思茅松苗木生长及养分特征对生物炭、黄腐酸和氮的响应OA

To explore the effects of coffee shell biochar,fulvic acid(FA),and N form on the growth and nu-trient status of Pinus kesiya var.langbianensis seedlings,experiments were conducted using an L9(34)orthogonal design with biochar supplement levels(0,25,50 g/L),FA concentrations(0,0.8,1.6 g/L),and N forms(no nitro-gen,nitrate nitrogen,ammonium nitrogen).A total of 9 treatments were used.The effects of factor levels and their combinations on the growth and nutrient characteristics of P.kesiya var.langbianensis seedlings were analyzed.Coffee shell biochar,FA and N significantly promoted the seedlings growth(P<0.05).Height,ground diameter,and biomass increased first and then decreased with increasing biochar concentration,and seedling growth was optimal at 25 g/L biochar.Biochar supplementation decreased the N content of seedlings,but increased the P and K content.With the increase in biochar,K content increased in parallel,whereas P content increased first and then decreased.FA application significantly increased the height,biomass,N,and P contents of the seedlings.N addi-tion promoted the growth of seedlings and increased the contents of N and P.The growth and P content of seed-lings treated with ammonium nitrogen were significantly higher than those of nitrate nitrogen,and ammonium ni-trogen significantly increased the P content.In contrast,nitrate nitrogen had no significant effect on P content.Positive interaction effects between FA and N were observed on height and N content of the seedlings.The range of effect degree of each factor on seedling growth was coffee shell biochar>N>FA.Correlation analysis showed that seedling height,BD,and biomass increased synergistically,and growth parameters were significantly correl-ated with P content(P<0.01),indicating P was a limiting element for seedling growth.Coffee shell biochar,FA and N promote seedling growth by enhancing the absorption of N,P and K.The optimal treatment is 25 g/L biochar and 0.8 g/L FA combined with ammonium nitrogen,and it is recommended to supplement P fertilizer ap-propriately during production.