三江平原大豆种植的土地适宜性评价

受全球气候变化、二氧化碳施肥效应以及市场需求的影响,国内一系列旨在促进大豆种植的政策,可能导致三江平原大豆种植面积的增加。在此大背景下,充分利用当地气候条件和肥厚的土壤资源,促进农业用地的合理配置的关键问题在于对大豆种植进行土地适宜性评价。作者依据FAO/IIASA发布的GAEZ研究框架:首先根据大豆对气候、土壤的需求,对三江平原气象资料进行气候清查,评价大豆种植的气候适宜性;再考虑地形因素对气候条件的影响,使用Fourier指数和坡度条件对评价结果进行修正;然后,进行土壤清查,选取土层厚度、质地、pH、排水级与淹水情况等作为评价指标,对三江平原大豆种植进行土壤适宜性评价,并对含白浆层的各类土壤进行适宜性降级处理;最后,在栅格像元尺度上进行图层叠加,得到三江平原大豆种植的土地适宜性评价结果。另外引入了适宜度指数(S_I),对三江平原23个县市大豆种植的土地适宜度进行了空间上的比较。结果表明:(1)除了坡度大于30%的山区外,三江平原大部地区适宜大豆种植,面积达8.5×10~4 km~2,约占总面积的78.75%;(2)沿松花江、倭肯河、穆棱河等两岸的平缓(2%~5%)和微起伏(5%~8%)地区,土壤质地和排水状况良好,最适宜大豆种植;(3)勃利、依兰、汤原、佳木斯、集贤、桦川、友谊、绥滨和富锦9个县市,适宜度指数均超过70%;其次是同江、桦南、虎林、宝清、抚远、七台河、萝北、鸡东、饶河和双鸭山10个县市;鹤岗、密山、鸡西、穆棱4县市,适宜度一般;(4)GAEZ模型流程化评价方法能够在区域尺度上有效实现大豆种植适宜性的空间差异分析,为土地资源的合理配置提供科学依据。

Evaluation of agricultural land suitability for soybean cultivation in the Sanjiang Plain, Northeast China

The Sanjiang Plain is one of the most important grain production base in China. The importance of the plain could increase with the promulgation of policies that encourage farmers to cultivate soybean to adapt to the global climate change and CO2 concentration rise. In order to make full use of the advantages in climate and soil conditions, there is the need for rational allocation of soybean cultivation areas in the Sanjiang Plain. In this paper, firstly, we carried out climate suitability evaluation for the cultivation of soybean based on climate and soil inventory with the GAEZ framework of FAO/IIASA. Then, we used soil thickness, soil texture, soil pH, land drainage and flooding conditions as indicators of soil suitability evaluation and the results of the analysis were degraded by Albic bleach soil in the Sanjiang Plain. Finally, the results of the agricultural land suitability evaluation were obtained by overlapping layers in GIS at the grid scale (30 m × 30 m) and Suitability Index (SI) calculated to geospatially compare soybean cultivation in the study area. The results showed that: 1) most parts of the Sanjiang Plain was suitable for soybean cultivation, except for areas with slope≥ 30%. 2) About 8.5 × 104 km2 (78.75% of the plain) was suitable for soybean cultivation, especially gentle slope (2%-5%) and undulating slope (5%-8%) areas along the bank of Songhua, Woken and Muleng Rivers with good soil texture and high drainage. 3) Nine counties with the highest SI (≥ 70%) included Boli, Yilan, Tangyuan, Jamusi, Jixian, Huachuan, Youyi, Suibin and Fujin. Then 10 counties (Tongjiang, Huanan, Hulin, Baoqing, Fuyuan, Qitaihe, Luobei, Jidong, Raohe and Shuangyashan) had higher SI (60%-70%); Hegang, Mishan, Jixi and Muleng counties had the lowest SI (SI≤ 60%). 4) For its simple and objective evaluation procedure, the GAEZ framework was applicable in locally distinguishing spatial differences in soybean cultivation areas needed in rational land allocation.