VI. Alps-Adria Scientific WorkshopObervellach, Austria 2007

RESPONSE OF MAIZE AND SOYBEANS TO FERTILIZATION WITH PHOSPHORUS AND POTASSIUM ON ACID SOIL

Vlado KOVACEVIC1,-Miranda SEPUT2- Luka ANDRIC3, -Jasna SOSTARIC1

1University J. J. Strossmayer in Osijek, Faculty of Agriculture, Trg Sv. Trojstva 3,

HR-31000 Osijek, Croatia; e-mail:

2Institute for Soil,Vinkovacka cesta 63a, HR-31000 Osijek, Croatia

3Agricultural Institute, Juzno predgradje 17, HR-31000 Osijek, Croatia

Introduction

Moderate supplies of soil with phosphorus (P) and potassium (K), alone or in their combination, are limiting factors of field crop yields, especially maize and soybeans under condition of continental part of Croatia(Kovacevic and Vukadinovic, 1992, Kovacevic, 1993). Ameliorative fertilization could be solution for normalization of plant nutrition under these conditions. For this reason has been conducted the field experiment with increased rates of P and K fertilizer to level 1500 kg either P2O5 or K2O ha-1on soil of moderate fertility in Bjelovar-Bilogora County with aim testing response of maize and soybeans. Responses of these crops to ameliorative NPK fertilization to level 3748 kg ha-1 were shown by earlier study (Rastija et al., 2006).

Material and methods

The field experiment

The field experiment of P and K fertilization was conducted in term April 23, 2004 (a = ordinary fertilization, b = a + P1, c = a + P2, d = a + P3 , e = a + P1, f = a + P2, g = a + P3 , h=a+P2K2. The amounts of added either/or phosphorus (P2O5) and potassium (K2O) were (kg ha-1) 500, 1000 and 1500, for the step 1, 2 and 3, respectively. The triplephoshate enriched with sulphur and zinc (45% P2O5 + 1. 2% S + 0.06% Zn) was used for P fertilization. It is produced as DC-Triplephoshat (original protected name) in Donau Chemie AG Werk Pischelsdorf 3435 Zwentendorf, Austria. Potassium salt (KCl containing 60% K2O) was source of K. Nitrogen amount was equilized for all treatments by adequate quatities of CAN (calcium ammonium nitrate: 27% N). The experiment was conducted in four replicates. The experimental plot measured 77 m2. Residual response of soybean (the growing season 2005) was tested for the 2005 growing season and the trial was fertilized in level of ordinary fertilization. Maize and soybean were sown at beginning of May by pneumatic sowing machine on the planned (theoretical) plant density (TPD: plants ha-1) 64935 and 600000, for maize and soybean, respectively. Maize harvest was made manually. Four middle rows of maize were plucked. Soybean harvested area was 1.5 m2. Plants of soybean were enumerated, pods were separated and harvested by special combine. Grain yield of maize were calculated on 90% TPD and 14% grain moisture basis. Yield of soybean were calculated on TPD and 13 grain moisture basis. The field experiment with five rates of NPK fertilization (NPK 10:30:20 in amounts 416, 1249, 2082, 2916 and 3748 kg ha-1) has been conducted on the same soil (Rastija et al., 2006) and according same model simultaneous with the trial of single application of P and K.

Sampling and sample analysis

Two soil samples were taken before starting the experiment (April 3, 2004). The second soil sampling was made in term November 15, 2005. The samples were taken by auger to 30 cm of depth (15 individual sampling in the mean sample). The ear-leaf of maize was taken at beginning of silking (middle of July 2004; 25 leaves in the mean sample). The uppermost full-developed leaf of soybean was taken at beginning of anthesis (middle of July 2005) from each experimental plot. Nutritional status of soil was made by extractions with AL-solution. Soil reaction and organic matter were determined according to ISO (1994, 1998). The total amount of P and K in the leaf samples was measured by the ICP-AES technique after their microwave digestion using concentrated HNO3+H2O2. The analyses were done in the laboratory of the Research Institute for Soil Science and Agricultural Chemistry (RISSAC), Budapest, Hungary.Oil content in the grain was determined by nuclear magnetic resonance (NMR) spectroscopy method. Protein and starch content in the grain was determined by Near Infrared spectroscopic method on Foss Tecator ("Infratec 1241 Grain Analyzer").

Weather and soil characteristics

The growing seasons 2004 and 2005 were favorable for the spring crops growing, including maize and soybeans. Sum of precipitation in the 4-month (May-August) period were 255 and 427 mm and they were mainly balanced distributed (Bjelovar Weather Bureau). In general, low yields of maize and soybeans are in connection with water deficit, especially during July and August (Josipovic et al. 2005).Acid reaction, moderate P and humus contents, as well as adequate supply of plant avaiable potassium (Table 1) are main characteristics of Pavlovac experimental field.

Results and discussion

Applied fertilization considerable influenced on increases of plant available P and K in soil, while differences of pH and humus among tretaments were in range of statistical error. Also, both P and K single fertilization gave tendency to decrease hydrolitical acidity (Table 1).

In general, grain yields of maize were high and ameliorative fertilization had moderate effects on maize yield as well as P and K in grain and leaves increases. Only applications of the highest K rate and PK combination resulted by significant yield increases, for 5% and 12%, respectively (Table 2). Only application both P and K nutrients resulted by increase of grain quality (protein content). We presume that surface incorporation of the fertilizer immediately before maize sowing and favorable weather conditions during the 2004 growing sweason could be responsible factors for low response of maize to applied fertilization. Moderate effects of ameliorative P and K fertilization on maize yields were found also on acid soil of Pozega-Slavonia County(Loncaric et al. 2005).

By application of the ameliorative rates of NPK fertilizer, grain yields of maize significantly increased to level of 14% compared to standard fertilization (12.33 and 14.00 t ha-1, for the control and the second rate of NPK fertilization, respectively. Only the higest rate of NPK fertilizer resulted by significant increase of protein in grain. Residual response of soybean (the growing season 2005) to the fertilization was considerably higher compared to maize, because yields of soybeans were increased up to 32%. Protein contents in soybean grain were independent on the fertilization, while oil contents were increased up to 0.66% compared to the control (Rastija, et al., 2006).

Bergmann (1992) reported adequate concentrations of P and K in leaves are in range from 0.35 to 0.60 % P (both for maize and soybeans), as well as from 2.50 to 4.50 % K (maize) and from 2.5 to 3.70% K (soybean). According to these criteria, in our study nutritional status of maize and soybeans are in normal range (Tables 2 -4).

Table 1.Properties of soil (0-30 cm)

Soil properties (0-30 cm: HA = Hydrolytical acidity)
Fertilization* / pH / AL-method (mg/100 g) / % / HA
kg ha-1 / H2O / KCl / P2O5 / K2O / Humus / Cmol kg-1
Soil status at starting of the experiment (April 3, 2004)
Control / 5.44 / 3.99 / 9.40 / 17.8 / 1.93
Soil status in the second year of the experiment (November 15, 2005)
a / control / 5.02 / 3.67 / 8.37 / 20.09 / 1.87 / 5.65
b
c
d / P-1
P-2
P-3 / 4.93
4.96
4.97 / 3.68
3.67
3.70 / 14.93
17.90
22.53 / 17.03
18.53
17.55 / 1.97
2.04
2.15 / 5.24
5.18
5.01
e
f
g / K-1
K-2
K-3 / 4.91
5.00
4.95 / 3.61
3.71
3.64 / 8.60
8.60
9.97 / 23.65
33.82
34.77 / 2.10
2.15
1.97 / 5.38
5.17
5.12
h / P2K2 / 5.12 / 3.77 / 23.5 / 35.43 / 1.99 / 4.79
LSD 5%
LSD 1% / n.s. / n.s. / 6.43
8.92 / 3.57
4.95 / n.s. / 0.79
n.s.

* 500, 1000 and 1500 P2O5 or/and K2O kg ha-1, for step 1, 2 and 3, respectively;

Table 2. Response of maize (the hybrid OsSK552) to fertilization

Fertilization (April 23, 2004) / Maize properties: the growing season 2004
kg ha-1 / t ha-1 / Percent in dry matter
Treatment / N / P2O5 / K2O / Grain / Grain / Leaves*
yield / Protein / P / K / P / K
a / control / 374 / 125 / 82 / 12.28 / 8.10 / 0.246 / 0.313 / 0.308 / 2.58
b
c
d / P-1
P-2
P-3 / 374
374
374 / 625
1125
1625 / 82
82
82 / 12.67
12.62
12.65 / 8.10
7.80
7.93 / 0.260
0.285
0.289 / 0.321
0.348
0.346 / 0.327
0.333
0.354 / 2.59
2.59
2.59
e
f
g / K-1
K-2
K-3 / 374
374
374 / 125
125
125 / 582
1082
1582 / 12.58
12.73
12.95 / 8.10
7.83
8.27 / 0.239
0.226
0.233 / 0.308
0.325
0.323 / 0.308
0.312
0.325 / 2.66
2.67
2.70
h / P2K2 / 374 / 1125 / 1082 / 13.75 / 9.03 / 0.288 / 0.361 / 0.358 / 2.59
LSD 5%
LSD 1% / 0.52
0.71 / 0.90
n.s. / 0.24
0.33 / 0.12
0.16 / 0.020
0.027 / 0.09
n.s.

* the ear-leaf at silking stage

Residual influences of the fertilization were higher becausesoybean yields were increased up to 21% (influences of P), 17% (influences of K) and 30% (PK influences). However, protein and oil contents in grain were indenpendent onfertilization (Table 3).

Some nutritional disorders were observed in soybean crops in eastern Croatia. Growth retardation and chlorosis were accompanied with the alkaline or neutral soil reaction. By the foliar diagnosis deficiency of zinc was promote by the excess of phosphorus or iron and aluminium in plants, while potassium deficiency was accompanied with the excess of magnesium uptake (Kovacevic et al.1991). Normalization of yield and soybean nutritional status was made by ameliorative fertilization (Kovacevic and Vukadinovic, 1992; Kovacevic and Grgic, 1995).

Table 3. Residual influences of NPK-fertilization (April 23, 2004) on soybean

Fertilization (April 23, 2004)* / Soybean properties (the 2005 growing season)
kg ha-1 / t/ha / Percent in dry matter
Treatment / N / P2O5 / K2O / Grain / Grain / Leaves**
yield / Protein / Oil / P / K
a / Control / 332 / 125 / 82 / 3.60 / 41.27 / 20.74 / 0.537 / 2.81
b
c
d / P-1
P-2
P-3 / 332
332
332 / 625
1125
1625 / 582
1082
1582 / 3.58
3.46
4.36 / 40.76
41.57
41.74 / 20.83
20.64
20.52 / 0.513
0.593
0.603 / 2.86
3.15
2.88
e
f
g / K-1
K-2
K-3 / 332
332
332 / 125
125
125 / 82
82
82 / 4.01
4.20
4.08 / 41.13
40.21
40.59 / 21.20
21.10
21.10 / 0.520
0.547
0.573 / 2.87
2.95
3.29
h / P2K2 / 332 / 125 / 82 / 4.67 / 40.28 / 21.14 / 0.593 / 3.05
LSD 5%
LSD 1% / 0.37
0.51 / n.s. / n.s. / 0.055
n.s. / 0.30
n.s.

* fertilization for 2005 (kg ha-1: 80 N + 125 P2O5 + 82 K2O).

** the uppermost full-developed threefoliate leaf before anthesis

References

Bergman W.:1992. Nutritional disorders of plants - development, visual and analytical

diagnosis. Gustav Fischer Vela Jena, Stuttgart, New York.

ISO:1994. Soil quality. Determination of pH. ISO 10390:1994

ISO : 1998. Soil quality. Determination of organic carbon by sulfochromic oxidation.

ISO 14235:1998.

Kovacevic V. -Grgić D.:1995. Response of soybeans to potassium fertilization on high

potassium fixing soil. Rostlinna vyroba vol. 41 no. 5 246-248 pp.

Kovacevic V. -Vukadinovic V.:1992. The potassium requirements of maize and

soyabeans on a high K-fixing soil. South African J. of Plant and Soil vol.9 no. 1 10-13.

Kovacevic V. -Vukadinovic V. -Komljenovic I.: 1991. Tipovi kloroze soje uslijed

debalansa ishrane na tlima istočne Hrvatske. Znan. Prak. Polj. Tehnol. XXI 15-23 pp.

LoncaricZ. -KovacevicV.-SeputM. -SimicB. -StojicB.:2005. Influencesof fertilization on yield and nutritional status of maize. Cereal Research Communicationsvol. 33 no.1 259-262.

Rastija M. -Kovacevic V. -Vrataric M. -Sudaric A.-Krizmanic M.: 2006.Response of maize and soybeans to ameliorative fertilization in Bjelovar-Bilogora county. Cereal Research Communications vol.34 no.1 641-644.