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Nataliya Bilyera, Candidate of Science, senior
lecturer
Mykola Gorodniy, Doctor of Science, professor
Olga Dudka, postgraduate
student
National University of Life and Environmental Sciences of Ukraine,
Kyiv, Ukraine
EVALUATION
OF PHOSPHORUS AND POTASSIUM SOIL STATUS UNDER SPRING BARLEY IN LONG-TERM FIELD
EXPERIMENT
Phosphorus is an essential
for all living organisms. In crop plants adequately supplied it usually makes
up to between 0.2 -0.5 % of the dry
weight and is a constituent of important cellular molecular components
including the nucleic acids, phospholipids, and ATP and other energy
transferring compounds. Phosphorus thus plays a role in an array of
physiological processes including energy generation, nucleic acid synthesis,
photosynthesis, respiration, membrane synthesis and stability, enzyme
activation/inactivation, redox reactions, signaling, carbohydrate metabolism
and nitrogen (N) fixation [1].
Potassium also
plays a major role in various physiological and biochemical processes. Most of
potassium, unlike other macronutrients, is dissolved in plant sap [2]. Potassium is important for strong stem development and lodging resistance, promotes starch accumulation and plays an important role in carbohydrate metabolism.
Numerous numbers of
long-term experiments have been conducted and it was established that long term
application of mineral fertilizers improves soil quality, reduces N
mineralization from soil and leads to reduction in P
sorption [3] and decreasing of pH (H2O), pH (KCl), EC and organic matter.
The availability of fertilizer P was obviously increased by long-term
applying fertilizer P together with manure, compared with applying fertilizer P
alone [4], but available
P was increased in the treatments that received only chemical fertilizers, and
thus, P accumulation might be a gradual saturation of the P-sorption capacity [5].
Therefore such experiments shoud be conducted at all soil types
to evaluate crop responses to P and K application and find right
fertilization rates.
Site characteristics. The trials were
carried out at the long-term experimental field of the Agrochemistry and Crop
Quality Department of the National University of Life and Environmental
Sciences of Ukraine, Kiev
during the years 2006-2008.
The local climate
can be defined as temperate with annual rainfall of about 562 mm (273 mm of it falls during
the vegetation period) and a mean annual air temperature of 7.5оС with mean temperature during
the vegetation period of 12.4оС.
The soil is a meadow-chernozemic calcareous loam. pHH2O was 8.1, SOM
content by Turin
is 4.22 %, mobile phosphorus and exchangeable potassium by Machigin (extraction
by 1%-(NH4)2CO3 ) was 27.1 and 155 mg/kg
respectively.
Treatments and
design. Organic (farmyard manure) and mineral fertilizers (ammonium nitrate,
ordinary superphosphate and potassium chloride) were applied systematically
over the last 50 years. The treatments were without fertilizers (control),
Farmyard manure (FYM) (mean annual rate 12 t/ha; FYM + Р (mean annual rate 81 kg/ha); FYM + РК (mean annual rate 166 kg/ha); FYM +
1 NPK (mean annual rate 239 kg/ha); FYM + 1,5 NPK (mean annual rate
358 kg/ha); NPK (mean annual rate 239 kg/ha).
The experiment is
systematic block with three replicates. Plot size was 175 m2. Crop management was handled according to standard
farm practices.
Sampling and
analyses. The soil was collected from the top layer (0-25 cm) and subsoil (25-50 cm) in the 10th
field under spring barley. The soil was air dried, grinded and sieved. Mobile P
and exchangeable K were extracted with 1% NH4CO3 and
measured colorimetrically by Machigin method. Analysis of variance has been
performed by using Agrostat and Excel MS.
Today international
net totally includes 620 long term experiments, and 15 of them are situated in
Ukraine [6]. Our long-term experiment is among of them and results obtained
there is valuable for understanding loss or improvement of soil fertility after
long term organic and mineral fertilizers application in Forest-Steppe of Ukraine.
Our research showed
that systematically fertilizers application in crop rotation over 50 years
promotes soil fertility improvement, as well as leads to better crops growth
and development. Application of FYM+1,5 NPK was resulted in highest mobile
Machigin P at tillering in topsoil (138 mg/kg) and subsoil (104 mg/kg),
that is respectively 4,4 and 4,2 times higher those in control. There was
significant increasing in Machigin P in soil in treatment with N-fertilizers
application if compared to application only P or PK fertilizers. This might be
due to acidifying of soil solution after N fertilizers application. Over the
last 50 years of fertilizers application both processes can occur: decreasing
of soil fertility in control and increasing – in treatments with fertilizers
application, especially when combining organic and mineral.
Long-term organic and mineral fertilizers application in crop rotation promotes increasing exchangeable Machigin K in soil. We have found that
long term application of FYM+1,5 NPK in crop rotation was resulted in
additional 77% of Machigin K in topsoil and 82% of Machigin K in subsoil, if compared to
treatment without fertilization. It can be explained by several processes: 1)
losses of soil Machigin K due to soil chemical degradation in control; 2)
increasing of soil Machigin K as a result of accumulation in soil after long
term application of organic and mineral fertilizers.
Whereas the crop
yield of spring barley in FYM+1,5 NPK treatment was 2,1 times higher than in control,
the difference in Machigin K between tillering and harvesting in control
(28,5mg/kg) and FYM+1,5 NPK (56,0 mg/kg) was predictable due to removing this
element with harvest.
Difference in
mobile Machigin P between the beginning and the end of vegetation period in
control (11,7 mg/kg) was 4.8 times lower than in FYM+1,5 NPK (55,7 mg/kg). It was caused not
only by removing with harvest, but also by P retrogradation (altering)
processes in meadow-chernozemic calcareous soil and P leaching in treatment
with very high P Machigin content. Therefore the amount of applied mineral P
can be reduced to avoid leaching and retrogradation losses and to increase its
agronomical effectiveness.
At the beginning of
vegetation there was significant increasing of mobile P and exchangeable K in
top soil on 107 and 73 mg/kg respectively after systematic 50-years application
of FYM and 1,5 NPK. After harvesting the difference in P and K content between
the most fertile plots and control (without fertilizers) was less due to high
removal with much higher yields of crops, and for P also due to leaching and P
retrogradation. To use P fertilizers more effective and avoid losses their
management should be revised.
References
1.
Vance C. P., C. Uhde-Stone and D. L. Allan (2003). Phosphorus
acquisition and use: critical adaptations by plants for securing a nonrenewable
resource. New Phytologist, 157: 423-447.
2.
Igras J. and V. Danyte (2007). Potassium concentartion
in tissue water as an indicator of crop potassium require. Proceedings of
international conference "Plant nutrition and its prospects” held at 5-6
September 2007: 47-50.
3.
Rizand
A., R.H. Marrs, M.W. Gough and T.C.E. Wells (1989). Long-term effects
of various conservation management treatments on selected soil properties of chalk
Grassland. Biological Conservation, 49 (2):105-112.
4. Liu, J. and F. Zhang (2000).
Dynamics of soil P pool in a long-term fertilizing experiment of wheat-maize
rotation. II. Dynamics of soil Olsen-P and inorganic P. Ying Yong Sheng Tai Xue Bao, 11 (3):365-368.
5. Park
M., O. Singvilay, W. Shin, E. Kim, J. Chung and T. Sa (2004). Effects of long-term compost and fertilizer application on
soil phosphorus status under paddy cropping system. Communications in
soil science and plant analysis, 35 (11&12): 1635–1644.
6. MIneev, V.G., V.G. Sychev and V.А. Romanenkov
(2006). About improving of management and metrological issues of geographical
webs of fertilizers trials. Agrochimiya, 2:78–85 [in Russian].
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