Spatio-temporal variations of wheat, rice and maize straw in major grain-producing counties of Anhui Province and utilization potential of straw nutrient returning to field

Abstract: Anhui Province of China is one of the most important agricultural production bases with abundant grain crop straw resources. It is necessary to clarify the temporal and regional characteristics of theoretical and crop residues for the differentiated development of fully quantitative utilization in straw sources in major grain-producing counties. Accurate evaluation of utilization potential to straw nutrient resources can essentially contribute to balancing the regulation of soil nutrients under straw returning. In this study, a systematic investigation was made on the spatiotemporal variation of wheat, rice and maize straw in major grain-producing counties of Anhui Province and utilization potential of a straw nutrient return to the field. The result showed that the total output of straw resources presented a slowly rising trend from 2011 to 2019. However, the straw production during 2011-2019 presented significant differences among three major grain crops, where the wheat straw firstly increased and then remained stable, while the rice straw was relatively stable with small fluctuation, and the maize straw showed an outstanding ascending. The theoretical amount of three main grain crop straws were 38.78 million tons in 2019, among which the wheat, rice, and maize straws accounted for 47.3%, 36.3%, and 16.4%, respectively. The wheat straw (73.0%) and maize straw (88.3%) were mainly concentrated in the North area of the Huai River. The rice straw was mainly distributed in the area between the Yangtze and the Huai River (41.7%), Western Anhui Province (21.3%), and the edge area of the Yangtze River (19.7%). The distribution of total straw yields from the three main grain crops in different agricultural areas was ranked as follows: North area of the Huai River (52.5%) ? Area between the Yangtze and the Huai River (24.3%) ? Western Anhui Province (10.5%) ? Edge area of the Yangtze River (9.1%) ? Southern Anhui Province (3.6%). The straw resources in 2019 were 13.38, 10.41, and 5.42 million tons for wheat, rice, and maize, respectively. The straw resources per unit sown area in the north area of the Huai River of Anhui Province were 4 505-6 310 and 4 171-5 395 kg/hm2 for wheat and maize, respectively. The rice straw per unit sown area were 4 487-5 326, 4 570-5 028, and 4 329-5 778 kg/hm2 for the Area between the Yangtze and the Huai River, Western Anhui Province and the Edge area of the Yangtze River, respectively. Furthermore, the contents of N, P2O5, and K2O were 0.253, 0.109, and 0.901 million tons, respectively, for the main grain crop straws in 2019. In the North area of Huai River of Anhui province, the nutrient inputs by wheat straw incorporation were N 35.8-50.1, P2O5 14.1-19.8, and K2O 139.8-195.8 kg/hm2, respectively, and the nutrient inputs under maize straw return scenario were N 42.7-55.2, P2O5 16.9-21.8 and K2O 93.4-120.9 kg/hm2, respectively. In the primary rice-growing regions (Area between the Yangtze and the Huai River, Western Anhui Province, and Edge area of the Yangtze River), the soil nutrient inputs from rice straw incorporation were N 38.0-50.8, P2O5 18.8-25.0, and K2O 151.6-202.3 kg/hm2, respectively. The finding can offer a great practical significance to improve the comprehensive utilization rate of straw resources, and further promote the green and high-quality development of agriculture for major grain-producing counties in Anhui Province of China.