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Effects of Polymeric Slow Release Fertilizer on

Chinese Cabbage Growth and Soil Nutrients
ab a a a
Dongdong Cheng , Yan Wang , Guizhe Zhao & Yaqing Liu
a
Research Center for Engineering Technology of Polymeric Composites of Shanxi
Province, North University of China, Taiyuan 030051, China
b
College of Chemical Engineering and Environment, North University of China, Taiyuan
030051, China
Accepted author version posted online: 15 Sep 2014.

To cite this article: Dongdong Cheng, Yan Wang, Guizhe Zhao & Yaqing Liu (2014): Effects of Polymeric Slow
Release Fertilizer on Chinese Cabbage Growth and Soil Nutrients, Archives of Agronomy and Soil Science, DOI:
10.1080/03650340.2014.965695

To link to this article: http://dx.doi.org/10.1080/03650340.2014.965695

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 Publisher: Taylor & Francis

Journal: Archives of Agronomy and Soil Science

DOI: 10.1080/03650340.2014.965695

Effects of Polymeric Slow Release Fertilizer on Chinese Cabbage Growth and Soil

Nutrients

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Dongdong Chenga,b, Yan Wanga, Guizhe Zhaoa, Yaqing Liua*

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a
Research Center for Engineering Technology of Polymeric Composites of Shanxi Province,

North University of China, Taiyuan 030051, China

an
b
College of Chemical Engineering and Environment, North University of China, Taiyuan
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030051, China
d

*Corresponding author. E-mail: lyq@nuc.edu.cn

e
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Abstract
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One pot experiment was conducted to study the effects of a new polymeric slow release
Ac

fertilizer (PRF) on Chinese cabbage growth and soil nutrients. The experiment comprised three

kinds of fertilizer (common compound fertilizer, 21% and 45% solubility of PRF in 25oC water,

all fertilizers with N:P2O5:K2O=10:5.7:20) and three fertilizer levels (0, 21.6, 43.2 g m-2).

Results showed that the high water-soluble PRFs (PRFHH and PRFHL) fit nutrient

requirements of Chinese cabbage and the high fertilization level significantly increased the

yield and improved quality of Chinese cabbage. Although the PRFHL treatment at 21.6 g

fertilizer m-2 had one-half less supplied nutrient than that of common compound fertilizer
 treatment (43.2 g fertilizer m-2), the yield of Chinese cabbage with PRFHH and PRFHL was 8.0%

more. The soluble sugar, vitamin C and leaf chlorophyll contents of Chinese cabbage can be

effectively improved with PRFHH (43.2 g m-2), PRFHL (21.6 g m-2), and PRFLH (low

water-soluble PRF, 43.2 g m-2). The PRF treatment reduced the nitrate content and improved

soil capacity of supplying nutrient effectively, and there were no changes in values of pH and

electrical conductivity of soil.

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Keywords: polymer, slow release fertilizer, Chinese cabbage, quality, soil nutrient

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Introduction

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In the past few decades, there was a significant increase in fertilizer consumption (Ju et al.
an
2004). Currently, the excessive use of fertilizers in China has caused environmental damage,

especially non-point source pollution (Zhang and Wang 2002; Jin et al. 2005). Fertilizer applied
M
in intensive farming systems in China has increased significantly, such as greenhouse vegetable

production systems (Cakmak 2002). The farmers increased production to obtain higher
d

economic value of the extra yields by large amounts of fertilizer and water measures because
e

the absorption ability of water and fertilizer is weak. For example, fertilizer N is often applied at
pt

a rate more than 1200 kg N ha-1 and irrigation water in 1000 mm crop-1 in Shouguang Shandong
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province, North China (Zhu et al. 2005; Zhang et al. 1996; Zhang et al. 2005). The high inputs

and low crop recoveries of fertilizer nutrients resulted in a significant increase of NO3--N in the
Ac

surface soil and groundwater systems (Sainju et al. 2001; Zhang et al. 1996; Yu et al. 2006; Ju et

al. 2007).

For these reasons, great attention has been given to find new types of fertilizers that, ideally,

should be low in cost with less application amounts and high nutrient use efficiency. The

slow/controlled release fertilizers possess a great potential for enhancing fertilizer efficiency

and reducing environment pollution (Shoji and Kanno 1994; Shaviv and Mikkelsen 1993).
 Several slow and controlled release fertilizers have been developed during the past 50 years,

including sulfur coated urea (SCU), urea formaldehyde (UF), and resin-coated urea (CRU).

Although all of these slow and controlled released fertilizers can improve the efficiency of the

fertilizer to some extent, but the high cost prevents their extensive application in agricultural

fields, except for certain nursery plants (Shaviv and Mikkelsen 1993; Bansiwal et al. 2006).

Besides, the residual membrane shell of resin-coated CRU cannot be degraded by microbial in

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short-term, which may lead to the destruction of soil after long-term application of resin-coated

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fertilizer
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A new slow release fertilizer product was synthesized in our laboratory, currently named as

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polymeric slow release fertilizer (PRF). The PRF was synthesized through cross-linking
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reaction and has slight solubility in water. Under the impact of enzymes and microorganisms in

soil, the nutrient was released when molecular chain of PRF was destroyed (CN Patent:
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201010518088.8). In order to discover the effects of different water-soluble PRFs on vegetable

growth and nutrient absorption, we conducted for a pot experiment with Chinese cabbage as a
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research crop.
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Materials and methods

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Preparation of polymeric slow release fertilizer

34.74 g of 37% (w/w) formaldehyde solution and 54 mL of distilled water were placed into a
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glass flask and stirred with 21.41 g of urea. 5% KOH solution was added to the above solution

to adjust the pH 8.0, and the flask was placed in a water bath at 25 oC for 2 h with stirring. And

then, 10.92 g of KH2PO4 (33.33 wt% water solution) and 30.04 g of K2SO4 were slowly added

into the above mixture. After being stirred for 40 min at 80 oC, the mixture was transferred to a

beaker in an oven at 100 °C for 3 h till the reaction completed, and then dried in an oven at 55 °C

until the weight was constant. The product was a white powder, and the average molecular
 weight was 10,790 g mol-1.

Growth conditions and treatments

The experiment was performed at the Research Center for Engineering Technology of

Polymeric Composites of Shanxi Province, North University of China to investigate the effects

of a new PRF on Chinese cabbage (local name: Shanghai Green) Brassica chinensis L.

campestris growth and soil nutrients under natural conditions. The annual rainfall and air

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temperature are 431.0 mm and 10 °C, respectively. The properties of soil were analyzed

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according to standard methods (Lu 2000). Soil pH, EC, available N, available P (extractant 0.5
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moL L-1 NaHCO3) and K (extractant 1 moL L-1 NH4OAc) were 8.22, 133.20 μS cm-1, 34.96,

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11.92 and 73.50 mg kg-1, respectively. The texture of soil was silt loam (12.0% clay, 38.0% sand,
an
and 50.0% silt contents), which was measured using micro-pipette method (Lu 2000). The

PRFs used in this study contains two types, which were low water-soluble of 21% and high
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water-soluble of 45% in 25°C water (1:20 w/v). All PRF was produced by the Research Center

for Engineering Technology of Polymeric Composites of Shanxi Province (Taiyuan, China).

d

The N, P, K and S contents of the PRF are 10.0%, 2.5%, 18.6%, and 4.4%), respectively. The
e

common inorganic compound fertilizer contains 10% N, 2.5% P, 18.6% K, 4.4% S (Common
pt

inorganic compound fertilizer was mixed by 21.41 g urea, 10.92 g KH2PO4, 30.04 g K2SO4 and
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64.3 g diatomite (Shengzhou Huali Diatomite Products Co., China).

Two days before sowing, all fertilizer treatment boxes (length × width × height=120 × 42 × 28
Ac

cm) were supplied with fertilizer, and the upper and lower soil was mixed, the layer thickness

was 25 cm. For each box, 4 g of Chinese cabbage seeds was uniformly sown in the box, and

then cover 2-3 cm deep soil on July 5, 2012 and 2013. After emergence, 15 plants were kept in

every box. Every box was introduced with 15 L of water every 2 d. Cabbage was harvested on

August 24, 2012 and 2013, and about 500 g soil samples from 0-20 cm layer were collected by

random sampling methods on August 24, 2012 and 2013.

 Every fertilizer included two levels, high amount and low amount. The experiment was

designed as a completely randomized block with three replicates and seven treatments:

- CK (no fertilizer),

- CCFH (common inorganic compound fertilizer, 43.2 g m-2),

- CCFL (common inorganic compound fertilizer, 21.6 g m-2 ),

- PRFLH (low water-soluble polymeric slow release fertilizer, 43.2 g m-2),

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- PRFLL (low water-soluble polymeric slow release fertilizer, 21.6 g m-2),

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- PRFHH (high water-soluble polymeric slow release fertilizer, 43.2 g m-2),
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- PRFHL (high water-soluble polymeric slow release fertilizer, 21.6 g m-2).

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an
Analysis of soil chemical properties

Soil inorganic nitrogen (NH4+-N and NO3--N, extraction with 0.01 mol L-1 CaCl2)
M
concentration was analyzed by AA3-A001-02E Auto-analyzer (Bran-Luebbe, Norderstedt,

Germany). Soil pH and EC were measured by pH Meter (PHS-3C, Precision Scientific

d

Instrument Co., Shanghai, China) and EC Meter (DDS-307, Precision Scientific Instrument Co.,
e

Shanghai, China). The contents of available P (0.5 moL L-1 NaHCO3 leaching) and K (1 moL
pt

L-1 NH4OAc extraction) were determined by Mo-Sb colorimetry and flame photometry (FP640,
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Precision Scientific Instrument Factory, Shanghai, China), respectively.

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Cabbage analysis of chlorophyll and quality

At harvest, all cabbages of each plot were individually weighed and washed with deinoized

water, and 500 g was oven dried at 80oC for determination of dry mass and N, P, K contents.

Chlorophyll a and b contents were determined by acetone extraction method (Zhao, 2002).

Vitamin C (VC) in the cabbage was analyzed in fresh plant samples (Lu 2000). Soluble sugar

and nitrate contents were determined as the method described by Chen et al. (2004). After the
 dry cabbage was collected, the dried plant material was ground so as to pass through a 2.0 mm

stainless screen in a Wiley mill, and the sample was decomposed by sulfuric acid/H2O2 method.

The N was analyzed by Kjeldahl method, P and K by Mo-Sb colorimetry and flame photometry

methods (Bao 2000).

The nutrient use efficiency (NUE) was calculated according to Equation (1):

NUE = (YxCx-Y0C0)/F×100. (1)

t
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Where: Y-the yield of cabbage; C-the content of nutrient in the plant; x-treatment with

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fertilizing; 0-control treatment with no fertilizing; F-the nutrient content of fertilizer.
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Statistical analysis

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Statistical analysis on the difference between the means of treatments was conducted using SAS
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program (Hu 2010).
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Results and discussion

Soil nutrient contents

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For the four treatments fertilized with common compound fertilizer and high water-soluble PRF,
e

the soil available N content was significantly higher than that without fertilizer (Table 1). The
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contents of available P in the soil of PRFLH, PRFLL, PRFHH treatments were significantly
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higher than CCFH, CCFL, PRFLL and control treatment. In addition, the content of soil

available P was similar between the common compound fertilizer and low water-soluble PRF
Ac

treatments, which was due to the less release of P from PRF and the P fixation of the common

compound fertilizer in the soil. Different fertilizer treatments also resulted in significant

differences in soil available K content. The highest available K content was found in PRFLH,

followed by PRFHH, CCFH, PRFHL, PRFLL, CCFL, and the control, which indicated that low

water-soluble PRF was useful for retarding the K release. The K release rate of PRF is

controlled by the solubility of PRF, and there was a negative correlation between the solubility
 and the molecular weight of PRF (Cheng 2013). So, compared with the high water-soluble PRF,

more K from the low water-soluble PRF was kept in the frequently irrigated soil in the short

term. For common fertilizer, K is completely dissolved and could not be stored in the soil with

low clay content for a long time. Compared with the control, soil EC was not significantly

changed with the addition of various fertilizers. At the common compound fertilizer application

rate of 43.2 g m-2, soil pH increased significantly, but the addition of PRF could not

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significantly change the pH of soil.

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PRF is a chemically degradable material with low solubility that would gradually decompose in
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soil (Zhao et al. 2010). The nutrient release cycle was determined by the solubility of fertilizer,

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the low water solubility of PRF has a longer term than high water solubility, which contained
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more amount of relative small molecules that can be degraded by soil microbial and enzyme in

short term (Cheng et al. 2013). At harvest, the available N, P, K of soil treated with high
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water-soluble PRF were higher than that with low water-soluble PRF, which was due to the

released amount of nutrients. It could be found that the amounts of N, P, K absorbed by Chinese
d

cabbage were 23.6%～24.5%, 12%～35.2%, 21.9%～28.6% higher, respectively, in the

e

treatments with high water-soluble PRF compared to low water-soluble PRF (Table 5). Besides,
pt

for the treatment of common compound fertilizer, the available N content in the soil was
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significantly higher than that of low water-soluble PRF. For N uptake, the common compound

fertilizer showed 23%～26% higher amounts than low water-soluble PRF. One possible
Ac

explanation of the result is that the N release in low water-soluble PRF was slower than that of

common compound fertilizer, considering the fact that most available N is absorbed by plant

and existed in the soil in small amounts. The highest pH of soil was observed with the CCFH

treatment, because large amounts of NH4+ are absorbed by soil particles. On the contrary,

slowly released NH4+ from PRF seemed to be absorbed mainly by the growing plant and only a

small amount remained in the soil, so the pH of PRF treatment cannot be changed significantly.
 Table 1

Chlorophyll contents

Chlorophyll is composed of carbon, hydrogen, oxygen, and nitrogen elements, and plays an

important role in nitrogen metabolism and carbon dioxide fixation in plants. Consequently, the

chlorophyll content can indirectly demonstrate soil N-supplying capacity and have long been

suggested as an index of the productive capacity of crop species (Ogunlela et al. 1989; Li et al.

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2013). In our study, it was found that fertilizer types affected chlorophyll differently (Table 2).

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Compared to that without fertilizer control (CK), the other fertilization treatments variously
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increased the chlorophyll a content of Chinese cabbage by a certain extent, except for the low

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amount of low water-soluble PRF treatment (PRFLL). At harvest time, the chlorophyll a
an
content was increased by 1.0-25.7% in dependence of fertilizer treatments compared to control.

However, there were no significant differences in chlorophyll a content between common

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compound fertilizer and high water-soluble PRF. For chlorophyll b, only the amounts in the

common compound fertilizer treatments (CCFH, CCFL) and high amount of high
d

water-soluble PRF treatment (PRFHH) were higher than in the control without fertilizer. The
e

treatments with common compound fertilizer and high water-soluble PRF had a positive effect
pt

on total chlorophyll content compared to low water-soluble PRF treatment. Besides, a similar
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observation was obtained on soil nutrient contents due to the effects of different fertilizer

treatments (Table 1). The available N content of soil from the high water-soluble release
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fertilizer was higher than that from the low water-soluble slow release fertilizer, so more N was

provided to the plant growth and promotion of chlorophyll synthesis. This indicates that the low

water-soluble slow release fertilizer released less amounts of nutrient in short term and cannot

meet the requirements of Chinese cabbage, and the high water-soluble release fertilizer could

significantly increase the synthesis of chlorophyll.

Table 2
 Cabbage yield and economic benefits

Different fertilizers had obvious effects on Chinese cabbage yields (Table 3). The control (CK)

had the lowest yield, only 3.10 kg m-2, due to absence of fertilizer application, followed by

CCFL, in which only half amount of fertilizers was applied. Among the other five treatments,

the PRFHH treatment produced the highest yield, followed by PRFHL, CCFH, PRFLH, and

PRFLL. Compared to the conventional fertilizer with the same amount of nutrients applied

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higher yields could be achieved when high water-soluble PRF was used, the difference was

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statistically significant. In addition, the treatment with low amount of high water-soluble
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release fertilizer had a higher yield than CCFH treatment even though only half of nutrient

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amounts were used. Besides, it could be found that N, P, K use efficiencies were 2.8%, 54.4%,
an
47.4%, respectively, higher in the PRFHL than CCFH treatments. This could be assumed due to

the improvement of nutrient utilization efficiency of Chinese cabbage and the reduction of
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fertilizer loss in the presence of PRF. The price of Chinese cabbage was 2 Yuan (RMB) kg-1 in

China in 2013. It can be found that the net income and the ratio of output to input were 32% and
d

48%, respectively, higher in the PRFHH than the common inorganic fertilizer (CCFHH)
e

treatments and the ratio of output to input of high water-soluble PRF was higher than those of
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low water-soluble PRF (Table 3). All these showed that the high water-soluble PRF can
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improve yield as well as increase revenue.

Table 3
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Cabbage quality

Treatments affected soluble sugars, Vitamin C, and NO3--N contents (Table 4). Compared to the

CK treatments, fertilization with PRFLH, PRFHH, and PRFHL significantly enhanced the

soluble sugar content. The treatments of PRFLH and PRFHL greatly increased the soluble

sugar content, up to 21.86 and 25.60 mg g-1, respectively. Vitamin C (VC) is regarded as one of

the important nutritive qualities of vegetables. In the experiment, the highest VC content was
 achieved when PRFLH was applied, followed by PRFLL. Statistically the lowest VC levels

occurred with CK, CCFH, and PRFHH treatments. Nitrate was one important factor, which can

limit safe quality of vegetables and hinder human health (Yousif et al. 2010). The U.S.

Environmental Protection Agency (EPA) reference dose for nitrate is equivalent to about 7.0

mg kg-1 body weight per day (Mensinga et al. 2003). A person weighing 60 kg, as

recommended by the U.S. Environmental Protection Agency, consumed this item would not

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exceed 420 mg per day. Because nitrate will be leached about 50% when cabbage is cooked, so

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the limited amount of nitrate is 840 mg. Assuming that everyone takes 500 g of vegetable every
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day, the most allowable concentration of nitrate in the vegetable is 1680 mg kg-1. The maximum

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of nitrate in vegetables is 1440 mg kg-1 according to the Standardization Administration of the
an
People’s Republic of China (GB/T 19338-2003). The results showed that the CCFHH, CCFHL

treatments had a high level NO3- content, up to 2211 and1534 mg kg-1, respectively. Application
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of PRF decreased NO3--N content of Chinese cabbage. The nutrients in PRF were released

slowly and well consistent with the plant absorption. It could be attributed to the improved
d

nitrogen quantity, which could increase the absorption of nitrate and result in less nitrate
e

accumulation in Chinese cabbage.

pt

In well aerated soils, urea from common compound fertilizer is rapidly hydrolyzed to NH4+
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which is thereafter converted in NO3- (Rodrigues et al. 2004). Thus, in PRF treatments, NH4+

and/or NO3- were available for plant uptake. Qiu et al. (2013) showed that the usage of slow
Ac

release fertilizer decreased the content of NO3--N and increased VC and soluble sugar contents

in the Chinese cabbage compared to common compound fertilizer. The results from Cao et al.

(2006) also showed that the application of controlled release fertilizer could increase VC by

12.5%.

Table 4

Nutrient uptake
 The effect of treatments on plant N, P, and K uptake was significant (Table 5). At all applied

nutrient levels plant nutrient uptake was higher at the application rate of 43.2 g m-2 compared to

the low rate of 21.6 g m-2. The uptake of K at 43.2 g fertilizer m-2 was not significantly different

from those of 21.6 g fertilizer m-2. The results from nutrient uptake showed that the high

water-soluble PRF was effective in improving nutrient absorption. Compared to common

compound fertilizer treatment, the maximum uptake of N, P, and K increased by 13.9, 22.0, and

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22.9%, respectively, in treatments with PRFs (Table 5). This was because the PRF has the

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capacity of continuous and sustainable supply of nutrients during the whole vegetation period.
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As opposed to that, common compound fertilizer released numerous nutrients at the beginning

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of the vegetation, and most of available N, P, K could not immediately be used by plant, H2PO4-
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and K+ could be fixed and adsorbed by soil, and a part of N could be volatilized in the form of

ammonia (Li et al. 2014). The remaining nutrient amounts were not able to supply such amount
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of nutrients as high water-soluble PRF.

Table 5
e d

Conclusions
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In the light of two-years’ results, it can be concluded that the application of PRF can effectively
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improve soil capacity of supplying nutrient, and did not change the soil pH and EC. High

water-soluble PRF can improve quality and increase both the plant growth and fruit yield of
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Chinese cabbage. Compared to the common compound fertilizer treatment of 43.2 g m-2, the

high water-soluble PRF treatment at 21.6 g m-2 could increase the yield 8%. Although the use of

low water-soluble PRF did not significantly enhance the yield, the use of low water-soluble

PRF significantly decreased the nitrate content.

Acknowledgments
 This work was supported by the project of Technology promotion of Shanxi Province (No

20130311009-6); The Graduate Innovation of Shanxi Province (No 20123094); and The

Graduate Technology Fund of North University of China (No 20120920).

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t
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Table 1. Effects of different fertilizer on N, P, K contents and pH, EC of soil.

us
Treatment Available N Available P Available K pH EC
(mg kg-1) (μS cm-1)
CK 33.55 c 11.81 cd 70.00 f 8.23 b 121.23 a
an
Common fertilizer
CCFH 47.13 a 13.50 cd 90.00 bc 8.36 a 136.23 a
M
CCFL 49.41 a 11.58 cd 75.00 ef 8.29 b 134.57 a

Low water soluble fertilizer

PRFLH 35.33 c 20.39 a 98.33 a 8.29 b 154.43 a
d

PRFLL 33.55 c 14.19 bc 81.67 de 8.28 b 144.03 a

e

High water soluble fertilizer

pt

PRFHH 46.92 a 16.52 b 93.33 ab 8.26 b 144.80 a

PRFHL 38.33 b 10.99 d 83.33 cd 8.25 b 134.03 a
ce

Note: The data in the table are the average values of 2012 and 2013. Different letters within the same column indicate
differences at the 0.05 significance level.
Ac
 Table 2: Effects of different fertilizer treatments on chlorophyll content.
Treatment Chlorophyll a Chlorophyll b Total Chlorophyll
(μg g-1)
CK 0.70 dc 0.24 b 0.94 c

Common fertilizer
CCFH 0.88 a 0.31 a 1.20 ab
CCFL 0.91 a 0.32 a 1.23 a

Low water soluble fertilizer

t
PRFLH 0.80 abc 0.26 b 1.06 bc

ip
PRFLL 0.71 d 0.24 b 0.95 c

cr
High water soluble fertilizer
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PRFHH 0.86 ab 0.30 a 1.17 ab

us
PRFHL 0.85 ab 0.26 b 1.11 ab
Note: The data in the table are the average values of 2012 and 2013. Different letters within the same column indicate
differences at the 0.05 significance level.
an
M
e d
pt
ce
Ac
 Table 3: Effects of different fertilizer treatments on yield and economic benefits of Chinese cabbage.
Treatments Fresh yield Rate of fertilizer application Fertilizer price Fertilizer cost Output value (Yuan Net income (Yuan The ratio of
(kg m-2) (×10-3 kg m-2) (Yuan (RMB) (×10-3 Yuan (RMB) m-2) (RMB) m-2) output to input

t
kg-1) (RMB) m-2)

rip
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CK 3.10 f — — — 6.22 6.22 —

sc
Common fertilizer
CCFH 5.51 c 43.2 2.033 87.8 11.02 10.93 53.67

u
CCFL 3.82 e 21.6 2.033 43.9 7.64 7.60 7.55

an
Low water soluble fertilizer
PRFLH 4.36 d 43.2 2.406 103.9 8.72 8.61 23.06

M
PRFLL 4.18 d 21.6 2.406 52.0 8.36 8.31 40.15

High water soluble fertilizer

PRFHH
PRFHL
7.29 a
5.78 b
43.2
21.6
ed
2.406
2.406
103.9
52.0
14.58
11.56
14.48
11.51
79.46
101.69
pt
Note: The data in the table are the average values of 2012 and 2013. Different letters within the same column indicate differences at the 0.05 significance level. The price of Chines cabbage was 2 Yuan
(RMB) kg-1.
ce
Ac
 Table 4. Effects of different fertilizer treatments on quality of Chinese cabbage.
Treatment Soluble sugar Vitamin C NO3—N Total N

(mg g-1)
CK 16.43 c 253 c 284 c 667 c

Common fertilizer
CCFH 17.06 c 298 bc 2211 a 880 a
CCFL 18.24 bc 323 abc 1534 b 814 a

t
Low water soluble fertilizer

ip
PRFLH 21.86 ab 417 a 598 c 762 b
PRFLL 17.31 c 408 a 377 c 658 c

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High water soluble fertilizer

us
PRFHH 18.70 bc 259 c 558 c 701 b
PRFHL 25.60 a 387 ab 441 c 578 d
Note: The data in the table are the average values of 2012 and 2013. Different letters within the same column indicate
differences at the 0.05 significance level.
an
M
e d
pt
ce
Ac
 Table 5. Effects of different fertilizer on Chinese cabbage N, P, K tissue content and nutrient
uptake.
Treatment Nutrient content (%) Nutrient uptake (g m-2)
N P K N P K
CK 1.81 c 0.46 c 3.08 a 4.10 e 1.04 e 6.96 d

Common fertilizer
CCFH 1.82 d 0.55 ab 3.35 a 8.90 b 2.18 b 13.3 abc
CCFL 1.59 d 0.54 ab 3.41 a 6.76 c 1.40 d 9.70 cd

t
Low water soluble fertilizer

ip
PRFLH 1.63 d 0.59 a 3.57 a 6.60 c 2.36 b 12.26 bc
PRFLL 1.59 c 0.57 a 2.94 a 5.46 d 1.96 c 11.88 bc

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High water soluble fertilizer

us
PRFHH 2.67 a 0.55 ab 3.35 a 10.14 a 2.66 a 16.34 a
PRFHL 2.42 b 0.51 b 3.54 a 6.64 c 2.30 b 14.54 ab
Note: The data in the table are the average values of 2012 and 2013. Different letters within the same column indicate
differences at the 0.05 significance level.
an
M
e d
pt
ce
Ac