Different Fertilization Modes of Sugarcane in Latosolic Red Soil of Guangxi

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1. Guangxi New Direction Modern Agriculture Development Co., Ltd., Nanning 530007, China; 2. Nanning Sugar Industry Co., Ltd., Nanning 530022, China; 3. College of Agronomy, Guangxi University, Nanning 530005, China

Abstract [Objectives] This study aimed to compare the effects of water-fertilizer integrated drip irrigation modes and traditional fertilization mode on growth, yield, production costs and economic benefit of sugarcane in latosolic red soil of Guangxi. [Methods] A field test was conducted. [Results] The agronomic traits and comprehensive economic benefit of sugarcane under the water-fertilizer integrated drip irrigation modes were superior to those under the traditional fertilization mode. Among them, the comprehensive economic benefit of sugarcane with special granular fertilizer as the base fertilizer and water-fertilizer integrated drip irrigation as topdressing were the highest, increased by 15 813 kg/ha, an increase of 15.8%. Considering the cost input, the comprehensive economic benefit increased by 5 676 yuan/ha. [Conclusions] Taking the production cost, economic benefit and input-output ratio into account, it is recommended to promote the application of water-fertilizer integrated drip irrigation mode in bases with water and fertilizer equipment conditions.

Key words Latosolic red soil, Fertilization mode, Water-fertilizer integration, Drip irrigation

1 Introduction

Sugarcane is the largest strategic cash crop and a pillar industry in Guangxi. It is the most important source for farmers’ income, and is the related to development of the peasant economy[1]. According to statistics, from 2013 to 2014, the sugarcane planting area in Guangxi is about 1 115 200 ha, and the total output is 789.693 million t. The number of employees in the sugar industry in Guangxi accounts for nearly 40% of the total population, about 20 million people[2].

Studies have shown that water and nutrients are key factors limiting sugarcane production. Appropriate water conditions and reasonable nutrient supply are the basic guarantee for high yield and quality of sugarcane. Water stress, nutrient deficiency and the unsynchronized supply of both are not conducive to sugarcane growth[3]. Water is an important factor affecting the elongation and sugarcane stems. Many studies have shown that precipitation contributes the most to sugarcane elongation. Water shortage often leads to reduced production and even harvest failure of sugarcane[4-7]. The demand for nutrients in sugarcane production is also large, but here are differences between different stages. Water and fertilizer integration technology can meet the different requirements of sugarcane for water and nutrients, achieving efficient use of water and fertilizer[8]. Compared with the traditional mode, water and fertilization integration technology can reduce the loss of fertilizer volatilization, fixation and leaching. Fertilizer utilization can be increased by 30%-50%, and water use efficiency can be increased by 40%-60%[9].

At present, there are not many reports on the water and fertilization integration technology in sugarcane. For different varieties, regional climate, soil and other conditions, the water and fertilizer supply parameters will also vary. Therefore, it is necessary to find a reasonable water and fertilizer supply model for the major sugarcane varieties growing in the latosolic red soil of Guangxi. At the same time, through soil testing and plant testing, the nutrients in soil and sugarcane will be comprehensively grasped. Studying and testing the special water-soluble fertilizer according to the fertilizer demand rules of sugarcane, constructing fertilizer stations and water-saving irrigation facilities according to different soil conditions and planting intensive conditions, guiding farmers in the demonstration base to drip fertilization according to the growth process of sugarcane, and establishing a complete and operable water and fertilizer integrated drip irrigation technology for sugarcane will be the future development trend of the sugarcane industry.

2 Materials and methods

2.1 Test materials

2.1.1Test site. The test site is located at Plot 13# in the north section of the 18th team of Xinfu Village, Ningwu Town, Wuming District, Nanning City, Guangxi.

2.1.2Test variety. The test variety was Yuetang 93/159.

2.1.3Test fertilizers. "New Direction" sugarcane special water-soluble fertilizer 25-7-18+TE, powder, produced in Nanning, Guangxi.

"New Direction" sugarcane special baser fertilizer 7-12-6S, solid particles, produced in Nanning, Guangxi.

"Gao Er Zhuang" compound fertilizer 13-6-10, solid particles, produced in Chongzuo, Guangxi.

"Gao Er Zhuang" compound fertilizer 21-7-18, solid particles, produced in Chongzuo, Guangxi.

Urea, 46% content, produced in Hechi, Guangxi.

2.1.4Test soil. The test soil was latosolic red soil, quaternary red soil parent material. The previous crop was sugarcane.

The contents of organic matter, available nitrogen, available phosphorus, available potassium, available calcium, available magnesium, available zinc and available boron in the test soil were 29.71%, 87.29, 26.02, 74.82, 916.80, 240.50, 1.49 and 0.69 mg/kg, respectively. The pH of the test soil was 5.5.

2.2 Test design and methodsThere were three treatments: A. "New Direction" sugarcane special water-soluble fertilizer, drip irrigation; B. "New Direction" sugarcane special base fertilizer 7-12-6S+, base fertilization; "New Direction" sugarcane special water-soluble fertilizer, drip irrigation at elongation stage; C. "Gao Er Zhuang" compound fertilizer 13-6-10+, baser fertilization; "Gao Er Zhuang" compound fertilizer 21-7-18, topdressing at elongation stage. There were three replications in each treatment. Each replication covered an area of 2 ha (one rotational irrigation plot), and all the rotational irrigation plots were arranged randomly.

The sugarcane in the test site was planted on April 10, 2017. It was earthed up on June 19, 2017. In the A treatment, from June 15 to October 14, total 12 times of drip irrigation were carried out at an interval of about 10 d, and the fertilization amount was 1 095 kg/ha. In the B treatment, the fertilization amount of the base fertilizer was 1 500 kg/ha; and total 12 times of drip irrigation were carried out from June 15 to October 14 at an interval of about 10 d, and the fertilization amount was 720 kg/ha. In the C treatment, the application amount of the base fertilizer was 1 500 kg/ha; and topdressing ("Gao Er Zhuang" compound fertilizer 21-7-18, 1 500 kg/ha; urea, 300 kg/ha) was carried out by the means of drip irrigation on June 15 along with cultivation and banking.

2.3 Measured indicatorsAfter planting, the seedling emergence rate and tillering rate of sugarcane were investigated during the germination and tillering stages. The plant height, stem diameter, effective stem number, field brix and yield of sugarcane were investigated at the time of sugarcane harvest.

2.4 Statistics and analysisThe test data were processed using Excel 2007 and analyzed by one-way ANOVA of DPS 7.05 software.

3 Results and analysis

3.1 Effects of different fertilization modes on seedling and tillering stages of sugarcaneAs shown in Table 1, among different treatments, the emergence rate of B treatment was the highest, with an average of 54.02%, significantly higher than those of A (44.23%) and C (47.21%) treatments. The difference between A and C treatment was not significant, but the emergence rate of C treatment was higher than that of A treatment. It indicated that the application of base fertilizer in the early stage could promote the emergence of sugarcane. In particular, the products of the B treatment had high phosphorus content and contained sulfur.

In addition, the tillering rate of A treatment in which the water-fertilizer integrated drip irrigation was conducted in the early stage of tilering was significantly higher than those of other treatments. The tillering rate of B treatment in which base fertilizer was applied and water-fertilizer integrated drip irrigation was conducted at the tillering stage was also higher than that of C treatment. It was proved that water-fertilizer integrated drip irrigation is beneficial to sugarcane tillering.

Table 1 Effects of different fertilization modes on growth of sugarcane at the seedling stage

TreatmentMay 12June 14July 15August 17Emergence rate∥%Tillering rate∥%A3 538 b5 971 b5 169 b4 752 b44.23 b69.24 aB4 322 a6 755 a6 015 a5 405 a54.02 a56.29 bC3 777 b5 659 b4 759 b4 336 b47.21 b49.83 b

3.2 Effects of different fertilization modes on plant height and monthly growth rate of sugarcaneTable 2 shows the effects of different fertilization modes on plant height and monthly growth rate of sugarcane. The results in Table 1 have shown that water-fertilizer integrated drip irrigation was beneficial to tillering of sugarcane. As shown in Table 2, the advantage of water-fertilizer integrated drip irrigation was further obvious when conducted at jointing stage. The plant heights and monthly growth rates of A and B treatments were significantly higher than those of C treatment. When the water-fertilizer integrated drip irrigation mode was used at the jointing stage, the monthly growth rate of sugarcane increased steadily. Under the traditional mode, sugarcane grew fast first and then slowly. It indicated that continuous supply of nutrients and water and topdressing in the mode of water-fertilization integrated drip irrigation were more conducive to the growth of sugarcane.

Table 2 Effects of different fertilization modes plant height and monthly growth rate of sugarcane cm

3.3 Effects of different fertilization modes on yield and sugar content of sugarcaneAs shown in Table 3, the effective stem number of B treatment was significantly greater than those of A and C treatments. This might be because that the base fertilizer had high phosphorus content and contained sulfur, which was related to the emergence, tillering and formation of effective stems of sugarcane. The differences in plant height and stem diameter between the three treatments were not significant. The plant height and stem diameter of B treatment were highest, followed by those of A treatment, and the plant height and stem diameter of C treatment were lowest.

Among the three treatments, the yield of B treatment was highest, with an average of 115 830 kg/ha, higher than those of A (107 901 kg/ha,P>0.05) and C (100 017 kg/ha, higher by 15 813 kg/ha, an increase of 15.8%) treatments. The yield of A treatment was higher than that of C treatment by 7 884 kg/ha, an increase of 7.9%. The difference between A and B treatments was not significant.

The field brix differed insignificantly among the three treatments. It indicated that neither water-fertilizer integrated drip irrigation mode nor traditional solid granular fertilization mode had great impact on sugar content of sugarcane.

Table 3 Effects of different fertilization modes on yield and sugar content of sugarcane

TreatmentEffective stems∥plants/haStem diameter∥mmPlant height∥cmYield∥ka/haYield increase∥kg/haIncrease amplitude∥%Brix∥%A71 280 b27.48 a283.3 a107 901 ab7 8847.918.10 aB81 075 a24.88 a323.8 a115 830 a15 81315.818.70 aC65 040 b28.17 a276.7 a100 017 b--18.00 a

3.4 Comparison of sugarcane economic benefits among different fertilization modesTable 5 shows the economic benefits of sugarcane in different fertilization modes. The purchase price of raw sugarcane was 450 yuan/t, and the artificial cutting cost was 150 yuan/t, so the net income was 300 yuan/t. Compared with that of C treatment, the incomes of A and B treatments were increased by 2 365.5 and 4 734 yuan/ha, respectively. Taking the cost of fertilizer input into account, the comprehensive economic benefits increased by 4 086 and 5 676 yuan/ha, respectively. The investment in water and fertilizer equipment was about 9 000 yuan/ha, so calculating the economic benefits like this was not ideal. However, the investment in water and fertilizer equipment is only a one-time investment, and the service life of the equipment can be more than 10 years. Therefore, if A and B treatments, especially B treatment can maintain such economic benefits, the input cost of water and fertilizer equipment will be recovered within two years, really achieving the purpose of saving water, reducing fertilizer, and increasing farmers’ income.

Table 4 Comparison of economic benefit among different fertilization modes

TreatmentYield∥kg/haEconomic income∥yuan/haIncome increase∥yuan/haFertilizer input∥yuan/ha Economic income increase∥yuan/haA107 90132 3702 365.56 679.54 086B115 83034 7494 7437 4675 676C100 01730 004.5-8 400-

Note: 1. The yield increase and economic benefit increase were compared with C treatment; 2. Referring to the 2016-2017 squeeze season, the purchase price of sugarcane was 450 yuan/t, and the artificial cutting cost was 150 yuan/t (i.e., the net income of sugarcane was 300 yuan/t); 3. The prices of the "New Direction" water-soluble fertilizer, "New Direction" sugarcane special base fertilizer, "Gao Er Zhuang" (content 29%), "Gao Er Zhuang" (content 46%) and urea were 6 100, 2 050, 2 210, 2 990 and 2 000 yuan/t, respectively.

4 Conclusions and discussions

The above research results show that water-fertilizer integrated irrigation mode has a significant promotion effect on the growth of sugarcane. Whether it is used throughout the growth period or used at the elongation stage, the yield of sugarcane can be significantly improved.

Whole-process water-fertilize integrated drip irrigation can save manure during base fertilization and hilling, achieving cost savings. However, no application of base fertilizer in the early stage have a certain impact on the germination, rooting and emergence of sugarcane, the emergence rate is significantly lower than the base fertilization treatments, indicating the importance of base fertilizer on sugarcane emergence and seedling growth. The soil testing formula that has high phosphorus content and contains sulfur is preferred.

From the perspective of economic benefit, the treatment which applies "New Direction" sugarcane special base fertilizer 7-12-6S+ as base fertilizer and conducts topdressing with "New Direction" sugarcane special water-soluble fertilizer by means of water-fertilizer integrated drip irrigation at the elongation stage is superior to traditional fertilization mode without water-fertilizer integrated drip irrigation. The average increase is 15 813 kg/ha, an increase of 15.8%. Considering the cost input, the comprehensive economic benefit increases by 5 676 yuan/ha.

As can be seen from the above results, the agronomic traits and comprehensive economic benefit of sugarcane under water-fertilizer integrated drip irrigation mode are superior to the traditional fertilization mode. The comprehensive economic benefit of the treatment that applied special granular fertilizer as base fertilizer and conducted topdressing under the mode of water-fertilizer integrated drip irrigation is the highest. Therefore, according to the soil nutrient status of the target plot, the nutrients needed by sugarcane can be supplemented to improve the emergence rate of sugarcane. In the middle and late stages, according to the nutrient and water needs of sugarcane growth stages, water-fertilizer integrated drip irrigation can be carried out to ensure effective stems, thereby maximizing sugarcane production and improving sugarcane sugar content. Therefore, it is recommended to promote the application of water-fertilizer integrated drip irrigation mode in bases with water and fertilizer equipment conditions.