Clarifying The Effect Of Simulated N & P Deposition With Litter Treatments On Phosphorus Fraction In Korean Pine Plantation And Its Natural Forest

Phosphorus(P)availability in the soil has decreased significantly,particularly in temperate regions,as a result of the conversion of secondary forests into pine plantations in Northeast China,making the ecosystem more vulnerable to nitrogen(N)-derived acidification and having a negative impact on plant production and ecological function.The soil nitrogen and phosphorus cycles are critical and interconnected,but phosphorus(P)cycling receives less attention as N deposition increases.Moreover,it remains poorly understood how N and P fertilization together affect the availability of P and other soil properties.Also,soil aggregation in the forest ecosystem is considered a significant physical process mainly influenced by manures,fertilizers,or a combination of both.This aggregation may directly alter the soil nutrients and their fractions in the soil through microbial changes.Besides,organic and inorganic fertilizer addition or removal in soil poses significant effects on soil nutrients.As climate change and other anthropogenic factors are causing deprivation in soil nutrient profiles and altering their proper functioning.Therefore,complete insight into fertilizer modification and its consequences is required to understand the sustainability of forest ecosystems.So,to evaluate the effects of N and P depositions on P fraction,soil organic carbon(SOC),soil total nitrogen(STN),soil total phosphorus(STP),and the impact of different soil aggregates in two forest types like Korean pine plantation(KPP)and it’s natural Korean pine forest(NKPF),therefore,a factorial experiment was laid out by adding N and P fertilization to different even-aged plantations in Liangshui National Nature Reserve(47°10′50″ N,128°53′20″ E),Dailing district,Yichun city,Heilongjiang Province in northeast China.The following results were revealed from the statistical analyses of the collected data.1)The results showed that soil-P fractions changed with N and P fertilization over time,although organic-P(Po)fractions were lower than inorganic-P(Pi)fractions.Residual P was increased along with N deposition in the soil.Soil organic carbon(SOC)was higher in NKPF soils as compared to KPP.In medium treatment,there is more availability of P fractions as compared to other treatments in both forest types,while high treatment showed some fixation of P in soils in both forest types.Furthermore,SOC showed a negative correlation with residual P,while p H showed a positive correlation.Total N in soil showed a negative correlation with soil p H and residual P.However,P fertilizer in combination with N fertilizer results in better levels of total phosphorus,organic and mineral fractions,and soil fertility.Maximum P was retained as residual P,while all other fractions showed positive correlations with each other and negative correlations with p H.2)The results indicated that H2O-Pi,Na HCO3-Pi,residual Pi,and SOC were retained higher in larger soil aggregates(>5mm)and decreased with decreasing aggregate size,while other variables,i.e.,Na OH-Pi,Na HCO3-Po,p H,and T-N,were not affected by aggregate size.H2O-Pi(48 ppm),Na HCO3-Pi(68 ppm),Na HCO3-Po(80ppm),Na OH-Po(623 ppm),HCL-Po(67 ppm),and SOC(36±1.6)were estimated in medium fertilizer treatment.Moreover,litter inputs increased organic-P fractions in soil,particularly at medium treatment.3)The results revealed that SOC was directly proportionate to forest litter amounts.Synthetic fertilizers affected soil total N(STN)and the highest amounts were recorded in plots with H: 30 g N m-2 a-1 + 20 g P m-2 a-1,as 3.03 ± 0.35 g kg-1 in AL.Similarly,altered litter/double was most effective in enhancing the quantity of soil total P(STP)(0.75 ± 0.04 g kg-1).However,The findings showed that forest litter is a significant source for increasing soil organic matter;nevertheless,to reach the soil’s maximal sustenance potential,fertilizer application must continue periodically in either form.Conclusively,the long-term balanced application of P fertilizer in combination with N fertilizer results in better and enhanced levels of total phosphorus,as well as its organic and mineral fraction and soil fertility in general.The application of N and P together has a positive effect on the P enrichment in two forest types.It is recommended that application of N and P at the rate of 15 g N m-2 a-1 + 10 g P m-2 a-1 is suitable to enhance P availability in both forest types.Moreover,combined application of N and P at the level of 30 g N m-2 a-1 + 20 g P m-2 a-1 under AL(altered/double litter)treatment level improved STN and P contents.