This is a very interesting question . Soil C: N ratio is undoubtedly used so frequently because of the stoichiometry of the decomposition of organic matter releasing N corroborating with microbial C: N ratio , which relates so well with soil fertility index values . But , soil C: P and soil C : K ratio unfortunately fail to relate with microbial C:P or C:K ratio..

Soil pH, C and NPK of the forest soils are interrelated, they definitely have contributions on controlling organo-chemical environment of the forest floors through bio-geo-chemical cycles and thus, they certainly might have correlations with the soil fertility index, somehow this part is still ignored in the research field of soil chemistry for the forest stands.

I dont think, it is ignored . We dont lay much emphasis on C: P or C:K ( this ratio hardly works including forest soils) because of the poor correlation compared to C:N ratio . You hardly see any study concnetrating on release of K from organic matter decomposition....why...

Statistically N shows inversely relationships with the P & K, when I computed the data of NPK of the soil samples collected from the mangroves ecosystem of the Sunderbans with N as independent variables to P & K using statistical analysis of multiple correlation coefficients formula, the value of r comes out to be negative that means they are inversely correlated.

When I compute NPK Data obtained from the mangroves soil applying statistical methods of multiple correlation coefficients with the N as the independent variable, it gives negative value, what does it mean, is there be any inversely relationship of N with the other two variables P & K?

Inverse relation between N and K is common , especially in fruit crops , mangroove soils , try to see with EC as well. However , N versus P looks unlikely , try to work put multiple cortelation avoiding some extreme values....just a guess...sometimes it works well...

Yes it reflects in the K value obtained in the analysis of mangrove soils. It is found that available potassium is five times richer than that of the required amount for the natural growth of mangroves, which supply the nutrients to the ambient environment. But how could I establish the inversely relationships between N & PK, that's now the matter, though multiple correlation coefficient is computed using the three variables NPK considering N as independent variable and PK as dependent variables.

Please first take linear correlation , do you get the same result...but N and K is common.The qiestion is all about N and P, try to see with different P fractions with N...

Linear correlation r of N & P shows the positive result, and it is 0.397919 which is normal, but I try to establish relationships of NPK as a whole, particularly relationships between N & PK, that's why I have to use the formula of multiple correlation coefficient of the statistical methods, it shows positive result at first, but in this statistical analysis, R is not an unbiased estimate of the population multiple correlation coefficient for small samples of only six in number, so a relatively unbiased version of R is given by R adjusted and that result shows the negative, and it is -0.3963 which I can not interpret.

Primarily mangroves forest ecosystem is totally different from terrestrial forest ecosystem.

Exactly , soil n could be separated into minerlaizable n and non-mineralizable N , then try to correlate ....these are all possibilities, because mangroove forests could have much lower rate of mineralization compared to teresstrial forest ecosystem.....

Truly, mangroves forests differ from that of the terrestrial, and it will show a different result when mineralizable N and non-mineralizable N are correlated, but in the mangrove sediments atmospheric carbon is sequestered as blue carbon, and they exist in both forms of mineralizable and non-mineralizable C, is any content of NPK, in any form, released from that carbon pool that control the correlation between N and PK, is there be any such probability?

I feel so strongly , there must be some release . what is the source of plant available N , is it KMnO4 -N or total N ..?? Likewise P and K ..??

My understanding is that all the three nutrients can not be brought under single roof for availability. For P & k there are three forms. say mobile, fixed, immobile, exchangeable, non exchangeable, which is not the case for N. Further for K, the Microbes (C dependent) play a very little and minor role in exchangeable K in Org. Matter (again C deciding), which is also very minimum in soil. But for C&N (diffusion), both have a positive correlation already in soil. May be a soil scientist can explain in detail.

C&N relationship in soils is well established, but still we are all awaiting for the establishment of the relationships between N & PK in an unbroken chain of existance in the same substratum of the forest stands to be drawn from the researchers' community.

After soil chemical analysis, obtained result for the content of organic carbon and nitrogen in kg/ha shows 0.00, whereas potassium content is 55.20 kg/ha for a surface soil sample collected in the Panagarh forest patches under the Bardhaman Forest Division of West Bengal, the soil was collected in the depth of 15 cm and the bulk density of the soil is 1.3 gm/cubic cm, visibly the sampled soil is the admixture of Alfisol and lateritic combination, is it possible for the soil sampled in the natural forests lacking both organic carbon and nitrogen, though the nature of forest vegetation is quite normal in the sampling spot?

Organic carbon , is it Walkley C...and N is KMnO4 - N..??

I simply doubt , organic carbon and N is nil...in forest soils , be it laterite or Alfisols...

I think so, I will repeat analysis for that particular soil sample. Yes, analyzed in the the same methods for C & N

Checked yesterday the sampling spot from where this sample was collected which shows the content for C & N is 0.00 after analysis, the sampling spot is slightly elevated with not more than 15 cm from the forest floor and the that area is tiny one, maximum 9 sq ft area, except only that topographical difference, the rest of the characteristics for a conventional forest is normal including the vegetation pattern, now I think whether the concentration of C & N is influenced by that tiny elevation, where somehow the microbial biomass decomposition of litterfall is suspended either by withering of the dry litters or water is not stored to accelerate the microbial decomposition, I cannot find any other reasons beyond such exceptional results of C & N.

Any way, I will repeat the test again following the same standard methods.

Researchers recorded available nitrogen, phosphorus, and potassium in open spaces ranged from 34-19 kg/ha, 9.3-10.9 and 132-143 kg/ha respectively, whereas, the available nutrients NPK under forest vegetation cover varies from 38-192, 9.9-13.9, and 159-184 kg/ha respectively, but for a forest soil available NPK shows the ranges of 140 - 455 kg/ha, 19.49 - 95.82 kg/ha, and 166.50 - 205.58 kg/ha as per result obtained after chemical analysis with the standard methods, and in the same forest, content of nitrogen varies 140 kg/ha, 255 kg/ha, and 455 kg/ha in the three pedons of 200 m linear distance from the each spots which were selected at random for soil sampling, does the content of NPK obtained from the analysis reveal the normal ranges, and for what reasons soil nutrients show such fluctuations only with a distance of 200 m where the density and nature of vegetation remain almost the same in a same forest patches?

I dont think , you have to worry for these figures , such variations are bound to come by , since forest density , species and stand dictate so much . and , more importantly , these figures must coorelate with organic carbon content ....Yes , there is likelihood that even within 200m distance, soil fertility could vary so much . I dont know how did you carry out soil sampling ..??

4 Samples were collected in a natural terrestrial forest patch, and the distance in between each spot was 200 m, i.e. from the first sample to 4th sample the distance was approximately 600 m of a straight line.

Available nitrogen ranges from 140 to 455 kg/ha, and organic carbon ranges from 90 to 237.6 kg/ha, may I use the data for the preparation of an article?

Perfect data , you are getting but earlier you were saying , i am getting 0.00 kg/ha organic carbon and available N. ...

Yes that's true, that is sampled in the another forest patch under Bardhaman Forest Division, where a sample after analysis shows its organic carbon and available nitrogen content simply nil i.e. 0.00, I will repeat the analysis for that particular sample.