Study on the Effect of "Crayfish-Rice Continuous Cropping" on Grain Production: A Case Study of Hubei Province

Qifei TANG

Hubei Rural Development Research Center, Yangtze University, Jingzhou 434023, China

Abstract Taking Hubei Province as an example, starting with the present situation and existing problems of grain production, this paper expounds the great significance of "crayfish-rice continuous cropping" model in improving grain quality, and analyzes the beneficial influence of "crayfish-rice continuous cropping" on grain production and the difficulties it faces. This paper also puts forward some measures and suggestions for the further popularization of "crayfish-rice continuous cropping" in order to maintain food security.

Key words Green agriculture, Crayfish-rice continuous cropping, Grain production, Hubei Province

1 Introduction

In 2019, the No.1 document of the Central Committee clearly put forward the need to stabilize grain output and further promote the high-quality grain project, gradually changing from the direction of increasing quantity to the direction of improving quality. At the present stage, China’s grain production has been out of the shackles of quantity, but the effective supply of green high-quality grain is still tight. Therefore, the exploration, demonstration and popularization of green and ecological grain production model are becoming more and more important. Hubei Province, as an important grain producing area in China, has explored the model of "crayfish-rice continuous cropping" by virtue of its excellent natural conditions and long planting history. In 2017, the comprehensive planting and breeding area of rice and fishing in Hubei Province reached 4.168 2 million mu. In 2018, A Three-Year Action Plan for the Promotion of "Crayfish-Rice Cropping and Rice-Fish Cropping and Raising" model was issued in Hubei Province. In 2019, the three-dimensional agricultural model of "crayfish-rice continuous cropping" was further popularized. Hubei Province will build 7 million mu of rice-fish comprehensive cropping and raising area along the river and lake area, but the deepening development of "crayfish-rice continuous cropping" model still faces obstacles. In this regard, against a backdrop of vigorously promoting green ecological agriculture, it is of great practical significance to explore the impact of "crayfish-rice continuous cropping" on grain production.

2 Present situation and problems of grain production

2.1 Status of productionHubei Province, as one of the 13 main grain producing areas in China, plays an important role in grain production. On the one hand, the total grain output, sown area and unit yield level in Hubei Province are showing a good development trend. The total grain output has increased year after year, with a bumper harvest of 28.39 million t in 2018. The sown area of grain has risen steadily, rising steadily with an increase of about 2.35% in the past decade. In addition, the per unit yield of grain production has also gradually increased, from 5 657.09 kg/ha in 2004 to 5 864 kg/ha in 2017, which is basically higher than the national average grain yield[1]. On the other hand, Hubei Province established "High-Quality Grain Project" in 2017 and implemented green and efficient agricultural models such as "crayfish-rice continuous cropping" and "semilate rice-ratooning rice-green manure". The proportion of planting area and yield of high-quality grain has been increasing. The rate of high-quality grain products has been achieved by more than 30%, and the quality of grain production has been improved.

2.2 ProblemsAlthough the absolute quantity of grain production in Hubei Province is considerable, the status of grain production in the whole country has gradually declined, from the ninth place in 2004 to the 11th place in 2018. The extensive use of pesticides and chemical fertilizers has a direct impact on the quality of grain. Pesticide use in Hubei Province reached a maximum of 140 000 t in 2010, and then showed a decreasing trend, but it still reached 110 000 t in 2017. Fertilizer use reached a peak of 3.549 million t in 2011 and began to decline year by year in 2013, but it was still as high as 3.179 3 million t in 2017. The proportion of the samples with all indexes up to the national standard grade 3 of "High Quality Rice" is low (Table 1), and there is still a lot of room to improve the quality of grain production.

Table 1 The proportion of rice in Hubei Province up to the national standard from 2014 to 2018 %

Data source: Report on the Quality of Harvested Grain from 2014 to 2018 by Hubei Provincial Grain Bureau.

The rate of early indica rice meeting the national standard of "High Quality Rice" is low, and the growth rate is slow. Although the percent of pass of middle and late indica rice increased greatly in 2018 driven by the "High Quality Grain Project" in Hubei Province, only half of the samples reached the national standard. This shows that the quality of grain production in Hubei Province needs to be further improved. Therefore, it has become an important part of maintaining food security to speed up the transformation and upgrading of traditional paddy field agriculture, strengthen green prevention and control, and realize the negative growth of chemical fertilizer and pesticide application.

3 Effect of "crayfish-rice continuous cropping" on grain production

3.1 Basic model of "crayfish-rice continuous cropping"Crayfish-rice continuous cropping is a three-dimensional ecological agriculture model of comprehensive planting and cultivation in rice field. Under this model, it makes full use of rice field resources during rice planting, rice planting and crayfish culture are combined organically, to realize the co-growth and synchronous yield increase of crayfish and rice, and improve the product quality at the same time. At the same time, the mode of combination of planting and raising realizes the improvement of rice quality and multiple cropping index of rice field, increases the output of land per unit area, broadens the channels of increasing farmers’ income, and stimulates farmers’ enthusiasm for growing grain. With its outstanding ecological and economic benefits, "crayfish-rice continuous cropping" is showing a momentum of vigorous development.

3.2 Effect of "crayfish-rice continuous cropping" on grain production

3.2.1Improving the ecological environment of rice fields and improving the quality of rice from the root. Crayfish-rice continuous cropping can effectively reduce the use of pesticides and chemical fertilizers, reduce agricultural non-point source pollution, and restore the ecology of rice fields. Crayfish sensitivity to pesticides determines that the safe pesticides, or biological pesticides become the only choice. And crayfish has strict requirements for the type and quantity of chemical fertilizer applied in rice fields, which greatly reduces the demand for traditional pesticides and chemical fertilizers. At the same time, the crayfish moves in the paddy field, and forages for food, which can help the paddy field to loosen and aerate the soil. Crayfish feeds on wild weeds and aquatic organisms that consume fertilizer in the field, which reduces the intervention of artificial weeding, insect removal and rice field control in the ecological environment of rice field, and gives full play to the function of ecological self-regulation of rice field. In addition, the rice stalks can also act as feed for the crayfish, and the rice stalks can be returned to the field to provide food resources for the growth of crayfish. This also avoids straw burning, reduces the damage of high temperature to paddy field organic matter, and reduces air pollution. Crayfish can realize weeding, loosening soil, fertilizing for rice field, and rice can provide bait, shade and avoid harm for crayfish. This follows the natural law of interdependence between animals and plants, creates the ecological environment of symbiosis and co-breeding of rice and crayfish, promotes the virtuous cycle of materials in rice field ecosystem, and achieves the purpose of protecting and repairing rice field ecology.

3.2.2Biological fertilizer retention to increase the organic nature of rice. From fry to maturity of crayfish, the metabolic process discharges a large number of feces to be as a natural fertilizer for rice, which not only plays the effect of increasing fertilizer, but also ensures the organic nature of crayfish-rice. During the rice growing season, crayfish constantly feeds on plankton and weeds as well as benthos in rice fields. Its food intake and fecal discharge increase day by day, and fertilizer nutrients are accumulated to ensure the nutrition needed for rice growth. In the free season of rice, crayfish feeds on pellet feed and other baits, the manure is accumulated in the rice field to enrich the nitrogen and phosphorus in the rice field, which is the source of rice fertilizer in the next season. Secondly, crayfish can also effectively maintain fertilizer. Crayfish-rice continuous cropping can effectively reduce the growth rate of weeds, and the amount of weed in rice fields without crayfish is 13 to 15 times as much as that in rice fields with crayfish[2]. Crayfish can effectively reduce the competition of weeds for fertilizer and ensure the effective supply of fertilizer in rice fields. In addition, the return of rice straw to the field in order to feed the crayfish also plays an obvious role in increasing the soil fertility of rice field and increasing the content of soil organic matter.

3.2.3Biological measures to control diseases and pests to ensure the green ecology of rice. The density ofChironomuslarvae and larvae of other insects in and near the rice field with "crayfish-rice continuous cropping system" can be reduced by at least 50%, and the density of adult mosquitoes will also decrease by 15%, which can effectively control diseases and pests in rice field[2]. Crayfish-rice continuous cropping can greatly reduce the number of pests. During crayfish culture,Chilosuppressalis,Sesamiainferensand other pests, which live in rice straw, are killed by water or eaten by crayfish. At the same time, crayfish can not only feed on weeds and grass seeds in the field, but also remove rice leaves, ensure aeration between rice plants, prevent the spread or outbreak of rice blast and other diseases in high temperature and humidity weather, and promote the healthy growth of rice plants.

Crayfish-rice continuous cropping embodies the principle of adjusting measures to local conditions, makes rational use of land, light, temperature, water and other natural resources, and improves the matching degree of grain production, crayfish culture and resources and environment. The idea of modern agricultural development with sustainable growth of agricultural benefits has been realized. However, "crayfish-rice continuous cropping" will affect the rice yield to a certain extent. Different from the traditional rice planting mode which relies too much on pesticides and chemical fertilizers to increase the yield of rice, the yield of rice which mainly depends on organic fertilizer has been reduced. In addition, "crayfish-rice continuous cropping" generally requires that a circular crayfish ditch with a width of 5 m and a depth of 1.5 m should be dug along the ridge of rice field, which will occupy part of the planting area of rice.

3.3 Predicament faced by "crayfish-rice continuous cropping"

3.3.1Difficulty in achieving a good price. It is difficult to achieve good price of ecologically organic crayfish-rice. The first reason is that the price policy is unreasonable. The current minimum purchase policy of rice is only based on the water content and impurity content of rice to establish the minimum purchase price of three kinds of rice varieties. For example, the minimum purchase prices of early indica rice, middle and late indica rice and japonica rice announced in 2019 were 120, 126 and 130 yuan per 50 kg, respectively. There is a lack of systematic requirements for the taste and quality of rice itself, and it does not reflect the price difference of rice with different quality grades. Because the quality standard of the minimum purchase price policy of rice is not perfect, and the current minimum purchase price of rice still has a strong orientation to the market price, farmers are more inclined to plant low-quality and high-yield rice. This leads to different quality of rice mixed together at the time of acquisition, unable to achieve high quality and high price. Second, information asymmetry leads to adverse selection. The characteristics of credit products are the distinct characteristics of green agricultural products, but the "crayfish-rice" indication system, certification system and other information transmission mechanisms as well as special marketing channels are not yet perfect. As a result, it is difficult for consumers to effectively judge the quality characteristics of pesticide, hormone and antibiotic residues before and after buying crayfish rice, which leads to information asymmetry and market failure.

Consumers will hold down prices to avoid possible losses caused by information asymmetry. Third, there are many varieties of "crayfish-rice", which is difficult to carry out unified standardized processing, and the quality of rice is difficult to improve, which greatly affects the market competitiveness. Crayfish-rice co-cropping comes from the summary of farmers’ rice production experience, and farmers choose rice varieties according to the yield, so it is difficult to avoid following the herd and blindness. The finally emerging "crayfish-rice" varieties are diversified, but there are few high quality rice varieties suitable for "crayfish-rice co-cropping". In the end, the variety affects the selling price.

3.3.2The high input in the early stage restricting the development of "crayfish-rice continuous cropping". Crayfish-rice continuous cropping must first carry out the transformation to the traditional rice field, including a series of field construction projects such as the ridge widening, heightening, strengthening, setting up filtering facilities at the inlet and outlet, excavating circular ditches, field ditches, and installing sunshade sheds. Second, "crayfish-rice continuous cropping" has higher requirements for lodging resistance and rice quality, and the selection of rice varieties is much stricter. In addition, "crayfish-rice continuous cropping" needs to have a certain scale, the area is generally 2 to 3.33 ha as a culture unit, and it is larger in some areas, needing land to be able to transfer effectively. Therefore, the early investment includes rice field transformation cost, high quality crayfish fry and rice seedling cost, land contract fee, labor cost and so on. Given that the current agricultural loans are limited and the agricultural insurance system is not perfect, the ordinary farmers neither have sufficient sources of funds, nor have ability to bear the risk.

3.3.3Transfer of focus of farmers and "non-grain conversion" of cultivated land. As crayfish prices have continued to rise in recent years, 80% of the income from "crayfish-rice continuous cropping" comes from crayfish. As a rational economic man, driven by comparative benefits, farmers pay more attention to "crayfish" than "rice". That is, farmers focus more on crayfish raising while neglecting the management of rice. In some areas, the ditch area exceeds the standard during the field transformation, and the rice is only used as an auxiliary tool for raising crayfish, and even a small number of individuals only raise crayfish and do not grow rice, leading to the tendency of "non-grain conversion" of cultivated land.

4 Actively developing "crayfish-rice continuous cropping" to maintain food security

4.1 Improving the quality assessment system and gradually reducing the minimum purchase priceIt is necessary to gradually improve and perfect the quality standards for the taste and quality of rice purchased, and at the same time adjust the minimum purchase price reasonably and dynamically according to the situation of grain supply and demand at home and abroad, send a clear signal of grain reform to the society, let the market play fully and form the mainstream price of grain from the market, guide farmers to scientifically adjust the planting structure, greatly expand the planting proportion of high-quality grain, and abolish the minimum purchase price when the conditions are mature. It is also necessary to promote the transformation from policy-oriented collection and storage to market-oriented acquisition under the guidance of the government, and establish a market operation mechanism for high quality grain and good grain prices.

4.2 Further creating and improving the "crayfish-rice" brand and strengthening promotion and maintenanceBrand is an effective means to solve information asymmetry, establish product credit in the hearts of consumers and expand the market. With the promotion of brand awareness, "Qianjiang crayfish-rice" has been formed in the construction of high quality grain project in Hubei Province[3]. Therefore, it is urgent to further create and perfect the "crayfish-rice" brand, give full play to the diffusion effect and aggregation effect of the brand, and do a good job of unified publicity, promotion and maintenance. A good brand is based on good quality. First of all, the local government should unify the production standards, testing standards and circulation standards of "crayfish-rice" to provide the basic guarantee for brand construction and maintenance. Second, the local government should strengthen the market management of "crayfish-rice", redesign and unify the logo of crayfish-rice, authorize its use in strict accordance with the standards, and strengthen practical supervision and inspection, and severely crack down on counterfeiting or entering the market in violation of regulatory norms. Third, the local government should uniformly establish a perfect crayfish-rice quality traceable information system from the field to the table, and force the operators of "crayfish-rice continuous cropping" to carry out production and management in accordance with the requirements and standards of crayfish-rice brands.

4.3 Uniform specification of rice varieties for "crayfish-rice continuous cropping"The agricultural departments should be based on the national high-quality grain standards, combined with the rice quality of different varieties produced in the practice of "crayfish-rice continuous cropping" in recent years, to issue a notice on the main varieties of rice in the area of "crayfish-rice continuous cropping". At the same time, it is necessary to strengthen the supervision of the rice seed market, the seed sales should go through the filing procedures, and there is a need to establish a seed production and management record system, promote seed enterprises and seed dealers to abide by the law, and expand the coverage of high-quality rice varieties.

4.4 Innovating ways of supporting agriculture and perfecting the agricultural insurance systemFirst, it is necessary to promote financial innovation in supporting agriculture, encourage and guide finance to actively carry out financing businesses such as factory building mortgages and deposit, orders, and accounts receivable, and innovate new varieties, new cycles, and new ways of loans through multi-party linking, so as to promote inclusive finance and improve the level of supporting agriculture. Second, it is necessary to promote agricultural insurance innovation, scientific and rational planning and dynamic flexible adjustment of the proportion of the three main bodies of the government, projects and new entities, innovate insurance types, expand coverage, and increase the amount of compensation. Third, it is necessary to promote the innovation of reward and subsidy policies, implement the policies of replacing compensation with awards, building before compensation, and combining awards with compensation for agricultural products with local characteristics, appropriately increase the intensity of financial support, and promote agricultural insurance to expand, raise standards, and increase quality. During the period of investment in infrastructure and equipment by high-quality grain enterprises, it is necessary to subsidize part of the financial funds in advance and increase the support of financial funds to grain enterprises.

4.5 Accelerating land transfer and actively developing order agricultureFarmers and agricultural cooperatives, agricultural enterprises or other organizations sign relevant contracts. Production is guided by relevant organizations, the production services are provided, and the specific production process is carried out by farmers. After the formation of large-scale planting, farmers can rely on relevant organizations to achieve scientific seed selection according to market demand. It is necessary to apply fertilizer scientifically according to soil testing formula, scientifically carry out the prevention and control of diseases and pests, promote and gradually popularize high-quality grain production, reduce costs, enhance competitiveness, and improve the efficiency of grain production.