses during the vegetable fallow period and produce certain economic benefits without affecting soil fertility for subsequent vegetable production.