1

Pannon University Georgikon Faculty of Agriculture

Graduate School of Plant Production and Horticultural Studies

Principal:

Dr. Richárd Gáborjányi

SUMMARY OF PhD THESIS

The investigations of some factors of soil fertility in an organic and

inorganic long-term experiment

Written by:

László Bankó

Supervisor:

Dr. Sándor Hoffmann

KESZTHELY

2008

2

PREFACE, OBJECTIVE OF THE STUDY

The significance of the subject of the dissertation

In the past decades in the agriculture as only aim the achievement of yield increase was

formulated. The industrial agriculture marked out the reach of maximal yield by all means,

which implied the increase of external imputs and pesticides. As a result of the application of

large quantity of fertilizers together with the destructive effect of machines the process of soil-

degradation has enhanced. According to the new principles yield optimum that can be realized

economically and effectively under the given circumstances is to be designated (Pepó 1999).

Novel approach is needed so as to ensure the maintenance of the quality of soil and water

(Németh et al. 2002; Van Cleemput et al. 1997). The aim of sustainable agriculture is to

maintain high yields with minimal environment pollution (Körschens 2002). Due to the fact

that world population is expected to increase by 2.6 billion by 2050 (Cohen 2003) intensive

farming and sustainability are also consequently imperative with regard to the future

(Sherwooda and Uphoff 2000).

Long-term experiments supply us with valuable information on sustainability and

environmental damage (Powlson and Poultron 2003). The role of EUROSOMNET, an

organization encompassing Eropean long-term experiments, is to promote the application of

practically usable informations that can be gathered and learnt from trials.

Climate change has also been an actual problem since climatic elements exert great

influence on the content and composition of soil organic matter. By rise of temperature soil

organic matter decreases (Davidson et al. 2000; Fang et al. 2005), and the labile organic

fraction will face a stronger reduce (Knorr 2005). With decreasing humidity of soil

decomposition in dry soils is still of significant magnitude (Szegi 1988). The maximum of

microbial biomass coincides with the optimum moisture content of cellulose-decomposition,

which in our country can only be experienced at low temperature (Bhardwaj and Novak 1978).

Relationship of temperature and decomposition is not proportionate. Cellulolysis is most

significant at 30°C, but there is no large difference between 20 and 30°C. In our country

temperature is not a limiting factor (Szegi 1988).

Cultivation is a violent intervention in the life of the soil, wich is followed by a considerable

reduce of soil fertility and soil organic matter (Kismányoky 1993; Nyíri 1993). By means of

reasonable cultivation and plant production strategy further loss of organic matter can be

avoided, even it’s quantity can be increased (Haynes and Beare 1997; Stefanovits et al. 1999;

Szőcs és Szőcs-né 2005). The impact of mineral fertilization and organic manuring on soil

organic matter is different which has already been pointed out by several researchers. With

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mineral fertilizers quantity of organic matter can be maintained (Hoffmann and Kismányoky

2001; Jenkinson 1992; Németh 1996; Tilman 1998), with farmyard manure can be increased

(Hoffmann és Berecz 2007; Lönhardné és Németh 1992; Németh 1983). Higher yield can be

reached by using fertilizers of mineral active agent and even more by combination of mineral

fertilizers and farmyard manures, as compared to farmyard manuring. (Garz et al. 2000;

Kismányoky 1993; Sarkadi 1967).

Soil organic matter can be divided into a stable and a labile part. Quantity of the labile

fraction directly refers to the fertility of the soil. As easily decomposable matter it supplies

available nutrients and energy to plants and the microorganisms of the soil, so it is one of the

most important of those factors that determine soil-fertility. As it gives notice of changes of

soil organic matter and is linked to state of cultivated soil, thus it can be used as indicator in

investigating soil-fertility, in monitoring of increase and reduce of soil organic matter

(Körschens 1980; Körschens et al. 1998).

In the past soil fertility investigations were based upon measurement of TOC. However, due

to the slow change of soil organic matter detecting the direct of change required a longer

period (Johnston 1991; Kismányoky 1993). Measurement of quantity of labile organic C –

meaning HWC and MBC – offers a solution. Their determinations makes prediction of long-

term trends possible before we could sense detectable change in the quantity of total organic C

(Körschens and Schulz 1999).

In the investigation of the impact of climate change a reduce of labile fraction can only be

proven by long-term study of the selected treatments or soils that are in natural state.

Both German (Körschens and Schulz 1999) and Anglo-Saxon researchers (Ghani et al.

2003) investigated the labile fraction. In Germany determination of HWC has been used by

agricultural technical advisory system. We carried out our investigations according to the

German method. My researches may possibly contribute to the application of this method in

Hungary.

The objective of the dissertation is to determine in the 40 year-old long-term experiment:

• the quantity of HWC and MBC in the treatments, their determination how and in what

extent can be used for monitoring soil fertility caused by the treatments;

• as a consequence of the organic and inorganic treatments what kind of changes happened

in the chemical parameters of the soil fertility;

• as a result of the long-term treatments the extent of the deviations evolved in the crop

results among the treatments;

• the organic carbon fractions’ relation with the studied soil-parameters and the best

indicator of soil fertility, the yield.

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MATERIALS AND METHODS

Introduction of the long-term experiment

The organic and mineral long-term field experiment was set up by Géza Láng in 1963 on

Ramann brown forest soil (Eutric cambisol) in Keszthely with 15 treatments in 4 replications

on 98 m² plots with two crop sequences. The soil was sandy loam, the ploughed layer of which

had a low humus content, poor supplies of phosphorus and moderate supplies of potassium.

In rotation ‘A’ farmyard manure doses and its mineral equivalents together with the

combinations of these, while in rotation ‘B’ the mineral doses plus corn-stalk and / or wheat

straw treatments can be compared. The selected treatments and the composition of the

rotations can be seen in Table 1 and Table 2, respectively.

Table 1. Selected treatments from the long-term field experiment. The farmyard manure- and the

mineral fertilizers of equivalent active agent content (Rotation ’A’), and the NPK-, + ploughed-in plant residue treatments (Rotation ’B’)

Applied fertilizer (kg/ha/year) Selected treatments Abbreviations

N P2O5 K2O Total

Rotation ’A’

1 Control ContA 0 0 0 0

8 1 farmyard manure (35 t/ha/5y) 1# 44 38 49 131

10 2 farmyard manure (70 t/ha/5y) 2# 88 76 98 262

12 3 farmyard manure (105 t/ha/5y) 3# 132 114 147 393

4 1 eqivalent NPK 1eqv 44 38 49 131

11 2 eqivalent NPK 2eqv 88 76 98 262

13 3 eqivalent NPK 3eqv 132 114 147 393

Rotation ’B’

1 Control ContB 0 0 0 0

7 NPK NPK 172 118 181 471

8 NPK+corn-stalk NPK+c 172 118 181 471

12 NPK+ corn-stalk +wheat straw NPK+c+w 172 118 181 471

Table 2. Composition of Rotation ’A’ and ’B’

Period Crop sequence

Rotation ’A’

1963-1985 sugar beet – maize – maize – winter wheat – red clover 1985-2003 sugar beet – maize – maize – winter wheat – winter wheat 2003 - potato – maize – maize – winter wheat – winter wheat

Rotation ’B’

1963 - potato – winter wheat – winter wheat – maize – maize

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Sampling

The first three replications of the rotations and the grassy area (0-25 cm) adjacent to the

field-experement was sampled in October, in 2004, 2005, 2006. Both HWC and MBC

determination was carried out each year, while those of TOC and HWN only in 2005. Analysis

of the labile fractions was made from fresh, that of the TOC from dried, ground soil-samples.

The available P and K, the pH was measured in the laboratory of the Department of Land Use

in 2000, 2002 and 2004.

In case of the labile fractions (HWC, MBC), due to the big standard deviations, it is

important to take into considerations the effect of the given year’s weather, the prior-crops and

the given cultivated plant. There were winter wheat in both rotations in 2003. In rotation ’A’

and ’B’ in 2004 corn, in 2006 corn and potato were raised. The residual effect of corn and

wheat was studied in rotation ’B’. Corn-stalk was incorporated in 2004 and 2005, while corn-

stalk was ploughed in in the preceding two years.

Studied parameters

Hot water carbon

Determination of hot water soluble organic matter was done according to the method of

Körschens and Schulz (1999). As it has not been widely known in Hungary, we can speak of a

new method. It was tried out, then successfully applied in the comparative analysis of the

selected treatments.

20 g soil was boiled in 100 ml distilled water for one hour. The boiling water dissolves part

of the easily decomposable fraction of the organic matter. After 60 minutes the reaction was

stopped by placing the solution in cold water. We let the solution cool. After 5 drops of

MgSO4 solution the suspension was centrifuged (3500 rpm 10’) and the supernatant was used

thereafter. To 10 ml solution 10 ml cromsulphuracid was added. After 20 minutes, 125 °C

destruction and cooling, 20 ml destilled water was added to the solution. In presence of

phenilantranil acid indicator titration was done by using 0.1 M Fe(II)-diammoniumsulphate

(Mohr’s salt).

Hot water nitrogen

Determination of the hot water soluble nitrogen (HWN), apart from smaller modifications,

was carried out according to Klejdahl (Buzás et al. 1988). To 10 ml solution placed into test

tubes, spatulafull reduced iron, 2 ml sulphuric acid, and 4 ml salicylic-sulphuric acid were

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added. Following the violent reaction a spatulafull of titanoxid catalyser started the release of

N during the 60 minutes, 380°C destruction. After adding concentrated NaOH the arising

ammonium was driven through 2% boric acid by using water steam.

Microbial biomass carbon

Microbial biomass (MBC) was analysed according to the fumigation-extraction method

(Vance et al. 1987). From each soil samples a fumigated and a non-fumigated determination

was carried out. As the effect of the cloroform the cell membranes of the microorganisms were

disintegrated, their organic matter got into the soil. From the non-fumigated sample only the

organic matter of the soil was extracted by the K2SO4-solution. Instead of the original 0.38

conversion factor the difference of the two measurement was divided by the other most

frequently used 0.45 value (Wu et al. 1990).

In case of the fumigated samples the extraction was preceded by fumigation. 20 g soil was

put into a desiccator for 24 hours. As a consequence of the vacuum the cloroform vaporized,

and it’s fume saturated the soil samples. The unfumigated samples were shaken (60 rpm / 45’)

in 80 ml 0.5 M K4SO4 solution and then the extracts were filtered. 8 ml extact was poured into

an Erlenmeyer flask, then 2 ml 66.7 mM K2Cr2O7 solution and 15 ml concentrated sulphuric

acid/phosphorous acid 2:1 medley were added. After cooling of the solution 20 ml destilled

water was poured in the flask for dilution. In presence of 1/40 ferroin indicator the titration

was carried out using 40 mM Mohr’s salt.

Total organic carbon

Soil orgaic C was measured using Turin method (Gyıri et al. 1994). 10 ml 0.4 N dicromate

was added to 0.2 g soil. During 5 minutes boiling the organic matter was oxidized. After

cooling the solution was diluted with distilled water to 100 ml. After adding 20 drops

concentrated H3PO4, in presence of 10 drops vitriolic diphenil-amine indicator the solution

was titrated with 0.2 N Mohr’s Salt.

Available phosphorous and potassium

The available phosphorous and potassium content were determined according to Egner et al

(1960). The determination was done with 3.75 pH ammonium lactate-acetate extractant.

Acidity

Reaction of soil, made out of air-dried soil samples, was measured in 1:2.5 soil: KCl neutral

salt solution suspension (Buzás et al. 1988).

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Statistical evaluation methods

Comparing the data of the studied parameters analysis of variance (ANOVA), as post hoc

test LSD and Duncan test were performed. The different letters on the figures mean significant

differences. In agricultural statistics least significance difference at α level of 0.05 is used.

Moreover correlation and regression analysis were accomplished. The statistical tests were

carried out by means of SPSS 9.0 for WINDOWS and MS Excel program.

RESULTS AND INTERPRETATION

From among the results presented in the dissertation only the more important ones are reviewed.

Hot water soluble carbon in the treatments

As an effect of the 4 decade long plant production significant differences evolved among

various treatments. In rotation ’A’ in the plots of the mineral fertilization and farmyard

manuring the values increased by 13 and 45% as compared to the control. Farmyard manuring

resulted in more favourable HWC values at every active agent level. In the order of the doses

this denoted 24, 21 and 49% greater HWC. The medium and the large farmyard manure doses,

with the exception of the small one and the mineral treatments, led to significantly higher

HWC values (LSD5%=52.69). Compared with Treatments 1# and 2# Treatment 3# resulted in a

significantly higher value, proved to be the most favourable treatment (172%).

In rotation ’B’ in all three treatmets significantly greater HWC values were determined than

in the soil of the control (LSD5%=43.9). Ploughed-in plant residues had a slightly greater

impact (10%) on HWC level as compared to Treatment NPK. Due to their long-term impact,

their favourable effect on the hot water extractable fraction was verified (Figure 1).

'A' vetésforgó

0

100

200

300

400

500

600

KontA 1# 2# 3# 1ekv 2ekv 3ekv

HWC (mg/kg)

a,b b,c c d a a,b,c a,b,c

'B' vetésforgó

0

100

200

300

400

500

600

KontB NPK NPK + k NPK + k + b

HWC (mg/kg)

a b b b

Figure 1. HWC in the treatments (2004-2006)

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Hot water soluble carbon, soil organic carbon and soil-fertility

Körschens and Schulz (1999) categorized the soils according to their organic matter

supplies, on the basis of HWC measurements, by processing the data of numerous Central

European rotation and monoculture long term experiments. The basis of the relationship was

that together with the growing HWC soil organic matter and soil-fertility also icreased. HWC

concentrations of our experiment could be placed within the frame of 200-400 mg/kg. The 200

mg/kg lower limit value indicated reduction of soil organic matter, an exhaustion of soil-

fertility. The 400 mg/kg upper limit indicated luxury supply, environment-contaminating

effect of the readily decomposable organic matter. The control, mineral and farmyard manure

treatments gave 250, 281 and 361 mg/kg HWC values on average, which were 40, 32 and 21

mg higher than the means reported by the German authors.

Proportion of hot water soluble carbon to total organic carbon

HWC formed 3.38% part of TOC. In the literature similar, 3-5% values were reported

(Kubát et al. 2004; Leinweber et al. 1995; Weigel et al. 1997). As an influence of the farmyard

manure doses the figures proportionately increased. Farmyard manuring was more favourable

at all three active agent levels than the mineral fertilization. Within the mineral fertilization

Treatment 2eqv gave the highest value. Farmyard manuring, mineral fertilization and plant

residue treatments gave 3.6, 3.16 and 3.45 % value. In case of the grassy area 4.9% rate was

stated as 669 mg/kg HWC and 1.36% TOC were determined. As compared to the treatments

TOC gave an increase of 142%, while HWC on average a more significant 209%.

Accumulation of labile fraction was more intensive. By discontinuing cultivation primarily the

increase of the labile fraction was observable.

Labile organic C

By multiplying HWC/TOC rate with 15 the rate of labile organic C can be given in relation

to the total organic C (Schulz 1997, 2002, 2004). The labile fraction represented a more

significant part in the organic treatments. In the farmyard manuring it increased from 49% to

60%. In the stalk and straw treatments 52%, while in the mineral treatments 43-52% were

established. In the unmanured parcels’ soil organic matter was represented by the stable

organic C (humus), which changeed very slowly during the plant production (Kismányoky

1993a; Körschens 2002).

As a consequence of the 4 decade-long plant production in the control plots TOC changed

only to a very small extent. The labile part calculated on the basis of the HWC here was the

smallest, 43%. In Treatment 3# and the grassy soil the value rose up to 60 and 74%.

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Relation of hot water soluble carbon and nitrogen

HWC and HWN were determined together from the samples taken in July and October in

2005. HWN showed temperal dynamism, the measurement in October gave an increase of

23%. Expresed in numbers these two measurement meant 30.3 and 36.4 mg/kg means. In

rotation ’A’ the treatments led to statistically proven higher HWN values (LSD5%=6.67). The

mineral fertilization was more advantageous at every active agent level. Treatments 3eqv

proved to be the most favourable one.

In case of HWC also the October measurement gave higher values. The 374.5 mg/kg mean

gave an increase of 48% compared to the July measuring. Thus HWC could be characterized

by a higher degree of change. We could conclude that the N in the form of readily

decomposable organic bonds was intensively taken up by plants in the second part of the

vegetative season. HWN/HWC rate was 8.4 and 10.3 in July and October.

Microbial biomass carbon in the treatments

The effect of the growing active agent is well pronounced in the concentration values. The

small and medium farmyard manure doses had smaller impact than the controll treatment,

however only Treatment 1# deviates significantly (LSD5%=72.2). The higher value of the

control is likely caused by the effect of the year, prior crop and nutritional stress (Juszczuk et

al. 2004; Liebersbach 2004; Nyíri 1993a; Rajkainé 1999). Mineral treatments meant 31 and

30% higher MBC concentrations as compared to the farmyard manuring and the controll.

Treatment 2eqv was of the most advantageous impact (48%), significantly only this and

Treatment 1eqv differed from the control. The large quantity mineral fertilizers (3eqv, NPK)

had strong negative impact on the microbial biomass.

In rotation ’B’ the ploughed-in plant residues, relative to the control and the NPK

treatments, gave an increase of 30% and a slight, non-sisnificant increase of 12%. The effect

of the treatments was mathematically proven (LSD5%=72.9) (Figure 2).

'A' vetésforgó

0

100

200

300

400

500

600

KontA 1# 2# 3# 1ekv 2ekv 3ekv

MBC (mg/kg)

b,c a a,b c,d d,e e b,cd

'B' vetésforgó

0

100

200

300

400

500

600

KontB NPK NPK + k NPK + k + b

MBC (mg/kg)

a b b b

Figure 2. MBC in the treatments (2004-2006)

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Proportion of microbial biomass carbon to total organic carbon

MBC comprised 4.3% of TOC. Farmyard manure doses proportionatelly increased it (2.7-

3.0-3.7%), but non of them reached the value of the control. In the fertilized plots – just like in

case of MBC – greater value was determined. Treatment 1eqv and 2eqv led to exceedingly

high figures. Within all of the treatments also 2eqv was the most advantageous one. In case of

HWC/TOC rate 2eqv yielded the highest % value as well, however only in the mineral

fertilization. As a consequence of larger mineral doses (3eqv, NPK) a decrease

of MBC/TOC rate was observed. Farmyard manuring, mineral fertilization and plant residue

incorporation meant 3.1, 4.6 and 3.3%.

In case of the grassy area 4.7% was calculated. TOC and MBC was 1.36% and 644 mg/kg.

The detected increase of TOC was 142% but of the MBC was 187% compared to the mean of

the selected treatments. Therefore MBC also verified the greater degree of accumulation of the

readily decomposable organic fraction.

Total organic carbon in the treatments

As a consequence of the treatments we could observe the accumulation of TOC, as it rose to

0.96% from the initial 0.87% value. A linear proportion was established among the active

agent content, organic inputs and TOC content.

In rotation ’A’ the Treatments controll and 1eqv denoted the smallest TOC concentration.

Farmyard manuring had a more essential impact on TOC accumulation. There were significant

differences in both treatment types between the single dose as compared to the triple one

(LSD5%=0.076). 1eqv and 2eqv were of negative and neutral effect, while 3eqv resulted in a

more significant increase (9%).

In rotation ’B’ the ploughed-in wheat straw and corn-stalk as well as Treatment NPK has

led to an increment of humus. Only the organic treatments meant significant deviation from

the control (LSD5%=0.148).

The effect of the organic treatments had a more favourable, essential impact on organic

matter increase, whereas the small and medium mineral fertilizer doses proved to be

applicable for maintaining humus level (Figure 3).

According to the analysis of the grassy area, in the soil not cultivated since the set up of the

long-term field experiment (1961) TOC grew at a significant rate. It represented 1.36% TOC

which agreed with 0.49% absolute value increase. Discontinuing cultivation issued in 156%

relative TOC improvement.

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'A' vetésforgó

0,00

0,25

0,50

0,75

1,00

1,25

KontA 1# 2# 3# 1ekv 2ekv 3ekv

TOC %

a b,c c,d d a a,b b,c

'B' vetésforgó

0,00

0,25

0,50

0,75

1,00

1,25

KontB NPK NPK + k NPK + k + b

TOC %

a a,b b b

Figure 3. TOC in the treatments (2005)

Between 1961-1983 the TOC differences evolved in proportion to the applied active agent

levels. Organic C accumulation of a great extent, with the exception of controll and 1eqv, was

characteristic of this period (107.6% on the average). The small, insignificant TOC reduction

detected in the control plots can be explained with the absence of treatments, together with the

yearly abstraction of nutritious elements in the form of yields and aboveground plant

materials. The effect of the small mineral fertilizer dose was inadequate for conserving TOC

level. The medium dose (2eqv) had a more adventegeous impact, while that of the large one

(3eqv) triggered a significant growth. As compared to Treatment NPK incorporating corn-

stalk was not humus improver, however the joint incorporation of corn-stalk and wheat straw

was twice as effective as that of the large dose of farmyard manure (3#), hence was regarded

as one of the most advantegeous treatment.

Between 1983-2005 intensity of TOC increase ebbed (102.2% on the average). Reduction of

TOC accumulation was measured in the large quantity of mineral (3eqv, NPK) as well as of

organic (3#, NPK+c+w) treatments. However, significant TOC growth could be observed in

the small quantity mineral and organic treatments. The explanation is that increase of TOC can

be descripted by logarithmic function.

In rotation ’A’ in the control treatment TOC remained close to its former value, it just

slightly grew. In rotation ’B’ TOC at first significantly increased then decreased in the next 22

years. This could be explained by the past and the heterogenity of the field. The efficiency of

plant residues were commensurable to that of farmyard manuring. It represented a greater

value in this period too (1.05 and 1.10%).

It can be stated that monitoring the quantitative and temperal dynamics of humus content

needs longer trial period. There is a need for comparison between periods and treatment types

so that we gain real picture on organic C change. The reciprocal relation between larger N

doses and TOC values can only be stated by comparing the two 20 years old period.

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Crop yields analisys of the examined period

According to our crop yields all treatments resulted in significant deviations as compared to

the control. Treatments 2eqv and 3eqv gave significantly higher yield than Treatment 1eqv

(LSD5%=0,69). The farmyard manuring and the mineral fertilization had an influence of 143%

and 164%, respectively. Whereas the effect of organic manuring was linear with the rising

doses, at Treatment 2eqv the yield curve reached its plateau, so increase in nutrients did not

affect further yield excess. Compared to Treatments NPK the effect of the ploughed-in plant

residues proved neutral or negative. In case of potato and corn negative and neutral effect

could be separated. As a consequence of Treatment NPK+K+B, on the average of the three

years, crop yields was severely reduced (Figure 4).

'A' vetésforgó

0

2

4

6

8

10

12

KontA 1# 2# 3# 1ekv 2ekv 3ekv

Term

és (t/ha)

a b b b b c c

'B' vetésforgó

0

2

4

6

8

10

12

KontB NPK NPK + k NPK + k + b

Term

és (t/ha)

a c b,c b

Figure 4. Crop yields in the treatments (2004-2006)

Available phosphorous and potassium in the treatments

At the initiation of the experiment AL-P2O5 and AL-K2O concentrations were 27 and 135

mg/kg, respectively. As a result of the continuous farmyard and mineral manuring the low

phosphorous and the medium potassium level significantly increased.

In case of available phosphorous Treatments 2# and 2eqv already gave significantly greater

values relative to the reference control (LSD5%=39.2). The mineral fertilization led to higher

values at all three active agent levels as compared to the farmyard manure doses. Significant

difference was only proven in relation of Treatments 3# and 3eqv. In rotation ’B’ the

treatments gave significantly higher values in comparison to the control (LSD5%=31.2). The

organic treatments slightly differed from each other (Figure 5).

In case of available potassium also significant differences evolved between the treatments.

There were no mathematically proven differences between the farmyard manure doses and

mineral treatments of equivalent active agent content. The effect of the largest manure and

mineral doses – at LSD5%=25.0 mg/kg – significantly differed from that of the other

13

treatments. In rotation ’B’ the treatments did not lead to proven differences (LSD5%=42.8)

(Figure 6).

'A' vetésforgó

0

50

100

150

200

250

KontA 1# 2# 3# 1ekv 2ekv 3ekv

AL-P

2O

5 (mg/kg) a a,b b,c d a,b c,d e

'B' vetésforgó

0

50

100

150

200

250

KontB NPK NPK + k NPK + k + b

AL-P

2O

5 (mg/kg) a b b b

Figure 5. AL-P2O5 in the treatments

'A' vetésforgó

0

50

100

150

200

250

300

KontA 1# 2# 3# 1ekv 2ekv 3ekv

AL-K

2O (mg/kg) a a a b a a b

'B' vetésforgó

0

50

100

150

200

250

300

KontB NPK NPK + k NPK + k + b

AL-K

2O (mg/kg) a a a a

Figure 6. AL-K2O in the treatments

Acidity in the treatments

In 1961 7.3 pH KCl was determined, which decreased, but not significantly, to 6.86 pH as a

result of the 40 years old treatments. Between treatments significantly proven differences were

determined (LSD5%=0.295). In rotation ’A’, the deviation of the smalles and greatest pH value

treatments, the control and 3#, was significant. Farmyard manuring proved to be having

favourable effect on the reaction of the soil, neutral pH has been maintained. The mineral

treatments did not differ significantly from the control. By increasing the NPK dose to its

triplicate did not even lead to detectable pH decrease. The reaction was around 6.8 pH. In

rotation ’B’ the treatments did not exert significant effect on the reaction. The ploughed-in

plant residues gave slightly greater pH value as opposed to the only mineral treatment (Figure

7).

14

'A' vetésforgó

6,0

6,2

6,4

6,6

6,8

7,0

7,2

7,4

7,6

KontA 1# 2# 3# 1ekv 2ekv 3ekv

pH KCl

a a,b b a,b a,b a,b a,b

'B' vetésforgó

6,0

6,2

6,4

6,6

6,8

7,0

7,2

7,4

7,6

KontB NPK NPK + k NPK + k + b

pH KCl

a a a a

Figure 7. pHKCl in the treatments

NOVEL SCIENTIFIC RESULTS

1. In the 41st–43rd year of our long-term experiment, after the sampling of the selected

treatments, in the course of the determination and evaluation of HWC and MBC - as easily

decomposable organic fractions - I came to the conclusion that the concentrations were in

close relationship with the applied active agent levels. The four decade-long treatments

exerted significant effect on the quantity of the labile organic fractions in the soil.

2. The mineral and farmyard manure treatments gave 13 and 45% higher HWC values, as

compared to the control. Incorporating plant residues denoted slightly, just 10% higher

HWC level in proportion to the mineral treatments. The ploughed-in organic materials, due

to their long-term effects, had favourable impact on the HWC level. HWC concentrations

were directly proportional to the applied inputs. Negative relationship were only observable

in case of large mineral doses. HWC/TOC rate were 3.3% on average. The rate was the

smallest in the control (2.9%), the largest in the large farmyard manure dose (4.0%). The

increasing doses enhanced, to a larger extend, the HWC than the total organic C values,

which was also expressed in the rate of the two fractions.

3. Soils can be grouped according to their organic matter supplies on the basis of HWC

measurements. High HWC values indicate an accumulation of humus and andvancement of

soil fertility, while low values a reduction of humus and soil-fertility. The unmanured parcel

15

can be characterised with around 200, the large farmyard manure dose with 400 mg/kg

HWC values. The lower limit value points to the exhaustion of soil fertility, the upper value

to the environment-contaminating effect of the large quantity organic materials.

4. Contrary to HWC, MBC values were better influenced by mineral fertilization (130%),

while farmyard manure resulted in a level consistent with the control (99%). MBC/TOC rate

was 4,3%, the values ranged from 2.7 to 5.3%. On the average, the farmyard manure,

mineral and plant residue treatments represented 3.1, 4.6 and 3.3%, respectively. Among all

the treatments the medium mineral fertilizer dose (2eqv) gave the highest MBC (463 mg/kg)

and MBC/TOC (5,3%) value. The mineral fertlizer dose (3eqv) had negative impact on both

parameter (363 mg/kg, 3.3%). Between MBC and Cext reciprocal relation was observed: if

MBC rose, Cext decreased, and vica versa. MBC and Cext gave medium, negative correlation

(r=-0,65, n=21). The significant, negative correlation confirmes that Cext denotes that

utilisable, easily decomsosable organic fraction, which is consumed by the microorganisms

during their growth.

5. TOC values were also increasing with the doses. Farmyard manuring and the

incorporation of plant residues gave 12 and 12% higher TOC values as compared to the

mineral fertilization. The TOC analisys of the 40 years long experiment proved the mild

raise of total organic C, the seperation of the treatment-effects in the 22. year’s measurement

of the field-experiment. Comparisation of the measurements of the two and the four decade

comfirmed a reduction of intensity of humus-accumulation, which were also realised on the

average of the treatments, in the large mineral and organic imputs.

6. The smallest and the highest pHKCl values were determined in the control (6.71) and

the medium (2#) and large dose farmyard manure (3#) treatments (7.04 and 6.96). The

impact of Treatment 2# significantly deviated from the control. The soil of the controll plots

was slightly acid. Both farmyard manuring and ploughed-in plant residues had beneficial

effect, the acidity remained at neutral pH. Triplicatig the mineral fertilizer dose did not even

lead to a reduce in acidity, the pHKCl was around 6.8.

7. Soil-fertility is best expressed by the yields. Between the nutrient-supply and the yield-

values a close correlation was proven. The increasing active agent doses exerted significant

effect on the available phosphorous and potassium concentration of the soil, via this on the

increase of the yields. Mineral fertilization led to 21% higher yield-level as compared to

16

farmyard manuring. The large mineral fertilizer dose (3eqv) as well as the joint-

incorporation of the corn and wheat remnants proved to be yield-reducing compared to the

medium dose (2eqv) and Treatment NPK, respectively.

8. HWC can be used for the preliminary detection of TOC’s changes, because a gain of

soil organic C happens through the labile fraction. HWC is an more suitable indicator, than

the biological parameter MBC, since so high temporal and spatial variances are

uncharacteristic. TOC changes rather slowly, it does not react quickly to the impacts

affecting soils. Among the studied chemical parameters TOC, AL-P2O5 and AL-K2O, and

the best indicator of soil fertility, the yield, have also resulted in the closest correlation with

HWC.

RECOMMENDATIONS FOR FURTHER RESEARCH

Establishing more reliable, exact relationship between the studied chemical properties of

soil as well as the best indicator of soil fertility, the yield require a long-term measurement

series. For this reason, I suggest the continuous, many-year examination of HWC and other

soil parameters reflecting soil fertility.

MBC is characterized by considerable spatial and temporal fluctuations, therefore its

applicability is questionable - it requires further investigation. Neither the proper conversion

factor nor the soil: K2SO4-rate were determined in the different treatments during the

investigation of the microbial biomass. We worked with the values recommended by the

literature. In case of both labile C fractions use of C-analyser determination would be

necessary to compare with the values of the titraton.

Determination of HWC could be used in researches related to climate change. By the raise

in temperature the organic C in our soils reduces. Measurement series spanning a longer

period are needful in the selected treatmets, or monitoring of uncultivated, unmanured natural

soils is recommended.

17

RECOMMENDATIONS FOR PRACTICAL PURPOSES

On the basis of the results of the study it could be stated that the mineral fertilization gave

21% higher yield level compared to the farmyard manuring. The deviations changed according

to the active agent levels (9, 31, 22%), the yield surplus was significant. The fertility of the

soil can only be preserved, even enhanced by the use of mineral active agents. The increase of

the medium mineral dose (2eqv) did not lead to an increase of yield, but directly to a reduce of

that, which in case of potato in 2003 was significant (2.3 t/ha), while in case of corn in 2004

and 2005 was of small degree (0.5 and 0.3 t/ha). However, calculated with plough-land size

the loss seems considerable. In case of potato the ploughed-in corn and wheat residues caused

significant yield decrease (-1.2 t/ha) as compared to Treatment NPK.

Nutrition demand is different for each plant, therefore in case of potato the application of

lower active agent and the omission of plant residue treatments is suggested. In case of corn

Treatment 3eqv and NPK+c+w had neutral effect. Due to the culmination of the yield curve,

the small yield decrease as well as economical considerations, at most the use of Treatment

2eqv would seem expedient in this case too.

In case of available phosphorous Treatment 3eqv, in case of potassium Treatment 3# meant

suitable state of supply. Thus, nutrient supply (input) exceeded the extraction (output) side, the

quantity of P and K extracted with yield. Treatments 2eqv, 2# and 3# were characterized by

medium P degree of supply, Treatment 2eqv and 2# were characterized by medium K degree

of supply. The soils were well filled up with nutritives. Exceeding medium supply is to be

avoided, not reasonable, because it leads to yield decrease and uneconomical too.

The organic treatments were more favorable to the pH, however mineral fertilization did not

reduce it significantly either. Triplicating the active agent the pH KCl did not fall below 6.8.

Therefore, increasing soil fertility with mineral fertilizers had no adverse, acidifying effect.

With liming this slight acidification can even be abolished.

HWC proved to be a more suitable indicator than MBC in the investigation of soil fertility.

By reason of the strong correlation between the chemical parameters and the yield results I

suggest adopting HWC for monitoring soil fertility in Hungary too, as it has already been used

in the agricultural advisory system in Germany.

18

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21

PUBLICATIONS ON THE SUBJECT OF THE DISSERTATION

Hoffmann, S., Bankó L. 2003. Sokéves szerves- és mőtrágyázás hatása a talaj

termékenységére. XLV. Georgikon Napok. Keszthely. 2003. szeptember 25-26. (CD-ROM)

Hoffmann, S., Balázs, J. Bankó, L. 2004. Grain yield and baking quality of some advanced

Hungarian winter wheat cultivars in the last dry period. Új kihívások, új lehetıségek a

mezıgazdaságban. XLVI. Georgikon Napok. Keszthely. 2004. szeptember 16-17. (CD-ROM)

Hoffmann, S., Hoffmann, B., Balázs, J., Bankó, L. 2004. Drought stress and baking quality of

some advanced hungarian winter wheat cultivars. Poster III. Alps-Adria Scientific Workshop

Dubrovnik, 1-6 March. Proceedings. 102-106.

Bankó, L. 2005. A talaj szervesanyagának vizsgálata a szerves- és mőtrágyázási össze-

hasonlító tartamkísérletben. XI. Ifjúsági Tudományos Fórum. Keszthely 2005. március. 24.

(CD ROM)

Hoffmann, S., Csitári, G., Balázs, J., Bankó, L. 2005. Impact of straw manuring on soil

organic matter dynamics and fertility. Poster. International Conference on The role of long-

term field experiments in agriculture and ecology. Practical Solutions for Managing Optimum

C and N Content in Agricultural Soils IV, Praha, June 20-22, 2005

Hoffmann, S., Schulz, E., Csitári, G., Banko, L. 2005. Organic-C pools as a function of FYM-

mineral fertilization. Poster. International Conference on The role of long-term field

experiments in agriculture and ecology. Practical Solutions for Managing Optimum C and N

Content in Agricultural Soils IV, Praha, June 20-22, 2005.

Hoffmann, S. – Schulz, E. – Csitári, G. – Bankó, L. 2006. Influence of mineral and organic

fertilizers on soil organic carbon pools. Archives of Agronomy and Soil Science, Vol. 52 No.

6. 627-635.

22

Hoffmann, S., Csitári, G., Bankó, L., Balázs, J. 2006. Soil fertility characteristics due to

different organic and mineral fertilization. Cereal Research Communications, Vol. 34 No. 1.

203-206.

Bankó, L., Hoffmann, S., és Debreczeni K. 2007. A talaj forróvíz-oldható C-frakciójának

vizsgálata trágyázási tartamkísérletben. Agrokémia és Talajtan. 56. 2. 271-284.

Hoffmann, S., Berecz, K., Hoffmann, B., Bankó, L. 2008. Yield response and N-utilization

depending on crop sequence and organic or mineral fertilization. VII. Alps-Adria Scientific

Workshop. Stara Lesna, Slovakias. (CD-ROM)