Fertilization Effect Of Robinia Pseudoacacia Forest In The Lower Yellow River Based On Site Conditions

Robinia pseudoacacia L.is an important fast-growing timber tree species in China,and has significant economic benefits as a timber forest.At present,the lower reaches of the Yellow River region soil salinization degree is very high,fragile ecological environment,plantation soil fertility decline is serious,locust because of its resistance to drought and barren,update the germination ability is strong,grow quickly,keep the characteristics of soil and water conservation in good performance to become the region's fast-growing and high-yielding progrm pioneer tree species,build nitrogen fixation trees acacia can greatly improve the soil environment.Therefore,it is an important research subject to construct fast-growing and high-yield robinia pseudoacacia plantations by clarifying the growth and development rules of fertilization on plantations in saline-alkali areas in the lower reaches of the Yellow River and the relationship between trees and soil environment,and summarizing the main limiting factors of the interaction between stand growth and soil characteristics of robinia pseudoacacia under different site conditions.Based on this,this study 2 a raw thorn acacia number one artificial pure forest of anhui province as the research object,saline-alkali land in saline-alkali land and the orthogonal experiment was carried out,using orthogonal design of four factors,four levels,with no fertilizer as blank group?CK?,aims to explore the inorganic fertilizer and organic fertilizer mix of both growth and physiological characteristics of black locust forest,soil physical and chemical properties,soil enzyme activity and the influence of soil microbial functional diversity,and select the most appropriate comprehensive test results of actual production fertilizer combination,balanced fertilization model of black locust plantation on the lower reaches of the Yellow River.The main findings are as follows:?1?In this experiment,the optimal fertilization levels of the two experimental plots are different,and the saline-alkali plots are N125g,P145g,K85g and FA55g.The non-saline-alkali lands are:N175g,P145g,K185g and FA55g.The soil in non-saline-alkali land is relatively fertile,and the demand for nutrients is not great.Excessive fertilization may have a negative effect on the growth and development of plants.Fertilization has a significant promoting effect on the growth of individual robinia pseudoacacia trees.In particular,N is conducive to the growth of robinia pseudoacacia tree height and biomass.P has a significant effect on the increase of leaf area index of robinia pseudoacacia trees,while single fertilization has no significant effect on the improvement of soil fertility.?2?Fertilization can also change the physiological characteristics and nutrient redistribution mechanism of individual robinia pseudoacacia trees in saline-alkali land.N,P in the plant body is more scarce,high fertilizer levels of N,P and K in the low fertilizer levels,more can promote acacia plant nutrient accumulation in the body,and the physiological and metabolic activity in trees,the growth and development of corresponding ability will improve,at the same time,the physiological indexes of forest trees can to a certain extent,indicating its growth environment conditions.?3?On saline-alkali land,N for acacia trees individual chlorophyll content,net photosynthetic rate,stomatal conductance,the influence of the largest,K had the greatest influence of intercellular CO₂ concentration,when the soil nutrient content is low,the amount of organic fertilizer can effectively promote the root activity increased,but when the fertilizer rate increases to a certain extent,increased root vigor index no longer,trees grow,tend to be stable;For non-saline-alkali land,N had the greatest influence on chlorophyll content,net photosynthetic rate and root activity of robinia pseudoacacia.While N fertilizer increased the total nitrogen content,it also increased the photosynthetic rate of plants,while excessive fertilization was not beneficial to the growth of trees.?4?Fertilization can significantly improve the soil environment of forest land under salt stress.Soil physical and chemical properties are more sensitive to P,and appropriate application of P fertilizer can effectively improve the soil,while the application of N and K fertilizer has no significant influence on the physical and chemical properties of the soil,and the soil enzyme activity is more dependent on the mass fraction of N and P in the soil.?5?Organic fertilizer can significantly affect the number of soil microorganisms.There is a close relationship between soil enzymes and soil microorganisms.The combination of inorganic fertilizer and organic fertilizer can significantly increase the number of soil microorganisms and effectively improve the soil environment.?6?Yellowish acid has a significant effect on the occurrence and expression of individual roots and the number of soil microorganisms in robinia pseudoacacia trees,especially in saline-alkali land.The physiological characteristics and growth status of robinia pseudoacacia trees were negatively correlated with fertilization.