Agroecosystem Optimization by Crop Rotation, Catch Crop and Manure in Organic Farming ; Agroekosistemų optimizavimas augalų kaita, tarpiniais pasėliais ir organinėmis trąšomis ekologinėje žemdirbystėje

De
1 LIETUVOS ŢEMĖS ŪKIO UNIVERSITETAS Skirmantė Balnytė AGROEKOSISTEMŲ OPTIMIZAVIMAS AUGALŲ KAITA, TARPINIAIS PASĖLIAIS IR ORGANINĖMIS TRĄŠOMIS EKOLOGINĖJE ŢEMDIRBYSTĖJE Daktaro disertacijos santrauka Biomedicinos mokslai, Agronomija (06B) Kaunas, 2010 2 Disertacija rengta 2004–2009 m. Lietuvos ţemės ūkio universitete. Mokslinis vadovas: Doc. dr. Vaclovas Boguţas (Lietuvos ţemės ūkio universitetas, biomedicinos mokslai, agronomija – 06B). Disertacija ginama Lietuvos ţemės ūkio universiteto Agronomijos mokslo krypties taryboje: Pirmininkas: Prof. habil. dr. Rimantas Velička (Lietuvos ţemės ūkio universitetas, biomedicinos mokslai, agronomija – 06B). Nariai: Habil. dr. Nijolė Anisimovienė (Gamtos tyrimų centro Botanikos institutas, biomedicinos mokslai, botanika – 04B); Prof. habil. dr. Vida Stravinskienė (Vytauto Didţiojo universitetas, biomedicinos mokslai, ekologija ir aplinkotyra – 03B ); Dr. Ţydrė Kadţiulienė (Lietuvos agrarinių miškų mokslų centras, Ţemdirbystės institutas, biomedicinos mokslai, agronomija – 06B); Doc. dr. Darija Jodaugienė (Lietuvos ţemės ūkio universitetas, biomedicinos mokslai, agronomija – 06B). Oponentai: Doc. dr. Irena Januškaitienė (Vytauto Didţiojo universitetas, biomedicinos mokslai, biologija – 01B ) Doc. dr.
Publié le : samedi 1 janvier 2011
Lecture(s) : 42
Source : VDDB.LABA.LT/FEDORA/GET/LT-ELABA-0001:E.02~2010~D_20110902_143932-39161/DS.005.1.01.ETD
Nombre de pages : 20
Voir plus Voir moins

1
LIETUVOS ŢEMĖS ŪKIO UNIVERSITETAS










Skirmantė Balnytė









AGROEKOSISTEMŲ OPTIMIZAVIMAS AUGALŲ KAITA,
TARPINIAIS PASĖLIAIS IR ORGANINĖMIS TRĄŠOMIS
EKOLOGINĖJE ŢEMDIRBYSTĖJE







Daktaro disertacijos santrauka
Biomedicinos mokslai, Agronomija (06B)











Kaunas, 2010
2
Disertacija rengta 2004–2009 m. Lietuvos ţemės ūkio universitete.

Mokslinis vadovas:
Doc. dr. Vaclovas Boguţas (Lietuvos ţemės ūkio universitetas, biomedicinos mokslai,
agronomija – 06B).


Disertacija ginama Lietuvos ţemės ūkio universiteto Agronomijos mokslo krypties
taryboje:

Pirmininkas:
Prof. habil. dr. Rimantas Velička (Lietuvos ţemės ūkio universitetas, biomedicinos
mokslai, agronomija – 06B).

Nariai:
Habil. dr. Nijolė Anisimovienė (Gamtos tyrimų centro Botanikos institutas,
biomedicinos mokslai, botanika – 04B);
Prof. habil. dr. Vida Stravinskienė (Vytauto Didţiojo universitetas, biomedicinos
mokslai, ekologija ir aplinkotyra – 03B );
Dr. Ţydrė Kadţiulienė (Lietuvos agrarinių miškų mokslų centras, Ţemdirbystės
institutas, biomedicinos mokslai, agronomija – 06B);
Doc. dr. Darija Jodaugienė (Lietuvos ţemės ūkio universitetas, biomedicinos mokslai,
agronomija – 06B).


Oponentai:
Doc. dr. Irena Januškaitienė (Vytauto Didţiojo universitetas, biomedicinos mokslai,
biologija – 01B )
Doc. dr. Vytautas Liakas (Lietuvos ţemės ūkio universitetas, biomedicinos mokslai,
agronomija – 06B)



Disertacija bus ginama viešajame Agronomijos mokslo krypties tarybos posėdyje 2010 m.
gruodţio 21 d., 11.00 val. Lietuvos ţemės ūkio universiteto Centrinių rūmų 261
auditorijoje.
Adresas: Studentų g. 11, LT–53361 Akademija, Kauno r.; tel.: (8-37) 752 254, faks.: (8-37)
397 500.


Daktaro disertacijos santrauka išsiuntinėta 2010 m. lapkričio 21 d.
Disertaciją galima perţiūrėti Lietuvos ţemės ūkio universiteto ir Lietuvos agrarinių miškų
mokslų centro, Ţemdirbystės instituto bibliotekose.
3
INTRODUCTION
Relevance of the subject. Under intensification of agricultural production, the
point is reached at which environmental impact increases significantly and risk to human
health is observed. Negative effects caused by intensive agricultural development
encourage searching for greater harmony with nature maintaining the potential productivity
of plants, growing organic production and preserving healthy environment. With
appearance of negative effects caused by long-term application of intensive farming
systems, priorities of organic (natural, stable, sustainable) farming emerge.
The system of organic farming is based on complete exploitation of the natural
resources of agrocenosis and stabilisation of a closed cycle of biogenic elements. Organic
farming requires assuring the balance of nutrients, controlling the spread of weeds, diseases
and pests. To achieve rational functioning of an agroecosystem, agrocenoses shall preserve
sustainability of the main nutrition elements through combining in crop rotation the main
crops and catch crops of the plants featuring different biological properties: one plants are able
to fix nitrogen from atmosphere, whereas others are capable of taking nutrients from deeper
layers or assimilating the nutrition elements available in complex compounds. This fact is
especially relevant for growing great amounts of cereal in organic farms that are focused on
crop production as crop rotation stability and productivity decreases, supply of plants with the
required amount of nitrogen becomes more difficult, crop weediness increases.
Stable yield and competitive production may be grown only by maintaining the
potential soil fertility determined by a range of factors. More or less changes in one factor
lead to change in another one or even in another few factors. The effect made on the plants
and soil by one agricultural practice should be assessed by various aspects. Due to the
aforementioned reasons, complex evaluation of optimisation possibilities (maintenance of
the potential soil fertility, control of crop and soil weediness, yield stabilisation) of
agroecosystems is required in organic agriculture. Efficiency of individual agricultural
practices in organic farming has been investigated widely. However, what concerns the
complex influence on agroecosystems made by crop rotations with a different nitrogen-
fixing crop rate, catch crops and fertilisation with organic fertilisers, the lack of studies has
been observed thus far.

Experimental hypothesis. Optimisation of agroecosystems in organic farming is
possible through application of a set of the following practices: by crop rotations with a
different ratio of nitrogen fixing crop, growing catch crops and fertilising with organic
fertilisers.

Experimental objective. To evaluate optimisation possibilities of agroecosystems
in organic farming by combining crop rotations with a different ratio of nitrogen fixing
crops, growing catch crops and fertilising with organic fertilisers.

Tasks. To analyse the influence of crop rotations with a different ratio of nitrogen-
fixing crops, catch crops and fertilisation with organic fertilisers on the following:
1. Soil enzyme activity;
2. Agrochemical properties of the soil and nitrogen balance;
3. Weed response;
4. Weed seed bank in the soil;
5. Crop yield and productivity.
4
Novelty of the research. It was evaluated complex effect of crop rotations with a
different ratio of nitrogen fixing crops, catch crops and farmyard manure on
agroecosystems in organic agriculture. This new knowledge provided posibility to maintain
potential soil fertility, to control the spread of weeds, to grow stable grain yield in organic
agriculture. For the first time in Lithuania was evaluated the effect of crop rotations on
nitrogen turnover and changes in organic compounds of the soil, the influence of the first
year grass-clover on weed seed bank, efficiency of crop rotations with short crop links in
organic agriculture.
Practical value of the results obtained. Results of the research demonstrated that
the most purposeful way in organic farming is crop rotations with short links of row,
legume and especially grass crops, where the nitrogen-fixing crops ratio not less than 43 %.
The effect of farmyard manure used did not last more than two years. Catch crops for green
manure are recomended in order to reduce the negative nitrogen balance when weed control
is ensured by other practices.

Statements to be defended
In organic farming:
 soil enzymes activity, nitrogen turnover and changes in organic carbon processes
are more active when crop rotation with N –fixing crops are used;
 the potential of soil fertility maintained by the crop rotations with short crop links,
catch crops for green manure and fertilizing with farmyard manure;
 crop rotations with short crop links are effective for weed control;
 grass-clover after one year application effectively decreases the weed seed bank in
the soil;
 A stable cereal crop yield can be achieved in crop rotation with short links of row,
legume and grass crops and fertilizing with farmyard manure.

Approval and publication of the dissertation work. The main results of the
dissertation work were published in scientific journals: the Lithuanian Academy of
Science's scientific journal „Agricultural Sciences“ in 2008; the Lithuanian University of
agriculture's scientific journal „VAGOS“ (2009). Scientific conferences: „Žemdirbio vasara
2005“, „Žemdirbio vasara 2010“ (LŢŪU), scientific conference dedicated to commemorate
90 years anniversary of Professor Antanas Stancevičius, „Šiuolaikinių žemdirbystės sistemų
aktualijos“, (LŢŪU, 2010); international scientific conference dedicated to commemorate
100 years anniversary of Professor Petras Vasinauskas „Farming systems and environment
quality (LŢŪU, 2006); international scientific conference „Soil in Sustainable
Environment“ (LŢŪU, 2008); international scientific conference of PhD students „Youth
seeks progress“ (Akademija-Kaunas, 2009).
Volume of the work. The dissertation is written in Lithuanian. It consists of an
introduction, overview of the literature, experimental materials and methods, anglysis and
discussion of experimental data, conclusions, list of articles published in realation to the
dissertation research, list of referentes, summary in English. The dissertation inludes 106
pages, 27 tables, 11 figures, 253 Literature references have been used.

5
EXPERIMENTAL MATERIALS AND METHODS
Experimental materials. Agroecosystem components (biodiversity) in organic
agriculture.
Experimental site and soil type. The field experiment was carried out in organic
certified field of the Experimental Station of the Lithuanian University of Agriculture
during the period of 2004-2009. The soil type – Calc(ar)i Epihypogleyic Luvisol (LVg-p-w-
cc). Soil texture: medium clay loam on heavy clay loam and clay. Arable layer (Ap 0-25
cm). pH – 7.26-7.30, the humus content – 2.26-2.43%, available nutrients: mobile kcl
–1 –1phosphorus – 254–296 mg kg , mobile potassium – 131–158 mg kg .

Experimental design . Details of three factor experimental design:
Factor A. Crop rotations with a different ratio of nitrogen fixing crops.
Four 7-year crop rotations with a different ratio of nitrogen fixing crops (table 1.) were
compared:
R1 – 43% of nitrogen fixing crops (grass-clover > grass-clover > winter wheat >
spring barley > peas > winter wheat > spring barley);
R2 – 43% of nitrogen fixing crops (grass-clover > winter wheat > peas > spring
barley > grass-clover > winter wheat > spring barley);
R3 – 29% of nitrogen fixing crops (grass-clover > potato > oat > spring barley >
peas > winter wheat > spring barley);
R4 – 14% of nitrogen fixing crops (grass-clover > winter wheat > potato > spring
barley > winter rape > winter wheat > spring barley).
Factor B. Farmyard manure:
M0 – without farmyard manure,
M1 – with farmyard manure.
Factor C. Catch crop:
C0 – without catch crop,
C1 – with catch crop.

The experiment was arranged in split-split plot design, three replicates used.
Experimental treatments were arranged randomly in the replications. The area of sub-sub
2plot was 126 m .

Catch crops after perennial grasses, were not grown however, the regrown aftercrop
was incorporated in respective plots as green manure. In crop rotations R2-R4 of 2003,
crop rotation R1 of 2004 and crop rotation R2 of 2007, the dry matter content of 5.2 Mg
-1 -1 -1ha , 5.6 Mg ha and 5.0 Mg ha was observed respectively. The plots were manured (30
-1Mg ha ): crop rotations R2-R4 in autumn 2003, crop rotation R1 in 2004, crop rotations
R1-R4 in 2007.
th thSoil enzyme activities (urease and saccharase) were evaluated in the 1 and 7 year
of the experiment.

6
Table 1. Crop rotations, catch crops and farmyard manure in the field experiment.
Crop rotation I Crop rotation II Crop rotation III Crop rotation IV Year
(R1) (R2) (R3) (R4)
Without catch crop
Grass-clover Grass-clover/M30 Grass-clover/M30 Grass-clover/M30 2003
Grass-clover/M30 Winter wheat Potato Winter wheat 2004
2005 Winter wheat Peas Hulless oat Potato
Spring barley Spring barley Spring barley Spring barley 2006
Peas Grass-clover Peas Winter rape 2007
Winter wheat Winter wheat Winter wheat Winter wheat 2008
Spring barley Spring barley Spring barley Spring barley 2009
With catch crop for green manure
Grass-clover Grass-clover/AM/M30 Grass-clover/AM/M30 Grass-clover/AM/M30 2003
Grass-clover/AM/M30 Winter wheat/WM Potato Winter wheat/WM 2004
Winter wheat/WM Peas/WM Hulless oat Potato 2005
Spring barley/WM Spring barley Spring barley/WM. Spring barley. 2006
Peas/M30 Grass-clover/AM/M30 Peas/M30 Winter rape/M30 2007
Winter wheat/WM Winter wheat/WM Winter wheat/WM Winter wheat/WM 2008
Spring barley Spring barley Spring barley Spring barley 2009
Note: AM – grass- clover aftercrop for green manure, WM – white mustard for green manure, M30 –
-1farmyard manure 30 Mg ha
Plants in crop rotations were grown applying the growth technologies acceptable in
organic farms. Before planting, cultivation was carried out twice. During growth of spring
barley and pea, crops were cultivated by a lightweight harrow across the rows. During
vegetation, potatoes were hillered twice. During harvesting of cereal and rape, secondary
production was chopped and spread, stubbles were disced twice. According to the table 1,
the catch crop of white mustard was grown. Due to spread of weeds, catch crops were not
sown only in the year 2007. Plots without catch crops were additionally disced twice. In the
late autumn, total yield of catch crops for green manure was chopped and ploughed into the
soil.
The study carried in: red clover (Trifolium pratense L.) ‛Liepsna‟ and grass (Phleum
-1pratense L.) ‛Gintaras‟ mixture sown at a seed rate 8,5 kg ha each, winter wheat (Triticum
–1aestivum L.) „Širvinta‟ sown at a seed rate 210 kg ha , potatoes (Solanum tuberosum L.)
-1‛Kosmos‟ sown at a seed rate 3,5 Mg ha , peas (Pisum sativum L.) ‛Eifel‟ sown at a seed
–1 –1rate 250 kg ha , huless oat (Avena sativa L.) ‛YXT‟ sown at a seed rate 160 kg ha , spring
–1barely (Hordeum vulgare L.) ‛Ūla‟ sown at a seed rate 200 kg ha , winter oilseed rape
-1(Brasica napus L.)‛Valesca‟ sown at a seed rate 4 kg ha , white mustard (Sinapis alba L.)
-1„Braco“ sown at a seed rate 25 kg ha .
In a certified organic experimental field, neither synthetic mineral fertilisers nor
chemical plant protective measures were applied.
Before sowing, seeds of winter wheat, barley and winter rape were coated with the
preparation Biokal 01by the wet method. For 1 ton of seeds, 10 l of an undiluted solution of
the preparation Biokal 01 was applied, with exposure of 48 hours. Before sowing, potato
tubers, seeds of pea and perennial grasses were coated with a diluted solution (1:3) of the
preparation Biokal 01 (10 l of Biokal 01 + 30 l of water), with exposure of 48 hours. Crops
were additionally sprayed with a diluted solution (1:20) of the preparation Biokal 01 (15 l
of Biokal 01 + 300 l of water). Winter wheat and spring barley were sprayed in the tillering
7
and heading stages, potatoes were sprayed in the germination and blooming stages, whereas
pea was sprayed in the blooming stage.

Experimental methods
Soil enzymes. To estimate the activity of soil enzymes soil samples were taken in
2004 and 2009 from the soil layer of 0–25 cm in May (intensive crop growing). The
activity of soil urease was determined in dry samples according to Hofmann and Schmidt,
that of saccharase according to Hofmann and Seegerer methods, modified by
A. I. Chunderova.
Soil agrochemical properties. Composite soil samples for soil agrochemical
properties were taken in spring befofe experiment and of the end experiment in each plot
treatment from the 0-20 cm layer. Soil chemical analyses carried out by methods: soil pH –
potentiometric method; available phosphorus (P O ) and available potassium (K O) – by A-2 5 2
L Egner-Riehm-Domingo method; Humus –tyurin method; total nitrogen – Kjeldal method;
mineral nitrogen – distilation and colorimetric (1 N KCL extraction) method.
Nitrate Balance. To estimate nitrate leaching to deeper soil horizons, galvanized
20.25 m tin lysimeters were installed at a depth of 40 cm in plots of all crop rotations with
and without a catch crop. Lysimeters were incorporated by hoses with water-gathe-ring
containers. Lysimetric water was collected from May 1 to October 30. Data of the
Meteorological Station of Kaunas Hydrometeorological Observatory were used for
determining the precipitation in the same period. We measured precipitation permeated
through the soil (drainage water). The lysimetric method is based on the drainage principle,
so rainfall water permeated through the soil can be established when a surplus in soil
moisture occurs.
We determined the amounts of mineral (NO and NH ) nitrogen in lysimetric and 3– 4–
rainfall water by the colorimetric method using disulphophenolic acid.
The content of nitrogen established in crops absolutely dry matter. Crops for yield
-2determination were harvested manually from plots of 1 m . Grass-clover over ground mass
-1yield was expressed by the content of absolutely dry matter Mg ha , Winter wheat, spring
barley, peas – by 15% of humidity and absolutely clean grain mass, winter rape – by 8.5%
-1of humidity and absolutely clean grain mass. The content of nitrogen (mg kg ) in
absolutely dry matter was determined by the Kjeldhal method.
The N balance was calculated using Welte and Timmermann (1985), Claupein (1994)
models. The N balance model when legumes are grown is as follows:
B=(N +N ) – (N +Nl ); symbiotically fixed in precipitation in yield eached
N balance model when legumes are not grown is as follows:
B =(N –(N +N ). The content of mineral nitrogen (ammonia and N in precipitation in yield leached
nitrate) in lysimeters and rainwater were determined by the colorimetric method using
disulphophenolic acid; the content of nitrogen in absolutely dry matter of plants was
determined by the Kjeldhal method. Symbiotically fixed atmospheric nitrogen was
determined by the method of difference N = N -N ). fixed in legumes in comparables
Weeds. Crop weeds amount and species were evaluated twice. First time at the stage
of intensive germination of weeds (in May), weed samples were taken from each trial field
-2in 10 places by frame 0.06 m , and at cereal milky ripeness stage weed samples were taken
-2from each trial field in 16 places by frame 0.25 m . In spring, the number of weed
seedlings was calculated, while at the cereals milky ripeness stage–the numbers of weeds
- 2 -2m and the weight of their dry matter g m and established number of species amount. To
8
establish the amount and species composition of weed seeds in the „seed bank“, soil
samples were taken after harvesting yield an arable soil layer of 0-25 cm. The samples were
taken from 10 places to make join soil samples of every trial plots. Used a method of hard
solution for isolation of weed seeds from the soil.
Crop yield. The crop yield was estimated by weighing method and was adjusted to
standard moisture – for cereals 15%, for rapeseed 9%. Grass-clover over ground mass yield
-1 was expressed by the content of absolutely dry matter Mg ha . Cereals and winter rape
were harvested by a self-propelled combine harvester “Sampo 500” at complete maturity
-1stage. Agriculture crops yield calculated as GE (gross energy) MJ ha content calculated
according to T. Tamulis data.
Methods of statistical data evaluation. The experimental data were processed using
analysis of variance and correlation-regression methods recommended in agronomy
science. The mean values were compared by the least significant difference test at P< 0.05
using SYSTAT 10. The Fisher LSD test was used to determine significant treatment effects.
The weed data did not meet normal distribution was transformed by using the function
Y=lnx+1 before statistical evaluation.

ANALYSES OF EXPERIMENTAL RESULTS AND DISCUSSION
Changes of soil enzime activity in organic farming. Soil enzime uresase and
saccharase actvity is one of the main indicators of soil biological activity and fertility
maintain that soil biological activity has great value as early and sensitive indicators of
changes in soil properties induced by different management strategies in the short-term.
Enzime activity is closely related to other important indicators of biological activity:
respiration intensivity, nitrification ability, total amount of micro organisms and even more
associated with soil humus content, amounts of mobile P O and K O , soil acidity and 2 5 2 5
crop yield. Activity of soil urease and saccharase was determined (in a 0-25 cm soil layer)
at the beginning of an experiment in the year 2004 and at the end of an experiment in the
year 2009. Data is provided in fig.1.
Comparison of the results of the recent experiment year with the results obtained at
the beginning of the experiment shows significant changes in activity of urease and
saccharase. During the period of crop rotations, the greatest increase of urease activity was
observed in the soil where the plants were rotated according to crop rotation R2 (43 % of
nitrogen-fixing crop every other year). In plots of crop rotation R3, urease activity was
significantly lower compared to one in plots of crop rotation R2 and crop rotation R4.
Manure application had no significant influence on variation in activity of urease, whereas
growth of catch crops for green manure demonstrated the upward tendency of activity of
the soil enzymes.
Assessment of variation in activity of saccharase in 2004–2009 showed that activity
of the ferment increased only in the soil where the plants were rotated according to crop
rotation R2. In the soil of crop rotation R1, R3 and R4 activity of saccharase decreased.
Manure application and growth of catch crops for green manure throughout the crop
rotation demonstrated no increase in activity of saccharase.
9

Fig.1 Changes of urease and saccharase activity in period 2004-2009.
Note: Different letters indicate significant differences between treatments
Crop rotations with different ratio of nitrogen fixing crop: R1 – 43% (grass-clover > grass-clover >
winter wheat > spring barley > peas > winter wheat > spring barley), R2 – 43% (grass-clover > winter
wheat > peas > spring barley > grass-clover > winter wheat > spring barley), R3 – 29% (grass-clover >
potato > oats > spring barley > peas > winter wheat > spring barley), R4 – 14% (grass-clover > winter
wheat > potato > spring barley > winter rape > winter wheat > spring barley). M0 – without manure,
M1 – with manure. C0 – without catch crop; C1 – with catch crop.
Throughout the crop rotation, the greater activity of saccharase was observed just in
the plots where the plants were rotated according to crop rotation R2. In the soil of crop
rotation R1, R3 and R4, activity of saccharase decreased compared to one observed at the
beginning of the experiment. Significant difference of variation in activity of saccharase
was established just between crop rotations R2 and R4. Manure application and growth of
catch crops for green manure throughout the crop rotation demonstrated no increase in
activity of saccharase.
Soil is considered an integral system where biological, chemical and physical
properties of the soil determining soil fertility are closely releated. On this basis, correlation
analysis between the soil urease and saccharase activity and the humus content was carried
out in 2004 and 2009. Data is provided in fig. 2 and fig. 3. In the years 2004 and 2009,
where indentified power significant positive low correlations between the urease activity
0.927 1.095and the humus content (y = 0.031x , r = 0.30, P<0.05; y = 0.034x , r = 0.39, 2004 2009
P<0.01). Between the saccharase activity and the humus content, was no statistically
significant correlations observed.

2004
0,2
0.927
0,15 yy = 0= ,00.3103x10, x92 72004
r = 0,30*0,1
r = 0.30 0,05
0
0 1 2 3 4
Humus %

Fig. 2. Soil urease activity as affected by the content of humus in 2004
*Note: Significant levels: - P ≤ 0.05>0.01


Urease activity
-1 -1
mg NH3 1g soil 24 h10
2009
0,2
1.095 y = 0.0341,095x2009
0,15 y = 0,034x
r = 0,39**
0,1 r = 0.39
0,05
0
0 1 2 3 4
Humus %

Fig. 3. Soil urease activity as affected by the content of humus in 2009
**Note: Significant levels: - P ≤ 0.01 > 0,001

Agrochemical properties of the soil. Agrochemical analysis of the soil was carried
out at the beginning of the experiment and at the end of the experiment. Soil agrochemical
properties in 2004 presented in table 2.
2008. The factors were analysed: crop rotations with a different ratio of nitrogen
fixing crop, manure application and a catch crop had no significant influence on the soil pH
(table 3). The content of mobile potassium after various preceding crops was different,
however, no significant differences were observed. In the soil of the plots were crops
rotated according to crop rotation R1, the greatest content of mobile potassium, i.e. 143.5
-1mg kg , was observed. The lowest content of mobile potassium in the arable horizon was
demonstrated by the plots where plants were rotated according to crop rotations R3 and R4,
-1i.e. 125.2 and 129.7 mg kg respectively. Such a result could be influenced by the potatoes
previously grown in these crop rotations, i.e. the greater content of potassium was removed
from the soil with the potato yield. Manure application had no significant influence on the
content of mobile potassium, however, the plots with manure application demonstrated the
upward tendency of the mobile potassium content. Compared to the plots without manure
-1application, the difference is 11.9 mg kg . Catch crops had no significant influence too.
The factors analysed had no significant influence on the content of mobile
phosphorus in the soil either. The slightly higher content of mobile phosphorus was
demonstrated by the plots where agricultural plants were rotated according to crop rotation
R1 (grass-clover > grass-clover > winter wheat > spring barley > peas > winter wheat >
spring barley) and crop rotation R4 (grass-clover > winter wheat > potato > spring barley >
winter rape > winter wheat > spring barley), and by the plots with catch crops. The content
of mobile phosphorus in the soil of the plots with manure application and without manure
application differed slightly.
The factors analysed had no significant influence on the content of total nitrogen,
nitrate nitrogen, ammonia nitrogen and mineral nitrogen available in the soil. Plots of crop
rotations with a different nitrogen-fixing crop ratio demonstrated the similar content of
different forms of nitrogen. Neither manure application no catch crops for green manure
had significant impact on nitrogen content in the soil. Only the upward tendency of the
nitrate and ammonia nitrogen content was observed in the plots manured in autumn of
2007.

Urease activity
-1 -1
mg NH3 1g soil 24 h

Soyez le premier à déposer un commentaire !

17/1000 caractères maximum.