Study On Forage Productivity And Soil Physical And Chemical Properties Of Alfalfa-Sainfoin Mixed Pasture In The Longzhong Loess Plateau

The Longzhong area belongs to the typical hilly and gully region of the Loess Plateau.The natural conditions are suitable for planting alfalfa,with a broad cultivation area of alfalfa in Gansu province.However,the alfalfa cultivation is mainly plant solely in this area,and the biomass at the early stage of establishment is low.But the peak of grass production of sainfoin comes earlier.The mixed sowing can make up for the low yield of alfalfa in the first two years and the drawback of short lifespan at the sainfoin.Therefore,alfalfa and sainfoin were used as research objects in this study,and the forage production and the soil physical and chemical properties of alfalfa and sainfoin under the mixing ratio of 1:0?H1?,7:3?H2?,5:5?H3?,3:7?H4?and 0:1?H5?were explored in the golden village of Lijiabao Town,Anding District,Dingxi City,Gansu province from 2016 to 2018.The results can guide the construction of artificial grassland in Longzhong region.The main results are as follow:?1?In the 2ⁿdd year of planting,the aboveground biomass of H2,H3 and H4treatment was increased by 46.0%,34.0%and 12.0%compared with H1 treatment,respectively,but lower than H5 treatment;in the 3^rdyear,the aboveground biomass of H2,H3 and H4 treatment increased by 36.5%,40.0%and 23.5%compared with H1 treatment,respectively,and by34.9%,38.4%and 22.1%compared with H5treatment.The results displayed an obvious effect of mixed sowing.With the increase of the establishment period,the underground biomass accumulation rate of alfalfa was high than that of sainfoins.?2?With the decrease of the proportion of alfalfa in mixed mixture,the relative density of alfalfa increased while sainfoin decreased;In the 2ⁿdd year of planting,alfalfa relative density of H2 treatment was less than 1,but sainfoin relative density was greater than 1.Alfalfa and sainfoin relative density of H3,H4 treatment were greater than 1;In the 3^rdd year,alfalfa and sainfoin relative density of H2,H3,H4treatment were greater than 1.In the 2^ndyear of planting growth,the relative yield total of the 1^stt utting of alfalfa and sainfoin is less than 1,but the 2ⁿdd grass is greater than 1.In the 3^rdd year,the relative yield total of two grass of alfalfa and sainfoin was greater than 1.With the decrease of the proportion of alfalfa in mixed mixture,the inter-species competition rate of alfalfa reduced when compared to sainfoin.Alfalfa had an advantage in inter-specific competition in H2 and H3 treatment,and sainfoin had a competitive advantage in H4 treatment.?3?In the 2ⁿdd year of planting growth,the crude protein content of alfalfa and sainfoin was the highest in H4 treatment;the content of acid detergent fiber and neutral detergent fiber of alfalfa were the lowest in H4 and H3 treatment.The content of acid detergent fiber of two grass of sainfoin was the lowest in H2 and H4treatment,and the content of neutral detergent fiber was the lowest in H4 treatment.The relative feeding value of the first cutting of alfalfa was the highest in H4treatment and the lowest in H1 treatment.The relative feeding value of the first grass of sainfoin was the highest in H2 treatment and the lowest in H5 treatment.The relative feeding value of the second cutting of alfalfa was the highest in H3 treatment and which was the lowest in H4 treatment.The relative feeding value of the second cutting of sainfoin was the highest in H4 treatment and which was the lowest in H5treatment.In general,the relative feeding value of the alfalfa was higher than sainfoins.?4?The content of soil organic matter and total nitrogen of alfalfa and sainfoin mixed pasture at 0-20 cm increased since the 2^ndyear.The content of organic matter increased by 1.15%-20.42%,and the total nitrogen increased by 15.63%-39.06%.In contrast,the content of available phosphorus and available potassium decreased.It indicates that the legume pasture needs extra phosphate fertilizer and potassium fertilizer to maintain pasture productivity.