施肥和混播对松嫩平原退化草地土壤和牧草产量的影响

Effects of Fertilization and Mixed Sowing on Soil Nutrients and Pasture Yield of Degraded Grassland in Songnen Plain

[目的]研究施肥和混播牧草对松嫩平原黑龙江省西部退化草地土壤养分和牧草产量的影响,为该区天然退化草地修复提供科学依据。[方法]试验以黑龙江省西部天然轻度退化草地为研究对象,沙打旺(Astragalus adsurgens)和披碱草(Elymus dahuricus)为补播草种,设2个间行混播〔豆禾比2∶2(B_(1))和1∶2(B_(2))〕和6个水平氮磷钾施肥组合〔N_(50)P_(40)K_(45)(A_(1)),N_(100)P_(240)K_(225)(A_(2)),N_(150)P_(0)K_(180)(A_(3)),N_(200)P_(120)K_(0)(A_(4)),N_(250)P_(80)K_(270)(A_(5)),N_(300)P_(200)K_(90)(A_(6))〕进行田间试验〔其中,每个元素后的下标数字分别表示N,P_(2)O_(5)和K_(20)的施用量(kg/hm^(2))〕。[结果]在确定混播比例的情况下,施肥能显著提高土壤速效养分含量和牧草产量。0—10 cm土层土壤养分变化受施肥和混播的影响较20—30 cm土层大。施肥、混播及二者交互对土壤速效氮含量影响显著(p<0.05)。0—10 cm土层速效氮、速效磷含量的变化趋势与氮、磷添加水平的高低基本一致。豆禾1∶2混播的0—10 cm土层全氮、速效氮、速效磷含量高于同一施肥水平下的豆禾2∶2混播。高氮(A_(6))处理的电导率显著高于其他处理(p<0.05)。豆禾2∶2混播+N_(150)P_(0)K_(180),豆禾1∶2混播+N_(300)P_(200)K_(90)的1 m^(2)样方地上生物量分别为290.68 g与254.31 g,是各自混播比例下最高的。[结论]综合考虑牧草产量及土壤养分变化情况,豆禾2∶2混播,N施量以150 kg/hm^(2)较适宜该区轻度退化草地修复。

[Objective]The effects of fertilization and mixed sowing on soil nutrients and pasture yield of degraded grassland in the Songnen Plain,Western Heilongjiang Province were studied,in order to provide a scientific basis for restoration of natural degraded grassland in local area.[Methods]The study was conducted on a natural lightly degraded grassland in the Songnen Plain of Western Heilongjiang Province.Astragalus adsurgens and Elymus dahuricus were used as reseeding grasses.Treatments consisted of two interrow mixed sowing ratios〔legume:grass ratio 2∶2(B_(1)) and 1∶2(B_(2))〕,and six nitrogen,phosphorus,and potassium application rate combinations:N_(50)P_(40)K_(45)(A_(1)),N_(100)P_(240)K_(225)(A_(2)),N_(150)P_(0)K_(180)(A_(3)),N_(200)P_(120)K_(0)(A_(4)),N_(250)P_(80)K_(270)(A_(5)),and N_(300)P_(200)K_(90)(A_(6)),where subscripts after each element indicated the application rate given as kg/hm^(2)N,P_(2)O_(5),and K_(20),respectively.[Results]Fertilization significantly improved available nutrients and pasture yield based on the ratio of mixed sowing.Soil nutrient changes in the surface soil layer(0—10 cm)were more affected by fertilization and mixed sowing than in the deeper layer(20—30 cm).Fertilization,mixed sowing,and their interaction had significant effects on the content of available soil nitrogen(p<0.05).The variation trends of available nitrogen and available phosphorus in the 0—10 cm soil layer were basically consistent with the additions of nitrogen and phosphorus.The contents of total nitrogen,available nitrogen,and available phosphorus in the 0—10 cm soil layer of legume-grass mixture in the 1∶2 ratio were greater than in the 2∶2 ratio at the same fertilization level.The productivity of the high nitrogen treatment(A_(6)) was significantly(p<0.05)greater than that of the other treatments.The greatest aboveground biomass values were observed for the legume-grass 2∶2 ratio+N_(150)P_(0)K_(180)treatment combination(290.68 g/m^(2)) and for the legume-grass 1∶2 ratio+N_(300)P_(200)K_(90)treatment combination(254.31 g/m^(2)).[Conclusion]Considering pasture yield and changes in soil nutrients,the legume-grass mixed sowing in the 2∶2 ratio and the fertilizer application rate of 150 kg/hm^(2)for nitrogen can be recommended.