Study On Temporal&Spatial Variation And Fluctuation Of Rice Production In Yangzhou City Since1978

Rice is the most important grain crop in Jiangsu Province, which plays an important role in ensuring food security. As one of the major rice-producing areas in Jiangsu Province, great temporal and spatial changes have taken place in terms of rice acreage, unit yield and total output in Yangzhou since reform and opening up. The temporal and spatial variation and the fluctuation of rice production and influencing factors in Yangzhou from1978to2011were studied by combining qualitative and quantitative analysis methods, suggestions for sustainable development of rice production were put forward. The main results are as follows:(1) Since1978, rice production in Yangzhou experienced increasing, wandering and recuperative periods according to the changes in rice total output. Although rice acreage in Yangzhou was in the upper reaches of province-controlled cities sorting, because the unit yield was lower than the province’s average, leading to rice total output was in the middle reaches of the province-controlled cities sorting. Changes of rice production in Yangzhou were consistent with trends of Jiangsu Province.(2) Since entering the new century, dominance of Indica rice in rice production was replaced by that of Japonica rice. Japonica rice was in dominant position in the leading rice-producing counties in Yangzhou, such as Baoying, Gaoyou and Jiangdu. Although Japonica rice acreage was increased recently, Indica rice occupied the leading position of rice production in Yizheng, resulting in lower unit yield.(3) Analyzed by H-P filter, it was found that the long-term fluctuation of rice total output was about11to12years. Short-term fluctuations analysis indicated that there were seven cycles of fluctuation, including strong and medium amplitude type, long and short expansion type. The continuous decline trend in rice acreage for more than10years was reversed in1998in Baoying, where total output was raised fast with increase in unit yield. Although a fluctuation in rice acreage was strongest, unit yield was obviously hit by natural disasters, total output was steadied and raised in Gaoyou. The acreage decline was under control and stabilized, unit yield was restored to a higher level in Jiangdu. The potential of rice total output growth was not very optimistic because unit yield stayed at7000kg/ha for a long term, and rice acreage was decreased every year in Yizheng. Possible decline would occurred after a period of stagnation in total output in Hanjiang, with decline of rice acreage and unit yield stability as the main character and smallest rice acreage in Yangzhou. Correlation analysis showed that rice total output in Yangzhou was largely affected by that in Gaoyou, Baoying and Jiangdu.(4) Wavelet analysis showed that there was more obvious cyclical regularity in4-year,12-year and15-year characteristic time-scale in rice production in Yangzhou, consistent with result of the H-P filter analysis. It was found that variation of rice production in Yangzhou in the new century is very similar to that in1980s by comprehensive analysis, indicating that increase of rice total output would get less,and decrease of rice total output would occur.(5) The increase of rice total output was largely owing to the growth of rice unit yield, while the reduction of rice total output was mainly due to the decline of rice acreage in Yangzhou in recent30years. The proportion of rice acreage to arable land was a major factor affecting change of rice acreage. Baoying, Gaoyou and Jiangdu used to be growth pole in rice total output in Yangzhou, growth potential in Yizheng yet to be developed, and rice acreage would decline in the future. Indica rice unit yield changed more frequently than that of Japonica rice, and both Indica rice and Japonica rice had unit yield enhancing potential in Yangzhou.Based on the above results, related suggestions on stabling rice acreage, increasing rice unit yield, coordinating rice production in different counties, establishing early warning and preventive mechanism were put forward to realize sustainable development of rice production in Yangzhou.