Effect Of Fertilization And Reseeding On The Production And Forage Quality Of Degraded Alfalfa Grassland

Lack of phosphorus and potassium in the alfalfa grassland above 7 years old in the mountainous area of southern Ningxia.The aboveground vegetation is sparse,the forage yield is low,and the quality is poor.Therefore,The test uses a two-factor randomized block test design to analyze and compare the different application amounts of P-K fertilizer?Al-A4:0-0 kg/hm²,75-60 kg/hm²,150-120 kg/hm² and 225-180 kg/hm²?and different supplementary seeding amounts of grass(forest-free sparrow,alkali grass and fescue were carried out at 1:1:1,and B1-B3 were:1000 grains/m²,2000 grains/m² and 3000 grains/m² on the production performance and forage quality of degraded alfalfa were evaluated by the grey relational degree method.The research results are as follows:?1?Phosphorus and potassium fertilizer can significantly increase alfalfa plant height,stem diameter,node spacing and leaf area,and reduce alfalfa dry to fresh ratio and stem to leaf ratio.Supplementary sowing amount had a significant effect on plant height and leaf area of two-crop alfalfa,alfalfa plant height was the highest in B2 and leaf area was the highest in B3.The mutual effects of fertilization,supplementation and seeding on the height of two stubble alfalfa plants were significant,but not on other indexes.On the whole,the effect of fertilizer was greater than that of supplementary seeding and interaction.?2?Whole cutting of alfalfa hay yield was treated with A3B3 at the highest,and the annual cumulative yield was up to 9503.23 kg/hm².and increased by 75.38%compared with A1B1.?3?The effects of different fertilizer rates on the initial fluorescence?F₀?and maximum fluorescence?F_m?of alfalfa were same.Both increased first and then decreased with the increase of fertilizer rates.The initial fluorescence and maximum fluorescence were highest in A2B1 and A3B2,respectively.PS ? maximum photochemical efficiency?F_v/F_m?of reseed and fertilizer treatment was not significant,the influence of the energy distribution parameters does not change significantly as more fertilizer reseed.?4?With the increase of phosphorus and potassium fertilizer,two forage ASH?ASH?,neutral detergent fiber?NDF?and content decreases,crude fat?CP?content gradually increased,phosphorus and potassium fertilizer can significantly improve the pasture nutritional quality,and relatively feeding value?RFV?with the fertilizer rate is on the rise in general;With the increase of supplemEntary sowing amount,the ash content of acid washing fiber in the first crop and forage in the second crop showed a decreasing trend,and the crude protein,relative feeding value and crude fat content in the first crop gradually increased.The influence of fertilization and reseeding on each index was not significant.