Introduction

Increasing demand of water for agriculture and domestic use with geographic constraints on water availability and use has rendered water scarcity a major problem for agriculture and other uses globally. Indeed, the demand for drinking and irrigation water alone exceeds available supply (FAO 2008; Vanham et al. 2018). In China, with per capita water resource availability amounting to only 1/4th of the global average (Ge et al. 2011; Guan et al. 2014; Sun et al. 2017), the limited water is one of the most significant limitations of sustainable agriculture (Jiang 2015). Various studies have been evaluated in China and confirmed that water insufficiency is existent at regional, national and global level (Kummu et al. 2013; Feng et al. 2014; Zhao et al. 2016; Gain et al. 2016; Liu et al. 2017). China's agricultural water use accounts for more than 70% of the total consumption, of which 90% is used for irrigation. As of 2015, China has 331.1 million ha of water-saving irrigation area of which 65.8 million ha is agricultural irrigated farmland. The effective coefficient of agricultural irrigation water is 0.532 million ha. Compared to developed countries, China's agricultural water-saving irrigation technology is still in the initial stage of development (Chen et al. 2018). Therefore, it is important to develop effective water-saving irrigation technology to protect, save and improve the utilization of water resources.

Irrigation and water conservation infrastructure construction is a strategic measure to strengthen agricultural infrastructure, improve comprehensive agricultural production capacity, and ensure national food security. China has been promoting construction of irrigation and water conservancy facilities, especially water-saving irrigation systems, which is an important measure to manage water resources and to understand the sustainable agriculture development from a water conservation and use efficiency perspective (Zhang 2011). At present, China's water-saving agricultural areas with sprinkler irrigation and micro-drip irrigation are still relatively low as compared to Europe and the USA, and water-saving irrigation development, its popularization and application are still lagging (Fan et al. 2017). In 2014, the irrigated farmland area in China reached about 645.33 million ha, among which sprinkler and micro-irrigation area was only 7.87 million ha, accounting for 12.19%, while that of the USA, Spain and Israel was 71.7, 67 and more than 90%, respectively (Cai et al. 2017).

Numerous studies have shown that water-saving irrigation can effectively improve crop growth and development, yield and product quality (Al-Omran et al. 2013; Thind et al. 2010; Choudary et al. 2010) and economic efficiency and water use efficiency (Beyaert et al. 2007; Zhao et al. 2011; Zhao 2011). Moreover, water-saving irrigation (sprinkler, drip and furrow irrigation) can tremendously enhance soil permeability and microbial abundance (Gu et al. 2018). Many other studies focused on the effects of different water-saving irrigation practices on plant morphological, physiological, cellular/anatomical characteristics, yield and product quality (Yang et al. 2019; Yin et al. 2020; Guo et al. 2020; Xue 2020; Zhang et al. 2020). Water-saving irrigation systems play an important role in rational allocation of water resources, improvement in water resource utilization and facilitating national food security, ecological security, and sustainable development.

Worldwide, China is the third largest producer of sugarcane. In China, Guangxi Province is the largest producer of cane sugar, which produces 6.34 million tons of cane sugar, amounting to about 67% of China’s total cane productivity (Chen et al. 2020). In Guangxi, sugarcane is mostly cultivated in hilly dry land and with significant slope, low soil water conservation and fertilizer efficiency. Influenced by subtropical monsoon, the annual precipitation in sugarcane region distributes unevenly in time and space, especially in spring and autumn season, adversely affecting the plant emergence and growth, and crop yield, which severely affect sugarcane productivity. In this study, GT42, a locally bred sugarcane variety, was grown under spray, drip and no irrigation system from 2017 to 2020, and key agronomic traits, yield and economic performance were determined. The field trial was conducted in a hilly slope in Liangqi Farm of Hengxian, a typical sugarcane crop production area in Guangxi Province.

Drip and spray irrigation are still new and have had very little information in Guangxi agriculture. Drip and spray irrigation therefore need to be compared with other irrigation practices in terms of crop growth, development, yield performance and water conservation. Therefore, we conducted this drip and sprinkler irrigation systems comparative study.

Materials and Methods

Plant Material, Field Experiment and Design

Plants sugarcane variety GT42 (Saccharum spp. intergeneric hybrid) used in the present study was provided by Sugarcane Research Institute, Guangxi Academy of Agricultural Sciences, Nanning, Guangxi, China. The compound fertilizer (45% Nitrophoska produced by EuroChem and made in Belgium) and pesticide (30% Durivo produced by Syngenta) were applied in the experimental site. Drip irrigation facilities, equipment and technology were provided by Dayu Irrigation Group Co., Ltd., China. Sprinkler irrigation was established by installing traditional fixed-type sprinklers.

The field experiment was conducted in Liangqi Farm of Guangxi State Reclamation, and the experimental area was hilly, arid, and sloping land with medium content of organic matter. The experiment duration was three years from 2017 until the end of January 2020 with the trial planted in March 2017 (Table 1). Irrigation was applied according to local weather conditions. If it did not rain for 10 successive days leading to sugarcane water shortage, irrigation was applied. If it rained normally with no sugarcane water shortage, irrigation was not applied.

Table 1 Field trial planting and harvesting periods of sugarcane crop and the climatic variables during the experimental period
Full size table

Experimental Design

Plot comparison was designed with three replicates. Each experimental plot occupied 0.12 ha. Table 2 represents the irrigation design. The control was rainfed sugarcane. The three different treatments shared the same fertilizer, pesticide, and practice.

Table 2 Irrigation layout
Full size table

Measurement of Bud Germination And Tillering

At the plantlet and tillering stage, three points along the diagonal of each plot were chosen with each point of five rows and ten meters to investigate germination and tillering by surveyed three-year data which were calculated using the following equations:

$$ {\text{Germination}}\;{\text{rate}}\;\left( \% \right) = \left( {{\text{total}}\;{\text{emergence}}\;{\text{number}}/{\text{total}}\;{\text{buds}}} \right) \times 100 $$
$$ {\text{Tillering}}\;\left( \% \right) = \left( {{\text{tiller}}\;{\text{number}}/{\text{total}}\;{\text{seedlings}}} \right) \times 100. $$

Agronomic Traits and Yield Sampling

Prior to sugarcane harvest every year, three points were taken on the diagonal for each treatment, and the plant height and stem diameter of twenty sugarcane plants were measured at each point, as well as the effective stem number of each ten meters in five rows. Cane yield was measured for the three successive years at three points per treatment and six rows per treatment with a length of 9.3 m (66.66m2) for harvesting and weighing.

Data Analysis

Data were presented as the mean ± SD. One-way ANOVA was performed using SPSS17.0 statistical software.

Results

Germination and Tillering

Table 3 shows how irrigation methods affected the germination and tillering in planting crop, first and second ratoon crops. Average germination rate was recorded highest in drip irrigation treatment followed by spray irrigation and the control and all three crop classes (Table 3). However, the germination rate was not found significantly different between spray and drip irrigation treatment, but they were significantly different as compared with the control. Though the tillering rate showed a trend similar to that of germination, the difference between treatments was not significant.

Table 3 Germination and tillering rate of sugarcane plants in different irrigation treatments
Full size table

Agronomic Traits During Growth

Analysis of plant height showed that results were not significant between drip and spray irrigation treatment, but they were recorded significantly different with the control (Table 4). A similar trend was evident for millable stalk (Table 4). However, stem width among the three treatments did not vary at all (Table 4).

Table 4 Important agronomic traits of sugarcane
Full size table

Cane Yield

Drip irrigation increased cane yield by 28.46 kg/ ha compared with spray irrigation, but this variation was not significant (Table 5). However, cane yield obtained with drip and spray irrigation system was approximately 33 and 25% higher than that of control, respectively, and this difference was statistically significant (Table 5). It can be concluded that drip irrigation and spray irrigation significantly increased the sugarcane yield.

Table 5 Sugarcane yield per unit area and yield increase under different irrigation systems
Full size table

Water Use Efficiency

Irrigation was applied according to the climatic conditions. Table 6 represents the water use and water-saving rate for three consecutive years (main crop and ratoons). Water use volume was 7 and 20 ton, and annual mean water use volume per mu was 42 and 120 ton under drip and spray irrigation, respectively. Compared with spray irrigation, drip irrigation saved 78 ton of water on average annually which amounts to 65% saving of irrigation water. Drip irrigation thus greatly increased water use efficiency compared to spray irrigation.

Table 6 Water use and water-saving rate of sugarcane under different irrigation systems
Full size table

Economic Benefit Analysis

Cane yield, output value and main costs of all treatments for three years are presented in Table 7. The three-year average investment for crop production with drip and spray irrigation and rainfed condition (control) were 2773, 2604 and 2071 Yuan, respectively. The three-year mean net income per mu for crop grown with drip and spray irrigation and under rainfed condition (control) was 1141, 1087 and 882 Yuan, respectively. Analysis of variance showed no significant difference for net income between spray and drip irrigation, but with control treatment (Table 7). The drip irrigation gave an additional value of precise application compared to spraying.

Table 7 Economic benefit analysis
Full size table

Discussion

Our findings revealed that the sugarcane productivity can be significantly increased with drip and spray irrigation system. Drip irrigation was found to be far superior to spray irrigation for both income and water saving. This may be attributed to precise application of water in the root zone at much slower rate which greatly reduced water loss, thus maximizing water use efficiency. Water supply for sustainable agriculture is under increasing pressure due to growing domestic demand (Chen et al. 2018). And, further strain was imposed with the rapid development of industries, agriculture and economy. The application of water-saving irrigation technology in agriculture thus is critically important and will play an active role in saving natural water resources, reducing soil salinization, increasing crop yield and promoting agricultural economy and food security (Liu 2018). The present experiment evaluated two different water-saving irrigation methods for sugarcane production, and their effectiveness and efficiency were assessed using sugarcane bud germination rate, tillering, plant growth, crop yield, water conservation and overall economic benefit. The spring drought in Guangxi sugarcane-growing regions negatively impacts sugarcane germination under rainfed condition. Sugarcane is a water-intensive crop, and sugarcane bud germination is particularly sensitive to water deficit (Lakshmanan and Robinson 2014). Also, seasonal drought adversely affects the sugarcane growth and productivity (Basnayake et al. 2015). Since all photosynthetic responses depend on water and nutrient availability, water and nutrient stress greatly impacts physiological processes and yield of sugarcane (Inman-Bamber 2004; Natarajan et al. 2020).

Previous studies have shown that supplying water by pipeline can save 20–30% water, spray irrigation 50%, micro-irrigation 60–70%, and drip and infiltrating irrigation over 80% (Lei et al. 2004). Compared with surface irrigation, spray irrigation can save water of about 30–50%, drip irrigation 40–60% and fertilizer 30–50% (Shi et al. 2006; Li et al. 2012; Gu et al. 2017). The annual mean water use volume per ha of drip and spray irrigation was 2800 and 8000 L, respectively. Compared with spray irrigation, drip irrigation saved 5200 L of water on average annually with a water saving of 65%, which accords with the previous studies (Gunarathna et al. 2018). Developed countries did comprehensive analysis of benefits (economic and environmental benefits) of water-saving irrigation systems as part of sustainable agriculture (Song 2019). Also, compared with surface irrigation, spray irrigation can save 1/6 labor, 7–13% land and 10–20% yield increase for grain crops, 20–30% yield increase for cash crops and 100–200% yield increase for vegetables (Zhao et al. 2019). Our experiment revealed that the spray and drip irrigation can increase yield by 24.97 and 32.53%, respectively. As compared to control, drip and spray irrigation increased 2.67 and 2.12 USD of average annual net income per ha, respectively. Our study revealed the high input requirement of water-saving irrigation technology which can be an impediment for extensive adoption of this technology in agriculture. However, the economic benefits brought by this technology to agricultural development and food security have exceeded its cost input, and it is likely to be a driving factor for the sustainable agricultural crop development in the near future.

In conclusion, this study demonstrated that drip irrigation offers substantial advantage over spray irrigation for sugarcane cultivation in Guangxi Province. Drip irrigation technique is a relatively simple technology; once established, it will run for a long period of time with minimum maintenance cost and can be deployed in both smallholder and large farms with considerable economic benefit.