Form and Interconversion Factor of Selenium in Soil

Ying XING Yongxian LIU Panxia LIANG Qing LIAO Liping PAN Taiqing HUANG Zepu JIANG

AbstractWith strawberry as a test material, the effects of the bioorganic fertilizer containing highefficiency nitrogenfixing Bacillus amyloliquefaciens on nutrient contents in strawberryplanted soil, wilt occurrence and strawberry yield and quality were studied by a plot experiment, so as to provide reference for scientific use of the bioorganic fertilizer and green production of strawberry. The results showed that after holeapplying the bioorganic fertilizer at a rate of 22.5 t/hm2, the contents of NH＋4N, available P, available K and organic matter did not change much with time; and when replacing 50% of chemical fertilizers with the bioorganic fertilizer at a rate of 11.25 t/hm2 (K3), the contents of NH＋4N and available P in the soil did not change much with time, and the contents of available K and organic matter decreased slightly with time, but were both higher than the CK (the unfertilized treatment). Meanwhile, the disease index values of strawberry wilt disease in treatments K2 and K3 were significantly lower than those of the CK and the conventional fertilization treatment (K1), and the vitamin C contents of strawberry fruit in the two treatments were significantly higher than that of the CK. The yield determination showed that the cumulative yields of treatments K2 and K3 increased by 9.8% and 3.3%, respectively, and the increase rates of the early yields (before the Spring Festival) were 30.6% and 21.9%, respectively. Therefore, the application of the bioorganic fertilizer can replace chemical fertilizers, and can achieve the effects of reducing the occurrence of wilt, improving the early yield of fruit commodity and improving fruit quality.

Key wordsBacillus amyloliquefaciens; Bioorganic fertilizer; Strawberry; Fertilizer efficiency; Fruit quality

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Received: October 11, 2018Accepted: December 11, 2018

Lili JIANG (1986-), female, P. R. China, PhD, research assistant, devoted to research about fruit tree protection.

*Corresponding author. Email: kywang@sdau.edu.cn.

In modern agricultural production, the large investment in chemical fertilizers has positively promoted the growth of crop yields, but meanwhile, it also brings serious ecological problems［1-2］. In facility cultivation, problems such as soil acidification and hardening, reduction of organic matter, secondary salinization and reduction of crop quality and resistance to stress caused by longterm excessive application of chemical fertilizers have attracted extensive attention［3］. In order to ensure the sustainable development of Chinas agriculture, the Ministry of Agriculture proposed the goal of zero growth in pesticide and fertilizer application in 2020, and launched the action of replacing chemical fertilizers with organic fertilizer in fruit, vegetable and tea production. Due to the shortcomings of traditional organic fertilizer, such as slow fertilizer efficiency and slow effect, it is difficult to take the responsibility of completely replacing fertilizers under the existing crop yield levels［4］. Microbial fertilizer can supply nutrients to crops through the life activities of specific microorganisms, and has the advantages of nontoxic environmental protection and energy conservation［5］. However, due to the limitation of many environmental factors on microbial colonization, the effect is often unstable. The bioorganic fertilizer refers to a kind of fertilizer having the advantages of both microbial fertilizer and organic fertilizer, which is formed by combining specific functional microorganisms and harmlesslytreated decomposed organic materials. The organic carrier contained therein provides sufficient nutrients and a suitable environment for the growth and reproduction of microorganisms. In recent years, bioorganic fertilizers have become more and more widely used in agricultural production, especially in the production of fruits and vegetables［6］.

During the completion of the soil improvement project supported by the national "Twelfth FiveYear" Science and Technology Support Program, the research team used the probiotics isolated from soil for domestication and improvement, and obtained highefficiency nitrogenfixing Bacillus amyloliquefaciens J25 (1) (patent Application No. 20140798221.8), phosphatesolubilizing bacteria, potassiumsolubilizing bacteria and antagonistic bacteria against wilt. And the microbial flora is compounded with an organic carrier consisting of humic acid, powdered rock phosphate and potassium to prepare a granular biofertilizer, which is sold under the trade name of "Fengtianbao" bioorganic fertilizer. The product can meet the nutrient demand of crops in the whole growing season and ensure the continuous high yield of crops. It can also improve the quality of agricultural products and the disease resistance of crops, and has obtained the certification of green food production materials (LSSZ011707150021). The promotion and application on tomato, cucumber and other crops have achieved excellent effects［7-8］.

Strawberry is popular among consumer because of its bright color and juicy taste, and has become one of the important special economic crops in China［9］. In this study, the "Miaoxiang" strawberry was used as a test material to study the effects of the "Fengtianbao" bioorganic fertilizer completely and partially replacing conventional chemical fertilizer on facility soil and strawberry disease resistance and yield, and its application prospect in facility strawberry was analyzed. This study provides reference for the promotion and application of the bioorganic fertilizer.

Materials and Methods

General situation of experimental field

The experiment was carried out in 2016 in the strawberry greenhouse of Xufeng Vegetable Professional Cooperative in Linzi District, Zibo City, Shandong Province. The tested soil was sandy loam soil with uniform high soil fertility, and the irrigation was convenient. Strawberry was planted for many years in the selected test area, and soilborne diseases such as wilt were serious. The soil nutrient conditions are shown in Table 1.

Experimental materials

The tested fertilizer was "Fengtianbao" bioorganic fertilizer, granular, B. amyloliquefaciens≥2.0×107/g, organic matter≥40%, provided by Shandong Fengtianbao Agricultural Technology Co., Ltd. The control compound fertilizer (151515) and water soluble fertilizer (212121) were produced by Shandong Youbang Fertilizer Group.

Table 1Soil nutrients of the experiment field

Organic matter content∥g/kgNH＋4N∥mg/kgAvailable P content∥mg/kgAvailable K content∥mg/kgpH

18.5155.371.5125.67.1

The tested strawberry variety was "Miaoxiang", which was transplanted with soil at the stage of five leaves and one heart. The field was ridged, and the ridges had a height of 35 cm, a width at the top of 50 cm and 75 cm at the bottom, with furrows having a width of 25 cm therebetween. During cultivation, strawberry was filmmulching planted two rows per ridge, with plant spacing of 15 cm, small row spacing of 25 cm, and a plantation density of about 120 000 plants/hm2.

Experimental methods

Experimental design

The experiment included three treatments. Treatment 1 (K1) was set by conventionally broadcasting common compound fertilizer (151515) at 1.5 t/hm2, followed by ridging, and topdressing the watersoluble fertilizer (212121) at a rate of 150 kg/hm2 during the fruit expansion period for 8 times in total until pulling up the plants. Treatment 2 (K2) was set by hole applying the bioorganic fertilizer to completely replace chemical fertilizers at 22.5 t/hm2, without applying any chemical fertilizer during the whole growth period. Treatment 3 (K3) adopted the bioorganic fertilizer to partially replace chemical fertilizers by furrowapplying common compound fertilizer (151515) at a rate of 0.75 t/hm2, followed by ridging, and holeapplying the bioorganic fertilizer at a rate of 11.25 t/hm2, and topdressing the watersoluble fertilizer (212121) at a rate of 150 kg/hm2 during the fruit expansion period for 4 times in total until pulling up the plants. A blank control (not applying any fertilizer) was also set. Each treatment included three replicates, in successive arrangement. Each plot had a length of 14 m, a width of 15 m, and an area of 210 m2. Guard rows were set between treatments.

Experimental operation

Transplanting was performed on September 15, 2016, and the plants were pulled out on June 14, 2017. The base fertilizer was applied 2-3 d before transplanting, followed by ridging. During transplanting, 2% imidacloprid granule was used to prevent pests such as Bemisia tabaci; 50% chlorothalonil WP was sprayed once during fruit setting to prevent gray mold and leaf spot disease; and 30% kresoximmethyl WP was sprayed once to prevent powdery mildew.

Item determination

At 60, 120 and 180 d after transplanting, 15 strawberry plants were randomly selected from each plot to investigate the incidence and disease index of wilt. The disease severity grading standards［10］ were as follows: grade 0: normal plants, no lesions in whole plants, grade 1: yellowing of 1-2 leaves on whole plants, grade 2: yellowing of most leaves on whole plants, grade 3: early withering of plants, grade 4: withering of whole plants, and grade 5: plant death. At the same time, 15 to 20 sampling points were selected in each plot, and a columntype soil sampler was used to draw 5-15 cm soil of the cultivated layer, which was mixed well, airdried, and sieved with 1 mm sieve, obtaining the soil sample for the determination of ammonium nitrogen, available phosphorus, available potassium and organic matter content by routine analysis method. The first batch of strawberry fruit was harvested to determine the single fruit weight and quality index. The soluble sugar content was determined by anthrone colorimetry; the titratable acid content was determined by NaOH standard solution titration; the ascorbic acid (VC) content was determined by 2,6dichloroindophenol titrimetric method［11］; and the soluble solid content was determined with a refractometer. Ripe strawberry fruit from each treatment was harvested, and the yield was recorded. The yield before January 27, 2017 (the Spring Festival) was recorded as early yield, followed by the later yield.

Data analysis

Data were processed using Microsoft Excel 2010 software and SPSS18.0 software, and the significance of differences between treatments was analyzed by studentnewmakeuls.

Results and Analysis

Effects of different fertilization treatments on soil fertility indexes in strawberry growth period

It could be seen from Fig. 1 that the nutrient variations in different fertilization treatments were different. At 60, 120 and 180 d after treatment, the contents of ammonium nitrogen, available phosphorus and available potassium in the unfertilized treatment (CK) gradually decreased over time, but the differences were not significant in statistical analysis; and the organic matter content did not change much with time. It indicated that planting strawberry without fertilization consumed the basic soil fertility to some extent. As to the conventional fertilization treatment (K1), the contents of ammonium nitrogen, available phosphorus and available potassium also decreased with the treatment time, but were higher than the CK in each treatment period. In the treatment completely replacing chemical fertilizers with the bioorganic fertilizer (K2), the contents of ammonium nitrogen, available phosphorus, available potassium and organic matter in the soil did not change much with time, and were always higher than the CK, indicating that the bioorganic fertilizer is rich in nitrogenfixing phosphatesolubilizing and potassiumsolubilizing bacteria, which can meet the nutrient supply required for strawberry growth and increase the organic matter content in the soil. The contents of ammonium nitrogen and available phosphorus in the treatment partially replacing chemical fertilizers with the bioorganic fertilizer (K3) did not change much with time, and the contents of available potassium and organic matter decreased slightly with time, but were higher than the CK.



Fig. 1Fluctuation of soil nutrients after different fertilization treatments

Lili JIANG et al. Application of Bioorganic Fertilizer Containing Highefficiency Nitrogenfixing Bacillus amyloliquefaciens on Strawberry

The occurrence of strawberry wilt under different fertilization treatments

It could be seen from Table 2 that the complete or partial replacement of chemical fertilizers with the bioorganic fertilizer can reduce the incidence and disease index of strawberry wilt to some extent. At 60 d after transplanting, the incidence of strawberry wilt in the treatment completely replacing chemical fertilizers with the bioorganic fertilizer (K2) was 0, which was significantly lower than that of the unfertilized treatment (CK) and the conventional fertilization treatment (K1) (P<0.05); and the incidence of strawberry wilt in the treatment partially replacing chemical fertilizers with the bioorganic fertilizer (K3) was 2.22%, which was also lower than those of the CK and treatment K1. At 120 d after transplanting, the incidences of strawberry wilt in treatments K2 and K3 were 2.22% and 4.44%, respectively, and the disease indexes were 0.44 and 1.33, respectively, which were significantly lower than the CK and treatment K1 (P<0.05). At 180 d after transplanting, the incidences of strawberry wilt in treatments K2 and K3 were 4.44% and 6.67%, respectively, and the disease indexes were 4.44 and 13.33, respectively, which further had larger differences from the CK and treatment K1. It could be seen that the prevention and control effect of the bioorganic fertilizer on strawberry wilt can be gradually improved over time.

Effect of different fertilization treatments on fruit quality of strawberry

It could be seen from Table 3 that the conventional fertilization (K1), complete replacement of chemical fertilizers with the bioorganic fertilizer (K2) and partial replacement of chemical fertilizers with the bioorganic fertilizer (K3) had a single fruit weight and sugaracid ratio higher than the CK, but the differences were not significant in statistical analysis. The vitamin C contents of strawberry fruit in the complete (K2) and partial (K3) replacement of chemical fertilizers with the bioorganic fertilizer were, respectively, 613.0 and 609.0 μg/kg, which were significantly higher than 586.3 μg/kg in the CK and 594.3 μg/kg in the conventional fertilization treatment (K1). Meanwhile, the soluble solid contents of strawberry fruit in treatments K2 and K3, respectively, were 7.70% and 7.83%, which were significantly higher than that in the CK (6.97%) and had no significant difference compared with the conventional fertilization treatment K1 (7.13%). It could be seen that the replacement of chemical fertilizers with the bioorganic fertilizer can improve the quality of strawberry fruit to some extent, and the improvement effect of completely replacing chemical fertilizers was slightly better than that of partially replacing chemical fertilizers.

Table 2Occurrence of strawberry wilt under different fertilization treatments

Treatment

60 d

Incidence∥%Disease index

120 d

Incidence∥%Disease index

180 d

Incidence∥%Disease index

CK8.89±3.85 a1.78±0.77 a11.11±3.85 a3.56±0.77 a13.33±0.00 a42.22±10.18 a

K18.89±3.85 a2.22±1.54 a13.33±0.00 a4.00±0.00 a13.33±0.00 a35.56±3.85 a

K20.00±0.00 b0.00±0.00 a2.22±3.85 b0.44±0.77 b4.44±3.85 b4.44±3.85 b

K32.22±3.85 ab0.44±0.77 a4.44±3.85 b1.33±1.33 b6.67±0.00 b13.33±6.67 b

Data are shown as average±SE, and different letters after data in the same column indicate a significant difference at the 0.05 level. The same below.

Table 3Effect of different fertilizer treatments on fruit quality of strawberry

TreatmentSingle fruit weight∥gSugaracid ratioVitamin C content∥μg/kgSoluble solid content∥%

CK16.73±0.68 a8.24±0.70 a586.3±4.5 b6.97±0.21 b

K117.80±0.92 a8.63±0.49 a594.3±5.7 b7.13±0.35 ab

K218.00±0.62 a9.48±0.82 a613.0±5.6 a7.70±0.46 a

K317.87±0.40 a9.64±0.56 a609.0±2.0 a7.83±0.21 a

Effect of different fertilization treatments on strawberry yield

As shown in Table 4, the early (before the Spring Festival) and later (after the Spring Festival) yields of the strawberry in the complete (K2) and partial (K3) replacement of chemical fertilizers with the bioorganic fertilizer were higher than that of the conventional fertilization treatment (K1), and the strawberry yield of the CK was significantly lower than that of treatment K1. The yieldincreasing effect in the early period (before the Spring Festival) was especially remarkable in the bioorganic fertilizer treatment, and the early yields of treatments K2 and K3 were, respectively, 4.05 and 3.78 t/hm2, which were 30.6% and 21.9% higher than that of treatment K1; the later yields were 32.80 and 30.88 t/hm2, respectively, with increase rates of 7.6% and 1.3% respectively; the cumulative yields in the whole season were 36.85 and 34.66 t/hm2, respectively, with the yield increase rates reaching 9.8% and 3.3%, respectively. Compared with the conventional fertilization treatment (K1), the early, later and cumulative yields of the unfertilized treatment (CK) were 2.63, 25.80 and 28.43 t/hm2, respectively, with reductions of 15.2%, 15.3% and 15.3%, respectively.

Table 4Effect of different fertilization treatments on strawberry yield

Treatment

Earlier period

Yield∥t/hm2Increase∥%

Later period

Yield∥t/hm2Increase∥%

Added up

Yield∥t/hm2Increase∥%

CK2.63±0.20 c-15.225.80±0.82 b-15.328.43±0.95 b-15.3

K13.10±0.21 b-30.47±1.93 a-33.56±2.02 a-

K24.05±0.25 a30.632.80±1.58 a7.636.85±1.75 a9.8

K33.78±0.20 a21.930.88±1.64 a1.334.66±1.70 a3.3

Discussion and Conclusions

In recent years, with the strengthening of peoples awareness of environmental protection, Chinas green food and pollutionfree agriculture have developed rapidly, and the application of bioorganic fertilizers has received increasing attention. The bioorganic fertilizer refers to fertilizers that combine functional microorganisms with harmlesslytreated decomposed organic materials. This type of fertilizers can increase soil fertility, help crop nutrient supply, and improve agricultural product quality and crop stress resistance［12］. The functional microorganisms and carriers contained in different fertilizer formulations are not completely identical, and the characteristics of the fertilizer efficiency are also quite different. Shen et al.［13］ reported that Streptomyces hygroscopicus B04 solid microbial agent can reduce the incidence of strawberry root rot, increase the vitamin C content of strawberry fruit, and increase sugaracid ratio. Guan et al.［14］ reported that the control effects of "Ningdun" microbial fertilizer on strawberry wilt and anthracnose were 74.46% and 72.18%, respectively, and the single fruit weight was improved. Zhang et al.［15］ reported that bioorganic fertilizer containing B. amyloliquefaciens QL18 can regulate the floristic composition of rhizosphere microorganisms of tomato and pepper, and reduce the occurrence of soilborne diseases.

In the study, it was found that after holeapplying the "Fengtianbao" bioorganic fertilizer containing B. amyloliquefaciens J25 (1), phosphatesolubilizing bacteria, potassiumsolubilizing bacteria and antagonistic bacteria at a rate of 22.5 t/hm2, the contents of ammonium nitrogen, available phosphorus, available potassium and organic matter did not change much with time, and were always higher than the unfertilized treatment (CK), indicating that it could completely replace chemical fertilizers and meet the nutrient requirements of strawberry during the whole growth period. When replacing 50% of the chemical fertilizers with the bioorganic fertilizer at a rate of 11.25 t/hm2, the contents of ammonium nitrogen and available phosphorus in the soil did not change much with time, and the contents of available potassium and organic matter decreased slightly with time, but were both higher than the CK. It might be due to that the living bacteria are not easy to form a population effect at a reduced dosage, and it is thus necessary to consume a certain amount of chemical fertilizers to meet the demand for potassium fertilizer of strawberry.

Due to the protected continuous cultivation and the application of large amount of chemical fertilizers, strawberry wilt occurred in the test area, and the incidence in the CK was as high as 13.33%. The incidence and disease index of strawberry wilt in the treatment completely or partially replacing chemical fertilizer with the bioorganic fertilizer were significantly lower than the CK, and the control effect was gradually improved with time. The identification of fruit quality showed that completely or partially replacing chemical fertilizers with the bioorganic fertilizer can improve the quality of strawberry fruit to some extent, and the improvement effect of completely replacing chemical fertilizers with the bioorganic fertilizer was slightly better than that of partially replacing chemical fertilizers with the bioorganic fertilizer. The yield determination showed that the cumulative yields of the treatments completely and partially replacing chemical fertilizers increased by 9.8% and 3.3%, respectively, and the early yields increased more significantly, by 30.6% and 21.9%, respectively. It could be seen that the "Fengtianbao" bioorganic fertilizer can replace chemical fertilizers to some extent, and can achieve the effects of overcoming the continuous cropping obstacles, reducing the occurrence of strawberry wilt, improving the quality of strawberry fruit, promoting early marketing of strawberry fruit and increasing the early yield of commercial fruit, thereby exhibiting very significant economic benefit.

References

［1］ KAUR T, BRAR B, DHILLON N. Soil organic matter dynamics as affected by longterm use of organic and inorganic fertilizers under maizewheat cropping system［J］. Nutrient Cycling in Agroecosystems, 2008, 81: 59-61.

［2］ ZHAO FJ, MA YB, ZHU YG, et al. Soil contamination in China: Current status and mitigation strategies［J］. Environmental Science ＆ Technology, 2015, 49: 750-759.

［3］ XIN YF. Effect of fungal biofertilizer from Chaetomium globosum on growth and quality of strawberry［J］. Journal of Southern Agriculture, 2013, 44(7): 1145-1149. (in Chinese)

［4］ HUANG HM. A review on application of bioorganic fertilizers in fruits and vegetables production［J］. Journal of Southern Agriculture, 2011, 42(8): 935-939. (in Chinese)

［5］ VESSEY JK. Plant growth promoting rhizobacteria as biofertilizers［J］.Plant and Soil, 2003, 255: 571-586.

［6］ ZHANG YM, ZHOU HJ, ZHANG JY. Research progress on bioorganic fertilizer［J］. Journal of Northeast Agricultural Sciences, 2010, 35(3): 37-40. (in Chinese)

［7］ JIANG LL, WU YG, WANG KY. Application effect of Fengtianbao microbial fertilizer on greenhouse tomato［J］. Bulletin of Agricultural Science and Technology, 2015(12): 171-172, 284. (in Chinese)

［8］ JIANG LL, WANG KY, WU YG. Evaluation of fertilizer efficiency of Fengtianbao bioorganic fertilizer on facility cucumber［J］. Bulletin of Agricultural Science and Technology, 2017(9): 166-167, 181. (in Chinese)

［9］ ZHANG JJ, LIU H. Effects of Different formulated fertilizations on the growth and fruiting of greenhouse Fragaia ananassa［J］. Journal of Northwest Forestry University, 2013, 28(2): 114-117. (in Chinese)

［10］ HYEON NM, PARK MS, KIM HG, et al. Biological control of strawberry Fusarium wilt caused by Fusarium oxysporum f. sp. fragariae using Bacillus velezensis BS87 and RK1 formulation［J］. Journal of Microbiology and Biotechnology, 2009, 19(5): 520-524.

［11］ LIU JP, LIU WY, ZHOU J, et al. Effects of applying humic acids and biofertilizer on the qualities and yield of strawberry and soil agrochemical characters［J］. Journal of Agricultural Resources and Environment, 2015, 32(1): 54-59. (in Chinese)

［12］ LIU X, SHAO XH, MAO X, et al. Effects of EM organic fertilizer on sweet corn growth and soil characteristics［J］. Jiangsu Agricultural Sciences, 2010(1): 301-304. (in Chinese)

［13］ SHEN T, YANG H, DAI LT, et al. Effects of solid fermentation agent of Streptomyces hygroscopicus B04 on strawberry growth and fruit quality［J］. Journal of Agricultural Resources and Environment, 2016, 33(1): 49-54. (in Chinese)

［14］ GUAN WF, DAI XQ, HU Q, et al. Biocontrol effect of biofertilizer ‘Nanjing Shield’ on strawberry ［J］. Northern Horticulture, 2016(2): 158-162. (in Chinese)

［15］ ZHANG P, WANG XH, LI R, et al. Effect of bioorganic fertilizer on pathogenic and functional bacteria composition in rhizospheric soil of field vegetables［J］. Acta Pedologica Sinica, 2013, 50(2): 381-387. (in Chinese)