Research on Reasonability of the Use of a New Liquid-Phase Biological Product in Different Soils

A simulation experiment has shown that it is reasonable to use biologically active mixtures such as the liquid-phase biological products (LBP) as soil fertilizers. LBP produced by bioconversion of organic raw materials. The biological product in its composition contains a large quantity of the microflora, available phosphorus and potassium. On fine-grain soils demonstrated the greatest effect on LBP, which accumulate mobile biogenic components and show increasing biological parameters such as nitrogen soil mineralization and redox rate. The results of the regression analysis indicated strong relationships between individual values in different soils. It is significant that between K2O and P2O5 showed significant relationships for all soils. For fine-grain sod-podzol soils revealed consistently high and positive correlation coefficients between these indices. In fact, we observed a high stable level of responsiveness of these soils on the typical LBP indicators.


Introduction
One of today's mainstream agricultural trends (agricultural methods) is to use less mineral fertilizers and more up-to-date bioproducts and -fertilizers to improve soil fertility (Prasad et al., 2015;Kumar et al., 2014).Current agricultural technologies can provide both high-quality, environmentally safe agricultural products and less contaminated environment (Platonycheva, 2009;Chintala et al., 2013Chintala et al., , 2014)).The bacteria inserted into the soil with the bioproducts multiply actively and work, enriching the soil with nutrients and acting favorably on the natural microorganisms promoting mineralization of the soil's organic materials and forming a favorable background for plant growth (Gil et al., 2008;Rajesh et al., 2003).
Investigations conducted at All-Russian Research Institute of Reclaimed Lands (VNIIMZ) led to creating two types of original-composition bioproducts: LBP A and LBP FGW (Rabinovich et al., 2007).Both products have the same input components and technologies but different fermentation stimulators: deciduous tree ashes and flour-grinding wastes in LBP A and LBP FGW , respectively.Externally, LBPs are solutions containing 3% or less of dry materials and giving nearly no sediment in setting.Their acidity is very favorable -alkalescent, 8.0 or lowers (Rabinovich et al., 2009).Analyses of the composition and properties of these bioproducts showed they were highly biogenic, physiological and nutritive -to be widely used in national economy.One of the key aspects of using the LBP is introducing them as microbiological fertilizers into practical agriculture.The objective of this work is to study the reasonability of using different LBPs on different-grain-size sod-podzol soils by monitoring of their nutritive elements and salt content dynamics.
Placed in plastic boxes naturally moistened soil samples weighing 250 g.By calculation, each sample's moisture was adjusted to the field one optimum for the sod-podzol soil.We used the following basic fertilizers: peat (P), straw mixed with carbamide (S+C) and multipurpose compost (MPC) -equivalent in nitrogen doses (these will then be used abbreviations).References used no liquid-phase bioproducts.Table 1 shows the experiment design.LBP dose (0.4 l/m 2 ) was chosen experimentally from a series of doses (0.1-1.0 l/m 2 ) tested on the sandy-loam sod-podzol soil in a micro-field experiment.The experiment used a process LBP solution in concentration 1:30.The soil sample boxes were thermostated at t = 22 o С for three months.At the beginning, middle and end of composting were sampled, all samples for planned analysis.
A set of physicochemical and microbiological parameters (Zvyagintsev, 1991;Russian State Standards (GOSTs 26483-85, 26489-85, 26951-86, 54650-2011, 26213-91) was evaluated in the samples selected.Microsoft Excel and Stat graphics Centurion software were used for processing the data.Statistical analysis was carried out on two criteria: 1) Evaluated the significance of differences between the values obtained for each indicator in the dynamics of the composting process (definition of a significance level "p"); 2) Identify the relationship between the indicators (regression analysis -regression equations and correlation coefficient R).

Results and Discussion
The reaction of the different soils under study on LBP was evaluated through generalized biological parameters such as mineralization coefficients.The nitrogen mineralization coefficient (MC) is a standardized number of microorganisms feeding on mineral nitrogen versus the number of bacteria using organic nitrogen.
The sand soil (Figure 1а) showed the maximum average total MC when adding LBP of any type to the S+C soil (average increase was 73%).The P soils generally showed higher mineralization than the MPC ones.
The sandy-loam soil showed the LBP effect in practically all variants.Especially effective was LBP A with S+C (63% higher mineralization), whereas LBP FGW had a negative effect and lowered MC, but LBP FGW with MPC produced approximately three times higher nitrogen mineralization.
The light-loam soil showed noticeable effect on mineralization level on both P and MPC soils for LBP FGW only.
The S+C soil showed no LBP effect at all (the reference level was the top in the light loams).The medium-loam soil with each fertilizer (Figure 1b) showed no mineralization increase for each LBP type.
Generally, LBP caused a higher nitrogen mineralization level mostly in fine-grain soils such as sand and sandy-loam because those soils initially had lower MC and lower accessible nitrogen content.That is why the nitrogen mobilization was inevitable in those soils.
At the same time, the soil reaction on different LBPs was analyzed by redox rate (RR) evaluation (the redox rate is catalase versus dehydrogenase arbitrary-unit activity actually reflecting the intensity of general biological breakup and synthesis).
LBP A increased sand soil's RR for all soil fertilizers, especially effectively on P soils (RR grew by 67%).LBP FGW was effective among sand soils with MPC only: LBP FGW increased RR by 78%, LBP A with MPC increased RR approximately twice.However, not all the other soils showed this effect.
Consequently, the redox processes in the sand soil (featuring the lowest initial content of total carbon = 1.14%) proved to be the most sensitive to LBP.As well as for the mineralization coefficient (MC), in the poorest sandy soil intensified all processes -to accumulate nutritive elements there.The analysis of individual microorganism groups quite often shows a high reliable increase in their number compared to the reference.Therefore, the sand soil shows a reliable rise in the number of nitrogen-transforming microorganism (ammonifiers) -by 3.12 million/g (48%), р < 0.001, in the middle of the composting with the P soil and LBP A , that continued until the experiment end.Also, we observed a reliable rise in the number of amylolytic microorganisms: by 10.07 million/g (44%), р < 0.05 in the beginning of composting with MPC+LBP A , by 20.4 million/g (37%), р < 0.05 in the middle of the process with P+LBP FGW , and by the average of 29.4 million/g (32%), р < 0.05 with S+C and each LBP type.
The light-loam soil showed a reliable decrease in the number of ammonifying microorganisms for each LBP type, with P (excluding LBP FGW in the middle of composting) and with MPC (excluding LBP FGW at the end of composting).The light-loam soil showed a reliable rise in the number of amylolytic microorganisms in many cases: 1) In the beginning of composting with P+LBP FGW -by 9.3 million/g (35%), р < 0.01; 2) In the middle of composting with P+LBP A -by 19.19 million/g (66%), р < 0.01; 3) At the finish of the process with P+LBP FGW -by 13.59 million/g (79%), р < 0.001 and P+LBP FGW -5.75 million/g (62%), р < 0.01.
Individual groups of microorganisms showed a very active growth in the middle-loam composting with LBP.
Phosphate-mobilizing microorganisms showed interesting dynamics confirming substantial differences in reaction of different soils to LBPs.There was a reliable growth in the number of phosphate mobilizers in the sand soil in the beginning of composting with P (by 2.33 million/g (55%) р < 0.001 for LBP A and by 2.0 million/g (52%) р < 0.001 for LBP FGW ) -see Figure 2, a.At the finish of composting, the number of phosphate mobilizers grew for MPC+LBP A by 1.12 million/g (42%), р < 0.05.
The sandy-loam soil showed the best growth of the phosphate mobilizers with the bio product based on FGW, both for P and MPC.Every background of the basic fertilizer showed the growth of the microorganisms of this group in the beginning of composting: 1) For the background of P -2.68 million/g (87%), р < 0.05 with LBP A and 4.2 million/g (92%), р < 0.001 with LBP FGW ; 2) For the background of S+C -0.48 million/g (10%), р < 0.05 with LBP A and 2.66 million/g (39%) for р< 0.001 with LBP FGW ; 3) For the background of MPC, the average increase for each bioproducts was 3.64 million/g (69%), р < 0.001.
The end of the experiment showed a reliable increase in the number of the microorganisms mobilizing organic phosphates in the sandy-loam soil with P+LBP FGW -9.76 million/g (74%), р < 0.01, as well as with S+C+LBP A -5.05 million/g (59%), р < 0.01.
The effect of LBP on the development of the phosphate mobilizers in the light-loam soil occurred only for the S+C background, with each of the LBPs.A reliable increase in the number of the microorganisms was found in variants S+C+LBP FGW (3.04 million/g (47%) р < 0.01) in the beginning of composting, and S+C+LBP A (6.22 million/g (31%) р < 0.05) in the middle of the process.The end of composting showed a reliable decrease in the number of microorganism of this group in every variant of using the bioproducts.
A reliable growth of the number of the microorganisms mobilizing organic phosphates in the medium-loam soil (Figure 2,b) occurred only at the end of composting with P+LBP FGW -1.14 million/g (22%), р < 0.05, as well as for each bioproducts with MPC: 2.82 million/g (40%), р < 0.05 with LBP A , and with LBP FGW -almost 2.0 (32%), р < 0.01.a b Figure 2. Average total content of phosphate-mobilizing microorganisms throughout the entire composting of the sand (a) and medium-loam (b) soil: 1 -P+LBP A ; 2 -P+LBP FGW ; 3 -P; 4 -S+C+LBP A ; 5 -S+C+LBP FGW ; 6 -S+C; 7 -MPC+LBP A ; 8 -MPC+LBP FGW ; 9 -MPC Therefore, the most favorable conditions for soil microorganism activation were in the sandy-loam soil, which is confirmed by the frequency of the results suggesting a reliable increase in the microbiological parameters for the LBP variants over the reference.Because of the similar humus content in the sandy-loam and middle-loam soils, the frequency of reliable increases in the microbiological parameters of the latter was quite high too.
Observations on the dynamics of nutritive elements accumulation in the soils suggested that it was different from the increase in the number of individual microorganisms.The active accumulation of the nutritive elements occurred in low-humus soils, especially in the sandy one.The accumulation of mobile phosphates in the sandy soil in the course of composting was the maximum for each of LBP types with every background fertilizers.A reliable rise of phosphorus was observed with LBP A in the middle and at the end of composting.It was 3.4; 7.2; 6.5 -in the middle of the process and 7.7; 3.5; 2.6 -at the end (mg/100 g of soil, corresponding to P, S+C, and MPC, р < 0.01 or р < 0.001).The same periods for LBP FGW showed reliable differences for S+C only -the increase was 8.4 and 3.1 mg/100g of soil (р < 0.001).
The sandy-loam soil showed the maximum positive effect in phosphate accumulation with each LBP and MPC.
There was a reliable rise in the middle and end of composting, with an average increase over reference about 8.9 mg/100g (р < 0.01 in the middle) and 2.7 mg/100g (р < 0.05 at the end).
The middle-loam soil reacted to LBP with a lower Р 2 О 5 accumulation, compared to the other soils studied.The maximum LBP effect was shown with S+C background (~4% above the reference).In the beginning of composting, a reliable increase in mobile phosphorus compounds was found only with S+C+LBP A (1.6 mg/100 g, р < 0.05), at the end of composting -with S+C+LBP FGW (2.8 mg/100 g, р < 0.01), and with P+LBP A (2.3 mg/100 g, р < 0.01).
Research the content of mobile forms of potassium in the soil is not possible to detect the same as that of the active growth of mobile phosphorus.The sand soil showed the maximum effect of LBP A and LBP FGW on S+C (average rise over reference was 5.5 mg/100 g (11%), р < 0.01).The sandy-loam soil showed a slight effect of each LBP for both P and MPC, so that a reliable K 2 О increase was found only in the beginning of composting, P+LBP FGW -0.9 mg/100 g, р < 0.01.A noticeable reliable K 2 О increase caused by LBP FGW was observed in the light-loam soil, in the middle of composting with S+C (by 8.6 mg/100 g (10%), р < 0.001) and MPC (by 8.6 mg/100 g (7%), р < 0.001), whereas P background had a lower effect.At the end of the light-loam soil composting, we observed a reliable K 2 О rise over reference in case of S+C+LBP A -0.9 mg/100 g, р < 0.01.The medium-loam soil showed no LBP effect on mobile potassium accumulation for each background fertilizer.
All soils under study demonstrated a trend of nitrate nitrogen accumulation in the course of composting.In all cases, the effect lowered depending on the background fertilizer used S+C > MPC > Т.For example, the sandy-loam soil showed a more noted nitrogen accumulation effect with S+C and MPC (10-12%) versus 8%.
Along with the analysis of the results on individual physicochemical and microbiological parameters, we tried to reveal pair relationships among some of them by regression analysis.Revealing such relationships allowed evaluating the degree of influence / correlation between the factors under analysis.
In our case, the regression analysis was aimed at revealing the predominant factors shaping the nutritive value of individual soils.That is why only physicochemical parameters (Р 2 О 5 , K 2 О, NH 4 , NO 3 , pH) were considered as an independent variable (y).All different soils showed strong correlation between contents of mobile phosphorus and potassium (Table 2), potassium and nitrate nitrogen (Table 3).Biological factors had an effect on shaping the nutritive element contents, but only in high carbon content soils -sandy-loam and middle-loam ones (Table 4).
The regression analysis suggests that the nutritive value in the medium-loam soil depends considerably on the living phase.That is why the nutritive element accumulation has a positive correlation to the number of amylolytic and phosphate-mobilizing microorganisms.However, a high number of soil microorganisms not always reflect the level of general biological activity of the soil.Actually, generalized parameters such as RR and MC can be considered as the measure of such activity.As noted above, the medium-loam soil had low RR.Thus, the regression analysis validated earlier conclusions that the medium-loam soil has a minimum need for the nutritive element increase, because it has initially the maximum MC providing the nutritive value of this soil.
That is why the medium-loam soil is less sensitive to LBPs (an inhibited or delayed effect).
At the same time, accumulation of the nutritive value in the finer-grain soils is considerably caused by addition of accessible nutritive elements from background fertilizers and LBP.In this case, the regression analysis shows a close relationship of each variable analyzed (y) and dependent variables (x) which are the changing variables characterizing the soil nutrition values from different points of view.Therefore, it is quite natural that the sand soil gives the highest general biological parameters (MC and RR) reflecting active disintegration and synthesis, accumulating nutritive elements (especially mobile potassium and exchange phosphorus).

Conclusion
Thanks to LBP, the sod-podzol soils form a favorable background of nutritive elements accessible to the plants.Moreover, this process is most effective in poor (low-humus) soils and fine-grain soils.That is why using LBP for fine-grain soils (first of all, the sand soil) gives an immediate effect.LBP reliably elevates the mobile phosphorus and demonstrates the same favorable trend for other nutritive elements.Coarse-grain and humus-rich sod-podzol soils demonstrate a different LBP effect.They do not accumulate Р 2 О 5 , but increase reliably the number of microorganisms of the widest variety of physiological groups.The sandy-loam and light-loam soils show no definite position within the soil series, because their organic material is substantially different.That is why the sandy-loam soil (total carbon = 1.9%) sometimes shows features of the medium-loam one (total carbon = 1.8%), and its reaction to LBP becomes unpredictable.
The results of the regression analysis indicated strong relationships between individual values in different soils.
It is significant that between K 2 O and P 2 O 5 showed significant relationships for all soils.For fine-grain sod-podzol soils revealed consistently high and positive correlation coefficients between these indices.In fact, we observed a high stable level of responsiveness of these soils on the typical LBP indicators.
Thus, this simulation experiment showed that it was reasonable to use LBP on fine-grain sod-podzol soils as an effective fertilizer.

Table 1 .
Experiment design

Table 2 .
Regression equations and correlation coefficients reflecting correlation between Р 2 О 5 and K 2 О in different soils

Table 3 .
Regression equations and correlation coefficients reflecting correlation between K 2 О and NO 3 in different soils

Table 4 .
Regression equations and correlation coefficients reflecting correlation between biological factors and nutritive element accumulation in different soils