不同盐碱地改良剂对土壤理化性质、紫花苜蓿生长及产量的影响

为明确国产化盐碱地改良剂在重度盐碱地的施用效果,采用田间试验和室内分析相结合的方法,以牧草和绿肥兼用型紫花苜蓿为供试作物,研究重度盐碱地施用国产1号(2 250 kg·hm-2)、国产2号(7 960kg·hm-2)和脱硫石膏(22 500 kg·hm-2)3种改良剂对土壤理化性质、紫花苜蓿(Medicago sativa L.)出苗率和鲜草产量的影响,以及施用脱硫石膏对土壤(0~20 cm)和紫花苜蓿茎、叶中重金属含量的影响。结果表明,与对照(不施改良剂)相比,施用改良剂处理的紫花苜蓿出苗率提高18.4%~31.7%,3茬鲜草总产量提高18.9%~43.5%;土壤pH下降0.11~1.46,容重降低0.01~0.06 g·cm-3、孔隙率提高1.15%~10.15%,土壤理化性状得到改善;施用脱硫石膏和含有脱硫石膏的国产2号使土壤和紫花苜蓿中汞、铅和铬含量有显著提高,但土壤重金属含量未超过国家《农业土壤环境质量标准》GB15618—2001规定的二级土壤使用标准,紫花苜蓿中汞、镉、铅和铬的含量检测符合国家饲料卫生指标(GB13078—2001)的规定。本研究表明,3种盐碱地改良剂以国产2号的施用效果最好,可在同类型盐碱地大力推广应用。

Effects of different saline-alkali land amendments on soil physicochemical properties and alfalfa growth and yield

Saline land improvement is important in offsetting contradictions between increasing population and declining soil areas. It enhances the quantity and quality of farm production, improves ecological environment and promotes regional development of sustainable agriculture. This study determined the effects of localized saline-alkali soil amendments on heavy saline-alkali soil. The experiment used alfalfa as trial crop to investigate the effects of desulfurized gypsum, Guochan-1 and Guochan-2 amendments on soil physical and chemical property and the emergence rate and fresh yield of alfalfa in waste saline-alkali soils with heavy soda. The effects of desulfurized gypsum on heavy metal contents of soils and leaves and stems of alfalfa were also investigated under field conditions. The experiment was conducted in a complete randomized design with four replicas of each treatment. Four treatments were control (without amendment), Guochan-1 (application rate of 2 250 kg·hm^-2), Guochan-2 (application rate of 7 960 kg·hm^-2) and desulfurized gypsum (application rate of 22 500 kg·hm^-2). The results showed that compared with the control, soil pH reduced by 0.11~1.46, soil density declined by 0.01~0.06 g·cm^-3 and porosity increased by 1.15%~10.15% after application of soil amendments. Furthermore, amendments improved soil perviousness and soil physical and chemical properties. Alfalfa emergence rate increased by 18.4% to 31.7%, fresh biomass of the three crops increased by 18.9%~43.5% and yield significantly increased under amendments over the control. Soil and plant Hg, Pb and Cr contents were significantly influenced by desulfurized gypsum and Guochan-2 appli-cations. Among the three amendments, Guochan-2 amendment produced the best effects regarding saline-alkali soil improvement. Whereas heavy metal content did not exceed Grade-II Soil National Standard for Agricultural Environment Quality, alfalfa Hg, Cd, Pb and Cr contents were within National Standard for Feed Qygienic Quality. This research suggested that among the three sa-line-alkali soil amendments, Guochan-2 produced the best effects. It was therefore recommended for wide application in similar sa-line-alkali soil conditions.