1302 Bulgarian Journal of Agricultural Science, 20 (No 6) 2014, 1302-1310 Agricultural Academy UTILIZATION OF CROP STRAW RESOURCES IN ANHUI PROVINCE, EASTERN CHINA YIRU YANG1,3, XINGXIANG WANG1, TAOLIN ZHANG1,3 and DECHENG LI2* 1 Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, P. R. China 2 State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, P. R. China 3 University of Chinese Academy of Sciences, Beijing 100049, P. R. China Abstract YIRU YANG, XINGXIANG WANG, TAOLIN ZHANG and DECHENG LI, 2014. Utilization of crop straw resources in Anhui Province, Eastern China. Bulg. J. Agric. Sci., 20: 1302-1310 Returning straw to fields is one of the most effective ways of maintaining and improving soil fertility. However, straw burning is a recurring phenomenon in China. To better understand the current situation facing the utilization of straw resourc- es in Anhui Province, a total of 731 typical fields and farmers were surveyed on a provincial scale in 2011 along a national highway, provincial highway and county road. Moreover, a total of 344 fields and farmers were surveyed on a county scale in three typical counties, i.e., Mengcheng County, Dingyuan County and Xuanzhou District. The average rates of straw return- ing were generally low in Anhui Province, with 30.2% for single-middle-season rice, 16.1% for early rice, 14.3% for wheat, 2.9% for rape, 1.8% for late rice and 1.8% for maize, respectively. The average return rate of wheat in the three typical counties was 13.2%, lower than the rates of the entire province; however, the return rates of other crops in the counties were all higher than those of the entire province. However, straw burning was still prevalent. The average rates of burning wheat, rape and maize straw reached 65.5%, 75.8% and 57.3% on the provincial scale, respectively, and 86.0%, 64.0% and 51.3% in the three typical counties, respectively. Only a small fraction of straw was utilized in traditional ways, adhering to the following order: household fuel>fodder>industrial raw material. Therefore, it is crucial to strengthen policy regarding the prohibition of straw burning and to enhance straw returning and the comprehensive utilization of straw resources. Key words: Anhui; stubble; straw burning; straw returning; straw resource utilization Introduction From 1995 to 2005, approximately 630 million tons of crop straws was produced in China per year, with 50% com- The residues remaining after wheat, rice, maize, yam, ing from eastern and south-central China (Liu et al., 2008). rape, cotton, sugarcane and other crops are harvested are Anhui Province, a typical agricultural province, is located generally called crop straws. Nitrogen, phosphorus, potas- in eastern China. The arable area in Anhui was 4.184 × 106 sium, magnesium, calcium and other major nutrient elements ha at the end of 2011, covering 30% of the total land area. and organic matter in crop straws can improve soil fertility The sown area of grain crops was 6.621 × 106 ha, and the to- and are necessary for crop growth (Wang et al., 2005). Straws tal grain output reached 31.355 × 106 tons (Statistics Bureau are multipurpose and precious renewable biomass resources of Anhui Province, 2012). The province features rich straw (Zhou et al., 2011). Returning straw to fields can increase the resources, dominated by rice, wheat, maize, rape, cotton, amount of soil organic matter and the carbon sequestration beans, melon and yam (Ruan et al., 2002). Anhui Province potential of farmland soil, which cannot only increase grain can be divided into several districts according to topogra- yield but also promote the sustainable utilization of cultivated phy: 1) a plain on the northern bank of the Huai River and land (Hendrix et al., 1998). an area along the Huai River in northern Anhui, which is *E-mail: [email protected]; [email protected] Utilization of Crop Straw Resources in Anhui Province, Eastern China 1303 mainly used for wheat-maize rotation; 2) a hilly terrain be- an on-site survey and consulting with local farmers; a total tween the Yangtze and Huai Rivers in central Anhui, which of 731 farmers and their farmlands were investigated. In the is mainly used for wheat-rice rotation; 3) mountainous areas second case, three typical regions, Mengcheng County in the in western Anhui; 4) a plain along the Yangtze River; and plain on the northern bank of the Huai River in northern An- 5) a low mountainous and hilly region in southern Anhui, hui, Dingyuan County in the hilly terrain between the Yang- which is mainly used for early rice/rape – late rice rotation. tze and Huai Rivers in central Anhui and Xuanzhou District Thus, rice and rape straws are mainly distributed in the hilly in the low mountainous and hilly region in southern Anhui, terrain between the Yangtze and Huai Rivers and the plain were chosen for a more detailed survey on straw utilization, along the Yangtze River, whereas wheat and maize straws and a total of 344 farmers and their farmlands were investi- are mainly distributed over the plain on the northern bank of gated. The spatial distribution of the investigated fields in the the Huai River (Xu and Wu, 2009). Along with the accelerat- province and three typical counties is shown in Figure 1. ing progress of agricultural modernization, rural labor trans- fer, structural changes in energy consumption and outdated Time of the investigation comprehensive utilization techniques have caused straws to Wheat straw throughout the entire province and rape become relatively overproduced and burnt out in the open straw in the plain along the Yangtze River, in the hilly terrain (Zárate et al., 2000) or discarded. Survey data collected in between the Yangtze and Huai Rivers in central Anhui and in 2008 regarding agricultural pollutant sources in Anhui Prov- the low mountainous and hilly region in southern Anhui were ince indicate that of the 40 million tons of straw resources, investigated in early June 2011. Early rice straw in these areas approximately 50% was returned to fields, 40% was burned was investigated in late July. Single-middle-season rice straw at random, 29% was used for fuel, 10% was used for fodder, throughout the entire province and maize and soybean straw compost or industrial raw materials and approximately 45% in the plain on the northern bank of the Huai River in north- was not used effectively (Tao and Wei, 2010). In recent years, ern Anhui were investigated in late September. The late rice governments at all levels have frequently issued many man- straw in the plain along the Yangtze River, in the hilly terrain dates to prohibit straw burning at random, advocating straw between the Yangtze and Huai Rivers in central Anhui and in returning and comprehensive utilization (Standing Commit- the low mountainous and hilly region in southern Anhui were tee of the National People’s Congress, 2005). Straw burning investigated in late October 2011. and discarding at random may be controlled to some extent in some areas. However, the rate at which straw decomposes is slower, which affects the planting and management of the next crop. Due to the unsatisfactory feasibility and operabil- ity of the current techniques and supporting policies for the comprehensive utilization of straws, straw burning at random is still prevalent in some regions. However, in China, information provided in reports re- garding straw utilization currently entails only rough esti- mates. Thus, to more accurately evaluate the utilization of straw resources in eastern China, in 2011, we selected An- hui Province as a representative of the agricultural regions of eastern China and surveyed the current utilization of main crop straw resources in the area. Materials and Methods Method of field survey Information regarding straw utilization was obtained on two scales, a provincial scale and a county scale. In the first case, data regarding crop stubble height, straw burning, straw returning and the comprehensive utilization of straw throughout Anhui Province were obtained along a national highway, provincial highway and county road by conducting Fig. 1. Spatial distribution of the investigated fields 1304 Yiru Yang, Xingxiang Wang, Taolin Zhang and Decheng Li Method of the investigation using ArcGIS 9.3 Desktop (ESRI, USA, 2008). The propor- Straw refers to what remains, except for roots and stubble, tions of straw burning, straw returning and other uses of vari- after crops are harvested. The utilization of straws is classi- ous crops in different regions were calculated from the weight- fied into the following activities: 1) straw burning, 2) straw ed averages of all sampling fields or farmers in the region. returning and 3) the removal of straw outside of a field for other uses, for example, as fuel or fodder. Straw returning re- Results fers to the act of returning straw directly to the original field, including straw mulching and turning over. Straw and stub- Stubble height ble burning in fields are excluded from straw returning and The average stubble heights of maize and soybean were 7.8 are classified as straw burning. The stubble height is the av- cm and 11.3 cm, respectively, on the provincial scale (Tables 1 erage height of 10-15 stubbles chosen at random in a field; it and 2), whereas the average stubble heights of maize and soy- is measured on site with a ruler. In this study, straw burning, bean were 12.6 cm and 4.8 cm, respectively, in the three typi- returning and other uses were investigated by conducting an cal regions, all of which were within the quality standard (15 on-site survey in the fields of Anhui Province and consulting cm) for agricultural machinery.